Thermal Behavior of Metakaolin-Based Geopolymer Cements Using Sodium Waterglass from Rice Husk Ash and Waste Glass as Alternative Activators

The aim of this work was to study the thermal behavior of metakaolin-based geopolymer cements using sodium waterglass (NWG) from rice husk ash and waste glass as alternative alkaline activators. Metakaolin-based geopolymer cements were obtained by adding freshly prepared NWG and metakaolin. The geopolymer cements obtained using sodium waterglass from rice husk ash and the one obtained with sodium waterglass from the waste glass were treated at room temperature for 28 days and then heated at 200, 400, 600 and 800 °C. The results show that the metakaolin-based geopolymer cements lose their compressive strength from room temperature to 400 °C. At 600 °C, the compressive strength of geopolymer cements increases relative up to 200 and 400 °C. At 800 °C, the reduction of compressive strength of geopolymer cements is assigned to the total evaporation of the rest of structural water. However, it is higher than that measured at ambient temperature for geopolymer cement obtained using the sodium waterglass from waste glass but lower for the sample obtained with sodium waterglass from rice husk ash. The total mass loss of geopolymer cements obtained with sodium waterglass from rice husk ash and one obtained with sodium waterglass from waste glass are about 12.57 and 15.04 %, respectively. This suggests that geopolymer cement obtained using sodium waterglass from waste glass are more condensed geopolymer structure indicating that it could a very suitable material for fire resistant application. The results indicate that NWG from rice husk ash and waste glass could be served as suitable alternative activators for producing metakaolin-based geopolymer cements with high-temperature performance.