(%) of Cement and Silica Fume
The materials for the concrete mixtures are given in Table I. The chemical compositions of the cement and silica fume are provided in Table II. The calculated Bogue composition (mass fractions) for the cement is 57.1% C3S, 15.3% C2S, 7.7% C3 A, and 8.4% C4AF.
| Table I: Materials Used in Concrete Mixtures | |
|---|---|
| coarse aggregate | crushed limestone |
| sand | crushed limestone |
| cement | C2: CEM I 52.5 PM CP2 (Montalieu a) |
| silica fume | Pechiney (Laudun) |
| superplasticizer | Sikament HR 401 (Sika) |
| a This and other tradenames and company products are identified to adequately specify the experimental procedure. In no case does such identification imply endorsement by the National Institute of Standards and Technology, nor does it imply that the products are necessarily the best available for the purpose. | |
| Table II: Chemical Composition in Mass
Fraction (%) of Cement and Silica Fume |
||
|---|---|---|
| Compound/Cement Notation | Cement | Silica fume |
| SiO2/S | 20.4 | 87.0 |
| CaO/C | 62.6 | 0.4 |
| Al2O3 /A | 4.7 | 0.3 |
| TiO2 | 0.3 | 0.0 |
| Fe2O3 /F | 2.8 | 0.7 |
| MgO | 1.9 | 1.6 |
| Na2O | 0.2 | 0.7 |
| K2O | 0.9 | 2.4 |
| SO3/
| 2.7 | 0.3 |
| C1 | - | 0.3 |
| MnO | 0.0 | 0.1 |
| LOI | 1.9 | 3.1 |
| Si | - | 3.3 |
Concretes containing no silica fume and having different water-to-cement (w/c) ratios on a mass basis were produced. Based on some of these compositions, several series of silica fume concretes with increasing silica fume-to-cement (s/c) mass ratios were made. The mixtures were designed to be workable using a plasticizer. For some mixtures, the paste volume was limited, in order to keep the sample temperature below the maximum critical temperature of the calorimeters (around 80 ºC). The mixture proportions are given in Tables III and IV.
| TABLE 3 Mixture proportions for concretes without silica fume. |
|||||
|---|---|---|---|---|---|
| w/c | 0.30 | 0.35 | 0.45 | 0.55 | 0.65 |
| Aggregates (kg) | 1748.3 | 1821.0 | 1731.3 | 1859.7 | 1912.9 |
| Cement (kg) | 529.5 | 455.3 | 438.1 | 330.7 | 274.7 |
| Superplasticizer (kg) | 5.82 | 2.96 | 0.0 | 0.0 | 0.0 |
| Total water (kg) | 158.9 | 159.3 | 197.3 | 181.6 | 178.6 |
| TABLE 4 Mixture proportions for concretes with silica fume |
||||
|---|---|---|---|---|
| w/c | 0.30 | 0.30 | 0.30 | 0.35 |
| s/c | 0.05 | 0.10 | 0.30 | 0.20 |
| Aggregates (kg) | 1800.4 | 1752.6 | 1679.9 | 1785.5 |
| Cement (kg) | 474.8 | 483.9 | 453.2 | 453.0 |
| Silica fume(kg) | 23.7 | 48.4 | 136.0 | 90.6 |
| Superplasticizer | 5.7 | 0.0 | 0.0 | 0.0 |
| Total water (kg) | 142.4 | 145.2 | 136.0 | 158.5 |
| w/c | 0.45 | 0.45 | 0.45 | 0.45 |
| s/c | 0.05 | 0.10 | 0.20 | 0.30 |
| Aggregates (kg) | 1671.0 | 1883.6 | 1874.1 | 1815.4 |
| Cement (kg) | 455.3 | 344.1 | 323.3 | 333.8 |
| Silica fume (kg) | 22.8 | 34.4 | 64.7 | 100.1 |
| Superplasticizer (kg) | 0.0 | 4.1 | 5.8 | 6.7 |
| Total water (kg) | 204.9 | 154.8 | 145.5 | 150.2 |
| w/c | 0.55 | 0.65 | 0.65 | 0.65 |
| s/c | 0.20 | 0.05 | 0.10 | 0.30 |
| Aggregates (kg) | 1843.7 | 1879.2 | 1815.2 | 1771.7 |
| Cement (kg) | 307.2 | 281.9 | 300.2 | 295.1 |
| Silica fume (kg) | 61.4 | 14.1 | 30.0 | 88.5 |
| Superplasticizer (kg) | 0.0 | 0.0 | 0.0 | 0.0 |
| Total water (kg) | 168.9 | 183.1 | 194.9 | 191.8 |
Before mixing, the materials were placed in a room having a regulated temperature equal to that of the adiabatic calorimeter to ensure thermal equilibrium at the beginning of the test. Immediately after mixing (within 5 to 8 minutes), a sample was put into the calorimeter. The calorimeter was designed to maintain the temperature of the casing surrounding the sample at the same temperature as the sample. The temperature and corresponding heat balance were maintained by an electrical regulator controlling an electrical-resistance heater. In general, the temperature of the concrete sample was recorded over several days.