The effect of curing temperature on the properties and structure of geopolymer composite based on potassium silicate and Metakaolin

Abstract

A carbon fibre/geopolymer composite whose matrix was based on potassium silicate and metakaolin was subjected to different curing temperature modes. The effect of the treatments was evaluated by testing the stiffness and water uptake resistance of the composite. The structure of the composites was analysed by scanning electron microscopy, X-ray diffraction and nuclear magnetic resonance. It was determined that the highest stiffness was achieved by the primary curing at 80°C. Contrary to this, curing at temperatures higher than 100°C increased the resistance to water uptake, resulting in smaller decrease in the storage modulus. Structural changes of the geopolymer were linked to the course of the curing temperature mode. Two types of the curing were suggested for the use of the carbon fibre/geopolymer composite in heat stress applications and in a humid environment, respectively.