ABSTRACT
All matrices were prepared with a constant water-tocementitious materials ratio of 0.4, a uniform cement factor of 391 kg/m3, and a constant amount of fly ash representing 20% of the cement weight. In proportioning the aggregate contents, particular attention was given to the coarse-to-fine aggregate ratio due to its critical role in generating a sufficient amount of mortar for the selected self-consolidating concretes. The ASTM C 29 was used to determine the compacted bulk unit weight and the calculated void content using different ratios of the combined coarse and fine aggregates. The optimum volumetric coarseto-fine aggregate ratio, utilized in the proportioning of the concrete constituents, was found at 0.52/0.48. The quantities of coarse and fine aggregates used in the matrices were 923 and 850 kg/m3, respectively. The optimum (minimum) dosages of the high range water-reducing admixture (HRWRA) and viscosity modifying admixture (VMA) used at the control hauling time of 10 minutes were 209 and 26 ml/100 kg, respectively. These dosages were obtained by evaluating the consistency and stability of concrete using different trial batches until a satisfactory slump flow of 635 ± 25 mm; and a visual stability index of 0 were attained.Table 1 displays the measured fresh properties at the selected hauling times.
