Predicting long-term impact of cementitious mine fill considering sand as a copper-tailings substitution

Abstract

It is of great importance to use different materials or techniques to enhance the quality/behavior of cementitious mine fill (CMF). This leads the mining industry to evaluate new production techniques or resources that will improve CMF performance by choosing easier, cheaper, faster, and reliable approaches. This study captures the effect of sand employed as tailings substitution on CMF properties by destructive and non-destructive methods. The mechanical (UCS), ultrasonic (UPV) and microstructure (XRD, FTIR, SEM) properties of the backfills, which were prepared with a fixed binder (3 wt%) and two different solids (70 and 75 wt%) content, cured up to 360 days were investigated. The amount of sand used in the mixtures was chosen to be 0% (control), 10%, 20%, 30, 40% and 50% of the tailings by weight. Results exposed that the growth in solid concentration, curing time (up to 90 days) and the amount of sand in the mixtures (up to 30%) had a boosting consequence on the fill's performance. However, both in long curing times and in the use of >30% sand, CMF's performance decreased. Moreover, perfectly compatible correlations were found between the UCS and UPV results, depending on the solid content of CMF and the sand substitution rate. The UCS results measured and predicted by these correlations were also obtained from the current work. As a result, this study presents the contribution of ultrasonic non-destructive testing as an alternative way and the link between them to the backfill technology.