the structure of concrete -definitions -significance -complexities -structure of the aggregate phase...
TRANSCRIPT
The Structure of Concrete
-DEFINITIONS
-SIGNIFICANCE
-COMPLEXITIES
-STRUCTURE OF THE AGGREGATE PHASE
-STRUCTURE OF HYDRATED CEMENT PASTE
-TRANSITION ZONE IN CONCRETE
-Siddharth shankar
22
DEFINITIONS The type amount size shape and distribution of phases
present in a solid constitute its structure
The gross elements of the structure of a material can readily be
seen whereas the finer elements are usually resolved with the
help of a microscope
The term macrostructure is generally used for the gross
structure visible to the human eye
The limit of resolution of the unaided human eye is
approximately one-fifth of a millimiter (200 μm)
The term microstructure is used for the microscopically
magnified portion of a macrostructure
Modern electron microscopes
The magnification capability of modern
electron microscopes is of the order of 105
times thus the application of transmission
and scanning electron microscopy
techniques has made it possible to resolve
the structure of materials to a fraction of a
micrometer
SIGNIFICANCE
Progress in the field of materials has
resulted primarily from recognition of the
principle that the properties of a material
originate from its internal structure
The properties can be modified by making
suitable changes in the structure of a
material
COMPLEXITIES
From examination of a cross section of concrete the
two phases that can easily be distinguished are
aggregate particles of varying size and shape and
the binding medium composed of an incoherent
mass of the hydrated cement paste (henceforth
abbreviated hcp)
Macroscopic level
At the macroscopic level therefore concrete may be
considered to be a two-phase material consisting of
aggregate particles dispersed in a matrix of the
cement paste
Microscopic level
At the microscopic level the complexities of the
concrete structure begin to show up It becomes
obvious that the two phases of the structure are
neither homogeneously distributed with respect to
each other nor are they themselves homogeneous
For instance in some areas the hcp mass appears
to be as dense as the aggregate while in others it is
highly porous
(a) 結構之示意圖 (b) 各組成所佔有體積之比例關係
混凝土之微結構
9
Three-phase theory
Three phases ndash Aggregate ndash Hardened cement paste (hcp) ndash Transition (interface) zone1048711
THREE PHASES OF CONCRETE
STRUCTURE OF THE AGGREGATE PHASE
AGGREGATE PHASE
The aggregate phase is predominantly responsible for the unit weight elastic modulus and dimensional stability of concrete
These properties of concrete depend to a large extent on the bulk density and strength of the aggregate which in turn are determined by the physical rather than chemical characteristics of the aggregate structure
In other words the chemical or mineralogical composition of the solid phases in aggregate is usually less important than the physical characteristics such as the volume size and distribution of pores
Aggregate particles
Natural gravel has a rounded shape and a smooth surface texture
Crushed rocks have a rough texture depending on the rock type and the choice of crushing equipment the crushed aggregate may contain a considerable proportion of fault or elongated particles which adversely affect many properties of concrete
Lightweight aggregate particles from pumice which is highly cellular are also angular and have a rough texture but those from expanded clay or shale are generally rounded and smooth
STRUCTURE OF HYDRATED CEMENT PASTE
Anhydrous portland cement is a gray powder that consists of angular particles typically in the size range 1 to 50 μm
It is produced by pulverizing a clinker with a small amount of calcium sulfate the clinker being a heterogeneous mixture of several minerals produced by high temperature reactions between calcium oxide and silica alumina and iron oxide
STRUCTURE OF HYDRATED CEMENT PASTE
The chemical composition of the principal
clinker minerals coresponds approximately
to C3S C2S C3A and C4AF in ordinary
portland cement their respective amounts
usually range between 45 and 60 15 and 30
6 and 12 and 6 and 8 percent
Setting ndash Solidification of the plastic cement paste
bullInitial set ndash beginning of solidification ndash Paste become unworkable ndash loss in consistency - not lt 45 min
bullFinal set ndash Time taken to solidify completely ndash Not gt 375min
Hardening ndash Strength gain with time ndash after final set
Hydration process
Crystal formation of Cement
Calcium silicate hydrate
The calcium silicate hydrate phase abbreviated C-S-
H makes up 50 to 60 percent of the volume of solids
in a completely hydrated portland cement paste and
is therefore the most important in determining the
properties of the paste
The fact that the term C-S-H is hyphenated signifies
that C-S-H is not a well-defined compound the CS
ratio varies between 15 to 20 and the structural
water content varies even more
Calcium silicate hydrate
The morphology of C-S-H also varies from poorly crystalline fibers to reticular network Due to their colloidal dimensions and a tendency to cluster C-S-H crystals could only be resolved with the advent of electron microscopy
Although the exact structure of C-S-H is not known several models have been proposed to explain the properties of the materials According to the Powers-Brunauer model the material has a layer structure with a very high surface area
Calcium hydroxide
Calcium hydroxide crystals (also called portlandite)
constitute 20 to 25 percent of the volume of solids in
the hydrated paste In contrast to the C-S-H the
calcium hydroxide is a compound with a definite
stoichiometry 化學計量學 Ca(OH)2
It tends to form large crystals with a distinctive
hexagonal-prism morphology The morphology usually
varies from nondescript to stacks of large plates and
is affected by the available space temperature of
hydration and impurities present in the system
Calcium hydroxide
Compared with C-S-H the strength-contributing
potential of calcium hydroxide due to van der Waals
forces is limited as a result of a considerably lower
surface area
Also the presence of a considerable amount of
calcium hydroxide in hydrated portland cement has
an adverse effect on chemical durability to acidic
solutions because of the higher solubility of calcium
hydroxide than C-S-H
Mono-Sulfoaluminate hellip Ettringite
Ettringite
Calcium sulfoaluminates
Calcium sulfoaluminate compounds occupy 15 to 20
percent of the solids volume in the hydrated paste
and therefore play only a minor role in the structure-
property relationships
It has already been stated that during the early
stages of hydration the sulfatealumina ionic ratio of
the solution phase generally favors the formation of
trisulfate hydrate C6AS3H32 also called ettringite
which forms needle-shaped prismatic crystals
Reaction rate C3A gt C3S gt C4AF gtC2S
Heat of hydration (Calg)
Compound 3 days 90 days 13 years
C3S 58 104 122
C2S 12 42 59
C3A 212 311 324
C4AF 69 98 102
Three-phase theory-Transition zone
Three-phase theory-Transition zone
A thin shell layer (10-50 μm thick) around large aggregate
Formation Water films around large aggregate during mixing
Characteristic Larger CH crystals more porous framework relatively weak1048711 1048711
Transition Zone
Miexhta and Monteiro Concrete
Transition zone -Influence on concrete properties
Fraction of transition zone in size is much smaller than other two phases its influence on concrete properties is far greater ndash It lower the strength ndash It increase the permeability ndash It prompt non-linear behavior ndash It favorites crack formation
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-
DEFINITIONS The type amount size shape and distribution of phases
present in a solid constitute its structure
The gross elements of the structure of a material can readily be
seen whereas the finer elements are usually resolved with the
help of a microscope
The term macrostructure is generally used for the gross
structure visible to the human eye
The limit of resolution of the unaided human eye is
approximately one-fifth of a millimiter (200 μm)
The term microstructure is used for the microscopically
magnified portion of a macrostructure
Modern electron microscopes
The magnification capability of modern
electron microscopes is of the order of 105
times thus the application of transmission
and scanning electron microscopy
techniques has made it possible to resolve
the structure of materials to a fraction of a
micrometer
SIGNIFICANCE
Progress in the field of materials has
resulted primarily from recognition of the
principle that the properties of a material
originate from its internal structure
The properties can be modified by making
suitable changes in the structure of a
material
COMPLEXITIES
From examination of a cross section of concrete the
two phases that can easily be distinguished are
aggregate particles of varying size and shape and
the binding medium composed of an incoherent
mass of the hydrated cement paste (henceforth
abbreviated hcp)
Macroscopic level
At the macroscopic level therefore concrete may be
considered to be a two-phase material consisting of
aggregate particles dispersed in a matrix of the
cement paste
Microscopic level
At the microscopic level the complexities of the
concrete structure begin to show up It becomes
obvious that the two phases of the structure are
neither homogeneously distributed with respect to
each other nor are they themselves homogeneous
For instance in some areas the hcp mass appears
to be as dense as the aggregate while in others it is
highly porous
(a) 結構之示意圖 (b) 各組成所佔有體積之比例關係
混凝土之微結構
9
Three-phase theory
Three phases ndash Aggregate ndash Hardened cement paste (hcp) ndash Transition (interface) zone1048711
THREE PHASES OF CONCRETE
STRUCTURE OF THE AGGREGATE PHASE
AGGREGATE PHASE
The aggregate phase is predominantly responsible for the unit weight elastic modulus and dimensional stability of concrete
These properties of concrete depend to a large extent on the bulk density and strength of the aggregate which in turn are determined by the physical rather than chemical characteristics of the aggregate structure
In other words the chemical or mineralogical composition of the solid phases in aggregate is usually less important than the physical characteristics such as the volume size and distribution of pores
Aggregate particles
Natural gravel has a rounded shape and a smooth surface texture
Crushed rocks have a rough texture depending on the rock type and the choice of crushing equipment the crushed aggregate may contain a considerable proportion of fault or elongated particles which adversely affect many properties of concrete
Lightweight aggregate particles from pumice which is highly cellular are also angular and have a rough texture but those from expanded clay or shale are generally rounded and smooth
STRUCTURE OF HYDRATED CEMENT PASTE
Anhydrous portland cement is a gray powder that consists of angular particles typically in the size range 1 to 50 μm
It is produced by pulverizing a clinker with a small amount of calcium sulfate the clinker being a heterogeneous mixture of several minerals produced by high temperature reactions between calcium oxide and silica alumina and iron oxide
STRUCTURE OF HYDRATED CEMENT PASTE
The chemical composition of the principal
clinker minerals coresponds approximately
to C3S C2S C3A and C4AF in ordinary
portland cement their respective amounts
usually range between 45 and 60 15 and 30
6 and 12 and 6 and 8 percent
Setting ndash Solidification of the plastic cement paste
bullInitial set ndash beginning of solidification ndash Paste become unworkable ndash loss in consistency - not lt 45 min
bullFinal set ndash Time taken to solidify completely ndash Not gt 375min
Hardening ndash Strength gain with time ndash after final set
Hydration process
Crystal formation of Cement
Calcium silicate hydrate
The calcium silicate hydrate phase abbreviated C-S-
H makes up 50 to 60 percent of the volume of solids
in a completely hydrated portland cement paste and
is therefore the most important in determining the
properties of the paste
The fact that the term C-S-H is hyphenated signifies
that C-S-H is not a well-defined compound the CS
ratio varies between 15 to 20 and the structural
water content varies even more
Calcium silicate hydrate
The morphology of C-S-H also varies from poorly crystalline fibers to reticular network Due to their colloidal dimensions and a tendency to cluster C-S-H crystals could only be resolved with the advent of electron microscopy
Although the exact structure of C-S-H is not known several models have been proposed to explain the properties of the materials According to the Powers-Brunauer model the material has a layer structure with a very high surface area
Calcium hydroxide
Calcium hydroxide crystals (also called portlandite)
constitute 20 to 25 percent of the volume of solids in
the hydrated paste In contrast to the C-S-H the
calcium hydroxide is a compound with a definite
stoichiometry 化學計量學 Ca(OH)2
It tends to form large crystals with a distinctive
hexagonal-prism morphology The morphology usually
varies from nondescript to stacks of large plates and
is affected by the available space temperature of
hydration and impurities present in the system
Calcium hydroxide
Compared with C-S-H the strength-contributing
potential of calcium hydroxide due to van der Waals
forces is limited as a result of a considerably lower
surface area
Also the presence of a considerable amount of
calcium hydroxide in hydrated portland cement has
an adverse effect on chemical durability to acidic
solutions because of the higher solubility of calcium
hydroxide than C-S-H
Mono-Sulfoaluminate hellip Ettringite
Ettringite
Calcium sulfoaluminates
Calcium sulfoaluminate compounds occupy 15 to 20
percent of the solids volume in the hydrated paste
and therefore play only a minor role in the structure-
property relationships
It has already been stated that during the early
stages of hydration the sulfatealumina ionic ratio of
the solution phase generally favors the formation of
trisulfate hydrate C6AS3H32 also called ettringite
which forms needle-shaped prismatic crystals
Reaction rate C3A gt C3S gt C4AF gtC2S
Heat of hydration (Calg)
Compound 3 days 90 days 13 years
C3S 58 104 122
C2S 12 42 59
C3A 212 311 324
C4AF 69 98 102
Three-phase theory-Transition zone
Three-phase theory-Transition zone
A thin shell layer (10-50 μm thick) around large aggregate
Formation Water films around large aggregate during mixing
