Effect of saline admixtures on mechanical and microstructural properties of cementitious matrices containing tailings

The addition of silane coupling agents as an additive in cement-based materials provides several technical, operational, and economic advantages such as a reduction in the amount of water to cement ratio and an improvement in flow behavior. In this study, we used mine tailings as the sole source of fine aggregates along with two different silane agents, namely methyl-trimethoxy silane or MTMS as a water repellent and dispersing agent and tetraethyl-orthosilicate or TEOS as the precursor of nano-silica. Based on the achieved results, the addition of 1% MTMS decreased the water requirement of cement and tailings mixture up to 25% for a specific slump height while the strength acquisition was mainly under the influence of MTMS rather than TEOS. The addition of these silane agents to the cementitious matrix containing tailings improved the matrix densification by filling influence of fine pores and formation of new sources of hydrated cement minerals such as C-S-H gels as discussed in differential thermogravimetric, mercury intrusion porosimetry, infrared spectroscopy, and scanning electron microscopy sections.