Fabrication and properties of slag-based geopolymer syntactic foams containing hollow glass microspheres

[Display omitted] •Slag-based geopolymer syntactic foams were fabricated containing hollow glass microspheres.•High compression strength of syntactic foams were achieved by high degree of geopolymerization and in-situ reinforcement.•The content of hollow glass spheres had a significant effect on the strength.•This study showed a high value-added route to reuse the solid waste. High porosity and high strength slag-based geopolymer syntactic foams were achieved by a combined route consisting in both embedding hollow glass microspheres and direct foaming with H2O2 and a surfactant. The effect of the hollow glass microspheres content on the pore morphology, porosity, density, mechanical strength, and thermal conductivity was investigated. Results showed that the hollow glass microspheres were dispersed homogenously and bonded well with the geopolymer matrix.