Characteristic Larger CH crystals more porous framework relatively weak1048711 1048711
Transition Zone
Miexhta and Monteiro Concrete
Transition zone -Influence on concrete properties
Fraction of transition zone in size is much smaller than other two phases its influence on concrete properties is far greater ndash It lower the strength ndash It increase the permeability ndash It prompt non-linear behavior ndash It favorites crack formation
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-
Modern electron microscopes
The magnification capability of modern
electron microscopes is of the order of 105
times thus the application of transmission
and scanning electron microscopy
techniques has made it possible to resolve
the structure of materials to a fraction of a
micrometer
SIGNIFICANCE
Progress in the field of materials has
resulted primarily from recognition of the
principle that the properties of a material
originate from its internal structure
The properties can be modified by making
suitable changes in the structure of a
material
COMPLEXITIES
From examination of a cross section of concrete the
two phases that can easily be distinguished are
aggregate particles of varying size and shape and
the binding medium composed of an incoherent
mass of the hydrated cement paste (henceforth
abbreviated hcp)
Macroscopic level
At the macroscopic level therefore concrete may be
considered to be a two-phase material consisting of
aggregate particles dispersed in a matrix of the
cement paste
Microscopic level
At the microscopic level the complexities of the
concrete structure begin to show up It becomes
obvious that the two phases of the structure are
neither homogeneously distributed with respect to
each other nor are they themselves homogeneous
For instance in some areas the hcp mass appears
to be as dense as the aggregate while in others it is
highly porous
(a) 結構之示意圖 (b) 各組成所佔有體積之比例關係
混凝土之微結構
9
Three-phase theory
Three phases ndash Aggregate ndash Hardened cement paste (hcp) ndash Transition (interface) zone1048711
THREE PHASES OF CONCRETE
STRUCTURE OF THE AGGREGATE PHASE
AGGREGATE PHASE
The aggregate phase is predominantly responsible for the unit weight elastic modulus and dimensional stability of concrete
These properties of concrete depend to a large extent on the bulk density and strength of the aggregate which in turn are determined by the physical rather than chemical characteristics of the aggregate structure
In other words the chemical or mineralogical composition of the solid phases in aggregate is usually less important than the physical characteristics such as the volume size and distribution of pores
Aggregate particles
Natural gravel has a rounded shape and a smooth surface texture
Crushed rocks have a rough texture depending on the rock type and the choice of crushing equipment the crushed aggregate may contain a considerable proportion of fault or elongated particles which adversely affect many properties of concrete
Lightweight aggregate particles from pumice which is highly cellular are also angular and have a rough texture but those from expanded clay or shale are generally rounded and smooth
STRUCTURE OF HYDRATED CEMENT PASTE
Anhydrous portland cement is a gray powder that consists of angular particles typically in the size range 1 to 50 μm
It is produced by pulverizing a clinker with a small amount of calcium sulfate the clinker being a heterogeneous mixture of several minerals produced by high temperature reactions between calcium oxide and silica alumina and iron oxide
STRUCTURE OF HYDRATED CEMENT PASTE
The chemical composition of the principal
clinker minerals coresponds approximately
to C3S C2S C3A and C4AF in ordinary
portland cement their respective amounts
usually range between 45 and 60 15 and 30
6 and 12 and 6 and 8 percent
Setting ndash Solidification of the plastic cement paste
bullInitial set ndash beginning of solidification ndash Paste become unworkable ndash loss in consistency - not lt 45 min
bullFinal set ndash Time taken to solidify completely ndash Not gt 375min
Hardening ndash Strength gain with time ndash after final set
Hydration process
Crystal formation of Cement
Calcium silicate hydrate
The calcium silicate hydrate phase abbreviated C-S-
H makes up 50 to 60 percent of the volume of solids
in a completely hydrated portland cement paste and
is therefore the most important in determining the
properties of the paste
The fact that the term C-S-H is hyphenated signifies
that C-S-H is not a well-defined compound the CS
ratio varies between 15 to 20 and the structural
water content varies even more
Calcium silicate hydrate
The morphology of C-S-H also varies from poorly crystalline fibers to reticular network Due to their colloidal dimensions and a tendency to cluster C-S-H crystals could only be resolved with the advent of electron microscopy
Although the exact structure of C-S-H is not known several models have been proposed to explain the properties of the materials According to the Powers-Brunauer model the material has a layer structure with a very high surface area
Calcium hydroxide
Calcium hydroxide crystals (also called portlandite)
constitute 20 to 25 percent of the volume of solids in
the hydrated paste In contrast to the C-S-H the
calcium hydroxide is a compound with a definite
stoichiometry 化學計量學 Ca(OH)2
It tends to form large crystals with a distinctive
hexagonal-prism morphology The morphology usually
varies from nondescript to stacks of large plates and
is affected by the available space temperature of
hydration and impurities present in the system
Calcium hydroxide
Compared with C-S-H the strength-contributing
potential of calcium hydroxide due to van der Waals
forces is limited as a result of a considerably lower
surface area
Also the presence of a considerable amount of
calcium hydroxide in hydrated portland cement has
an adverse effect on chemical durability to acidic
solutions because of the higher solubility of calcium
hydroxide than C-S-H
Mono-Sulfoaluminate hellip Ettringite
Ettringite
Calcium sulfoaluminates
Calcium sulfoaluminate compounds occupy 15 to 20
percent of the solids volume in the hydrated paste
and therefore play only a minor role in the structure-
property relationships
It has already been stated that during the early
stages of hydration the sulfatealumina ionic ratio of
the solution phase generally favors the formation of
trisulfate hydrate C6AS3H32 also called ettringite
which forms needle-shaped prismatic crystals
Reaction rate C3A gt C3S gt C4AF gtC2S
Heat of hydration (Calg)
Compound 3 days 90 days 13 years
C3S 58 104 122
C2S 12 42 59
C3A 212 311 324
C4AF 69 98 102
Three-phase theory-Transition zone
Three-phase theory-Transition zone
A thin shell layer (10-50 μm thick) around large aggregate
Formation Water films around large aggregate during mixing
Characteristic Larger CH crystals more porous framework relatively weak1048711 1048711
Transition Zone
Miexhta and Monteiro Concrete
Transition zone -Influence on concrete properties
Fraction of transition zone in size is much smaller than other two phases its influence on concrete properties is far greater ndash It lower the strength ndash It increase the permeability ndash It prompt non-linear behavior ndash It favorites crack formation
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-
SIGNIFICANCE
Progress in the field of materials has
resulted primarily from recognition of the
principle that the properties of a material
originate from its internal structure
The properties can be modified by making
suitable changes in the structure of a
material
COMPLEXITIES
From examination of a cross section of concrete the
two phases that can easily be distinguished are
aggregate particles of varying size and shape and
the binding medium composed of an incoherent
mass of the hydrated cement paste (henceforth
abbreviated hcp)
Macroscopic level
At the macroscopic level therefore concrete may be
considered to be a two-phase material consisting of
aggregate particles dispersed in a matrix of the
cement paste
Microscopic level
At the microscopic level the complexities of the
concrete structure begin to show up It becomes
obvious that the two phases of the structure are
neither homogeneously distributed with respect to
each other nor are they themselves homogeneous
For instance in some areas the hcp mass appears
to be as dense as the aggregate while in others it is
highly porous
(a) 結構之示意圖 (b) 各組成所佔有體積之比例關係
混凝土之微結構
9
Three-phase theory
Three phases ndash Aggregate ndash Hardened cement paste (hcp) ndash Transition (interface) zone1048711
THREE PHASES OF CONCRETE
STRUCTURE OF THE AGGREGATE PHASE
AGGREGATE PHASE
The aggregate phase is predominantly responsible for the unit weight elastic modulus and dimensional stability of concrete
These properties of concrete depend to a large extent on the bulk density and strength of the aggregate which in turn are determined by the physical rather than chemical characteristics of the aggregate structure
In other words the chemical or mineralogical composition of the solid phases in aggregate is usually less important than the physical characteristics such as the volume size and distribution of pores
Aggregate particles
Natural gravel has a rounded shape and a smooth surface texture
Crushed rocks have a rough texture depending on the rock type and the choice of crushing equipment the crushed aggregate may contain a considerable proportion of fault or elongated particles which adversely affect many properties of concrete
Lightweight aggregate particles from pumice which is highly cellular are also angular and have a rough texture but those from expanded clay or shale are generally rounded and smooth
STRUCTURE OF HYDRATED CEMENT PASTE
Anhydrous portland cement is a gray powder that consists of angular particles typically in the size range 1 to 50 μm
It is produced by pulverizing a clinker with a small amount of calcium sulfate the clinker being a heterogeneous mixture of several minerals produced by high temperature reactions between calcium oxide and silica alumina and iron oxide
STRUCTURE OF HYDRATED CEMENT PASTE
The chemical composition of the principal
clinker minerals coresponds approximately
to C3S C2S C3A and C4AF in ordinary
portland cement their respective amounts
usually range between 45 and 60 15 and 30
6 and 12 and 6 and 8 percent
Setting ndash Solidification of the plastic cement paste
bullInitial set ndash beginning of solidification ndash Paste become unworkable ndash loss in consistency - not lt 45 min
bullFinal set ndash Time taken to solidify completely ndash Not gt 375min
Hardening ndash Strength gain with time ndash after final set
Hydration process
Crystal formation of Cement
Calcium silicate hydrate
The calcium silicate hydrate phase abbreviated C-S-
H makes up 50 to 60 percent of the volume of solids
in a completely hydrated portland cement paste and
is therefore the most important in determining the
properties of the paste
The fact that the term C-S-H is hyphenated signifies
that C-S-H is not a well-defined compound the CS
ratio varies between 15 to 20 and the structural
water content varies even more
Calcium silicate hydrate
The morphology of C-S-H also varies from poorly crystalline fibers to reticular network Due to their colloidal dimensions and a tendency to cluster C-S-H crystals could only be resolved with the advent of electron microscopy
Although the exact structure of C-S-H is not known several models have been proposed to explain the properties of the materials According to the Powers-Brunauer model the material has a layer structure with a very high surface area
Calcium hydroxide
Calcium hydroxide crystals (also called portlandite)
constitute 20 to 25 percent of the volume of solids in
the hydrated paste In contrast to the C-S-H the
calcium hydroxide is a compound with a definite
stoichiometry 化學計量學 Ca(OH)2
It tends to form large crystals with a distinctive
hexagonal-prism morphology The morphology usually
varies from nondescript to stacks of large plates and
is affected by the available space temperature of
hydration and impurities present in the system
Calcium hydroxide
Compared with C-S-H the strength-contributing
potential of calcium hydroxide due to van der Waals
forces is limited as a result of a considerably lower
surface area
Also the presence of a considerable amount of
calcium hydroxide in hydrated portland cement has
an adverse effect on chemical durability to acidic
solutions because of the higher solubility of calcium
hydroxide than C-S-H
Mono-Sulfoaluminate hellip Ettringite
Ettringite
Calcium sulfoaluminates
Calcium sulfoaluminate compounds occupy 15 to 20
percent of the solids volume in the hydrated paste
and therefore play only a minor role in the structure-
property relationships
It has already been stated that during the early
stages of hydration the sulfatealumina ionic ratio of
the solution phase generally favors the formation of
trisulfate hydrate C6AS3H32 also called ettringite
which forms needle-shaped prismatic crystals
Reaction rate C3A gt C3S gt C4AF gtC2S
Heat of hydration (Calg)
Compound 3 days 90 days 13 years
C3S 58 104 122
C2S 12 42 59
C3A 212 311 324
C4AF 69 98 102
Three-phase theory-Transition zone
Three-phase theory-Transition zone
A thin shell layer (10-50 μm thick) around large aggregate
Formation Water films around large aggregate during mixing
Characteristic Larger CH crystals more porous framework relatively weak1048711 1048711
Transition Zone
Miexhta and Monteiro Concrete
Transition zone -Influence on concrete properties
Fraction of transition zone in size is much smaller than other two phases its influence on concrete properties is far greater ndash It lower the strength ndash It increase the permeability ndash It prompt non-linear behavior ndash It favorites crack formation
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-
COMPLEXITIES
From examination of a cross section of concrete the
two phases that can easily be distinguished are
aggregate particles of varying size and shape and
the binding medium composed of an incoherent
mass of the hydrated cement paste (henceforth
abbreviated hcp)
Macroscopic level
At the macroscopic level therefore concrete may be
considered to be a two-phase material consisting of
aggregate particles dispersed in a matrix of the
cement paste
Microscopic level
At the microscopic level the complexities of the
concrete structure begin to show up It becomes
obvious that the two phases of the structure are
neither homogeneously distributed with respect to
