Durability behaviour of high-volume fly ash self-compacting recycled aggregate concrete

This study presents utilisation of high-volume fly ash (HVFA) in the design of self-compacting concrete (SCC) containing alternative aggregate particles. Class F fly ash was used in a binary blend of Portland cement at a fixed dosage of 50% by weight of powder, and natural coarse and fine aggregates were replaced with coarse and fine recycled concrete aggregates (RCAs), respectively, at replacement levels of 0, 50 and 100% by volume. The durability properties of the SCC mixes were studied using the rapid chloride penetration test, initial surface absorption test and capillary suction test. The results of the study showed that the concrete mix made with replacement of natural coarse aggregates with 50% coarse RCAs, the concrete mix made replacement of natural fine aggregates with 50% fine RCAs and the concrete mix made with replacement of both natural coarse and fine aggregates with the respective RCAs at 50% replacement levels had satisfactory performance without compromising their fresh and hardened-state properties. Furthermore, the incorporation of HVFA in SCCs improved the hardened-state properties at later ages of curing due to the secondary pozzolanic reaction.