INFLUENCE OF WATER CONTENT AND COMIPACTIVE
EFFORT ON THE COMPRESSIVE STRENGTH OF RCC MIXTURES
Ibralrirn. Asi,
and Omar S. Baghabra Al-Ainoudi
ABSTRACT
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.