A novel foaming-sintering technique for developing eco-friendly lightweight aggregates for high strength lightweight aggregate concrete

To address the scarcity of natural aggregates and reduce energy consumption in the concrete industry, a sustainable lightweight aggregate (LWA) was prepared with a self-foaming and sintering method by utilizing waste glass powder as the primary precursor and incineration bottom ash as a foaming agent. The effect of NaOH content (0 M, 2 M, and 8 M) on the physical properties of LWA was investigated. Replacing manufactured sand with sintered LWA (0 M-LWA and 2 M-LWA) by 50 vol% and 100 vol% to investigate their impact on the physical properties, mechanical properties, shrinkage, and alkali-silica reaction of high strength LWA concrete. The high strength LWA concrete prepared with 0 M-LWA possessed a density of 2127 kg/m³ and compressive strength of 108.7 MPa, which were slightly lower than that with manufactured sand. Due to the porous and lightweight nature of 2 M-LWA, the density and compressive strength of LWA concrete significantly decreased with the increased 2 M-LWA volume. Nevertheless, 100%-2M showed satisfying density of 1835 kg/m³ and compressive strength of 50 MPa. The internal curing effect of 2 M-LWA effectively mitigated the autogenous shrinkage of LWA concrete. The alkali-silica reaction expansion of all LWA was innocuous.