performance of concretes made using portland limestone ......restrained ring results • the delay...
TRANSCRIPT
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 1 of 38
Prepared by
T.J. Barrett, H. Sun, L. Barcelo, and
J. Weiss, [email protected]
Prepared for
American Concrete Institute, April 15th, 2013
Purdue University
School of Civil Engineering
Performance of Concretes Made
Using Portland Limestone Cement
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 2 of 38
Outline for PLC Talk
• Motivation: Question What, Why, Who, How (Where)
• What are Potential Consequences
• Previous Shrinkage Study
– Phase I –Clinker #1
– Phase II – Using Added
Limestone
– Phase III – Clinker #2
(4 Clinker study)
• Current Shrinkage Investigation
– Three Systems – OPC, PLC, PLC-S
• Summary
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 3 of 38
Portland Limestone Cement
What is it?
• PLC has been added to current cement specifications ASTM C595/AASHTO M240
– 5 to 15% interground limestone
– Min. CaCO3 content
– Physical requirements same as OPC
– New test requirements MBI and TOC
• Type IL blended cements, Type IT ternary cements
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 4 of 38
PLC – Why Do We Want It?
Cement and CO2 Production
• You will hear cement accounts for
7-8% of global CO2 (Mehta 1998)
• Where is the
CO2 coming from
– Calcination (50)
– Combustion (40)
– Transportation (10)
• Concrete has relatively low
carbon emission per unit;
however widespread use of concrete makes it a
major contributor to manmade CO2 emissions
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 5 of 38
Portland Limestone Cements
Why do we want it?
• Sustainability
– less energy is consumed
– Less CO2 & greenhouse
gases are produced
Sustain-
ability
Sustain-
ability
Reduce
Clinker
Life Cycle
Performance
Reduce
Cement
Content
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 6 of 38
Portland Limestone Cement
Who Has Used This Before?
• Technical information
on use of limestone of
up to 15% (PLC)
Summary of Contents
• environmental benefits
• history of use of
cements with
limestone
• chemical and physical
effects on properties
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 7 of 38
Portland Limestone Cement
How is it Made … In North America
• Similar performance
to OPC is targeted
• PLC is generally
ground finer than OPC
– Overcome dilution
– Higher fineness may
act as a nucleating
agent to increase
early age strengths
– Improve packing
• Higher reaction rates may show benefits of
blending with other supplementary materials
Finer
Cement
Less
Clinker
Time
f’c
28 d
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 8 of 38
Outline for PLC Talk
• Motivation: Question What, Why, Who, How (Where)
• What are Potential Consequences
• Previous Shrinkage Study
– Phase I –Clinker #1
– Phase II – Using Added
Limestone
– Phase III – Clinker #2
(4 Clinker study)
• Current Shrinkage Investigation
– Three Systems – OPC, PLC, PLC-S
• Summary
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 9 of 38
PLC Performance Studies
Matschei et al 2007
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 10 of 38
Fineness and Shrinkage Cracking
• Burrows (1998) – Monogaph
• Bentz, D.P., et al. (2001) ACERS
• Chariton, T., and Weiss, W. J., (2002)
ACI SP – Cracking Data shown
• Several reports say finer
cements crack earlier
• Blaine fineness often used
in these studies however
we are not really after
surface area
• Rather we are after the
space between particles –
pore sizes important
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 11 of 38
Origins of Shrinkage
(Young and Laplace Equation)
Thomas Young (1773 – 1829) Pierre-Simon, marquis de
Laplace (1749 - 1827)
(1805-06)