each other nor are they themselves homogeneous
For instance in some areas the hcp mass appears
to be as dense as the aggregate while in others it is
highly porous
(a) 結構之示意圖 (b) 各組成所佔有體積之比例關係
混凝土之微結構
9
Three-phase theory
Three phases ndash Aggregate ndash Hardened cement paste (hcp) ndash Transition (interface) zone1048711
THREE PHASES OF CONCRETE
STRUCTURE OF THE AGGREGATE PHASE
AGGREGATE PHASE
The aggregate phase is predominantly responsible for the unit weight elastic modulus and dimensional stability of concrete
These properties of concrete depend to a large extent on the bulk density and strength of the aggregate which in turn are determined by the physical rather than chemical characteristics of the aggregate structure
In other words the chemical or mineralogical composition of the solid phases in aggregate is usually less important than the physical characteristics such as the volume size and distribution of pores
Aggregate particles
Natural gravel has a rounded shape and a smooth surface texture
Crushed rocks have a rough texture depending on the rock type and the choice of crushing equipment the crushed aggregate may contain a considerable proportion of fault or elongated particles which adversely affect many properties of concrete
Lightweight aggregate particles from pumice which is highly cellular are also angular and have a rough texture but those from expanded clay or shale are generally rounded and smooth
STRUCTURE OF HYDRATED CEMENT PASTE
Anhydrous portland cement is a gray powder that consists of angular particles typically in the size range 1 to 50 μm
It is produced by pulverizing a clinker with a small amount of calcium sulfate the clinker being a heterogeneous mixture of several minerals produced by high temperature reactions between calcium oxide and silica alumina and iron oxide
STRUCTURE OF HYDRATED CEMENT PASTE
The chemical composition of the principal
clinker minerals coresponds approximately
to C3S C2S C3A and C4AF in ordinary
portland cement their respective amounts
usually range between 45 and 60 15 and 30
6 and 12 and 6 and 8 percent
Setting ndash Solidification of the plastic cement paste
bullInitial set ndash beginning of solidification ndash Paste become unworkable ndash loss in consistency - not lt 45 min
bullFinal set ndash Time taken to solidify completely ndash Not gt 375min
Hardening ndash Strength gain with time ndash after final set
Hydration process
Crystal formation of Cement
Calcium silicate hydrate
The calcium silicate hydrate phase abbreviated C-S-
H makes up 50 to 60 percent of the volume of solids
in a completely hydrated portland cement paste and
is therefore the most important in determining the
properties of the paste
The fact that the term C-S-H is hyphenated signifies
that C-S-H is not a well-defined compound the CS
ratio varies between 15 to 20 and the structural
water content varies even more
Calcium silicate hydrate
The morphology of C-S-H also varies from poorly crystalline fibers to reticular network Due to their colloidal dimensions and a tendency to cluster C-S-H crystals could only be resolved with the advent of electron microscopy
Although the exact structure of C-S-H is not known several models have been proposed to explain the properties of the materials According to the Powers-Brunauer model the material has a layer structure with a very high surface area
Calcium hydroxide
Calcium hydroxide crystals (also called portlandite)
constitute 20 to 25 percent of the volume of solids in
the hydrated paste In contrast to the C-S-H the
calcium hydroxide is a compound with a definite
stoichiometry 化學計量學 Ca(OH)2
It tends to form large crystals with a distinctive
hexagonal-prism morphology The morphology usually
varies from nondescript to stacks of large plates and
is affected by the available space temperature of
hydration and impurities present in the system
Calcium hydroxide
Compared with C-S-H the strength-contributing
potential of calcium hydroxide due to van der Waals
forces is limited as a result of a considerably lower
surface area
Also the presence of a considerable amount of
calcium hydroxide in hydrated portland cement has
an adverse effect on chemical durability to acidic
solutions because of the higher solubility of calcium
hydroxide than C-S-H
Mono-Sulfoaluminate hellip Ettringite
Ettringite
Calcium sulfoaluminates
Calcium sulfoaluminate compounds occupy 15 to 20
percent of the solids volume in the hydrated paste
and therefore play only a minor role in the structure-
property relationships
It has already been stated that during the early
stages of hydration the sulfatealumina ionic ratio of
the solution phase generally favors the formation of
trisulfate hydrate C6AS3H32 also called ettringite
which forms needle-shaped prismatic crystals
Reaction rate C3A gt C3S gt C4AF gtC2S
Heat of hydration (Calg)
Compound 3 days 90 days 13 years
C3S 58 104 122
C2S 12 42 59
C3A 212 311 324
C4AF 69 98 102
Three-phase theory-Transition zone
Three-phase theory-Transition zone
A thin shell layer (10-50 μm thick) around large aggregate
Formation Water films around large aggregate during mixing
Characteristic Larger CH crystals more porous framework relatively weak1048711 1048711
Transition Zone
Miexhta and Monteiro Concrete
Transition zone -Influence on concrete properties
Fraction of transition zone in size is much smaller than other two phases its influence on concrete properties is far greater ndash It lower the strength ndash It increase the permeability ndash It prompt non-linear behavior ndash It favorites crack formation
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-
Macroscopic level
At the macroscopic level therefore concrete may be
considered to be a two-phase material consisting of
aggregate particles dispersed in a matrix of the
cement paste
Microscopic level
At the microscopic level the complexities of the
concrete structure begin to show up It becomes
obvious that the two phases of the structure are
neither homogeneously distributed with respect to
each other nor are they themselves homogeneous
For instance in some areas the hcp mass appears
to be as dense as the aggregate while in others it is
highly porous
(a) 結構之示意圖 (b) 各組成所佔有體積之比例關係
混凝土之微結構
9
Three-phase theory
Three phases ndash Aggregate ndash Hardened cement paste (hcp) ndash Transition (interface) zone1048711
THREE PHASES OF CONCRETE
STRUCTURE OF THE AGGREGATE PHASE
AGGREGATE PHASE
The aggregate phase is predominantly responsible for the unit weight elastic modulus and dimensional stability of concrete
These properties of concrete depend to a large extent on the bulk density and strength of the aggregate which in turn are determined by the physical rather than chemical characteristics of the aggregate structure
In other words the chemical or mineralogical composition of the solid phases in aggregate is usually less important than the physical characteristics such as the volume size and distribution of pores
Aggregate particles
Natural gravel has a rounded shape and a smooth surface texture
Crushed rocks have a rough texture depending on the rock type and the choice of crushing equipment the crushed aggregate may contain a considerable proportion of fault or elongated particles which adversely affect many properties of concrete
Lightweight aggregate particles from pumice which is highly cellular are also angular and have a rough texture but those from expanded clay or shale are generally rounded and smooth
STRUCTURE OF HYDRATED CEMENT PASTE
Anhydrous portland cement is a gray powder that consists of angular particles typically in the size range 1 to 50 μm
It is produced by pulverizing a clinker with a small amount of calcium sulfate the clinker being a heterogeneous mixture of several minerals produced by high temperature reactions between calcium oxide and silica alumina and iron oxide
STRUCTURE OF HYDRATED CEMENT PASTE
The chemical composition of the principal
clinker minerals coresponds approximately
to C3S C2S C3A and C4AF in ordinary
portland cement their respective amounts
usually range between 45 and 60 15 and 30
6 and 12 and 6 and 8 percent
Setting ndash Solidification of the plastic cement paste
bullInitial set ndash beginning of solidification ndash Paste become unworkable ndash loss in consistency - not lt 45 min
bullFinal set ndash Time taken to solidify completely ndash Not gt 375min
Hardening ndash Strength gain with time ndash after final set
Hydration process
Crystal formation of Cement
Calcium silicate hydrate
The calcium silicate hydrate phase abbreviated C-S-
H makes up 50 to 60 percent of the volume of solids
in a completely hydrated portland cement paste and
is therefore the most important in determining the
properties of the paste
The fact that the term C-S-H is hyphenated signifies
that C-S-H is not a well-defined compound the CS
ratio varies between 15 to 20 and the structural
water content varies even more
Calcium silicate hydrate
The morphology of C-S-H also varies from poorly crystalline fibers to reticular network Due to their colloidal dimensions and a tendency to cluster C-S-H crystals could only be resolved with the advent of electron microscopy
Although the exact structure of C-S-H is not known several models have been proposed to explain the properties of the materials According to the Powers-Brunauer model the material has a layer structure with a very high surface area
Calcium hydroxide
Calcium hydroxide crystals (also called portlandite)
constitute 20 to 25 percent of the volume of solids in
the hydrated paste In contrast to the C-S-H the
calcium hydroxide is a compound with a definite
stoichiometry 化學計量學 Ca(OH)2
It tends to form large crystals with a distinctive
hexagonal-prism morphology The morphology usually
varies from nondescript to stacks of large plates and
is affected by the available space temperature of
hydration and impurities present in the system
Calcium hydroxide
Compared with C-S-H the strength-contributing
potential of calcium hydroxide due to van der Waals
forces is limited as a result of a considerably lower
surface area
Also the presence of a considerable amount of
calcium hydroxide in hydrated portland cement has
an adverse effect on chemical durability to acidic
solutions because of the higher solubility of calcium
hydroxide than C-S-H
Mono-Sulfoaluminate hellip Ettringite
Ettringite
Calcium sulfoaluminates
Calcium sulfoaluminate compounds occupy 15 to 20
percent of the solids volume in the hydrated paste
and therefore play only a minor role in the structure-
property relationships
It has already been stated that during the early
stages of hydration the sulfatealumina ionic ratio of
the solution phase generally favors the formation of
trisulfate hydrate C6AS3H32 also called ettringite
which forms needle-shaped prismatic crystals
Reaction rate C3A gt C3S gt C4AF gtC2S
Heat of hydration (Calg)
Compound 3 days 90 days 13 years
C3S 58 104 122
C2S 12 42 59
C3A 212 311 324
C4AF 69 98 102
Three-phase theory-Transition zone
Three-phase theory-Transition zone
A thin shell layer (10-50 μm thick) around large aggregate
Formation Water films around large aggregate during mixing
Characteristic Larger CH crystals more porous framework relatively weak1048711 1048711
Transition Zone
Miexhta and Monteiro Concrete
Transition zone -Influence on concrete properties
Fraction of transition zone in size is much smaller than other two phases its influence on concrete properties is far greater ndash It lower the strength ndash It increase the permeability ndash It prompt non-linear behavior ndash It favorites crack formation
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-
Microscopic level
At the microscopic level the complexities of the
concrete structure begin to show up It becomes
obvious that the two phases of the structure are
neither homogeneously distributed with respect to
each other nor are they themselves homogeneous
For instance in some areas the hcp mass appears
to be as dense as the aggregate while in others it is
highly porous
(a) 結構之示意圖 (b) 各組成所佔有體積之比例關係
混凝土之微結構
9
Three-phase theory
Three phases ndash Aggregate ndash Hardened cement paste (hcp) ndash Transition (interface) zone1048711
THREE PHASES OF CONCRETE
STRUCTURE OF THE AGGREGATE PHASE
AGGREGATE PHASE
The aggregate phase is predominantly responsible for the unit weight elastic modulus and dimensional stability of concrete
These properties of concrete depend to a large extent on the bulk density and strength of the aggregate which in turn are determined by the physical rather than chemical characteristics of the aggregate structure
In other words the chemical or mineralogical composition of the solid phases in aggregate is usually less important than the physical characteristics such as the volume size and distribution of pores
Aggregate particles
Natural gravel has a rounded shape and a smooth surface texture
Crushed rocks have a rough texture depending on the rock type and the choice of crushing equipment the crushed aggregate may contain a considerable proportion of fault or elongated particles which adversely affect many properties of concrete
Lightweight aggregate particles from pumice which is highly cellular are also angular and have a rough texture but those from expanded clay or shale are generally rounded and smooth
STRUCTURE OF HYDRATED CEMENT PASTE
Anhydrous portland cement is a gray powder that consists of angular particles typically in the size range 1 to 50 μm
It is produced by pulverizing a clinker with a small amount of calcium sulfate the clinker being a heterogeneous mixture of several minerals produced by high temperature reactions between calcium oxide and silica alumina and iron oxide
STRUCTURE OF HYDRATED CEMENT PASTE
The chemical composition of the principal
clinker minerals coresponds approximately
to C3S C2S C3A and C4AF in ordinary
portland cement their respective amounts
usually range between 45 and 60 15 and 30
6 and 12 and 6 and 8 percent
Setting ndash Solidification of the plastic cement paste
bullInitial set ndash beginning of solidification ndash Paste become unworkable ndash loss in consistency - not lt 45 min
bullFinal set ndash Time taken to solidify completely ndash Not gt 375min
Hardening ndash Strength gain with time ndash after final set
Hydration process
Crystal formation of Cement
Calcium silicate hydrate
The calcium silicate hydrate phase abbreviated C-S-
H makes up 50 to 60 percent of the volume of solids
in a completely hydrated portland cement paste and
is therefore the most important in determining the
properties of the paste
