Facile preparation and properties of foamed fly‐ash/slag‐based hollow glass microspheres/geopolymer composites

Abstract In order to reuse the multiple solid waste and improve the porosity of geopolymer composites, a unique foaming process was developed to fabricate novel green foamed fly‐ash/slag‐based hollow glass microspheres/geopolymer (HGMs/FSGP) composites. A thorough investigation was carried out on the synergic effects of cetyltrimethylammonium bromide (CTAB), hydrogen peroxide (H 2 O 2 ) and HGMs on the microstructure, strength and thermal conductivity. Results showed that the foamed HGMs/FSGP composites with the amorphous structure could be fabricated by foaming combined with HGMs at room temperature. The density of the samples changed from 1.16 to 0.47 g/cm 3 with 1–5 wt.% H 2 O 2 . The acceptable compressive strength (0.71–15.05 MPa) of the HGMs/FSGP composites was attributed to the fractured HGMs, the good bond between HGMs and geopolymer matrix, and crack deflection across the HGMs. With proper H 2 O 2 and HGMs, the composites obtained their lowest thermal conductivity of 0.116 W/(m⋅K), which could find use in insulation fields.