The Study of Ranong Metakaolin-Based Porous Geopolymers as Insulating Materials for Construction

An increased concern of global warming has driven an increased demand of thermal-insulating materials, particularly in a construction industry. Traditional thermal-insulating construction materials are porous ceramic and light-weight cement brick which have high porosity and heat resistance. However, the manufacturing of cement is a major carbon dioxide (CO2) emission as it has been reported that 0.73-0.85 tons of CO2 were released from every single ton of cement production. Geopolymer is one of the alternatives to replace the cement-based materials. The present study aims to improve the properties of Ranong metakaolin-based porous geopolymers prepared by mixing the metakaolin in an alkaline activator at a weight ratio of metakaolin: activator of 55:45. A 3-μm Al powder employed as pore former was added into the geopolymer mixtures, and the samples were cured at 27-60°C for 24 h followed by aging at room temperature for 28 days. The addition of 0.1-0.4 wt.% Al powder resulted in porous structures having bulk densities in a range of 0.58-0.93 g/cm3, thermal conductivities in a range of 0.172-0.390 W/m∙K and compressive strengths in a range of 3.1-22.4 MPa. The properties of the fabricated porous geopolymers satisfy the TIS 1510-2541 standard and the CIBSE Guide A, indicating potential application as green thermal-insulating materials for building and construction.