Experimental Study of Fabric Reinforced Cement Based Composites under Dynamic Loading Deju ZHU, Barzin MOBASHER Civil and Environmental Engineering, Arizona State University, USA
Alva PELED Structural Eng. Dept., Ben Gurion University, Israel
ACI Fall Convention Pittsburgh, Oct. 24– 28, 2010
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Outline
Introduction Objectives Setup of dynamic tensile testing Specimen preparation and data analysis Failure behavior of composites Conclusions
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Introduction 20 AR Glass Fabric
16 Stress, MPa
•HPFRCC, Strain-hardening behavior •Cases for dynamic loading: • blast explosions, • projectiles, • earthquakes, • fast moving traffic, • wind gusts, wind driven objects, • machine vibrations. •Inherent brittleness and low tensile strength, dynamic loading can cause severe damage. •mechanical properties at high strain rates for analysis of structural components.
GFRC Vf =5%
12
E-Glass Fabric
8 PE Fabric 4
ECC Mortar
0
0
0.01 0.02 0.03 Strain, mm/mm
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0.04
High Speed Testing System at ASU
Servohydraulic system, Speed Up to 14 m/s, Load Capacity: 90 kN load
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High Strain Rate Tensile Test
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Data Processing
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Data Processing
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Data Processing
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Typical Response under high speed Tension
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Videos of AR-Glass Fabric and Composites
AR-Glass Fabric
AR-Glass Composite
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Failure of AR-Glass Composite AR glass composites (plain cement): (a)-(c) multiple microcracking, (d) main crack widening and other micro-cracks closing, (e) complete failure AR glass composites (5%silica fume): (a)-(c) multiple microcracking, (d) main crack widening and other micro-cracks closing, (e) complete failure
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Microstructure of AR-Glass Composite
SEM micrographs of AR glass fabric embedded in cement matrix, side view
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Stress-Strain Curves of AR-Glass Fabric and AR-Glass Composite
Stress, MPa
3000
8
AR Glass Specimen (4 yarns)
AR_Glass_PC 6
2000
4
2
1000
0
0 0
0.02
0.04
Strain, mm/mm
Stress-strain of AR-Glass Fabric
0.06
10 Strain Rate, s-1
Strain Rate, s -1 21 15 17 15
22 21 13 17 23
8
Stress, MPa
Strain Rate, s -1 19 18 22 18 23
Stress, MPa
4000
AR_Glass_SF
6
4
2
0
0
0.004
0.008
0.012
0.016
Strain, mm/mm
0
0.01
0.02
0.03
Strain, mm/mm
Stress-strain of AR-Glass Stress-strain of AR-Glass Composite (plain cement) Composite(5% Silica Fume)
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Videos of PE Fabric and PE Composite
PE Fabric
PE Composite with Silica Fume
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Failure of PE Composite PE composites (5% silica fume): (a)intact, (b-d) developing of multiple cracks, (e) complete failure
PE composites (plain cement): (a) intact, (b) single cracking, (c)-(d) crack widening, (e) complete failure.
