Sustainable concrete using recycled aggregates -

Abstract

Recycled aggregate concrete (RAC) is a sustainable and renewable green concrete that is prepared by partial substitution of natural aggregates with recycled and reused aggregates. The application of RAC effectively resolves the shortage problem in natural aggregates and the concrete batch plants waste disposal of old cylinders. The proposed research is a two-phase program. The objective of the first phase is to achieve a concrete mix that fits the criteria of high performance concrete with partial substitution of natural aggregates with recycled aggregates. The trial batches will investigate the compatibility of the natural and recycled aggregates in concrete. The objective of the second phase is to assess the flexure, shear, and bond and anchorage characteristics of reinforcing bars embedded in structural concrete elements prepared using the optimum RAC batch achieved in the first phase. The significance of the proposed research program is three-fold. Attaining a RAC mix using local available recycled material will have a significant implication on the concrete industry in Lebanon, and will mitigate the construction waste disposal problem. The applications will be in normal strength reinforced concrete. The significance of the research is also reflected in the need to investigate whether the partial substitution of natural aggregates with recycled aggregates would not lead to reduction in the flexural and shear strength of reinforced concrete elements and in the bond characteristics of reinforcing bars anchored in these elements. What is of utmost importance is to use the data of the second phase of the proposed research program along with available data in the literature to verify the validity of the current design specifications set by the available codes of practice as related to RAC. The research conclusions related to appropriate RAC mixes are spreading faster than the development of appropriate design specifications.