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Casting schedule and details of test specimens
| Test details | Specimen details | Age (days) | Total for (1 mix) | Total (5 mixes) | |||
|---|---|---|---|---|---|---|---|
| 3 | 7 | 28 | 56 | ||||
| Compressive strength | Cubes (150 × 150 x 150 mm) | 3 | 3 | 3 | 3 | 12 | 60 |
| Split cylinder test | Cylinders (150 mm high × 300 mm dia.) | 3 | 3 | 3 | 3 | 12 | 60 |
| Flexural strength test | Beams (100 × 100 × 500 mm) | - | - | 3 | - | 3 | 15 |
| Water permeability test | Cube (96.8 mm × 96.8 mm × 150 mm) | - | - | 3 | 3 | 6 | 240 (48 for each mix) |
| Cube (146.9 mm × 146.9 mm × 150 mm) | - | - | 3 | 3 | 6 | ||
| Cylinder (96.8 mm high × 150 mm diameter) | - | - | 3 | 3 | 6 | ||
| Cylinder (146.9 mm high × 150 mm diameter) | - | - | 3 | 3 | 6 | ||
Cost comparison between normal and blended concretes
| Items | Quantity of concrete | Quantity of cement | Quantity of RHA (6%) | Quantity of fine aggregates | Quantity of coarse aggregates | |
|---|---|---|---|---|---|---|
| Weight of materials | Raw concrete | 1 m3 (35.31 cft) | 8.62 cft | --- | 15.73 cft | 31.47 cft |
| Blended concrete | 1 m3 (35.31 cft) | 8.10 cft | 1.38 cft | 15.73 cft | 31.47 cft | |
| Cost of materials | Raw concrete | USD 21.57/- | USD 13.80/- | --- | USD 2.0/- | USD 5.77/- |
| Blended concrete | USD 21.09/- | USD 12.97/- | USD 0.35/- | USD 2.0/- | USD 5.77/- | |
| Difference in cost | USD 0.47/- (2.2% of normal concrete) | USD 0.82/- (6% of pure cement) | --- | --- | --- |
Weights of the material mix
| Mixture No: | Mixture Type | Water (kg) | OPC (kg) | Rice Husk Ash (kg) | Sand (kg) | Coarse Aggregates (kg) | Slump flow (mm) |
|---|---|---|---|---|---|---|---|
| SM1 | OPC | 33.10 | 55.17 | 0 | 111.42 | 222.86 | 95 |
| SM2 | 6% Replacement | 33.10 | 51.84 | 3.31 | 111.42 | 222.86 | 105 |
| SM3 | 12% Replacement | 33.10 | 48.55 | 6.62 | 111.42 | 222.86 | 112 |
| SM4 | 18% Replacement | 33.10 | 45.24 | 9.93 | 111.42 | 222.86 | 123 |
| SM5 | 24% Replacement | 33.10 | 41.93 | 13.24 | 111.42 | 222.86 | 135 |
| Total | 139.25 | 242.75 | 33.1 | 557.1 | 1114.3 |
Split cylinder strength activity index of concrete
| Split cylinder strength activity index | ||||||||
|---|---|---|---|---|---|---|---|---|
| Ratio | 3 Days | 7 Days | 28 Days | 56 Days | ||||
| Split cylinder strength (MPa) | S.A.I | Split cylinder strength (MPa) | S.A.I | Split cylinder strength (MPa) | S.A.I | Split cylinder strength (MPa) | S.A.I | |
| 0% | 0.953 | 100.0 | 1.179 | 100.0 | 1.891 | 100.0 | 3.358 | 100.0 |
| 6% | 1.000 | 105.0 | 1.281 | 108.7 | 2.124 | 112.3 | 3.563 | 106.1 |
| 12% | 0.863 | 90.6 | 1.014 | 86.0 | 1.275 | 67.4 | 3.049 | 90.8 |
| 18% | 0.884 | 92.8 | 0.932 | 79.1 | 1.597 | 84.4 | 2.844 | 84.7 |
| 24% | 0.836 | 87.8 | 0.891 | 75.6 | 1.329 | 70.3 | 2.570 | 76.5 |
Strength Activity Index of concrete samples
| Strength Activity Index | ||||||||
|---|---|---|---|---|---|---|---|---|
| Ratio | 3 Days | 7 Days | 28 Days | 56 Days | ||||
| Compressive Strength (MPa) | S.A.I | Compressive strength (MPa) | S.A.I | Compressive strength (MPa) | S.A.I | Compressive strength (MPa) | S.A.I | |
| 0% | 3.229 | 100.0 | 6.932 | 100.0 | 13.563 | 100.0 | 23.251 | 100.0 |
| 6% | 3.380 | 104.7 | 7.535 | 108.7 | 14.640 | 107.9 | 25.404 | 109.3 |
| 12% | 3.294 | 102.0 | 6.050 | 87.3 | 13.090 | 96.5 | 21.744 | 93.5 |
| 18% | 2.885 | 89.3 | 5.813 | 83.9 | 12.056 | 88.9 | 20.022 | 86.1 |
| 24% | 2.583 | 80.0 | 5.425 | 78.3 | 11.303 | 83.3 | 17.438 | 75.0 |
Composition of OPC and RHA
| Chemical composition (%) | OPC | RHA |
|---|---|---|
| Silicon dioxide (SiO2) | 22.0 | 77.34 |
| Aluminum oxide (Al2O3) | 5.50 | 6.92 |
| Ferric oxide (Fe2O3) | 3.50 | 4.89 |
| Calcium oxide (CaO) | 64.25 | 3.56 |
| Magnesium oxide (MgO) | 2.50 | 1.59 |
| Sulfur trioxide (SO3) | 2.90 | 0.34 |
| Sodium oxide (Na2O) | 0.20 | 1.27 |
| Potassium Oxide (K2O) | 1.00 | 2.69 |
| Loss on ignition | 0.64 | 4.81 |
| Physical properties | ||
| Specific gravity | 3.04 | 2.13 |
| Specific surface (m2/kg) | 308 | 600 |
| Compressive strength 3 days (MPa) | 20.76 | |
| 7 days | 31.89 | |
| 28 days | 39.41 | |
| 56 days | 42.52 | |
| Consistency (%) | 29.25 | |
| Initial Setting Time (min) | 110 | |
| Final Setting Time (min) | 228 |