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Test matrix
| Concrete mix | Specimens ID | Percentage of fiber by volume | Temperatures | Strengthening | No. of specimens | ||
|---|---|---|---|---|---|---|---|
| Polypropylene (PP) | Steel (SF) | Total | |||||
| M-C0 | C0-RT | – | – | – | 26°C | – | 3 |
| C0-600 | 600° C | 3 | |||||
| C0-RT-S | 26°C | WWM | 3 | ||||
| C0-600-S | 600°C | 3 | |||||
| M-SF | SF-RT | – | 0.6 | 0.6 | 26°C | – | 3 |
| SF-600 | 600°C | 3 | |||||
| SF-RT-S | 26°C | WWM | 3 | ||||
| SF-600-S | 600°C | 3 | |||||
| M-PPF | PPF-RT | 0.2 | 0 | 0.2 | 26°C | – | 3 |
| PPF-600 | 600°C | 3 | |||||
| PPF-RT-S | 26°C | WWM | 3 | ||||
| PPF-600-S | 600°C | 3 | |||||
| M-SF+PPF | SF+PPF-RT | 0.2 | 0.6 | 0.8 | 26°C | – | 3 |
| SF+PPF-600 | 600°C | 3 | |||||
| SF+PPF-RT-S | 26°C | WWM | 3 | ||||
| SF+PPF-600-S | 600°C | 3 | |||||
| Total No. of specimens | 48 | ||||||
Summary of test results
| Specimen ID | Compressive strength | Initial stiffness | ||
|---|---|---|---|---|
| (MPa) | Relative Variation* | (N/mm) | Relative Variation* | |
| C0-RT | 30.2 | – | 20133.3 | – |
| C0-600 | 14.1 | −53.3% | 2169.2 | −89.2% |
| C0-RT-S | 50.6 | +67.5% | 25948.7 | 28.9% |
| C0-600-S | 29.9 | −1.0% | 8542.9 | −57.6% |
| SF-RT | 40.7 | – | 26688.5 | – |
| SF-600 | 28.5 | −29.9% | 4560.0 | −82.9% |
| SF-RT-S | 71.0 | +74.4% | 47333.3 | 77.4% |
| SF-600-S | 56.5 | +38.8% | 19316.2 | −27.6% |
| PPF-RT | 32.9 | – | 43866.7 | – |
| PPF-600 | 18.0 | −45.3% | 3600.0 | −85.0% |
| PPF-RT-S | 60.1 | +82.7% | 25849.5 | 8.0% |
| PPF-600-S | 34.5 | +4.9% | 11311.5 | −52.7% |
| SF+PPF-RT | 40.5 | – | 27000.0 | – |
| SF+PPF-600 | 30.9 | −23.7% | 4414.3 | −83.7% |
| SF+PPF-RT-S | 66.1 | +63.2% | 46386.0 | 71.8% |
| SF+PPF-600-S | 44.3 | +9.4% | 14644.6 | −45.8% |
WWM and mortar properties
| Material | Unit | Values | |
|---|---|---|---|
| WWM | Thickness per layer | mm | 0.6 |
| Elastic modulus | MPa | 108 | |
| Yield stress | MPa | 382 | |
| Ultimate stress | MPa | 544 | |
| Mortar for WWM composite | Compressive strength-28 day | MPa | 45 |
| Tensile strength-28 day | MPa | 3.8 | |
| Bond strength | MPa | 0.79 |
Mix proportions used for concrete in kg/m3
| Material | Weight |
|---|---|
| Cement | 378 |
| Crush sand | 294 |
| Silica sand | 489 |
| Coarse aggregate (dagg.= 20 mm) | 675 |
| Coarse aggregate (dagg. = 10 mm) | 320 |
| Water | 190.5 |
| Super-plasticizer | 1.0 Liters |
Physical and mechanical properties of fibers
| Properties | Fiber Type | |
|---|---|---|
| Polypropylene (PP) | Steel (SF) | |
| Shape | Crimped | Hooked ends |
| Length (mm) | 50 | 60 |
| Section dimensions (mm) | 1.0 × 0.6 (Rectangular) | 0.75 (Circular) |
| Specific gravity | 0.90 | 7.85 |
| Modulus of elasticity (GPa) | 4.0 | 200 |
| Tensile strength (MPa) | 550 | 1225 |