Commercially available construction and demolition waste recycled coarse aggregate in the manufacture of concrete

摘要

As a consequence of ever increasing demand for quality aggregate for the construction of concrete based infrastructures many parts of the world are facing the problem of the scarcity of good quality aggregate for concrete. Among all alternate sources for aggregate, the recycling of construction and demolition (C&D) waste has an upper hand as it is available everywhere. A C&D waste is typically composed of wood, plaster, concrete, bitumen, roofing materials, glass, plastics, metal, insulating materials, and other similar materials depending on the locality of its origin. Recycled concrete aggregate derived from crushing of the concrete elements of C&D waste, is inhomogeneous unlike natural aggregate derived from a crushed rock. Thus, a thorough evaluation of physical and mechanical properties of such aggregate before using in concrete is needed. This study presents a comparative evaluation of recycled concrete aggregate (RCA) obtained from a commercial recycling plant with respect to a natural virgin aggregate in maximum size range of 10-20 mm. The comparison showed a significant reduction in the value of the specific gravity, bulk density, and abrasion resistance for the RCA. The water absorption of the RCA was more than eight folds to that of natural crushed aggregate. The study further presents the influence of 50% and 100% replacement of natural coarse aggregate with RCA on the compressive strength, flexural strength and water absorption of concrete mixes and concludes that 50% replacement of natural aggregate with RCA has insignificant influence on compressive and flexural strength of concrete but the overall durability of such concrete is inferior to the control concrete which limits its applicability.