Statistically significant effects of mixed recycled aggregate on the physical-mechanical properties of structural concretes

The mixed recycled aggregate obtained from processed construction and demolition waste accounts for the largest share of recycled aggregate produced worldwide. Efficient and appropriate use of these new resources will help reduce and confront the major environmental problems facing today's economic growth model. The research discussed in this paper assessed the performance of structural concretes containing 20%, 25%, 50%, 75% or 100% mixed recycled coarse aggregate, analysing fresh concrete workability, density and air content and hardened concrete compressive, flexural and splitting tensile strength. An analysis of variance (ANOVA) run on the findings to determine the effect of the factors on the variables showed that curing age and percentage of recycled aggregate had a statistically significant impact on concrete performance. The decline in strength relative to conventional concrete was smaller at longer curing ages. Concretes bearing up to 50% recycled aggregate exhibited declines in performance of 10% or under in most of the properties studied, even at late ages. In light of the present findings, the mixed recycled aggregates used in this research may be deemed apt for use in structural concrete with a characteristic strength of up to 30 MPa.