Mechanical properties and durability of concrete containing fly ash and GGBS for marine environment: A comprehensive study from laboratory perspective

Abstract

The degradation of concrete structures in the marine environment is generally caused by sulfate attack and chloride ion penetration. To improve the durability of concrete in the marine environment, fly ash (FA) and ground granulated blast furnace slag (GGBS) were partially used to replace cement in a ternary system. The crushed sand was used to reduce the shortage of river sand. In this study, the concrete containing crushed sand, FA, and GGBS was prepared in the laboratory, in which river sand was partially replaced with crushed sand and cement was substituted with FA and GGBS. The amounts of FA/binder and GGBS/binder were fixed at 20% and 35%, respectively, while the content of crushed sand/fine aggregate was set at 60%. The mechanical properties were investigated via compression and splitting tensile tests. The durability of the concrete was examined using a rapid chloride penetration test, sulfate attack test, accelerated corrosion test, and abrasion-wear resistance test. The results showed that the partial replacement of cement by FA and GGBS improved both the mechanical properties and durability of concrete. The inclusion of FA and GGBS in concrete significantly improved its resistance to chloride permeability, specifically, the total charge passed of the mixture with FA and GGBS decreased from 86.2% to 136.9% in comparison with the mixture without FA and GGBS. The addition of FA and GGBS could reduce the change in the length (i.e., improved sulfate resistance) of concrete when it is in contact with the sulfate solution. The changes in the length of the mixture containing FA and GGBS were 3.5 times and 3.2 times smaller than those of the mixture without FA and GGBS. The concrete mixture containing FA and GGBS has a two-time higher corrosion resistance to chloride ion ingress than conventional concrete without FA and GGBS inclusion. The abrasion resistance was improved significantly with the inclusion of FA and GGBS, the abrasion resistance of the mixtures containing FA and GGBS significantly improved by 52 to 59% in comparison with the mixture without FA and GGBS. These results demonstrate that the inclusion of FA and GGBS in concrete can improve both the mechanical properties and durability of concrete, which can be applied in marine environments for sustainable development.