The fact that the term C-S-H is hyphenated signifies
that C-S-H is not a well-defined compound the CS
ratio varies between 15 to 20 and the structural
water content varies even more
Calcium silicate hydrate
The morphology of C-S-H also varies from poorly crystalline fibers to reticular network Due to their colloidal dimensions and a tendency to cluster C-S-H crystals could only be resolved with the advent of electron microscopy
Although the exact structure of C-S-H is not known several models have been proposed to explain the properties of the materials According to the Powers-Brunauer model the material has a layer structure with a very high surface area
Calcium hydroxide
Calcium hydroxide crystals (also called portlandite)
constitute 20 to 25 percent of the volume of solids in
the hydrated paste In contrast to the C-S-H the
calcium hydroxide is a compound with a definite
stoichiometry 化學計量學 Ca(OH)2
It tends to form large crystals with a distinctive
hexagonal-prism morphology The morphology usually
varies from nondescript to stacks of large plates and
is affected by the available space temperature of
hydration and impurities present in the system
Calcium hydroxide
Compared with C-S-H the strength-contributing
potential of calcium hydroxide due to van der Waals
forces is limited as a result of a considerably lower
surface area
Also the presence of a considerable amount of
calcium hydroxide in hydrated portland cement has
an adverse effect on chemical durability to acidic
solutions because of the higher solubility of calcium
hydroxide than C-S-H
Mono-Sulfoaluminate hellip Ettringite
Ettringite
Calcium sulfoaluminates
Calcium sulfoaluminate compounds occupy 15 to 20
percent of the solids volume in the hydrated paste
and therefore play only a minor role in the structure-
property relationships
It has already been stated that during the early
stages of hydration the sulfatealumina ionic ratio of
the solution phase generally favors the formation of
trisulfate hydrate C6AS3H32 also called ettringite
which forms needle-shaped prismatic crystals
Reaction rate C3A gt C3S gt C4AF gtC2S
Heat of hydration (Calg)
Compound 3 days 90 days 13 years
C3S 58 104 122
C2S 12 42 59
C3A 212 311 324
C4AF 69 98 102
Three-phase theory-Transition zone
Three-phase theory-Transition zone
A thin shell layer (10-50 μm thick) around large aggregate
Formation Water films around large aggregate during mixing
Characteristic Larger CH crystals more porous framework relatively weak1048711 1048711
Transition Zone
Miexhta and Monteiro Concrete
Transition zone -Influence on concrete properties
Fraction of transition zone in size is much smaller than other two phases its influence on concrete properties is far greater ndash It lower the strength ndash It increase the permeability ndash It prompt non-linear behavior ndash It favorites crack formation
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-
(a) 結構之示意圖 (b) 各組成所佔有體積之比例關係
混凝土之微結構
9
Three-phase theory
Three phases ndash Aggregate ndash Hardened cement paste (hcp) ndash Transition (interface) zone1048711
THREE PHASES OF CONCRETE
STRUCTURE OF THE AGGREGATE PHASE
AGGREGATE PHASE
The aggregate phase is predominantly responsible for the unit weight elastic modulus and dimensional stability of concrete
These properties of concrete depend to a large extent on the bulk density and strength of the aggregate which in turn are determined by the physical rather than chemical characteristics of the aggregate structure
In other words the chemical or mineralogical composition of the solid phases in aggregate is usually less important than the physical characteristics such as the volume size and distribution of pores
Aggregate particles
Natural gravel has a rounded shape and a smooth surface texture
Crushed rocks have a rough texture depending on the rock type and the choice of crushing equipment the crushed aggregate may contain a considerable proportion of fault or elongated particles which adversely affect many properties of concrete
Lightweight aggregate particles from pumice which is highly cellular are also angular and have a rough texture but those from expanded clay or shale are generally rounded and smooth
STRUCTURE OF HYDRATED CEMENT PASTE
Anhydrous portland cement is a gray powder that consists of angular particles typically in the size range 1 to 50 μm
It is produced by pulverizing a clinker with a small amount of calcium sulfate the clinker being a heterogeneous mixture of several minerals produced by high temperature reactions between calcium oxide and silica alumina and iron oxide
STRUCTURE OF HYDRATED CEMENT PASTE
The chemical composition of the principal
clinker minerals coresponds approximately
to C3S C2S C3A and C4AF in ordinary
portland cement their respective amounts
usually range between 45 and 60 15 and 30
6 and 12 and 6 and 8 percent
Setting ndash Solidification of the plastic cement paste
bullInitial set ndash beginning of solidification ndash Paste become unworkable ndash loss in consistency - not lt 45 min
bullFinal set ndash Time taken to solidify completely ndash Not gt 375min
Hardening ndash Strength gain with time ndash after final set
Hydration process
Crystal formation of Cement
Calcium silicate hydrate
The calcium silicate hydrate phase abbreviated C-S-
H makes up 50 to 60 percent of the volume of solids
in a completely hydrated portland cement paste and
is therefore the most important in determining the
properties of the paste
The fact that the term C-S-H is hyphenated signifies
that C-S-H is not a well-defined compound the CS
ratio varies between 15 to 20 and the structural
water content varies even more
Calcium silicate hydrate
The morphology of C-S-H also varies from poorly crystalline fibers to reticular network Due to their colloidal dimensions and a tendency to cluster C-S-H crystals could only be resolved with the advent of electron microscopy
Although the exact structure of C-S-H is not known several models have been proposed to explain the properties of the materials According to the Powers-Brunauer model the material has a layer structure with a very high surface area
Calcium hydroxide
Calcium hydroxide crystals (also called portlandite)
constitute 20 to 25 percent of the volume of solids in
the hydrated paste In contrast to the C-S-H the
calcium hydroxide is a compound with a definite
stoichiometry 化學計量學 Ca(OH)2
It tends to form large crystals with a distinctive
hexagonal-prism morphology The morphology usually
varies from nondescript to stacks of large plates and
is affected by the available space temperature of
hydration and impurities present in the system
Calcium hydroxide
Compared with C-S-H the strength-contributing
potential of calcium hydroxide due to van der Waals
forces is limited as a result of a considerably lower
surface area
Also the presence of a considerable amount of
calcium hydroxide in hydrated portland cement has
an adverse effect on chemical durability to acidic
solutions because of the higher solubility of calcium
hydroxide than C-S-H
Mono-Sulfoaluminate hellip Ettringite
Ettringite
Calcium sulfoaluminates
Calcium sulfoaluminate compounds occupy 15 to 20
percent of the solids volume in the hydrated paste
and therefore play only a minor role in the structure-
property relationships
It has already been stated that during the early
stages of hydration the sulfatealumina ionic ratio of
the solution phase generally favors the formation of
trisulfate hydrate C6AS3H32 also called ettringite
which forms needle-shaped prismatic crystals
Reaction rate C3A gt C3S gt C4AF gtC2S
Heat of hydration (Calg)
Compound 3 days 90 days 13 years
C3S 58 104 122
C2S 12 42 59
C3A 212 311 324
C4AF 69 98 102
Three-phase theory-Transition zone
Three-phase theory-Transition zone
A thin shell layer (10-50 μm thick) around large aggregate
Formation Water films around large aggregate during mixing
Characteristic Larger CH crystals more porous framework relatively weak1048711 1048711
Transition Zone
Miexhta and Monteiro Concrete
Transition zone -Influence on concrete properties
Fraction of transition zone in size is much smaller than other two phases its influence on concrete properties is far greater ndash It lower the strength ndash It increase the permeability ndash It prompt non-linear behavior ndash It favorites crack formation
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-
混凝土之微結構
9
Three-phase theory
Three phases ndash Aggregate ndash Hardened cement paste (hcp) ndash Transition (interface) zone1048711
THREE PHASES OF CONCRETE
STRUCTURE OF THE AGGREGATE PHASE
AGGREGATE PHASE
The aggregate phase is predominantly responsible for the unit weight elastic modulus and dimensional stability of concrete
These properties of concrete depend to a large extent on the bulk density and strength of the aggregate which in turn are determined by the physical rather than chemical characteristics of the aggregate structure
In other words the chemical or mineralogical composition of the solid phases in aggregate is usually less important than the physical characteristics such as the volume size and distribution of pores
Aggregate particles
Natural gravel has a rounded shape and a smooth surface texture
Crushed rocks have a rough texture depending on the rock type and the choice of crushing equipment the crushed aggregate may contain a considerable proportion of fault or elongated particles which adversely affect many properties of concrete
Lightweight aggregate particles from pumice which is highly cellular are also angular and have a rough texture but those from expanded clay or shale are generally rounded and smooth
STRUCTURE OF HYDRATED CEMENT PASTE
Anhydrous portland cement is a gray powder that consists of angular particles typically in the size range 1 to 50 μm
It is produced by pulverizing a clinker with a small amount of calcium sulfate the clinker being a heterogeneous mixture of several minerals produced by high temperature reactions between calcium oxide and silica alumina and iron oxide
STRUCTURE OF HYDRATED CEMENT PASTE
The chemical composition of the principal
clinker minerals coresponds approximately
to C3S C2S C3A and C4AF in ordinary
portland cement their respective amounts
usually range between 45 and 60 15 and 30
6 and 12 and 6 and 8 percent
Setting ndash Solidification of the plastic cement paste
bullInitial set ndash beginning of solidification ndash Paste become unworkable ndash loss in consistency - not lt 45 min
bullFinal set ndash Time taken to solidify completely ndash Not gt 375min
Hardening ndash Strength gain with time ndash after final set
Hydration process
Crystal formation of Cement
Calcium silicate hydrate
The calcium silicate hydrate phase abbreviated C-S-
H makes up 50 to 60 percent of the volume of solids
in a completely hydrated portland cement paste and
is therefore the most important in determining the
properties of the paste
The fact that the term C-S-H is hyphenated signifies
that C-S-H is not a well-defined compound the CS
ratio varies between 15 to 20 and the structural
water content varies even more
Calcium silicate hydrate
The morphology of C-S-H also varies from poorly crystalline fibers to reticular network Due to their colloidal dimensions and a tendency to cluster C-S-H crystals could only be resolved with the advent of electron microscopy
Although the exact structure of C-S-H is not known several models have been proposed to explain the properties of the materials According to the Powers-Brunauer model the material has a layer structure with a very high surface area
Calcium hydroxide
Calcium hydroxide crystals (also called portlandite)
constitute 20 to 25 percent of the volume of solids in
the hydrated paste In contrast to the C-S-H the
calcium hydroxide is a compound with a definite
stoichiometry 化學計量學 Ca(OH)2
It tends to form large crystals with a distinctive
hexagonal-prism morphology The morphology usually
varies from nondescript to stacks of large plates and
is affected by the available space temperature of
hydration and impurities present in the system
Calcium hydroxide
Compared with C-S-H the strength-contributing
potential of calcium hydroxide due to van der Waals
forces is limited as a result of a considerably lower
surface area
Also the presence of a considerable amount of
calcium hydroxide in hydrated portland cement has
an adverse effect on chemical durability to acidic
solutions because of the higher solubility of calcium
hydroxide than C-S-H
Mono-Sulfoaluminate hellip Ettringite
Ettringite
Calcium sulfoaluminates
Calcium sulfoaluminate compounds occupy 15 to 20
percent of the solids volume in the hydrated paste
and therefore play only a minor role in the structure-
property relationships
It has already been stated that during the early
stages of hydration the sulfatealumina ionic ratio of
the solution phase generally favors the formation of
trisulfate hydrate C6AS3H32 also called ettringite
which forms needle-shaped prismatic crystals
Reaction rate C3A gt C3S gt C4AF gtC2S
Heat of hydration (Calg)
Compound 3 days 90 days 13 years
C3S 58 104 122
C2S 12 42 59
C3A 212 311 324
C4AF 69 98 102
Three-phase theory-Transition zone
Three-phase theory-Transition zone
A thin shell layer (10-50 μm thick) around large aggregate
Formation Water films around large aggregate during mixing
Characteristic Larger CH crystals more porous framework relatively weak1048711 1048711
Transition Zone
Miexhta and Monteiro Concrete
Transition zone -Influence on concrete properties
Fraction of transition zone in size is much smaller than other two phases its influence on concrete properties is far greater ndash It lower the strength ndash It increase the permeability ndash It prompt non-linear behavior ndash It favorites crack formation
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-
Three-phase theory
Three phases ndash Aggregate ndash Hardened cement paste (hcp) ndash Transition (interface) zone1048711
THREE PHASES OF CONCRETE
STRUCTURE OF THE AGGREGATE PHASE
AGGREGATE PHASE
The aggregate phase is predominantly responsible for the unit weight elastic modulus and dimensional stability of concrete
These properties of concrete depend to a large extent on the bulk density and strength of the aggregate which in turn are determined by the physical rather than chemical characteristics of the aggregate structure
In other words the chemical or mineralogical composition of the solid phases in aggregate is usually less important than the physical characteristics such as the volume size and distribution of pores
Aggregate particles
Natural gravel has a rounded shape and a smooth surface texture
