The Influence of Recycled Aggregates on the Bond Strength of Reinforcing Bars to Low Cement Recycled Aggregate Concrete (LCRAC)

Abstract

Aiming at reducing the environmental impact of structural concrete, the authors conducted a study to analyse the viability of using low binder concrete (LBC) in reinforced concrete (RC) structures. The study focused on the bond behaviour between LBC and the reinforcing bars (rebars) and is presented in a companion paper. Afterwards, with the goal of further improving the eco-efficiency of LBC, the authors studied the possibility of partially replacing natural aggregates by recycled aggregates from construction and demolition waste (CDW), giving rise to what they called a low cement recycled aggregate concrete (LCRAC). This paper presents a research study conducted to analyse the viability of using LCRAC in RC structures, namely by studying the bond behaviour between LCRAC and reinforcing bars. Similarly to the first study, an experimental program including monotonic pull-out tests was set, this time with the aim of assessing the influence of replacing natural aggregates by recycled aggregates from CDW on the bond behaviour between LCRAC and rebars. Additionally, concrete’s compressive and tensile strength tests and rebars’ rib measurement and rebars’ tensile strength tests were also carried out to characterize the materials’ properties. The following main conclusions were drawn: (1) recycled aggregates appear to have a negligible effect on bond behaviour, (2) nevertheless, contrary to natural aggregates, the size of recycled aggregates should be larger than the rebars’ ribs spacing, and (3) this study corroborated the conclusion that packing density improves concrete-to-rebar bond behaviour.