Use of Reclaimed Concrete Aggregate in New Concrete: Challenges Opportunities

摘要

Many applications currently utilize virgin aggregates to produce relatively moderate strength concrete and thus not utilizing the aggregate's full potential. Residential Concrete, Class R as per CSA A23.1-09, is an example of such applications. Through minor alterations to the mix design, the use of Reclaimed Concrete Aggregate (RCA) may be implemented to provide equivalent durability while maintaining the required compressive strength for such concrete applications. This paper presents preliminary results from an ongoing study that tested concrete samples with RCA replacement levels of up to 100% and incorporated use of locally available Supplementary Cementing Materials (SCMs) and chemical admixtures. During the mix optimization process, compressive strength and shrinkage were evaluated. Minor modifications to the mix design and batching procedures were able to eliminate the major drawbacks (shrinkage, slump retention, and strength) of incorporating RCA in concrete. By implementing RCA and locally available SCMs, the environmental impacts of concrete production, such as Class R concrete, may be significantly reduced along with providing more economically feasible material.