After Lura et al 2007
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 12 of 38
Shrinkage Concepts (Young-Laplace)
0.001 0.01 0.1 1
Pore Radius (m)
0
40
80
120
160
Cap
illa
ry S
tress (
MP
a) = 0.072 N/m
= 0.036 N/m
Sealed - SRA
Unsealed - Plain Unsealed - SRA
Sealed - LWA
Unsealed - LWA
Sealed - Plain Sealed - SRA
Unsealed - Plain Unsealed - SRA
Sealed - LWA
Unsealed - LWA
Sealed - Plain
0.1 1.0 10.0 100.0 1000.0
Kelvin Radius (nm)
30
40
50
60
70
80
90
100
Rela
tive H
um
idit
y (
%)
= 72 x 10-3 N/m (Plain)
= 36 x 10-3 N/m (~5% SRA)
20 40 60 80 100
Relative Humidity (%)
-5000
-4000
-3000
-2000
-1000
0
Sh
rin
kag
e S
train
()
w/c = 0.30
w/c = 0.30+5%SRA
Menisci Radius (nm)
r1 r1 r2
r3 r3 r4
r
cos2
capillary stress ()
pore geometry (r)
surface tension ()
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 13 of 38
Important Take Aways
• Shrinkage is related to the space between
pores that empty
• Some pores are
more important
– pores less than a
few nm (other effects)
– pores greater than
50 nm (low stress)
• Pore size is related
to the particle size distribution of the cement
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 14 of 38
Important Distinction Between Blaine
Fineness for PLC and OPC Will Be Made
• Example of a PSD
for Cement with
different Blaine
fineness from
Bentz et al. (2001)
• You can notice
that the change in
Blaine fineness (a measure of permeability)
also significantly alters the pore size
distribution (shifting the entire curve)
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 15 of 38
Outline for PLC Talk
• Motivation: Question What, Why, Who, How (Where)
• What are Potential Consequences
• Previous Shrinkage Study
– Phase I –Clinker #1
– Phase II – Using Added
Limestone
– Phase III – Clinker #2
(4 Clinker study)
• Current Shrinkage Investigation
– Three Systems – OPC, PLC, PLC-S
• Summary
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 16 of 38
Bucher et al. (2009a) – Phase I
Commerically Ground Blends
• 0%, 5%, 10% limestone replacement by mass
• 0% limestone, Type I/II, Blaine fineness 382 m2/kg
• 5% limestone, Blend of 0% and 10%
• 10% limestone, Type GU, Blaine fine. 461 m2/kg
• HRWRA
• w/cm = 0.30
• Mortar - 55%
aggregate by
volume
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 17 of 38
Original Ring
• Using an
Instrumented Ring
Restrained Ring Test
0 10 20 30
Time (Days)
-200
0
Ste
el
Str
ain
()
-100
Measured Strain
• Using an
Instrumented Ring
• Measure Strain
that Develops in
Steel
Pres
Determine Pressure
• Using an
Instrumented Ring
• Measure Strain
that Develops in
Steel
• Determine the
Pressure Required
to Obtain that
Strain
Pres
Obtain Stress
• Using an
Instrumented Ring
• Measure Strain
that Develops in
Steel
• Determine the
Pressure Required
to Obtain that
Strain
• Apply Pressure to
Concrete and
Obtain Tensile
Stress
22
22
2
22
2 ICOC
ICOC
OS
ISOSSSteelRrConcrete RR
RR
R
RREtt
IC
Hossain and Weiss, CCC, 2004
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 18 of 38
Restrained Ring Results
• The delay in time to cracking indicates that cements with limestone are slightly more resistant to cracking than plain cement systems.
0 5 10Limestone Content (%)
50
60
70
80
90
100
Tim
e o
f C
rac
kin
g (
Ho
urs
)
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 19 of 38
Shrinkage in Paste
20 30 40 50 60 70 80 90 100Relative Humidity [%]
-5000
-4500
-4000
-3500
-3000
-2500
-2000
-1500
-1000
-500
0S
hri
nk
ag
e []
0% LSTN
5% LSTN
10% LSTN
160 days
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 20 of 38
Phase II (Bucher 2009b) Cement with
Limestone Replacement (Not Interground)
• Bucher et al. (2009) examined how limestone
addition of limestone/replacement of cement
influenced shrinkage & cracking of mortar.
