Effect of Iron Ore and Copper Ore Tailings on Engineering Properties and Hydration Products of Sustainable Cement Mortar

The prohibition of river sand mining has convincingly drawn the research attention in finding the practicable alternatives. In the approach of finding these alternatives, it is essential to ensure a minimal or zero impairment to the ecological balance which can be mainly attained by making use of industrial wastes/by-products. The wastes from the mining industries are the major contributors in causing the impairment to environment, their influence on the stability of mortars on using as fine aggregates need to be systematically investigated with the view of long-term performance concerns. Thus, the present study explores the applicability of mine tailings and finding the optimum dosage in cement mortars by investigating the engineering properties and microstructure development with the aid of qualitative and quantitative analysis associated to hydration products. The studies confirm that, the increased consumption of portlandite for secondary hydration reactions followed by the additional formation of calcium silicate hydrate (CSH) and calcium aluminum silicate hydrate (CASH) phases in mine tailing-based mortars helped in achieving a quality microstructure. These additional formations of CSH and CASH phases are also confirmed through FTIR by identifying the shift of Si-O-Si stretching vibration bands towards a lower wavenumber. The lowering of Ca/Si atomic ratio and increased formation of mineralogical compounds related to CSH and CASH in XRD patterns also confirms the same. Gismondine, Chabazite and Hillebrandite are the additional phases formed and found to be taken part in refining the pore structure. This enhanced performance of mine tailing mortars was also verified with the aid of modified Andreasen and Andersen particle packing model. The formation of high-quality microstructure is reflected in the hardened properties of optimized cement mortar which in the proportion of 20% for iron ore tailing (IOT) and 30% for copper ore tailing (COT).