Utilization of waste concrete recycling materials in self-compacting concrete

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This paper evaluates the feasibility of preparing self-compacting concrete (SCC) by incorporating waste concrete recycling materials (WCRMs). Some or all of the natural materials were substituted with WCRMs, such as recycled coarse aggregate (RCA), recycled fine aggregate (RFA) and recycled powder (RP). Nine SCC mixtures were produced, including eight self-compacting recycled concrete mixes and one control mix without WCRMs. The SCC mixes were designed with four different RCA replacement rates (0%, 25%, 50% and 100%) along with a constant amount of RFA (10%) and varying percentages of RP (10% and 20%). The water/binder ratio was designed as 0.4 for all the SCC mixtures. The workability properties (e.g., flowability, viscosity and passing ability) and mechanical properties (e.g., compressive, splitting tensile and flexural strengths) of self-compacting recycled concrete were investigated. The findings indicate that the substitution ratio of WCRMs will affect the workability and mechanical behavior of SCC. This study demonstrates that the decline in the workability and mechanical behavior of self-compacting recycled concrete results from the cooperation of WCRMs. When natural materials are substituted and the amount of WCRMs is limited, the workability of self-compacting recycled concrete can satisfy the European standard EFNARC (2005). Meanwhile, this study also finds that the self-compacting recycled concrete can achieve acceptable mechanical performance when compared to the ordinary SCC without WCRMs.