Stabilisation of pores in glass foam by using a modified curing-sintering process: sustainable recycling of automotive vehicles’ waste glass

Abstract

Glass foams are porous high-performance insulation materials. The uniformly distributed and homogenously sized fine pores are crucial for the insulation properties of glass foam. To improve the homogeneity and stability of pores, stabilising chemicals are used in glass foam manufacturing. However, these chemicals release greenhouse gases during sintering. Therefore, there is a continuous quest for developing a sustainable pore stabilising method. This research aimed to enhance the stability and uniformity of pores in glass foam by curing glass powder without any chemical stabilising agent. The glass powder, fly ash additives, and foaming agent were mixed using water and cured in sealed plastic bags. Then the raw glass foam was sintered at 800℃. Given the surface interaction and pozzolanic reactivity of glass and fly ash, bonding was developed along surfaces of particles during curing, which provided stability to the particles and was helpful to maintain viscosity during sintering. Consequently, it was possible to resist the pore collapse within the glass matrix and achieve uniformity in pore size distribution. Subsequently, glass foams possessed high compressive strength (4.1±1MPa with porosity 73.5±2.3%) and low thermal conductivity (<0.2 W/m.K). Furthermore, compared with the pellet making process in powder sintering methods, the curing process makes glass foam manufacturing more convenient for large-scale production. By recycling waste glass of automotive vehicles as to the primary raw material and eliminating chemical stabilising agents, the glass foam manufacturing process will be more sustainable.