Studies on properties of coral aggregate strengthened by granulated blast furnace slag (GBFS) and concrete prepared by strengthened coral aggregates

Abstract To enhance the mechanical, durability and deformation properties of coral coarse aggregate concrete (CAC), alkali-activated granulated blast furnace slag (GBFS) paste (AGP) coated CCA is used to strengthen coral coarse aggregate (CCA). The strengthened coral aggregate concrete (SCAC) was prepared by strengthened CCA (SCCA). The influences of the strengthening parameters (molarity of sodium hydroxide (Mol) and modulus of sodium silicate (Ms) of AGP) on the microstructures and properties of SCCA and SCAC were studied by axial compression tests and scanning electron microscopy. The results showed that microstructures and properties of SCAC were greatly improved after using SCCA. Compared to CAC, the cubic compressive strength ( f cu ) of SCAC increased by 23.74% on average. With the increase of Ms, the f cu of SCAC first increased and then decreased, while the influence of Mol was negligible. The deformation properties of SCAC also varied with the change of strengthening parameters. With the increase of Ms of AGP, the peak strain ( ε o ) of SCAC increased, and the maximum increase in ε o was 28.32% in comparison to CAC. The decline of the stress-strain curve of SCAC became gentle, and its curve curvature was enhanced, which caused the energy dissipation capacity and ductility of SCAC to be 122.76% and 15.28% greater than those of CAC, respectively.