Workability and Compressive Strength of Recycled Aggregate Concrete with Different Water-Cement Ratios

Use of demolishing waste in new concrete to develop green concrete has proved the need of the day with respect to the preservation of the environment from negative effects and natural sources of the aggregates. This research work presents laboratory investigations on the effect of different water-cement ratios on the workability and compressive strength of concrete made with 50% replacement of natural coarse aggregates with coarse aggregates from demolishing waste. Basic properties: water absorption, specific gravity, and abrasion resistance of both types of aggregates were assessed. A total of eight mixes were designed with water-cement ratios from 0.45 to 0.75 with an increment of 0.05. One mix with 100% conventional aggregates was designed and considered as a control mix to equate the results. A slump test was done to check the workability of all blends. Followed by casting, curing for 28 days, and testing of specimens for compressive strength were done. Test results show that a higher water-cement ratio increases the workability of the concrete but the compressive strength reduces. Assessment of the obtained results with those of the control mix shows a 70% improvement in slump values and 6.7% reduction in compressive strength with water cement ratio equal to 0.55 in comparison to the control mix made with water cement ratio equal to 0.45.