Preparation and characterization of lightweight aggregate foamed geopolymer concretes aerated using hydrogen peroxide

In this study, novel green lightweight foamed geopolymer concretes (LFGC) aerated using hydrogen peroxide based on fly ash, metakaolin and expanded polystyrene (EPS) particles was developed for thermal insulation materials. Physical properties, mechanical strength, thermal characteristics and permeability of LFGC were evaluated by designing and optimizing the components of EPS particles, hydrogen peroxide, metakaolin and fly ash. Meanwhile, the internal microstructure was also investigated by pore structure and scanning electron microscope. The results show that as the content of EPS particles and hydrogen peroxide increased, the compressive strength of LFGC decreased by 57.6% and 9.7%, respectively. The lightweight and thermal insulation properties are enhanced as the EPS particles and hydrogen peroxide content increase due to the contribution of low-density EPS particles and closed foamed air voids. The LFGC presented its dry density range of 300–650 kg/m3, the compressive strength between 2.0 and 5.5 MPa and the thermal conductivity between 0.122 and 0.195 W/m∙K, showing better mechanical strength than the traditional ordinary cement foamed concrete with the same density. Meanwhile, the microstructure also shows that the EPS particles have good compatibility with the foamed geopolymer pastes.