Influences of curing factors on mechanical properties of glass fiber-reinforced epoxy composite for coating concrete and mortar

Abstract

This experimental investigation aims to study the effects of curing factors on mechanical properties of epoxy composites for industrial floor coating. The epoxy composite system comprised of diglycidyl ether of bisphenol A (DGEBA) epoxy resin, diethylene triamine (DETA) curing agent, woven glass fiber reinforcement and sand filler. Both epoxy composite coating layer without any substrate and the epoxy composite coated concrete/mortar substrate, were investigated. An experimental design had been applied so that the results, obtained from a minimal number of experiments, would still be statistically conclusive by the technique of Central Composite Rotatable (CCR). Empirical models displaying the relationships between the curing factors and their corresponding response on mechanical properties were analyzed by the technique of Response Surface Methodology (RSM). The mechanical properties were analyzed as a function of the cure temperature, the cure time and the amount of added sand. Results studied showed that curing the epoxy composite at ambient temperature of 31 ํC gives better impact strength and fracture toughness, but less compressive strength than that of cured at a higher temperature of 99 ํC. The compressive strength can be improved by extending the cure time. Adding sand as a filler prominently improves the fracture toughness, but slightly decrease the compressive strength and the impact strength. Results drawn from this study illustrated that the most appropriate cure condition for each mechanical property varies. The optimum cure condition compromised from all mechanical properties is at the cure temperature of 31 ํC for 56.2 h, which is the longest cure time studied, with the amount of sand filler 29%. Curing at this condition minimize the reduction in mechanical property from the greatest achievable value. The highest reduction is 24.2% in the compressive strength of epoxy composite.