Development of heat resistant geopolymer-based materials from red mud and rice husk ash

Abstract

Geopolymer is an inorganic polymer composite developed by Joseph Davidovits in 1970s. Such material has potentials to replace Ordinary Portland Cement (OPC)-based materials in the future because of its lower energy consumption, minimal CO₂ emissions and lower production cost as it utilizes industrial waste resources. Hence, geopolymerization and the process to produce geopolymers for various applications like building materials can be considered as green industry. Moreover, in this study, red mud and rice husk ash were used as raw materials for geopolymeric production, which are aluminum industrial and agricultural wastes that need to be managed to reduce their negative impact to the environment. The red mud and rice husk ash were mixed with sodium silicate (water glass) solution to form geopolymer paste. The geopolymer paste was filled into 5-cm cube molds according to ASTM C109/C109M 99, and then cured at room temperature for 28 days. These products were then tested for compressive strength and volumetric weight. Results indicated that the material can be considered lightweight with a compressive strength at 28 days that are in the range of 6.8 to 15.5 MPa. Moreover, the geopolymer specimens were also tested for heat resistance at a temperature of 1000oC for 2 hours. Results suggest high heat resistance with an increase of compressive strength from 262% to 417% after exposed at high temperature.