a comparative study of thermal and mechanical properties ...€¦ · médéa university - algeria...

A comparative study of thermal and mechanical properties of two composites with mineral matrix

and vegetable fibres for use in the field of construction

by

Mohamed Bentchikou

Médéa University - AlgeriaLaboratory of Biomaterials and Transport Phenomena

Médéa UniversitY

1

Workshop « Review of Geopolymers 17 – 21st of October 2011

Introduction (cont...)

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Why this combination of materials with different pr operties Why this combination of materials with different pr operties ??

CEMENT (MINERAL MATRIX ) and CELLULOSE FIBRES(Strength, High density and (Weakness, Lightweight and

High thermal conductivity) Low thermal conductivity)

Lightweight Compositewith

low conductivity and Acceptable strength Insulated material

Construction material

What has been done in this work

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Raw Materials

• Cement : CEM I 42.5 N (Normo 4) SN EN 197-1 (European standards)

• Fibres : waste papers and packages

Selection by sievingFine separate (Ф<1.25mm)

Coarse agglomerates

(1.25<Ф< 5 mm)

Cement paste (0% fibre) with W/C = 0.36 : Reference

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l = 1.2 l = 1.2 ÷÷ 1.7 mm1.7 mmФФ = 20 = 20 ÷÷ 4040 µµmm

• Crushed ceramic bricks : 0 ÷ 5mm

Raw Materials (cont...)

Fibres

Kinetic of absorption water by fibres

5Mh: humid mass of fibres sampleMs : dry mass of fibres sample

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Cement paste (Reference 0 %)

W/C = 0.36

Composite with X % of fibres

W/C = f (% en fibres)

Necessary water

W/C versus fibres content

C

.%35%)0(Wfibres

m+=

Concentration (%) 0 4 8 10 16

W/CComposite 1 ( binary ) 0.36 0.4 0.52 0.56 0.68

Composite 2 ( ternary ) 0.51 0.59 - 0.83 0.99

Results

Physical Characteristics of the compositesApparent Bulk density

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0

500

1000

1500

2000

2500

0 2 4 6 8 10 12 14 16 18

Bul

k de

nsity

(kg/

m3 )

Fibres Concentration (%)

Composite 1 - Binary

Composite 2 - Ternary

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Ref 2 Bentchikou M, Hanini S, Silhadi K, Guidoum A (2007) : Elaboration et étude d’un mortier composite à matrice minérale et fibres cellulosiques : application à l’isolation thermique en bâtiment. Can. J. Civ. Eng. 34: 37- 45.

Ref 3 and 4 Khedari J, Suttisonk B, Pratinthong N and Hirunlabh J (2001): Newlightweight composite construction materials with low thermal conductivity, Cement & Concrete Composites. 23, 65-70.

Apparent Bulk density (Cont…)

Physical Characteristics of materials

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Specific Heat / volumetric heat transfer coefficien t

Fiber content (%) 0 4 10 16

composite 1(Binary)

Specific Heat (J/kg. °C) 990 1030 1080 1130

volumetric heat transfer coefficient (J/m3. °C) 1.9305 1.7716 1.4796 1.1639

composite 2(Ternary)

Specific Heat (J/kg. °C) 910 990 1020 1041

volumetric heat transfer coefficient (J/m3. °C) 1.778 1.679 1.475 1.310

• Trend• For the Ternary , this increase is little be more slowly than for the Binary•Specific heat, compared with volumetric heat transfer coefficient) :

opposite tendency is observed

Ternary composite store more energy than the Binary one

Physical Characteristics of materials (cont...)

10

22

24

26

28

30

32

34

36

0 50 100 150 200 250 300

Tem

pératu

re (

°C

)

Time (min)

T1/6 °C

T1/2 °C

T2/3 °C

Even Period Odd Period

2

24PLS

BRCπ

ρλ+

=

λλ2

2/

2 2cosh

4

−==L

BA

T

TTar

L

SBh

P

L

L/3

L/2

L/6

A BSample

Acquisition centre(Data logger)

Alimentation and regulation unit

Design of device for Design of device for experimentalexperimental tests of thermal conductivitytests of thermal conductivity

………………..

Physical Characteristics of materials (cont...)

Physical Characteristics of materials (cont...)

Apparent thermal conductivity

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0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

0 5 10 15 20

Fibres concentration (%)

The

rmal

Con

duct

ivity

(W

/m°C

)

Composite 2 - Ternary

Composite 1 - Binary

Flexural Strength

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Mechanical Characteristics of materials (cont...)

Compressive Strength

13

0

20

40

60

80

100

0 5 10 15 20

Com

pre

ssiv

e s

trength

(M

Pa)

Fibres Content (%)

Composite 1

Composite 2

Mechanical Characteristics of materials (cont...)

Effect of W/C

W/C= 0.64

500µµµµm

W/C= 0.56

500µµµµm

Effect of W/C on the dispersion of fibres in the matrix.

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Mechanical Characteristics of materials (cont...)

Effet of W/C (cont…)

0

5

10

15

20

25

30

0.5 0.6 0.7 0.8

Com

pre

ssiv

e s

trength

(M

pa)

W/C

res compre 1J

res compre 7J

res compre 28J

Concentration (%) 0 2 4 6 8 10 12 14 16

W/C optimum 0.23 0.32 0.41 0.49 0.57 0.66 0.75 0.83 0.92

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Mechanical Characteristics of materials (cont...)

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105 days Curring humide medium

200 µm

Cement paste (0%) Composite with 8% of fibres

200 µm

Composite with 16% of fibres 200 µm

Results (Cont....)

Microstructure changes with fibres content

Hydration rate of cement

hydration rate of cement versus fibres concentration for curing at 20°C and 100% HR (saturated medium)

50

60

70

80

0 2 4 6 8 10

Hyd

rata

tion

rate

(%)

Fibres content (%)

17

30

40

50

60

70

0 2 4 6 8 10H

ydra

tatio

n ra

te (%

)Fibres content (%)

hydration rate of cement versus fibres concentration for curing at 20°C and 50% HR (dry medium)

( ) ( )c

ac

F

FFTH

−=

100%

Results (Cont....)

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Porosity (by SEM):Porosity (by SEM):

Porosity (by MIP):Porosity (by MIP):

Microstructure (Cont…)

Results (Cont....)

Durability Aspects

Carbonation Carbonation

0

20

40

60

80

100

0 2 4 6 8 10 12 14 16 18

Co

mp

ress

ive

Str

eng

th (M

pa)

Fibres Content (%)

carbonated

Not carbonated

Gain >50%

Gain >45%

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�Incorporation of fibres in mineral matrix decrease thermal conductivity.

�Incorporation of fibres in mineral matrix decrease compressive strength but for 16%, the composite is still in the acceptable range for hollow non-load bearing concrete (ASTMC 109/C 109 M-98) .

�The tertiary composite has less strength than the binary for low concentration of fibres but for high fibre content there is no big difference

Conclusion

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�At 16%, the tertiary is less efficient than the binary from insulation efficiency point of view but its capacity of storing Energy is better than that of the binary.

�the carbonation induce amelioration of mechanical strength (50% gain)

Conclusion (cont...)

Projects in progress

- Incorporation of more fibres in the matrix

- Evaluation of thermal conductivity of the composite at ≠ saturation degree

- Composites DURABILITY to wet - Dry cycling

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Projects in future

- Using admixtures to improve strength and finding applications in structure uses,

- Conceive industrial mean for manufacturing the product,

- Application of coating or film for outside applications

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Thank You

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