INFLUENCE OF WATER CONTENT AND COMIPACTIVE EFFORT ON THE COMPRESSIVE STRENGTH OF RCC MIXTURES
and Omar S. Baghabra Al-Ainoudi
Roller-compacted concrete (RCC) is a concrete mixture with a low water to cement ratio. It is usually used in pavements that are subjected to high traffic loading. Design and curing of RCC mixtures are similar to those of conventional Portland cement concrete (PCC), while mixing and laying are similar to those used for asphalt concrete (AC). Therefore, RCC is a mixture of aggregate, high amount of cement (compared with PCC, low amount of water to form a zero-slump Portland cement concrete that is laid down by spreader box, a grader or a paver and compacted by a vibratory roller. It has many advantages over AC and PCC mixtures.
This paper reports the influence of water to cement ratio, total aggregate to cement ratio, and compactive effort on the compressive strength of RCC mixtures. Four water to cement ratios were used (0.30, 0.35, 0.40 and 0.45), while the total aggregate to cement ratio was varied from 5.4 to 7.0. For each trial mixture, three compactive efforts were implemented: 50, 100 and 150 kneading tamps.
Results of this investigation indicate that there is an optimum water to cement (W/C) ratio irrespective of the compactive effort. However, the compressive strength increases with the increase in the compactive effort. The compressive strength also increases with decreasing the ratio of total aggregate to cement. Based on the results of the present investigation, the compressive strength at the optimum W/C ratio is estimated to be two times that of normal PCC using the same materials used for RCC and at the optimum W/C ratio of the PCC.