Long-term flexural performance of reinforced concrete beams with recycled coarse aggregates

Abstract

[Abstract:] The aim of this study is to investigate the behaviour of recycled aggregate concrete subjected to sustained loading. For the tests, eight reinforced concrete beams were manufactured with recycled coarse aggregate, using water-to-cement ratios of 0.50 and 0.65, and four replacement percentages: 0%, 20%, 50%, and 100%. First, the basic concrete properties, mechanical strength and modulus of elasticity, were determined after 28 d, and at the ageing load. The beam specimens were then loaded at 42 d, using a four-point bending test. Bending moments and deformations were obtained during the loading process, when cracking and serviceability conditions were reached, as well as the long-term deformations of recycled concrete beams up to 1000 d.

Based on these results, it can be reported that long-term deformations are greater for recycled aggregate concrete than for conventional concrete, regarding both strain and deflection. Furthermore, a direct relationship was found between these deformations and the replacement percentage used. Lastly, code-based expressions were used to calculate the long-term deflections of RC beams subjected to sustained loading, which included the recycled coarse aggregate content and corrections previously proposed to predict the mechanical properties, creep, and shrinkage of recycled aggregate concrete.