Thermal insulation performance of rock wool reinforced kaolinite-based porous geopolymer

The development of thermal insulation materials with superior comprehensive properties is crucial to building energy conservation. This paper presents a kaolinite-based porous geopolymer type composite thermal insulation material through alkali activation, room temperature foaming technology, and the rock wool fiber reinforcement. The effects of rock wool fiber contents and heat treatment on the comprehensive properties of the kaolinite-based porous geopolymer were investigated. The addition of rock wool fiber can enhance the mechanical properties of kaolinite-based porous geopolymer, while heat treatment can generate a hierarchical porous structure, resulting in a dramatical improvement in thermal insulation performance. With a rock wool fiber content of 15 wt%, the sample exhibits a porosity of ∼90%, density of 0.118 g/cm3, thermal conductivity of 0.057 W/(m·K), and a maximum compressive strength of 0.66 MPa, increased by ∼22% compared to samples without addition of rock wool. Additionally, the optimized thermal insulation material followed waterproofing treatment exhibits excellent hydrophobicity with a contact angle of up to 98.5°. Therefore, this novel thermal insulation material not only has a simple manufacturing process and eco-friendly properties, but also showcases properties including lightweight construction, high strength, and low thermal conductivity. Consequently, it holds immense potential in the area of building energy conservation.