Preparation of high-performance thermal insulation composite material from alkali-activated binders, foam, hollow glass microspheres and aerogel

Abstract

• Physical foaming, hollow glass microspheres and aerogel were used for AAB. • CMC minimized foam and slurry delamination and improved foaming effect. • KH550 treated hollow glass microspheres showed enhanced the interfacial bonding. • PE100-hydrophobic aerogel had extern hydrophilic and internal hydrophobic effect. Herein, a high-performance thermal insulation composite material was prepared by adding physical foaming agent (FA), hollow glass microspheres (HGMs) and aerogel (AG) with alkali-activated binders (AABs) as the matrix. The results of orthogonal experiments revealed that AG has the greatest effect on thermal conductivity, followed by the effect of FA and HGMs. The thermal conductivity value of AABs was reduced from 0.6057 to 0.0870 W/(m·K) at an AG dosage of 4 g (42.48 kg/m 3 ) in the single factor experiments. The effect of compressive strength followed an order of: HGMs < FA < AG. Under the temperature condition of 400–800 °C, the FA exacerbated the linear shrinkage of the sample, HGMs inhibited the linear shrinkage at 400 °C and 600 °C, and exacerbated it at 800 °C, while AG inhibited the linear shrinkage. X-ray diffraction and scanning electron microscopy analyses revealed that the sample maintained stable performance below 800 °C. Orthogonal experiment results concluded that the optimal level combination was 6 g FA, 6 g HGMs and 3 g AG (A6B6C3) and exhibited the minimal thermal conductivity (0.0434 W/(m·K)). The compressive strength of A6B6C3 at 30 °C was 0.38 MPa, which gradually increased with temperature, reaching the maximum of 0.79 MPa at 800 °C. This composite can meet the thermal insulation, mechanical and high temperature resistance properties. In addition, accredited to simple preparation process, short curing period, and low cost, this approach can be deemed of great significance for applications in composite thermal insulation materials in nuclear power plants and other key areas.