Long term characteristics of sustainable concrete incorporating manganese ore tailings and nano-silica as cementitious material

Abstract

The incorporation of industrial by-products possessing latent hydration capacity as a partial cement replacement presents an effective strategy for advancing sustainable concrete production and reduction of hazardous substances in the environment. In this study, a mortar system containing ordinary Portland cement, nano-silica (NS) and Manganese Ore Tailings (MOT) was carefully designed to produce concrete. The hydration behaviour of the mortar system was examined through setting time observations. The duration of the initial hydration reaction took longer in the MOT samples, the delay increased as the MOT content increased. This could be due to the release of SO 4 2− ions from gypsum when MOT dissolves in water. The retardation in hydration time was significant at 25%, 30%, and 35% MOT content with delays of 2h, 3.5h, and 5.5h, respectively, compared to the control mix. Concrete mixtures with up to 10%MOT-10%NS demonstrated up to 29% improvement in mechanical properties and 37% lower shrinkage strain compared to conventional concrete. Nano-silica proved to enhance the strength and shrinkage characteristics of MOT concrete significantly due to the filler effect. Incorporating MOT in concrete offers a viable and eco-friendly solution for the safe disposal of the toxic components in MOT.