Influence of activated bauxite tailings on the macroscopic properties and microstructure of low water-binder ratio concrete

The objective of this study is to explore the influence of activated bauxite tailings on the properties of concrete under a low water-to-binder ratio. The workability, hydration heat, compressive strength, XRD patterns, thermogravimetric analysis, pore structure, and water absorption of concrete with varying incorporation levels of activated bauxite tailings were examined. Results demonstrate that incorporating tailings diminishes the concrete’s slump and fluidity, while shortening its setting time. Compared to T0 (which contains only fly ash), as the tailings incorporation increases, the end time of the induction stage of the concrete continuously decreases. When the tailings incorporation is 36 %, the concrete achieves the highest compressive strength. Incorporating activated tailings does not affect the types of hydration products. Meanwhile, as the content of tailings increases, the quantity of hydration products also continuously increases compared to T0. Incorporating tailings reduces the volume of harmful pores in the concrete and optimizes its pore structure. When the tailings incorporation is 36 %, the concrete exhibits the lowest water absorption rate of 2.67 %. The multifractal analysis results indicate that incorporating tailings reduces the connectivity of concrete pores and enhances the homogeneity of the pore structure. • The 28-day strength of T36 is the highest. • Incorporating tailings does not affect the phase composition of hydration products. • Incorporating tailings refines the concrete’s pore structure. • Multifractal theory is employed to investigate the influence mechanism of tailings on the concrete’s pore structure.