Early-age hydration characteristics of composite binder containing iron tailing powder

The early-age hydration characteristics of composite binder containing iron tailing powder were investigated by determining the hydration heat, non-evaporable water content, pore structure, and morphology of hardened paste as well as the compressive strength of mortar. The results show that the reaction degree of iron tailing powder is extremely low at early age. Addition of coarse iron tailing powder negatively affects the properties of composite binder paste and mortar. Compared to samples containing coarse iron tailing powder, the samples containing fine iron tailing powder show a large amount of hydration heat, high non-evaporable water content, fine pore structure of hardened paste and high compressive strength of mortar. The iron tailing powder significantly promotes the hydration of binder at low water-to-binder ratio. The iron tailing powder particles are well graded with cement particles in the paste, but the large iron tailing powder particles bond poorly with the surrounding hydrates. The decreasing ratio of compressive strength of mortar is much lower than the replacement level of iron tailing powder, especially for the mortar containing fine iron tailing powder at low water-to-binder ratio. (C) 2017 Elsevier B.V. All rights reserved.