Crushed rocks have a rough texture depending on the rock type and the choice of crushing equipment the crushed aggregate may contain a considerable proportion of fault or elongated particles which adversely affect many properties of concrete
Lightweight aggregate particles from pumice which is highly cellular are also angular and have a rough texture but those from expanded clay or shale are generally rounded and smooth
STRUCTURE OF HYDRATED CEMENT PASTE
Anhydrous portland cement is a gray powder that consists of angular particles typically in the size range 1 to 50 μm
It is produced by pulverizing a clinker with a small amount of calcium sulfate the clinker being a heterogeneous mixture of several minerals produced by high temperature reactions between calcium oxide and silica alumina and iron oxide
STRUCTURE OF HYDRATED CEMENT PASTE
The chemical composition of the principal
clinker minerals coresponds approximately
to C3S C2S C3A and C4AF in ordinary
portland cement their respective amounts
usually range between 45 and 60 15 and 30
6 and 12 and 6 and 8 percent
Setting ndash Solidification of the plastic cement paste
bullInitial set ndash beginning of solidification ndash Paste become unworkable ndash loss in consistency - not lt 45 min
bullFinal set ndash Time taken to solidify completely ndash Not gt 375min
Hardening ndash Strength gain with time ndash after final set
Hydration process
Crystal formation of Cement
Calcium silicate hydrate
The calcium silicate hydrate phase abbreviated C-S-
H makes up 50 to 60 percent of the volume of solids
in a completely hydrated portland cement paste and
is therefore the most important in determining the
properties of the paste
The fact that the term C-S-H is hyphenated signifies
that C-S-H is not a well-defined compound the CS
ratio varies between 15 to 20 and the structural
water content varies even more
Calcium silicate hydrate
The morphology of C-S-H also varies from poorly crystalline fibers to reticular network Due to their colloidal dimensions and a tendency to cluster C-S-H crystals could only be resolved with the advent of electron microscopy
Although the exact structure of C-S-H is not known several models have been proposed to explain the properties of the materials According to the Powers-Brunauer model the material has a layer structure with a very high surface area
Calcium hydroxide
Calcium hydroxide crystals (also called portlandite)
constitute 20 to 25 percent of the volume of solids in
the hydrated paste In contrast to the C-S-H the
calcium hydroxide is a compound with a definite
stoichiometry 化學計量學 Ca(OH)2
It tends to form large crystals with a distinctive
hexagonal-prism morphology The morphology usually
varies from nondescript to stacks of large plates and
is affected by the available space temperature of
hydration and impurities present in the system
Calcium hydroxide
Compared with C-S-H the strength-contributing
potential of calcium hydroxide due to van der Waals
forces is limited as a result of a considerably lower
surface area
Also the presence of a considerable amount of
calcium hydroxide in hydrated portland cement has
an adverse effect on chemical durability to acidic
solutions because of the higher solubility of calcium
hydroxide than C-S-H
Mono-Sulfoaluminate hellip Ettringite
Ettringite
Calcium sulfoaluminates
Calcium sulfoaluminate compounds occupy 15 to 20
percent of the solids volume in the hydrated paste
and therefore play only a minor role in the structure-
property relationships
It has already been stated that during the early
stages of hydration the sulfatealumina ionic ratio of
the solution phase generally favors the formation of
trisulfate hydrate C6AS3H32 also called ettringite
which forms needle-shaped prismatic crystals
Reaction rate C3A gt C3S gt C4AF gtC2S
Heat of hydration (Calg)
Compound 3 days 90 days 13 years
C3S 58 104 122
C2S 12 42 59
C3A 212 311 324
C4AF 69 98 102
Three-phase theory-Transition zone
Three-phase theory-Transition zone
A thin shell layer (10-50 μm thick) around large aggregate
Formation Water films around large aggregate during mixing
Characteristic Larger CH crystals more porous framework relatively weak1048711 1048711
Transition Zone
Miexhta and Monteiro Concrete
Transition zone -Influence on concrete properties
Fraction of transition zone in size is much smaller than other two phases its influence on concrete properties is far greater ndash It lower the strength ndash It increase the permeability ndash It prompt non-linear behavior ndash It favorites crack formation
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-
THREE PHASES OF CONCRETE
STRUCTURE OF THE AGGREGATE PHASE
AGGREGATE PHASE
The aggregate phase is predominantly responsible for the unit weight elastic modulus and dimensional stability of concrete
These properties of concrete depend to a large extent on the bulk density and strength of the aggregate which in turn are determined by the physical rather than chemical characteristics of the aggregate structure
In other words the chemical or mineralogical composition of the solid phases in aggregate is usually less important than the physical characteristics such as the volume size and distribution of pores
Aggregate particles
Natural gravel has a rounded shape and a smooth surface texture
Crushed rocks have a rough texture depending on the rock type and the choice of crushing equipment the crushed aggregate may contain a considerable proportion of fault or elongated particles which adversely affect many properties of concrete
Lightweight aggregate particles from pumice which is highly cellular are also angular and have a rough texture but those from expanded clay or shale are generally rounded and smooth
STRUCTURE OF HYDRATED CEMENT PASTE
Anhydrous portland cement is a gray powder that consists of angular particles typically in the size range 1 to 50 μm
It is produced by pulverizing a clinker with a small amount of calcium sulfate the clinker being a heterogeneous mixture of several minerals produced by high temperature reactions between calcium oxide and silica alumina and iron oxide
STRUCTURE OF HYDRATED CEMENT PASTE
The chemical composition of the principal
clinker minerals coresponds approximately
to C3S C2S C3A and C4AF in ordinary
portland cement their respective amounts
usually range between 45 and 60 15 and 30
6 and 12 and 6 and 8 percent
Setting ndash Solidification of the plastic cement paste
bullInitial set ndash beginning of solidification ndash Paste become unworkable ndash loss in consistency - not lt 45 min
bullFinal set ndash Time taken to solidify completely ndash Not gt 375min
Hardening ndash Strength gain with time ndash after final set
Hydration process
Crystal formation of Cement
Calcium silicate hydrate
The calcium silicate hydrate phase abbreviated C-S-
H makes up 50 to 60 percent of the volume of solids
in a completely hydrated portland cement paste and
is therefore the most important in determining the
properties of the paste
The fact that the term C-S-H is hyphenated signifies
that C-S-H is not a well-defined compound the CS
ratio varies between 15 to 20 and the structural
water content varies even more
Calcium silicate hydrate
The morphology of C-S-H also varies from poorly crystalline fibers to reticular network Due to their colloidal dimensions and a tendency to cluster C-S-H crystals could only be resolved with the advent of electron microscopy
Although the exact structure of C-S-H is not known several models have been proposed to explain the properties of the materials According to the Powers-Brunauer model the material has a layer structure with a very high surface area
Calcium hydroxide
Calcium hydroxide crystals (also called portlandite)
constitute 20 to 25 percent of the volume of solids in
the hydrated paste In contrast to the C-S-H the
calcium hydroxide is a compound with a definite
stoichiometry 化學計量學 Ca(OH)2
It tends to form large crystals with a distinctive
hexagonal-prism morphology The morphology usually
varies from nondescript to stacks of large plates and
is affected by the available space temperature of
hydration and impurities present in the system
Calcium hydroxide
Compared with C-S-H the strength-contributing
potential of calcium hydroxide due to van der Waals
forces is limited as a result of a considerably lower
surface area
Also the presence of a considerable amount of
calcium hydroxide in hydrated portland cement has
an adverse effect on chemical durability to acidic
solutions because of the higher solubility of calcium
hydroxide than C-S-H
Mono-Sulfoaluminate hellip Ettringite
Ettringite
Calcium sulfoaluminates
Calcium sulfoaluminate compounds occupy 15 to 20
percent of the solids volume in the hydrated paste
and therefore play only a minor role in the structure-
property relationships
It has already been stated that during the early
stages of hydration the sulfatealumina ionic ratio of
the solution phase generally favors the formation of
trisulfate hydrate C6AS3H32 also called ettringite
which forms needle-shaped prismatic crystals
Reaction rate C3A gt C3S gt C4AF gtC2S
Heat of hydration (Calg)
Compound 3 days 90 days 13 years
C3S 58 104 122
C2S 12 42 59
C3A 212 311 324
C4AF 69 98 102
Three-phase theory-Transition zone
Three-phase theory-Transition zone
A thin shell layer (10-50 μm thick) around large aggregate
Formation Water films around large aggregate during mixing
Characteristic Larger CH crystals more porous framework relatively weak1048711 1048711
Transition Zone
Miexhta and Monteiro Concrete
Transition zone -Influence on concrete properties
Fraction of transition zone in size is much smaller than other two phases its influence on concrete properties is far greater ndash It lower the strength ndash It increase the permeability ndash It prompt non-linear behavior ndash It favorites crack formation
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-
STRUCTURE OF THE AGGREGATE PHASE
AGGREGATE PHASE
The aggregate phase is predominantly responsible for the unit weight elastic modulus and dimensional stability of concrete
These properties of concrete depend to a large extent on the bulk density and strength of the aggregate which in turn are determined by the physical rather than chemical characteristics of the aggregate structure
In other words the chemical or mineralogical composition of the solid phases in aggregate is usually less important than the physical characteristics such as the volume size and distribution of pores
Aggregate particles
Natural gravel has a rounded shape and a smooth surface texture
Crushed rocks have a rough texture depending on the rock type and the choice of crushing equipment the crushed aggregate may contain a considerable proportion of fault or elongated particles which adversely affect many properties of concrete
Lightweight aggregate particles from pumice which is highly cellular are also angular and have a rough texture but those from expanded clay or shale are generally rounded and smooth
STRUCTURE OF HYDRATED CEMENT PASTE
Anhydrous portland cement is a gray powder that consists of angular particles typically in the size range 1 to 50 μm
It is produced by pulverizing a clinker with a small amount of calcium sulfate the clinker being a heterogeneous mixture of several minerals produced by high temperature reactions between calcium oxide and silica alumina and iron oxide
STRUCTURE OF HYDRATED CEMENT PASTE
The chemical composition of the principal
clinker minerals coresponds approximately
to C3S C2S C3A and C4AF in ordinary
portland cement their respective amounts
usually range between 45 and 60 15 and 30
6 and 12 and 6 and 8 percent
Setting ndash Solidification of the plastic cement paste
bullInitial set ndash beginning of solidification ndash Paste become unworkable ndash loss in consistency - not lt 45 min
bullFinal set ndash Time taken to solidify completely ndash Not gt 375min
Hardening ndash Strength gain with time ndash after final set
Hydration process
Crystal formation of Cement
Calcium silicate hydrate
The calcium silicate hydrate phase abbreviated C-S-
H makes up 50 to 60 percent of the volume of solids
in a completely hydrated portland cement paste and
is therefore the most important in determining the
properties of the paste
The fact that the term C-S-H is hyphenated signifies
that C-S-H is not a well-defined compound the CS
ratio varies between 15 to 20 and the structural
water content varies even more
Calcium silicate hydrate
The morphology of C-S-H also varies from poorly crystalline fibers to reticular network Due to their colloidal dimensions and a tendency to cluster C-S-H crystals could only be resolved with the advent of electron microscopy
Although the exact structure of C-S-H is not known several models have been proposed to explain the properties of the materials According to the Powers-Brunauer model the material has a layer structure with a very high surface area
Calcium hydroxide
Calcium hydroxide crystals (also called portlandite)
constitute 20 to 25 percent of the volume of solids in
the hydrated paste In contrast to the C-S-H the
calcium hydroxide is a compound with a definite
stoichiometry 化學計量學 Ca(OH)2
It tends to form large crystals with a distinctive
hexagonal-prism morphology The morphology usually
varies from nondescript to stacks of large plates and
is affected by the available space temperature of
hydration and impurities present in the system
Calcium hydroxide
Compared with C-S-H the strength-contributing
potential of calcium hydroxide due to van der Waals
forces is limited as a result of a considerably lower
surface area
Also the presence of a considerable amount of
calcium hydroxide in hydrated portland cement has
an adverse effect on chemical durability to acidic
solutions because of the higher solubility of calcium
hydroxide than C-S-H
Mono-Sulfoaluminate hellip Ettringite
Ettringite
Calcium sulfoaluminates
Calcium sulfoaluminate compounds occupy 15 to 20
percent of the solids volume in the hydrated paste
and therefore play only a minor role in the structure-
property relationships
It has already been stated that during the early
stages of hydration the sulfatealumina ionic ratio of
the solution phase generally favors the formation of
trisulfate hydrate C6AS3H32 also called ettringite
which forms needle-shaped prismatic crystals
Reaction rate C3A gt C3S gt C4AF gtC2S
Heat of hydration (Calg)
Compound 3 days 90 days 13 years
C3S 58 104 122
C2S 12 42 59
C3A 212 311 324
C4AF 69 98 102
Three-phase theory-Transition zone
Three-phase theory-Transition zone
