1 Introduction
2 Experimental Work
2.1 Material
Properties | Coarse aggregate | Fine aggregate | Specification and reference | |
---|---|---|---|---|
Crushed limestone | River sand | |||
Bulk specific gravity | – | 2.6 | 2.55 | ASTM-C127-01 (2017) |
Water absorption ratio | % | 1.5% | 1% | ASTM C128-01 (2017) |
Unit weight | kg/m3 | 1500 | 1560 | ASTM-C29 (2010) |
Chemical component (wt.%) | Cement | FA |
---|---|---|
SiO2 | 20.65 | 60.28 |
Al2O3 | 4.4 | 28.59 |
Fe2O3 | 5.05 | 4.99 |
Total SiO2 + Al2O3 + Fe2O3 | 30.1 | 93.86 |
CaO | 62.20 | 2.38 |
Na2O | 0.38 | 0.48 |
MgO | 1.90 | 2.92 |
Loss on Ignition | 1.34 | – |
Insoluble Residue | 0.88 | 1.1 |
Physical and mechanical properties | ||
Specific gravity | 3.15 | 2.3 |
Specific surface area (cm2/g) | 3500 | 4500 |
Properties | Fibers | Steel reinforcement rebar | ||
---|---|---|---|---|
Steel (SF) | Polypropylene (PPF) | Main reinforcement | Stirrup | |
Length, (mm) | 35 | Gradient of 18 | – | – |
Diameter | 0.8 (mm) | 18 (μm) | 10 mm | 8 mm |
Specific gravity | 7.85 | 0.91 | 7.85 | 7.85 |
Shape | Hooked end | Fiber mesh | – | |
Tensile strength, (Mpa) | ≥ 1000 | 300–400 | 360 | 360 |
Elastic modulus, (Gpa) | 210 | 3.6 | 210 | 210 |
Melting point, (°C) | – | 160 °C | – | – |
Mix ID | NSC | HSC | FAC | FAC-SF | FAC-PP | FAC-(SF + PP) | ||
---|---|---|---|---|---|---|---|---|
Component | Unit | Concrete type | Normal strength Concrete | High strength concrete | 30% FA | 30% FA + 0.5% SF | 30% FA + 0.5%PPF | 30% FA + 0.5% SF + 0.5%PP |
Cement | kg/m3 | 350 | 550 | 550 | 550 | 550 | 550 | |
FA | – | – | 165 | 165 | 165 | 165 | ||
Sand | 680 | 834.7 | 852.9 | 843.7 | 822.9 | 816.4 | ||
Crushed limestone | 1020 | 834.7 | 852.9 | 843.7 | 822.9 | 816.4 | ||
Water | 200 | 176 | 165 | 165 | 176 | 176 | ||
HRWR | – | 7.65 | 4.5 | 6.75 | 6.75 | 12.15 | ||
PPF | – | – | – | – | 4.5 | 4.5 | ||
SF | – | – | – | 39 | – | 39 | ||
Water–binder ratio (W/B) | 0.57 | 0.32 | 0.3 | 0.3 | 0.32 | 0.32 | ||
Compressive strength | ||||||||
28 day | MPa | 35 | 75 | 68 | 64 | 66 | 70 | |
600 | oC | 23.8 | 39 | 44.88 | 44.8 | 36.3 | 50 | |
Tensile strength | ||||||||
28 day | MPa | 1.8 | 5.9 | 5.5 | 6.5 | 6 | 7 | |
600 °C | oC | 0.94 | 1.9 | 1.77 | 3.79 | 1.29 | 3.9 |
2.2 Specimen Perpetration
No | Specimen ID | Specimen type | Mix ID | Elevated temperature | |
---|---|---|---|---|---|
Time (hour) | Temperature (oC) | ||||
1 | N25 | One unit | NSC | – | – |
2 | N | NSC | 1.5 | 600 | |
3 | FSP25 | FAC-(SF + PP) | – | – | |
4 | FSP | FAC-(SF + PP) | 1.5 | 600 | |
5 | N-N25 | Composite | NC/NC | ||
6 | N-N200 | NC/NC | 1.5 | 200 | |
7 | N-N400 | 400 | |||
8 | N-N600 | 600 | |||
9 | H-N25 | HSC/NC | – | – | |
10 | H-N600 | HSC/NC | 1/.5 | 600 | |
11 | F-N25 | FAC/NC | – | – | |
12 | F-N600 | FAC/NC | 1.5 | 600 | |
13 | FS-N25 | FAC/NC | – | – | |
14 | FS-N600 | FAC/NC | 1.5 | 600 | |
15 | FP-N25 | FAC/NC | – | – | |
16 | FP-N600 | FAC/NC | 1.5 | 600 | |
17 | FSP-N25 | FAC-(SF + PP)/NC | – | - | |
18 | FSP -N200 | FAC-(SF + PP)/NC | 1.5 | 200 | |
19 | FSP -N400 | 400 | |||
20 | FSP -N600 | 600 | |||
21 | FSP –N30min | FAC-(SF + PP)/NC | 0.5 | 600 | |
22 | FSP –N60min | 1 | 600 | ||
23 | FSP –N90min | 1.5 | 600 | ||
24 | FSP –N120 | 2 | 600 | ||
25 | FSP –N180 | 3 | 600 |
2.3 Heating Stage
2.4 Loading Test
3 Results