• 3 sizes of limestone were used to replace 10% of
the cement by volume (Unlike Other Phases)
– small 3 micron
– medium 17 micron, and
– large 100 micron
• Note these are not
equivalent performance
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 21 of 38
Phase II (Bucher 2009b) Shrinkage and
Cracking Studies Cement/Limestone
• Fineness
influences
stress
• Fine limestone
was similar
• Binder was
a cement
with additional
limestone of different particle sizes
• Note these are not equivalent performance
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 22 of 38
Phase III – An Additional System
Investigatged (Barrett et al. 2012)
• Used a commercially interground cement
• No increase in cracking tendancy
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 23 of 38
Outline for PLC Talk
• Motivation – The Questions
What, Why, Who, How (Where)
• What are Potential Consequences
• Previous Shrinkage Study
– Phase I –Clinker #1
– Phase II – Using Added Limestone
– Phase III – Clinker #2 (4 Clinker study)
• Current Shrinkage Investigation (IV)
– Three Systems – OPC, PLC, PLC-S
• Summary
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 24 of 38
Phase IV - Objectives
• Shrinkage and cracking potential in 3 systems
• Clinker and limestone interground (industrial)
• w/c = 0.39, mortar with 55% sand volume
OPC
(3.7% L)
PLC
(11% L)
PLC-Slag
(10% L + 12% Slag)
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 25 of 38
Study Outline
• Task 1: Particle Size and Pore
Size Distribution
• Task 2: Chemical Shrinkage
• Task 3: Autogenous Shrinkage
• Task 4: Restrained Shrinkage
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 26 of 38
Particle Size Distribution - Cumulative
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 27 of 38
Pore Size Distribution
1 10 100Kelvin Radius (nm)
0
0.4
0.8
1.2
1.6
2
Dif
fere
nti
al
Po
ros
ity
g o
f w
ate
r /
g o
f o
ve
n d
ry s
am
ple
(%
) OPC
PLC
PLC-slag
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 28 of 38
Study Outline
• Task 1: Particle Size and Pore
Size Distribution
• Task 2: Chemical Shrinkage
• Task 3: Autogenous Shrinkage
• Task 4: Restrained Shrinkage
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 29 of 38
Fundamental Volume Change
• Le Chatelier
• 1850-1936
• Volume of the reactants
larger than the volume
of the products
• Chemical Shrinkage
+ =
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 30 of 38
Chemical Shrinkage
• Observed by Le
Chatelier over a
century ago
• “the volume
reduction associated
with the hydration
reactions in a
cementitious
material”
• Powers conceptual
model shown ~
6.4% reduction
0 20 40 60 80 100
Degree of Hydration (%)
0
20
40
60
80
100
Vo
lum
e (
%)
Hy
dra
tio
n C
eas
es
CapillaryWater
Hydration Product
Gel
HydrationProduct
Solid
Unhydrated Cement
Chemical Shrinkage
(after Powers)
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 31 of 38
Chemical Shrinkage per gram of binder
0 2 4 6 8 10 12
Age of Specimen (Days)
0.00
0.02
0.04
0.06
0.08
Ch
em
ica
l S
hri
nk
ag
e
(Ml/g
of
bin
de
r)
GU OPC
GUL PLC
GULB-S PLC
w/b = 0.34
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 32 of 38
Study Outline
• Task 1: Particle Size and Pore
Size Distribution
• Task 2: Chemical Shrinkage
• Task 3: Autogenous Shrinkage
• Task 4: Restrained Shrinkage
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 33 of 38
0 20 40 60 80 100
Degree of Hydration (%)
0
20
40
60
80
100
Vo
lum
e (
%)
Hy
dra
tio
n C
eas
es
CapillaryWater
Hydration Product
Gel
HydrationProduct
Solid
Unhydrated Cement
Chemical Shrinkage
Measured by External Deformation of a Sealed Body
(after Jensen & Hansen 2001)
Cement
Water (Pore Soln.)
Autogenous strain is “the bulk strain of a closed,
isothermal, cementitious material system not subjected
to external forces Autogenous
Shrinkage
Air
(after Powers)
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 34 of 38
ASTM C 1698 Autogenous Shrinkage
• Autogenous shrinkage (Corrugated Tube)
• OPC and PLC have similar shrinkage
• PLC-S has a slightly lower early shrinkage
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 35 of 38
Study Outline
• Task 1: Particle Size and Pore
Size Distribution
• Task 2: Chemical Shrinkage
• Task 3: Autogenous Shrinkage
• Task 4: Restrained Shrinkage
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 36 of 38
Restrained Shrinkage
• Dual restrained
ring test
• Shows similar
stress
development
and age of
cracking
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 37 of 38
Study Outline - Summary
• Task 1: Particle Size and Pore Size
Distribution
– Less big particles PLC, PLCS
– pores similar as related to shrinkage
• Task 2: Chemical Shrinkage
– Less early age chemical shrinkage
• Task 3: Autogenous Shrinkage
– Lower shrinkage for PLC, PLCS
• Task 4: Restrained Shrinkage
– OPC, PLC, PLCS Similar
-
ACI 2013 Minnesota Developed by Barrett, Sun, Barcelo, and Weiss Slide 38 of 38
Summary
• PLC is not just a dilution of OPC
• PLC, PLC-Slag are engineered differently to
obtain ‘Similar Performance’ (f’c at 28 days)
• Have shown similar or less autogenous
shrinkage and similar or less restrained
shrinkage cracking
• Explained using Young-Laplace equation
showing that the increase in Blaine fineness
does not alter pores in range of interest