A study into the relationships between the mechanical properties of recycled concrete aggregate

Abstract

The advances in construction industry have exhausted the available natural resources and placed high impact on the surrounding environment. This has encouraged the engineers to search for more innovative materials in design. The use of Recycled Concrete Aggregate (RCA) in new concrete offers a solution to such a problem of worldwide dimensions. That is to make construction more "green" and environmentally friendly and preserve resources; hence contribute to sustainability development. In this paper, a detailed investigation is conducted to analyze the relationships between the mechanical properties of Recycled Aggregate Concrete (RAC). Five concrete mixes were designed to study the effect of different RCA content on concrete mechanical properties: concrete made entirely with natural aggregate as control mix and four types of concrete made with natural fine and recycled coarse aggregate (30%, 50%, 75% and 100% replacement of coarse recycled aggregate). The source of RAC in this study was from the concrete specimens tested in the laboratory. Based on the results of sixty specimens carried out; the relations between compressive strength, density, splitting tensile strength, flexural strength and elastic modulus are investigated and discussed in details. A comparison is made against the suggested equations in Codes of Practice and by other researchers. It is found that such relations could be different from that of conventional concrete and new equations need to be developed.