a comparative study of thermal and mechanical properties ...€¦ · médéa university - algeria...
TRANSCRIPT
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...)
2
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
3
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...)
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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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