3.1 Failure Pattern
No | Specimen ID | Specimen type | Mix ID | Failure pattern |
---|---|---|---|---|
1 | N25 | One unit | NSC | – |
2 | N | NSC | – | |
3 | FSP25 | FAC-(SF + PP) | – | |
4 | FSP | FAC-(SF + PP) | – | |
5 | N-N25 | Composite | NC/NC | Mixed failure B |
6 | N-N200 | NC/NC | Mixed failure B | |
7 | N-N400 | Mixed failure B | ||
8 | N-N600 | Mixed failure B | ||
9 | H-N25 | HSC/NC | Fracture of NSC | |
10 | H-N600 | HSC/NC | Fracture of NSC | |
11 | F-N25 | FAC/NC | Mixed failure B | |
12 | F-N600 | FAC/NC | Fracture of NSC | |
13 | FS-N25 | FAC/NC | Fracture of NSC | |
14 | FS-N600 | FAC/NC | Fracture of NSC | |
15 | FP-N25 | FAC/NC | Fracture of NSC | |
16 | FP-N600 | FAC/NC | Mixed failure A | |
17 | FSP-N25 | FAC-(SF + PP) /NC | Fracture of NSC | |
18 | FSP -N200 | FAC-(SF + PP) /NC | Fracture of NSC | |
19 | FSP -N400 | Fracture of NSC | ||
20 | FSP -N600 | Fracture of NSC | ||
21 | FSP –N30min | FAC-(SF + PP) /NC | Fracture of NSC | |
22 | FSP –N60min | Fracture of NSC | ||
23 | FSP –N90min | Fracture of NSC | ||
24 | FSP –N120 | Mixed failure B | ||
25 | FSP –N180 | Spalling |
3.2 Interfacial Shear Properties
Specimen ID | \({\tau }_{max}\)(MPa) | K (N/mm3) | G (N/mm) |
---|---|---|---|
N25 | 3.5 | 18 | 0.35 |
N600 | 1.39 | 11.6 | 0.14 |
FSP25 | 5.62 | 23.4 | 3.5 |
FSP600 | 3.63 | 13.67 | 1.42 |
N-N25 | 2.41 | 13.4 | 0.58 |
N-N200 | 2.28 | 11.66 | 0.42 |
N-N400 | 1.4 | 9.59 | 0.19 |
N-N600 | 1.14 | 10.8 | 0.08 |
H-N25 | 2.77 | 15.09 | 0.59 |
H-N600 | 1.36 | 7.77 | 0.18 |
F-N25 | 2.88 | 16.76 | 0.57 |
F-N600 | 1.83 | 9.58 | 0.32 |
FS-N25 | 2.68 | 14.25 | 0.98 |
FS-N600 | 2.06 | 10.96 | 0.74 |
FP-N25 | 2.9 | 15.18 | 1.00 |
FP-N600 | 1.03 | 6.87 | 0.11 |
FSP-N25 | 3 | 14.90 | 0.99 |
FSP-N200 | 2.9 | 11.56 | 1.1 |
FSP-N400 | 2.68 | 10.68 | 1.12 |
FSP-N600 | 2.44 | 8.91 | 1.14 |
FSP-N30min | 2.68 | 12.25 | 1.02 |
FSP-N60min | 2.74 | 11.58 | 1.06 |
FSP-N90min | 2.45 | 8.91 | 1.14 |
FSP-N120min | 1.4 | 5.88 | 0.36 |
FSP –N180min | 0 | 0 | 0 |
3.3 Interfacial Shear Load Slip Displacement Curve
3.4 Effect of Temperature
3.5 Effect of Time Exposure
3.6 Effect of Concrete Type
3.7 Effect of Fiber Type
4 Discussion
5 Finite Element Analysis
5.1 Interfacial Properties
5.2 Concrete Constitutive Model
Mix ID | Temperature | Density | Thermal conductivity | Specific heat |
---|---|---|---|---|
(oC) | (kg/m3) | (W.m−1.K−1) | (J/kg.K) | |
NSC | 25 | 2300 | 2 | 985 |
200 | 2185 | 1.6 | 985 | |
400 | 2185 | 1.24 | 1033 | |
600 | 2143 | 1.15 | 1149 | |
FAC-(SF + PP) | 25 | 2450 | 2.94 | 1060 |
200 | 2425 | 2.68 | 1003 | |
400 | 2401 | 1.34 | 999 | |
600 | 2376 | 0.78 | 1293 |
Parameters | Experimental | Finite element | Prediction | |||
---|---|---|---|---|---|---|
\({\tau }_{Exp}\)(MPa) | \({K}_{Exp}\)(N/mm3) | \({\tau }_{FE}\)(MPa) | \({K}_{FE}\)(N/mm3) | \({K}_{FE}/{K}_{Exp}\) | \({\tau }_{FE}/{\tau }_{Exp}\) | |
FSP-N25 | 3 | 14.90 | 3.05 | 13.65 | 0.92 | 1.01 |
FSP-N200 | 2.9 | 11.56 | 2.85 | 11.54 | 0.99 | 0.98 |
FSP-N400 | 2.68 | 10.68 | 2.77 | 9.89 | 0.93 | 1.03 |
FSP-N600 | 2.44 | 8.91 | 2.33 | 8.63 | 0.97 | 0.95 |
FSP-N30min | 2.68 | 12.25 | 2.91 | 13.18 | 1.07 | 1.01 |
FSP-N60min | 2.74 | 11.58 | 2.65 | 10.6 | 0.91 | 0.97 |
FSP-N90min | 2.45 | 8.91 | 2.33 | 8.63 | 0.96 | 0.95 |
FSP-N120min | 1.4 | 5.88 | 1.33 | 5.52 | 0.94 | 0.95 |