Self-consolidating concrete using recycled concrete aggregate and high volume of fly ash, and slag

This paper studies the effect of using recycled concrete aggregate (RCA) on the properties of self-consolidating concrete (SCC). Twenty concrete mixtures with different mixtures of fly ash (FA), slag (S) and RCA were developed and tested. The mixtures were sorted into five categories, with constant water to cementitious materials (w/c) ratio of 0.38, based on their RCA content: 0, 25, 50, 75, and 100% of natural coarse aggregate (NCA) replaced by RCA. The results showed that as the percentage of RCA (0-100%) has increased in the mixes replacing NCA; the compressive strengths of the concrete mixes has decreased at 3, 14, and 28 days, and the tensile strengths decreased at 28 days. Moreover, the partial replacement of cement by (SCMs) had an adverse effect on the 28-days-compressive strength; however, it increased the resistance to chloride permeability. Moreover, several mixes have met the minimum Illinois Department of Transportation compressive strength requirements.