Mechanical Properties of Recycled Coarse Aggregate Concrete with Pre-soaking in Lime Water and Carbonated Aggregates

Abstract

The recycled coarse aggregates were strengthened by pre‑soaking lime water combined with accelerated carbonation， the physical property of recycled coarse aggregates were tested. The effect of carbonated recycled coarse aggregates on the mechanical properties of recycled concrete was investigated， and the strengthening mechanism of carbonation was also analyzed by microscopic testing means. The strength changes of modified recycled concrete at various ages were studied by cubic compressive， splitting tensile and flexural strength tests. The results show that the physical properties of recycled coarse aggregates are significantly improved by pre‑soaking lime water combined with carbonation， with 15.2%-22.9% reduction in water absorption and 15.2%-17.7% reduction in crushing index； the interfacial transition zone of recycled concrete is more compact after strengthening， which is beneficial to the quality of recycled coarse aggregates； the strengths at 7， 28 d decrease with the increases of replacement rate； the strength of recycled concrete with coarse aggregates strengthened by pre‑soaking in lime water and carbonation is comparable to that of ordenary concrete with 50% replacement rate.