Physical Properties of Recycled Concrete Aggregates as Granular Road Base and Subbase Material

Abstract

Recycled concrete aggregates (RCA) are obtained from waste concretes which are emerged as one of the construction and demolition wastes. As in many fields of civil engineering, the use of RCAs as granular road base (GRB) and granular road sub-base (GRSB) material eliminates their adverse effects such as big landfill area needs and environmental pollution and contributes greatly to economic sustainability. However, in order for these materials to become GRB and GRSB material, they must comply with the technical specifications. In this study, the suitability of RCAs to the conditions of GRB and GRSB was investigated by flakiness index, particle density and water absorption, Los Angeles (LA) abrasion and magnesium sulfate soundness tests. 3 different RCAs were obtained by crushing the concrete blocks of the debris of the demolished buildings. Natural aggregates (NA) and crushed aggregates (CA) were used to compare the RCAs with conventional aggregates. Tests were carried out for 23 different designs, which were formed with pure forms of these 5 different materials and their mixtures in certain proportions. As a result of the tests, it was found that the RCAs had very good properties in terms of flakiness index. It was found that the RCAs had lower particle density and higher water absorption values than the conventional aggregates. For LA abrasion and magnesium sulfate soundness tests, too much material loss was observed for the RCAs, which shows that the RCAs are in some cases disadvantageous. However, the poor properties of the RCAs largely eliminated by mixing them with the CA and NA.