Effects of fly ash, blast furnace slag and metakaolin on mechanical properties and durability of coral sand concrete

This paper investigates the effects of fly ash (FA), blast furnace slag (BFS) and metakaolin (MK) on the mechanical properties, drying shrinkage, carbonation and chloride permeability of coral sand concretes (CSC), in which the replacement levels of supplementary cementitious materials (SCMs) below 35% by weight are compared. The control mixture contain only ordinary Portland cement (OPC) as the binder and nature aggregate concrete (NAC) while the remaining mixtures include binary and ternary blends of FA, BFS, and MK addition. Test results indicate that CSC show slightly lower compressive strength, higher drying shrinkage and carbonation depths compared to that of NAC due to high porosity of coral sand aggregate. Moreover, CSC exhibit better chloride penetration than that of NAC. The incorporating of MK has efficient pozzolanic reaction in improving the development of compressive strength and chloride permeability performance, and reducing drying shrinkage values of CSC than that of modified CSC with FA and BFS addition. Furthermore, the incorporation of MK manifests better carbonation resistance than that of control group and CSC containing FA and BFS.