A thin shell layer (10-50 μm thick) around large aggregate
Formation Water films around large aggregate during mixing
Characteristic Larger CH crystals more porous framework relatively weak1048711 1048711
Transition Zone
Miexhta and Monteiro Concrete
Transition zone -Influence on concrete properties
Fraction of transition zone in size is much smaller than other two phases its influence on concrete properties is far greater ndash It lower the strength ndash It increase the permeability ndash It prompt non-linear behavior ndash It favorites crack formation
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-
AGGREGATE PHASE
The aggregate phase is predominantly responsible for the unit weight elastic modulus and dimensional stability of concrete
These properties of concrete depend to a large extent on the bulk density and strength of the aggregate which in turn are determined by the physical rather than chemical characteristics of the aggregate structure
In other words the chemical or mineralogical composition of the solid phases in aggregate is usually less important than the physical characteristics such as the volume size and distribution of pores
Aggregate particles
Natural gravel has a rounded shape and a smooth surface texture
Crushed rocks have a rough texture depending on the rock type and the choice of crushing equipment the crushed aggregate may contain a considerable proportion of fault or elongated particles which adversely affect many properties of concrete
Lightweight aggregate particles from pumice which is highly cellular are also angular and have a rough texture but those from expanded clay or shale are generally rounded and smooth
STRUCTURE OF HYDRATED CEMENT PASTE
Anhydrous portland cement is a gray powder that consists of angular particles typically in the size range 1 to 50 μm
It is produced by pulverizing a clinker with a small amount of calcium sulfate the clinker being a heterogeneous mixture of several minerals produced by high temperature reactions between calcium oxide and silica alumina and iron oxide
STRUCTURE OF HYDRATED CEMENT PASTE
The chemical composition of the principal
clinker minerals coresponds approximately
to C3S C2S C3A and C4AF in ordinary
portland cement their respective amounts
usually range between 45 and 60 15 and 30
6 and 12 and 6 and 8 percent
Setting ndash Solidification of the plastic cement paste
bullInitial set ndash beginning of solidification ndash Paste become unworkable ndash loss in consistency - not lt 45 min
bullFinal set ndash Time taken to solidify completely ndash Not gt 375min
Hardening ndash Strength gain with time ndash after final set
Hydration process
Crystal formation of Cement
Calcium silicate hydrate
The calcium silicate hydrate phase abbreviated C-S-
H makes up 50 to 60 percent of the volume of solids
in a completely hydrated portland cement paste and
is therefore the most important in determining the
properties of the paste
The fact that the term C-S-H is hyphenated signifies
that C-S-H is not a well-defined compound the CS
ratio varies between 15 to 20 and the structural
water content varies even more
Calcium silicate hydrate
The morphology of C-S-H also varies from poorly crystalline fibers to reticular network Due to their colloidal dimensions and a tendency to cluster C-S-H crystals could only be resolved with the advent of electron microscopy
Although the exact structure of C-S-H is not known several models have been proposed to explain the properties of the materials According to the Powers-Brunauer model the material has a layer structure with a very high surface area
Calcium hydroxide
Calcium hydroxide crystals (also called portlandite)
constitute 20 to 25 percent of the volume of solids in
the hydrated paste In contrast to the C-S-H the
calcium hydroxide is a compound with a definite
stoichiometry 化學計量學 Ca(OH)2
It tends to form large crystals with a distinctive
hexagonal-prism morphology The morphology usually
varies from nondescript to stacks of large plates and
is affected by the available space temperature of
hydration and impurities present in the system
Calcium hydroxide
Compared with C-S-H the strength-contributing
potential of calcium hydroxide due to van der Waals
forces is limited as a result of a considerably lower
surface area
Also the presence of a considerable amount of
calcium hydroxide in hydrated portland cement has
an adverse effect on chemical durability to acidic
solutions because of the higher solubility of calcium
hydroxide than C-S-H
Mono-Sulfoaluminate hellip Ettringite
Ettringite
Calcium sulfoaluminates
Calcium sulfoaluminate compounds occupy 15 to 20
percent of the solids volume in the hydrated paste
and therefore play only a minor role in the structure-
property relationships
It has already been stated that during the early
stages of hydration the sulfatealumina ionic ratio of
the solution phase generally favors the formation of
trisulfate hydrate C6AS3H32 also called ettringite
which forms needle-shaped prismatic crystals
Reaction rate C3A gt C3S gt C4AF gtC2S
Heat of hydration (Calg)
Compound 3 days 90 days 13 years
C3S 58 104 122
C2S 12 42 59
C3A 212 311 324
C4AF 69 98 102
Three-phase theory-Transition zone
Three-phase theory-Transition zone
A thin shell layer (10-50 μm thick) around large aggregate
Formation Water films around large aggregate during mixing
Characteristic Larger CH crystals more porous framework relatively weak1048711 1048711
Transition Zone
Miexhta and Monteiro Concrete
Transition zone -Influence on concrete properties
Fraction of transition zone in size is much smaller than other two phases its influence on concrete properties is far greater ndash It lower the strength ndash It increase the permeability ndash It prompt non-linear behavior ndash It favorites crack formation
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-
Aggregate particles
Natural gravel has a rounded shape and a smooth surface texture
Crushed rocks have a rough texture depending on the rock type and the choice of crushing equipment the crushed aggregate may contain a considerable proportion of fault or elongated particles which adversely affect many properties of concrete
Lightweight aggregate particles from pumice which is highly cellular are also angular and have a rough texture but those from expanded clay or shale are generally rounded and smooth
STRUCTURE OF HYDRATED CEMENT PASTE
Anhydrous portland cement is a gray powder that consists of angular particles typically in the size range 1 to 50 μm
It is produced by pulverizing a clinker with a small amount of calcium sulfate the clinker being a heterogeneous mixture of several minerals produced by high temperature reactions between calcium oxide and silica alumina and iron oxide
STRUCTURE OF HYDRATED CEMENT PASTE
The chemical composition of the principal
clinker minerals coresponds approximately
to C3S C2S C3A and C4AF in ordinary
portland cement their respective amounts
usually range between 45 and 60 15 and 30
6 and 12 and 6 and 8 percent
Setting ndash Solidification of the plastic cement paste
bullInitial set ndash beginning of solidification ndash Paste become unworkable ndash loss in consistency - not lt 45 min
bullFinal set ndash Time taken to solidify completely ndash Not gt 375min
Hardening ndash Strength gain with time ndash after final set
Hydration process
Crystal formation of Cement
Calcium silicate hydrate
The calcium silicate hydrate phase abbreviated C-S-
H makes up 50 to 60 percent of the volume of solids
in a completely hydrated portland cement paste and
is therefore the most important in determining the
properties of the paste
The fact that the term C-S-H is hyphenated signifies
that C-S-H is not a well-defined compound the CS
ratio varies between 15 to 20 and the structural
water content varies even more
Calcium silicate hydrate
The morphology of C-S-H also varies from poorly crystalline fibers to reticular network Due to their colloidal dimensions and a tendency to cluster C-S-H crystals could only be resolved with the advent of electron microscopy
Although the exact structure of C-S-H is not known several models have been proposed to explain the properties of the materials According to the Powers-Brunauer model the material has a layer structure with a very high surface area
Calcium hydroxide
Calcium hydroxide crystals (also called portlandite)
constitute 20 to 25 percent of the volume of solids in
the hydrated paste In contrast to the C-S-H the
calcium hydroxide is a compound with a definite
stoichiometry 化學計量學 Ca(OH)2
It tends to form large crystals with a distinctive
hexagonal-prism morphology The morphology usually
varies from nondescript to stacks of large plates and
is affected by the available space temperature of
hydration and impurities present in the system
Calcium hydroxide
Compared with C-S-H the strength-contributing
potential of calcium hydroxide due to van der Waals
forces is limited as a result of a considerably lower
surface area
Also the presence of a considerable amount of
calcium hydroxide in hydrated portland cement has
an adverse effect on chemical durability to acidic
solutions because of the higher solubility of calcium
hydroxide than C-S-H
Mono-Sulfoaluminate hellip Ettringite
Ettringite
Calcium sulfoaluminates
Calcium sulfoaluminate compounds occupy 15 to 20
percent of the solids volume in the hydrated paste
and therefore play only a minor role in the structure-
property relationships
It has already been stated that during the early
stages of hydration the sulfatealumina ionic ratio of
the solution phase generally favors the formation of
trisulfate hydrate C6AS3H32 also called ettringite
which forms needle-shaped prismatic crystals
Reaction rate C3A gt C3S gt C4AF gtC2S
Heat of hydration (Calg)
Compound 3 days 90 days 13 years
C3S 58 104 122
C2S 12 42 59
C3A 212 311 324
C4AF 69 98 102
Three-phase theory-Transition zone
Three-phase theory-Transition zone
A thin shell layer (10-50 μm thick) around large aggregate
Formation Water films around large aggregate during mixing
Characteristic Larger CH crystals more porous framework relatively weak1048711 1048711
Transition Zone
Miexhta and Monteiro Concrete
Transition zone -Influence on concrete properties
Fraction of transition zone in size is much smaller than other two phases its influence on concrete properties is far greater ndash It lower the strength ndash It increase the permeability ndash It prompt non-linear behavior ndash It favorites crack formation
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-
STRUCTURE OF HYDRATED CEMENT PASTE
Anhydrous portland cement is a gray powder that consists of angular particles typically in the size range 1 to 50 μm
It is produced by pulverizing a clinker with a small amount of calcium sulfate the clinker being a heterogeneous mixture of several minerals produced by high temperature reactions between calcium oxide and silica alumina and iron oxide
STRUCTURE OF HYDRATED CEMENT PASTE
The chemical composition of the principal
clinker minerals coresponds approximately
to C3S C2S C3A and C4AF in ordinary
portland cement their respective amounts
usually range between 45 and 60 15 and 30
6 and 12 and 6 and 8 percent
Setting ndash Solidification of the plastic cement paste
bullInitial set ndash beginning of solidification ndash Paste become unworkable ndash loss in consistency - not lt 45 min
bullFinal set ndash Time taken to solidify completely ndash Not gt 375min
Hardening ndash Strength gain with time ndash after final set
Hydration process
Crystal formation of Cement
Calcium silicate hydrate
The calcium silicate hydrate phase abbreviated C-S-
H makes up 50 to 60 percent of the volume of solids
in a completely hydrated portland cement paste and
is therefore the most important in determining the
properties of the paste
The fact that the term C-S-H is hyphenated signifies
that C-S-H is not a well-defined compound the CS
ratio varies between 15 to 20 and the structural
water content varies even more
Calcium silicate hydrate
The morphology of C-S-H also varies from poorly crystalline fibers to reticular network Due to their colloidal dimensions and a tendency to cluster C-S-H crystals could only be resolved with the advent of electron microscopy
Although the exact structure of C-S-H is not known several models have been proposed to explain the properties of the materials According to the Powers-Brunauer model the material has a layer structure with a very high surface area
Calcium hydroxide
Calcium hydroxide crystals (also called portlandite)
constitute 20 to 25 percent of the volume of solids in
the hydrated paste In contrast to the C-S-H the
calcium hydroxide is a compound with a definite
stoichiometry 化學計量學 Ca(OH)2
It tends to form large crystals with a distinctive
hexagonal-prism morphology The morphology usually
varies from nondescript to stacks of large plates and
is affected by the available space temperature of
hydration and impurities present in the system
Calcium hydroxide
Compared with C-S-H the strength-contributing
potential of calcium hydroxide due to van der Waals
forces is limited as a result of a considerably lower
surface area
Also the presence of a considerable amount of
calcium hydroxide in hydrated portland cement has
an adverse effect on chemical durability to acidic
solutions because of the higher solubility of calcium
hydroxide than C-S-H
Mono-Sulfoaluminate hellip Ettringite
Ettringite
Calcium sulfoaluminates
Calcium sulfoaluminate compounds occupy 15 to 20
percent of the solids volume in the hydrated paste
and therefore play only a minor role in the structure-
property relationships
It has already been stated that during the early
stages of hydration the sulfatealumina ionic ratio of
the solution phase generally favors the formation of
trisulfate hydrate C6AS3H32 also called ettringite
which forms needle-shaped prismatic crystals
Reaction rate C3A gt C3S gt C4AF gtC2S
Heat of hydration (Calg)
Compound 3 days 90 days 13 years
C3S 58 104 122
C2S 12 42 59
C3A 212 311 324
C4AF 69 98 102
Three-phase theory-Transition zone
Three-phase theory-Transition zone
A thin shell layer (10-50 μm thick) around large aggregate
Formation Water films around large aggregate during mixing
Characteristic Larger CH crystals more porous framework relatively weak1048711 1048711
Transition Zone
Miexhta and Monteiro Concrete
Transition zone -Influence on concrete properties
Fraction of transition zone in size is much smaller than other two phases its influence on concrete properties is far greater ndash It lower the strength ndash It increase the permeability ndash It prompt non-linear behavior ndash It favorites crack formation
