Comparison of Properties of Recycled Aggregate Concrete with Conventional Concrete

Abstract

One of the key challenge being faced by countries globally, is increasing "construction and demolition waste (C&D) ". Parallel with this demand for adopting techniques of concrete waste disposal is the demand for providing affordable housing to increasing global population. Now in order to provide affordable housing the overall cost of construction has to be reduced, this could be achieved by employing techniques, technologies and methods of project management. But if want to look for solutions through which we can mitigate the challenge of concrete waste disposal on one hand and decrease the cost of construction on the other hand, substitution of concrete with other cheap material is the way. "Recycled Concrete Aggregate (RCA) " is conventional concrete substituted with recycled aggregates. Often a concrete after a duration of year or so has gone through cycles of creep and shrinkage strain. Due to these cycles of strain the coarse aggregates of the concrete loses a part of its strength. When this coarse aggregate is used as a substitute in freshly prepared concrete there is a slight reduction in the compressive strength of the concrete however under the ambit of standards set by various codes it becomes absolutely safe and economical to use. In this project itself, two concrete mix designs viz. M40 and M60 are taken for examining the percentage substitution of coarse aggregate that can allow for safe and economical usage in industries. The criteria to decide the allowable percentage substitution is taken on the basis "target mean strength" which means any replacement of coarse aggregate with recycled aggregate that yields a strength greater than the target mean strength of the concrete (according to IS 456) will be considered safe. The result of this experimental programme has shown that M40 can be fairly used up to fifty percent replacement of coarse aggregates with recycled aggregates and M60 can be used up to thirty percent replacement.