Degree of hardening of epoxy-modified mortars without hardener in tropical climate curing regime

Abstract

Previous studies show that the epoxy resin will harden in the presence of calcium hydroxide from cement hydration process under steam curing. In this study, commercially available epoxy resin without any hardener was used as a polymeric admixture to prepare epoxy-modified mortars subjected to dry, and 5 day wet followed by dry curing in tropical environment. The mortars were prepared with a mass ratio of cement to fine aggregate 1:3, water-cement ratio of 0.48 and epoxy content of 5, 10, 15 and 20% of the cement. The tests conducted were workability, setting time, compressive strength, flexural strength, and degree of hardening of epoxy resin. The results of the study show that the optimum epoxy content that produced the highest strength was 10% under wet-dry curing. However, the degree of epoxy hardening starts to decrease with an increase in epoxy content above 10%. It was also found that a significant improvement in strength development is achieved along with additional dry curing period due to gradually hardening reaction of epoxy resin with cement hydrates.