Effect of hydrogen peroxide and bagasse ash additions on thermal conductivity and thermal resistance of geopolymer foams

Abstract

This research investigates the properties of geopolymer foams from metakaolin blended with bagasse ash activated by sodium hydroxide and sodium silicate and using hydrogen peroxide (H2O2) as a foaming agent at 0.5, 1.0, and 1.5 wt%. Geopolymer foams were cured at 50 °C for 24 h and kept in ambient condition until the testing day. The porosity increased with higher H2O2 and decreased with increasing bagasse ash content. The increase in porosity resulted in a decrease in compressive strength. A significant reduction in thermal conductivity from 0.3194−0.4519 to 0.1532−0.1857 W/m K was achieved at foams with 1–1.5 wt% H2O2 addition and 10−20 wt% bagasse ash replacement. The thermal resistance of the geopolymer foams after firing at 600 °C and 800 °C for 1 h was determined. It was found that the optimum mixture was 1 wt% H2O2 and 30 % wt% bagasse. All geopolymer mixtures demonstrated an improvement in compressive strength after the firing indicating impressive thermal resistance.