Hydration kinetics of cement-calcined activated bauxite tailings composite binder

Abstract

To explore the influence of bauxite tailings particle size and content on the hydration process of cement-tailings composite binder, the hydration kinetics of blended cement containing activated bauxite tailings was investigated. Hydration heat of cement-bauxite tailings composite binder was measured at 20 °C. The Krstulovic–Dabic kinetics model was used to explore the kinetics of blended cement containing bauxite tailings. The hydration process of blended cement was analyzed by the X-ray diffraction (XRD). Results demonstrate that the induction period of the composite binder increased with increase in the bauxite tailings content. The hydration heat increased with increase in powder selection frequency of the tailings. The kinetics model could effectively simulate the hydration process of cement- bauxite tailings composite binder. With the increase of the tailings content, the value of α1 decreased and that of α2 increased. Calcined activated bauxite tailings could react with calcium hydroxide owing to the pozzolanic reaction. The calcium hydroxide content of the composite binder decreased compared with pure cement and decreased with increase in the bauxite tailings content, particularly for bauxite tailings incorporations exceeding 30%.