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-
STRUCTURE OF HYDRATED CEMENT PASTE
The chemical composition of the principal
clinker minerals coresponds approximately
to C3S C2S C3A and C4AF in ordinary
portland cement their respective amounts
usually range between 45 and 60 15 and 30
6 and 12 and 6 and 8 percent
Setting ndash Solidification of the plastic cement paste
bullInitial set ndash beginning of solidification ndash Paste become unworkable ndash loss in consistency - not lt 45 min
bullFinal set ndash Time taken to solidify completely ndash Not gt 375min
Hardening ndash Strength gain with time ndash after final set
Hydration process
Crystal formation of Cement
Calcium silicate hydrate
The calcium silicate hydrate phase abbreviated C-S-
H makes up 50 to 60 percent of the volume of solids
in a completely hydrated portland cement paste and
is therefore the most important in determining the
properties of the paste
The fact that the term C-S-H is hyphenated signifies
that C-S-H is not a well-defined compound the CS
ratio varies between 15 to 20 and the structural
water content varies even more
Calcium silicate hydrate
The morphology of C-S-H also varies from poorly crystalline fibers to reticular network Due to their colloidal dimensions and a tendency to cluster C-S-H crystals could only be resolved with the advent of electron microscopy
Although the exact structure of C-S-H is not known several models have been proposed to explain the properties of the materials According to the Powers-Brunauer model the material has a layer structure with a very high surface area
Calcium hydroxide
Calcium hydroxide crystals (also called portlandite)
constitute 20 to 25 percent of the volume of solids in
the hydrated paste In contrast to the C-S-H the
calcium hydroxide is a compound with a definite
stoichiometry 化學計量學 Ca(OH)2
It tends to form large crystals with a distinctive
hexagonal-prism morphology The morphology usually
varies from nondescript to stacks of large plates and
is affected by the available space temperature of
hydration and impurities present in the system
Calcium hydroxide
Compared with C-S-H the strength-contributing
potential of calcium hydroxide due to van der Waals
forces is limited as a result of a considerably lower
surface area
Also the presence of a considerable amount of
calcium hydroxide in hydrated portland cement has
an adverse effect on chemical durability to acidic
solutions because of the higher solubility of calcium
hydroxide than C-S-H
Mono-Sulfoaluminate hellip Ettringite
Ettringite
Calcium sulfoaluminates
Calcium sulfoaluminate compounds occupy 15 to 20
percent of the solids volume in the hydrated paste
and therefore play only a minor role in the structure-
property relationships
It has already been stated that during the early
stages of hydration the sulfatealumina ionic ratio of
the solution phase generally favors the formation of
trisulfate hydrate C6AS3H32 also called ettringite
which forms needle-shaped prismatic crystals
Reaction rate C3A gt C3S gt C4AF gtC2S
Heat of hydration (Calg)
Compound 3 days 90 days 13 years
C3S 58 104 122
C2S 12 42 59
C3A 212 311 324
C4AF 69 98 102
Three-phase theory-Transition zone
Three-phase theory-Transition zone
A thin shell layer (10-50 μm thick) around large aggregate
Formation Water films around large aggregate during mixing
Characteristic Larger CH crystals more porous framework relatively weak1048711 1048711
Transition Zone
Miexhta and Monteiro Concrete
Transition zone -Influence on concrete properties
Fraction of transition zone in size is much smaller than other two phases its influence on concrete properties is far greater ndash It lower the strength ndash It increase the permeability ndash It prompt non-linear behavior ndash It favorites crack formation
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-
Setting ndash Solidification of the plastic cement paste
bullInitial set ndash beginning of solidification ndash Paste become unworkable ndash loss in consistency - not lt 45 min
bullFinal set ndash Time taken to solidify completely ndash Not gt 375min
Hardening ndash Strength gain with time ndash after final set
Hydration process
Crystal formation of Cement
Calcium silicate hydrate
The calcium silicate hydrate phase abbreviated C-S-
H makes up 50 to 60 percent of the volume of solids
in a completely hydrated portland cement paste and
is therefore the most important in determining the
properties of the paste
The fact that the term C-S-H is hyphenated signifies
that C-S-H is not a well-defined compound the CS
ratio varies between 15 to 20 and the structural
water content varies even more
Calcium silicate hydrate
The morphology of C-S-H also varies from poorly crystalline fibers to reticular network Due to their colloidal dimensions and a tendency to cluster C-S-H crystals could only be resolved with the advent of electron microscopy
Although the exact structure of C-S-H is not known several models have been proposed to explain the properties of the materials According to the Powers-Brunauer model the material has a layer structure with a very high surface area
Calcium hydroxide
Calcium hydroxide crystals (also called portlandite)
constitute 20 to 25 percent of the volume of solids in
the hydrated paste In contrast to the C-S-H the
calcium hydroxide is a compound with a definite
stoichiometry 化學計量學 Ca(OH)2
It tends to form large crystals with a distinctive
hexagonal-prism morphology The morphology usually
varies from nondescript to stacks of large plates and
is affected by the available space temperature of
hydration and impurities present in the system
Calcium hydroxide
Compared with C-S-H the strength-contributing
potential of calcium hydroxide due to van der Waals
forces is limited as a result of a considerably lower
surface area
Also the presence of a considerable amount of
calcium hydroxide in hydrated portland cement has
an adverse effect on chemical durability to acidic
solutions because of the higher solubility of calcium
hydroxide than C-S-H
Mono-Sulfoaluminate hellip Ettringite
Ettringite
Calcium sulfoaluminates
Calcium sulfoaluminate compounds occupy 15 to 20
percent of the solids volume in the hydrated paste
and therefore play only a minor role in the structure-
property relationships
It has already been stated that during the early
stages of hydration the sulfatealumina ionic ratio of
the solution phase generally favors the formation of
trisulfate hydrate C6AS3H32 also called ettringite
which forms needle-shaped prismatic crystals
Reaction rate C3A gt C3S gt C4AF gtC2S
Heat of hydration (Calg)
Compound 3 days 90 days 13 years
C3S 58 104 122
C2S 12 42 59
C3A 212 311 324
C4AF 69 98 102
Three-phase theory-Transition zone
Three-phase theory-Transition zone
A thin shell layer (10-50 μm thick) around large aggregate
Formation Water films around large aggregate during mixing
Characteristic Larger CH crystals more porous framework relatively weak1048711 1048711
Transition Zone
Miexhta and Monteiro Concrete
Transition zone -Influence on concrete properties
Fraction of transition zone in size is much smaller than other two phases its influence on concrete properties is far greater ndash It lower the strength ndash It increase the permeability ndash It prompt non-linear behavior ndash It favorites crack formation
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-
Crystal formation of Cement
Calcium silicate hydrate
The calcium silicate hydrate phase abbreviated C-S-
H makes up 50 to 60 percent of the volume of solids
in a completely hydrated portland cement paste and
is therefore the most important in determining the
properties of the paste
The fact that the term C-S-H is hyphenated signifies
that C-S-H is not a well-defined compound the CS
ratio varies between 15 to 20 and the structural
water content varies even more
Calcium silicate hydrate
The morphology of C-S-H also varies from poorly crystalline fibers to reticular network Due to their colloidal dimensions and a tendency to cluster C-S-H crystals could only be resolved with the advent of electron microscopy
Although the exact structure of C-S-H is not known several models have been proposed to explain the properties of the materials According to the Powers-Brunauer model the material has a layer structure with a very high surface area
Calcium hydroxide
Calcium hydroxide crystals (also called portlandite)
constitute 20 to 25 percent of the volume of solids in
the hydrated paste In contrast to the C-S-H the
calcium hydroxide is a compound with a definite
stoichiometry 化學計量學 Ca(OH)2
It tends to form large crystals with a distinctive
hexagonal-prism morphology The morphology usually
varies from nondescript to stacks of large plates and
is affected by the available space temperature of
hydration and impurities present in the system
Calcium hydroxide
Compared with C-S-H the strength-contributing
potential of calcium hydroxide due to van der Waals
forces is limited as a result of a considerably lower
surface area
Also the presence of a considerable amount of
calcium hydroxide in hydrated portland cement has
an adverse effect on chemical durability to acidic
solutions because of the higher solubility of calcium
hydroxide than C-S-H
Mono-Sulfoaluminate hellip Ettringite
Ettringite
Calcium sulfoaluminates
Calcium sulfoaluminate compounds occupy 15 to 20
percent of the solids volume in the hydrated paste
and therefore play only a minor role in the structure-
property relationships
It has already been stated that during the early
stages of hydration the sulfatealumina ionic ratio of
the solution phase generally favors the formation of
trisulfate hydrate C6AS3H32 also called ettringite
which forms needle-shaped prismatic crystals
Reaction rate C3A gt C3S gt C4AF gtC2S
Heat of hydration (Calg)
Compound 3 days 90 days 13 years
C3S 58 104 122
C2S 12 42 59
C3A 212 311 324
C4AF 69 98 102
Three-phase theory-Transition zone
Three-phase theory-Transition zone
A thin shell layer (10-50 μm thick) around large aggregate
Formation Water films around large aggregate during mixing
Characteristic Larger CH crystals more porous framework relatively weak1048711 1048711
Transition Zone
Miexhta and Monteiro Concrete
Transition zone -Influence on concrete properties
Fraction of transition zone in size is much smaller than other two phases its influence on concrete properties is far greater ndash It lower the strength ndash It increase the permeability ndash It prompt non-linear behavior ndash It favorites crack formation
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-
Calcium silicate hydrate
The calcium silicate hydrate phase abbreviated C-S-
H makes up 50 to 60 percent of the volume of solids
in a completely hydrated portland cement paste and
is therefore the most important in determining the
properties of the paste
The fact that the term C-S-H is hyphenated signifies
that C-S-H is not a well-defined compound the CS
ratio varies between 15 to 20 and the structural
water content varies even more
Calcium silicate hydrate
The morphology of C-S-H also varies from poorly crystalline fibers to reticular network Due to their colloidal dimensions and a tendency to cluster C-S-H crystals could only be resolved with the advent of electron microscopy
Although the exact structure of C-S-H is not known several models have been proposed to explain the properties of the materials According to the Powers-Brunauer model the material has a layer structure with a very high surface area
Calcium hydroxide
Calcium hydroxide crystals (also called portlandite)
constitute 20 to 25 percent of the volume of solids in
the hydrated paste In contrast to the C-S-H the
calcium hydroxide is a compound with a definite
stoichiometry 化學計量學 Ca(OH)2
It tends to form large crystals with a distinctive
hexagonal-prism morphology The morphology usually
varies from nondescript to stacks of large plates and
is affected by the available space temperature of
hydration and impurities present in the system
Calcium hydroxide
Compared with C-S-H the strength-contributing
potential of calcium hydroxide due to van der Waals
forces is limited as a result of a considerably lower
surface area
Also the presence of a considerable amount of
calcium hydroxide in hydrated portland cement has
an adverse effect on chemical durability to acidic
solutions because of the higher solubility of calcium
hydroxide than C-S-H
Mono-Sulfoaluminate hellip Ettringite
Ettringite
Calcium sulfoaluminates
Calcium sulfoaluminate compounds occupy 15 to 20
percent of the solids volume in the hydrated paste
and therefore play only a minor role in the structure-
property relationships
It has already been stated that during the early
stages of hydration the sulfatealumina ionic ratio of
the solution phase generally favors the formation of
trisulfate hydrate C6AS3H32 also called ettringite
which forms needle-shaped prismatic crystals
Reaction rate C3A gt C3S gt C4AF gtC2S
Heat of hydration (Calg)
Compound 3 days 90 days 13 years
C3S 58 104 122
C2S 12 42 59
C3A 212 311 324
C4AF 69 98 102
Three-phase theory-Transition zone
Three-phase theory-Transition zone
A thin shell layer (10-50 μm thick) around large aggregate
Formation Water films around large aggregate during mixing
Characteristic Larger CH crystals more porous framework relatively weak1048711 1048711
Transition Zone
Miexhta and Monteiro Concrete
Transition zone -Influence on concrete properties
Fraction of transition zone in size is much smaller than other two phases its influence on concrete properties is far greater ndash It lower the strength ndash It increase the permeability ndash It prompt non-linear behavior ndash It favorites crack formation
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-
Calcium silicate hydrate
The morphology of C-S-H also varies from poorly crystalline fibers to reticular network Due to their colloidal dimensions and a tendency to cluster C-S-H crystals could only be resolved with the advent of electron microscopy
Although the exact structure of C-S-H is not known several models have been proposed to explain the properties of the materials According to the Powers-Brunauer model the material has a layer structure with a very high surface area
Calcium hydroxide
Calcium hydroxide crystals (also called portlandite)
constitute 20 to 25 percent of the volume of solids in
the hydrated paste In contrast to the C-S-H the
calcium hydroxide is a compound with a definite
stoichiometry 化學計量學 Ca(OH)2
