Alkali-Activated Foamed Lightweight Soil Mixed with Bauxite Tailings: Development and Properties

Abstract

Realizing the efficient resource utilization of bauxite tailings (BTs) is a crucial imperative within the global context of low-carbon development. This study aims to utilize BTs as a primary precursor without high temperature calcination to develop a green alkali-activated foamed mixture lightweight soil (FMLS), primarily composed of ordinary Portland cement (OPC), BTs, water glass, and foam. The effect of BTs content, fly ash, and water glass modulus on the fresh properties, durability, uniaxial compression performance, and pore structure of FMLS with BTs (FMLSB) were studied, with two different replacement percentages (10% and 20% by weight) of BTs for OPC designed. The results indicate that FMLSB exhibited better fluidity after adding water glass, with values ranging from 185 mm to 240 mm. The water absorption of FMLSB with 10% BTs content and a water glass modulus of 1 was the lowest, at 67.63%. The 28d unconfined compressive strength of FMLSB reached 0.51 MPa at a wet density of 557 kg/m3. The ratio of 7d to 28d unconfined compressive strength was the highest at a water glass modulus of 1, reaching 78.43%. The uniaxial compression stress-strain curve of FMLSB exhibited an elastic-plastic stage and a failure platform stage, with concurrent strain softening and strain hardening. The pore structure was dense when the content of fly ash and BTs was 30%, resulting in a compressive strength of 0.48 MPa. The resource utilization of BTs will also produce significant economic and environmental benefits.

Keywords: Bauxite tailings, Alkali-activated, Foamed mixture lightweight soil, Uniaxial compressive performance, Pore structure