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Microstructure of PE Composite
SEM micrographs of PE fabric in the cement matrix and (a) cross section of reinforcing yarn, (b) top view of loop
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Stress-Strain Curves of PE Fabric and PE Composite PE_PC
1.2
Stress, MPa
Stress, MPa
1.6
3
Strain Rate, s -1 26 21 18 26
0.8
Strain Rate, s-1 22 21 22 21 23
2
PE_SF
1 0.4
0
0
0.01
0.02
0.03
Strain, mm/mm
Stress-strain of PE Composite (plain cement)
0.04
0
0
0.05
0.1
0.15
0.2
Strain, mm/mm
Stress-strain of PE Composite (5% Silica Fume)
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0.25
Videos of Carbon Fiber Bundle and Carbon Composite
Carbon Fiber Bundle
Carbon Composite (plain cement)
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Failure of Carbon Composite
Carbon composites: (a)intact, (b) few of cracks visible, (c-e) yarn pullout
Carbon composites (multiple cracking): (a) intact, (b) multiple cracking, (c)-(e) multiple crack widening
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Microstructure of Carbon Composite
SEM micrographs of carbon fiber bundle embedded in cement matrix: (a) view of cross section and (b) side view
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Stress-Strain Curves of Carbon Fiber and Carbon Composite Strain Rate, s-1 17 20 18 17 21
Carbon Fibre Bundle
Stress, MPa
1200
800
20 Strain Rate, s-1 9 11 9
16
Stress, MPa
1600
Carbon Composite
12
8
400
4
0
0 0
0.005
0.01
0.015
0.02
0.025
0
Strain, mm/mm
Stress-Strain of Carbon Fiber Bundle
0.04
0.08
0.12
Strain, mm/mm
Stress-Strain of Carbon Composite
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Comparison of Different Composites 20
20
Carbon Composite Carbon Composite
16 Stress, MPa
Stress, MPa
16 12 8 4
12 8
AR Glass Composite
PE Composite
4
AR Glass Composite PE Composite
0 0
0.02
0.04 0.06 0.08 Strain, mm/mm
0.1
0 0
0.05
0.1 0.15 Strain, mm/mm
0.2
0.25
Comparison of typical stress-strain curves Carbon Composite (plain cement) of different composites (plain cement) AR-glass and PE composites (5% silica fume)
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Summary Tables Table 2- Composites Properties (plain cement) under High Rate Loading
PE
Strain Rate (1/s) 23 (4)
Young’s Modulus (MPa) 140 (24)
Strength (MPa) 1.31(0.17)
Toughness (MPa) 0.016(0.007)
Maximum strain (mm/mm) 0.021(0.007)
AR-Glass Carbon
18(3) 10(1)
1176(323) 2247(463)
5.56(0.51) 17.86(0.82)
0.032(0.009) 1.21(0.14)
0.01(0.002) 0.10(0.014)
Composites
Table 3- Composites Properties (5% silica fume) under High Rate Loading Composites
Strain Rate Young’s Modulus (1/s) (MPa)
Strength (MPa)
Toughness (MPa)
Maximum strain (mm/mm)
PE
22 (1)
156 (15)
2.33(0.28) 0.343(0.101)
0.207(0.04)
AR-Glass
19(4)
919(164)
8.27(0.86) 0.127(0.024)
0.025(0.004)
(the values in parenthesis are standard deviation) Deju Zhu, Alva Peled, Barzin Mobasher. Dynamic Tensile Testing of Fabric-Cement Composites. Construction and Building Materials, 2010, in press.
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Strain Rate Effect on Composites with plain cement
Stress, MPa
1.5
4
(b) PE composite Strain rate = 2.2x10-5 s-1 Strain rate = 23 s-1
1.2
(c) Carbon composite 20 Stress, MPa
(a) AR Glass composite Strain rate = 2.2x10-5 s-1 Strain rate = 18 s-1
6 Stress, MPa
25
1.8
8
0.9 0.6
Strain rate = 2.2x10-5 s-1 Strain rate = 10 s-1
15 10
2
5
0.3 0
0
0.005 0.01 Strain, mm/mm
Composite
PE AR Glass Carbon
Strain Rate (1/s) 23 (4) 18 (3) 10 (1)
0.015
0 0
0.01 0.02 Strain, mm/mm
High speed loading (1000 mm/s) Young’s Strength Toughness Modulus (MPa) (MPa) (MPa) 140 (24) 1176 (323) 2247 (463)
1.31 (0.17) 5.56 (0.51) 17.86 (0.82)
0.016 (0.007) 0.032 (0.009) 1.21 (0.14)
0 0
0.03
0.02
0.04 0.06 0.08 Strain, mm/mm
0.1
Quasi-static loading (0.004 mm/s)a Max. strain (mm/mm) 0.021 (0.007) 0.01 (0.002) 0.10 (0.014)
Strength (MPa)
Max. strain (mm/mm)
1.36 (0.12) 5.11 (0.25) 26.63 (2.87)
1.98 (0.97) 1.03 (0.07) 0.03 (0.01)
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