Construction and Demolition Waste used as Recycled Aggregates in Concrete: Solutions for Increasing the Marketability of Recycled Aggregate Concrete

Abstract

The use of crushed construction and demolition waste as a recycled aggregate in the production of new concrete has been successfully demonstrated by researchers as well as by practitioners in the field. Despite presenting suitable performance, the acceptance and utilization of recycled aggregate concrete (RAC) has not become widespread. In expanding urban areas, the intensive construction of new infrastructure, as well as rehabilitation and retrofitting of existing infrastructure, opens many potential markets for RAC produced in various grades, including non-structural hardscaping, pavements and even structural applications. The goal of this study was to show that use of recycled aggregates in concrete is both economically viable and technically feasible. In order to elucidate the inhibiting factors, the supply and demand for recycled aggregates were studied in a growing southeastern metropolitan area. The additional effort required for source separation and other quality assurance practices was analyzed to understand the costs associated with producing concrete-grade recycled aggregates. Recycled aggregates obtained during a case study in Charlotte, North Carolina were characterized in the laboratory and successfully used in several types of concrete. A series of applications for RAC were identified and local concrete suppliers were surveyed regarding their comfort levels with these uses. Incentives encouraging the production of RAC were considered from the perspective of demolition contractors, concrete suppliers and developers. The results of the case study and survey were used to determine the feasibility of developing a more diverse market for recycled aggregates by suggesting an appropriate palette of RAC products.