It tends to form large crystals with a distinctive
hexagonal-prism morphology The morphology usually
varies from nondescript to stacks of large plates and
is affected by the available space temperature of
hydration and impurities present in the system
Calcium hydroxide
Compared with C-S-H the strength-contributing
potential of calcium hydroxide due to van der Waals
forces is limited as a result of a considerably lower
surface area
Also the presence of a considerable amount of
calcium hydroxide in hydrated portland cement has
an adverse effect on chemical durability to acidic
solutions because of the higher solubility of calcium
hydroxide than C-S-H
Mono-Sulfoaluminate hellip Ettringite
Ettringite
Calcium sulfoaluminates
Calcium sulfoaluminate compounds occupy 15 to 20
percent of the solids volume in the hydrated paste
and therefore play only a minor role in the structure-
property relationships
It has already been stated that during the early
stages of hydration the sulfatealumina ionic ratio of
the solution phase generally favors the formation of
trisulfate hydrate C6AS3H32 also called ettringite
which forms needle-shaped prismatic crystals
Reaction rate C3A gt C3S gt C4AF gtC2S
Heat of hydration (Calg)
Compound 3 days 90 days 13 years
C3S 58 104 122
C2S 12 42 59
C3A 212 311 324
C4AF 69 98 102
Three-phase theory-Transition zone
Three-phase theory-Transition zone
A thin shell layer (10-50 μm thick) around large aggregate
Formation Water films around large aggregate during mixing
Characteristic Larger CH crystals more porous framework relatively weak1048711 1048711
Transition Zone
Miexhta and Monteiro Concrete
Transition zone -Influence on concrete properties
Fraction of transition zone in size is much smaller than other two phases its influence on concrete properties is far greater ndash It lower the strength ndash It increase the permeability ndash It prompt non-linear behavior ndash It favorites crack formation
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-
Calcium hydroxide
Calcium hydroxide crystals (also called portlandite)
constitute 20 to 25 percent of the volume of solids in
the hydrated paste In contrast to the C-S-H the
calcium hydroxide is a compound with a definite
stoichiometry 化學計量學 Ca(OH)2
It tends to form large crystals with a distinctive
hexagonal-prism morphology The morphology usually
varies from nondescript to stacks of large plates and
is affected by the available space temperature of
hydration and impurities present in the system
Calcium hydroxide
Compared with C-S-H the strength-contributing
potential of calcium hydroxide due to van der Waals
forces is limited as a result of a considerably lower
surface area
Also the presence of a considerable amount of
calcium hydroxide in hydrated portland cement has
an adverse effect on chemical durability to acidic
solutions because of the higher solubility of calcium
hydroxide than C-S-H
Mono-Sulfoaluminate hellip Ettringite
Ettringite
Calcium sulfoaluminates
Calcium sulfoaluminate compounds occupy 15 to 20
percent of the solids volume in the hydrated paste
and therefore play only a minor role in the structure-
property relationships
It has already been stated that during the early
stages of hydration the sulfatealumina ionic ratio of
the solution phase generally favors the formation of
trisulfate hydrate C6AS3H32 also called ettringite
which forms needle-shaped prismatic crystals
Reaction rate C3A gt C3S gt C4AF gtC2S
Heat of hydration (Calg)
Compound 3 days 90 days 13 years
C3S 58 104 122
C2S 12 42 59
C3A 212 311 324
C4AF 69 98 102
Three-phase theory-Transition zone
Three-phase theory-Transition zone
A thin shell layer (10-50 μm thick) around large aggregate
Formation Water films around large aggregate during mixing
Characteristic Larger CH crystals more porous framework relatively weak1048711 1048711
Transition Zone
Miexhta and Monteiro Concrete
Transition zone -Influence on concrete properties
Fraction of transition zone in size is much smaller than other two phases its influence on concrete properties is far greater ndash It lower the strength ndash It increase the permeability ndash It prompt non-linear behavior ndash It favorites crack formation
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-
Calcium hydroxide
Compared with C-S-H the strength-contributing
potential of calcium hydroxide due to van der Waals
forces is limited as a result of a considerably lower
surface area
Also the presence of a considerable amount of
calcium hydroxide in hydrated portland cement has
an adverse effect on chemical durability to acidic
solutions because of the higher solubility of calcium
hydroxide than C-S-H
Mono-Sulfoaluminate hellip Ettringite
Ettringite
Calcium sulfoaluminates
Calcium sulfoaluminate compounds occupy 15 to 20
percent of the solids volume in the hydrated paste
and therefore play only a minor role in the structure-
property relationships
It has already been stated that during the early
stages of hydration the sulfatealumina ionic ratio of
the solution phase generally favors the formation of
trisulfate hydrate C6AS3H32 also called ettringite
which forms needle-shaped prismatic crystals
Reaction rate C3A gt C3S gt C4AF gtC2S
Heat of hydration (Calg)
Compound 3 days 90 days 13 years
C3S 58 104 122
C2S 12 42 59
C3A 212 311 324
C4AF 69 98 102
Three-phase theory-Transition zone
Three-phase theory-Transition zone
A thin shell layer (10-50 μm thick) around large aggregate
Formation Water films around large aggregate during mixing
Characteristic Larger CH crystals more porous framework relatively weak1048711 1048711
Transition Zone
Miexhta and Monteiro Concrete
Transition zone -Influence on concrete properties
Fraction of transition zone in size is much smaller than other two phases its influence on concrete properties is far greater ndash It lower the strength ndash It increase the permeability ndash It prompt non-linear behavior ndash It favorites crack formation
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-
Mono-Sulfoaluminate hellip Ettringite
Ettringite
Calcium sulfoaluminates
Calcium sulfoaluminate compounds occupy 15 to 20
percent of the solids volume in the hydrated paste
and therefore play only a minor role in the structure-
property relationships
It has already been stated that during the early
stages of hydration the sulfatealumina ionic ratio of
the solution phase generally favors the formation of
trisulfate hydrate C6AS3H32 also called ettringite
which forms needle-shaped prismatic crystals
Reaction rate C3A gt C3S gt C4AF gtC2S
Heat of hydration (Calg)
Compound 3 days 90 days 13 years
C3S 58 104 122
C2S 12 42 59
C3A 212 311 324
C4AF 69 98 102
Three-phase theory-Transition zone
Three-phase theory-Transition zone
A thin shell layer (10-50 μm thick) around large aggregate
Formation Water films around large aggregate during mixing
Characteristic Larger CH crystals more porous framework relatively weak1048711 1048711
Transition Zone
Miexhta and Monteiro Concrete
Transition zone -Influence on concrete properties
Fraction of transition zone in size is much smaller than other two phases its influence on concrete properties is far greater ndash It lower the strength ndash It increase the permeability ndash It prompt non-linear behavior ndash It favorites crack formation
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-
Ettringite
Calcium sulfoaluminates
Calcium sulfoaluminate compounds occupy 15 to 20
percent of the solids volume in the hydrated paste
and therefore play only a minor role in the structure-
property relationships
It has already been stated that during the early
stages of hydration the sulfatealumina ionic ratio of
the solution phase generally favors the formation of
trisulfate hydrate C6AS3H32 also called ettringite
which forms needle-shaped prismatic crystals
Reaction rate C3A gt C3S gt C4AF gtC2S
Heat of hydration (Calg)
Compound 3 days 90 days 13 years
C3S 58 104 122
C2S 12 42 59
C3A 212 311 324
C4AF 69 98 102
Three-phase theory-Transition zone
Three-phase theory-Transition zone
A thin shell layer (10-50 μm thick) around large aggregate
Formation Water films around large aggregate during mixing
Characteristic Larger CH crystals more porous framework relatively weak1048711 1048711
Transition Zone
Miexhta and Monteiro Concrete
Transition zone -Influence on concrete properties
Fraction of transition zone in size is much smaller than other two phases its influence on concrete properties is far greater ndash It lower the strength ndash It increase the permeability ndash It prompt non-linear behavior ndash It favorites crack formation
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-
Calcium sulfoaluminates
Calcium sulfoaluminate compounds occupy 15 to 20
percent of the solids volume in the hydrated paste
and therefore play only a minor role in the structure-
property relationships
It has already been stated that during the early
stages of hydration the sulfatealumina ionic ratio of
the solution phase generally favors the formation of
trisulfate hydrate C6AS3H32 also called ettringite
which forms needle-shaped prismatic crystals
Reaction rate C3A gt C3S gt C4AF gtC2S
Heat of hydration (Calg)
Compound 3 days 90 days 13 years
C3S 58 104 122
C2S 12 42 59
C3A 212 311 324
C4AF 69 98 102
Three-phase theory-Transition zone
Three-phase theory-Transition zone
A thin shell layer (10-50 μm thick) around large aggregate
Formation Water films around large aggregate during mixing
Characteristic Larger CH crystals more porous framework relatively weak1048711 1048711
Transition Zone
Miexhta and Monteiro Concrete
Transition zone -Influence on concrete properties
Fraction of transition zone in size is much smaller than other two phases its influence on concrete properties is far greater ndash It lower the strength ndash It increase the permeability ndash It prompt non-linear behavior ndash It favorites crack formation
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-
Reaction rate C3A gt C3S gt C4AF gtC2S
Heat of hydration (Calg)
Compound 3 days 90 days 13 years
C3S 58 104 122
C2S 12 42 59
C3A 212 311 324
C4AF 69 98 102
Three-phase theory-Transition zone
Three-phase theory-Transition zone
A thin shell layer (10-50 μm thick) around large aggregate
Formation Water films around large aggregate during mixing
Characteristic Larger CH crystals more porous framework relatively weak1048711 1048711
Transition Zone
Miexhta and Monteiro Concrete
Transition zone -Influence on concrete properties
Fraction of transition zone in size is much smaller than other two phases its influence on concrete properties is far greater ndash It lower the strength ndash It increase the permeability ndash It prompt non-linear behavior ndash It favorites crack formation
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-
Heat of hydration (Calg)
Compound 3 days 90 days 13 years
C3S 58 104 122
C2S 12 42 59
C3A 212 311 324
C4AF 69 98 102
Three-phase theory-Transition zone
Three-phase theory-Transition zone
A thin shell layer (10-50 μm thick) around large aggregate
Formation Water films around large aggregate during mixing
Characteristic Larger CH crystals more porous framework relatively weak1048711 1048711
Transition Zone
Miexhta and Monteiro Concrete
Transition zone -Influence on concrete properties
Fraction of transition zone in size is much smaller than other two phases its influence on concrete properties is far greater ndash It lower the strength ndash It increase the permeability ndash It prompt non-linear behavior ndash It favorites crack formation
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-
Three-phase theory-Transition zone
Three-phase theory-Transition zone
A thin shell layer (10-50 μm thick) around large aggregate
Formation Water films around large aggregate during mixing
Characteristic Larger CH crystals more porous framework relatively weak1048711 1048711
Transition Zone
Miexhta and Monteiro Concrete
Transition zone -Influence on concrete properties
Fraction of transition zone in size is much smaller than other two phases its influence on concrete properties is far greater ndash It lower the strength ndash It increase the permeability ndash It prompt non-linear behavior ndash It favorites crack formation
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-
Three-phase theory-Transition zone
A thin shell layer (10-50 μm thick) around large aggregate
Formation Water films around large aggregate during mixing
Characteristic Larger CH crystals more porous framework relatively weak1048711 1048711
Transition Zone
Miexhta and Monteiro Concrete
Transition zone -Influence on concrete properties
Fraction of transition zone in size is much smaller than other two phases its influence on concrete properties is far greater ndash It lower the strength ndash It increase the permeability ndash It prompt non-linear behavior ndash It favorites crack formation
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-
Transition Zone
Miexhta and Monteiro Concrete
Transition zone -Influence on concrete properties
Fraction of transition zone in size is much smaller than other two phases its influence on concrete properties is far greater ndash It lower the strength ndash It increase the permeability ndash It prompt non-linear behavior ndash It favorites crack formation
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-
Transition zone -Influence on concrete properties
Fraction of transition zone in size is much smaller than other two phases its influence on concrete properties is far greater ndash It lower the strength ndash It increase the permeability ndash It prompt non-linear behavior ndash It favorites crack formation
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-
Microstructural improvement
Use of silica fume
ndash reduce the porosity of the ITZ geometrical effect
(no space) reduces the amount of CH due to
pozzolanic reaction
- Slide 1
- DEFINITIONS
- Modern electron microscopes
- SIGNIFICANCE
- COMPLEXITIES
- Macroscopic level
- Microscopic level
- Slide 8
- 混凝土之微結構
- Three-phase theory
- THREE PHASES OF CONCRETE
- STRUCTURE OF THE AGGREGATE PHASE
- AGGREGATE PHASE
- Aggregate particles
- STRUCTURE OF HYDRATED CEMENT PASTE
- Slide 16
- Slide 17
- Crystal formation of Cement
- Calcium silicate hydrate
- Slide 20
- Calcium hydroxide
- Slide 22
- Mono-Sulfoaluminate hellip Ettringite
- Ettringite
- Calcium sulfoaluminates
- Slide 26
- Slide 27
- Slide 28
- Three-phase theory -Transition zone
- Three-phase theory -Transition zone
- Transition Zone
- Transition zone -Influence on concrete properties
- Microstructural improvement
-