Combined effect of high temperatures and crystalline slag on the mechanical behavior of geopolymers mortars

Abstract

As part of protecting the environment from carbon dioxide emissions, all research aims to reduce the use of cement in concrete with cheaper and energy efficient materials. Geopolymer mortar is an environmentally friendly mortar made from industrial solid waste and by-products such as crystalline slag (CS). This research aims to produce a geopolymer mortar from local materials available in Algeria which are not sufficiently valued at present. The aim of this study is to provide geopolymer mortar at high temperatures, operating with a constant hardening temperature of around 60° C. The alkaline activator used in this study was a combination of sodium silicate (Na2SiO3) and 10 M NaOH solution. In addition, crystalline geopolymer mortars (MCS) as the binder material at a curing temperature of 60 °C, ratios of two mixtures of binder were prepared by substituting the sand with 40% CS and 100% CS. For this purpose, the mortar sample with the highest compressive strength was subjected to temperatures of 200, 400, 600 and 800 °C for exposure times of 10 °C per minute and changes in temperature and changes in the physical and mechanical properties was analyzed. As a result of the experiments, the highest mechanicals values were obtained from the mortar samples with a 40% CS content. Following the high temperature tests, 400 °C and 600 °C were determined as critical temperatures for changes in mechanical properties and changes in physical properties, respectively. However, the geopolymer mortars lost around 60% of strength at 800 °C which is the final temperature.