Development of self-foaming cold-bonded lightweight aggregates from waste glass powder and incineration bottom ash for lightweight concrete

To address the scarcity of natural aggregates and reduce the energy consumption of the concrete industry, a self-foaming geopolymer cold-bonded lightweight aggregate (GCBLA) was developed using waste glass powder as the main precursor and municipal solid waste incineration bottom ash as a foaming agent. The impact of alkali content (2 M, 4 M, 8 M, and 12 M NaOH) on the physical properties of GCBLA was investigated. To evaluate the feasibility of GCBLA application, GCBLA was used to replace 50 vol% and 100 vol% of manufactured sand to prepare lightweight mortars compared with expanded clay. Results indicated that with the increased volume of GCBLA, the density, thermal conductivity, and compressive strength of mortars decreased due to the porous and lightweight nature of GCBLA. The internal curing effect of GCBLA effectively mitigated the autogenous shrinkage of the mortars. Moreover, a remarkable 39% carbon reduction and 34% energy reduction were achieved compared to expanded clay while maintaining similar density and strength. However, the high shrinkage of GCBLA resulted in gaps between GCBLA and the cement matrix, increasing the total drying shrinkage of the mortars.