Superplasticizers are used in the preparation of cemented paste backfill (CPB) to improve its rheological properties. CPB produced from sulphide-bearing tailings can generate acid mine drainage (AMD), which has negative environmental impact. The AMD potential can be assessed based on the reactivity of the CPB when exposed to the atmosphere. However, the effect of superplasticizers on the reactivity of CPB is unknown. This paper presents findings from experimental investigations on the effects of polycarboxylate superplasticizers (PCSP) on the reactivity of CPB containing pyrite. The reactivity of cured CPB specimens was determined by monitoring the rate of oxygen consumption in an enclosed chamber. Microstructural tests, namely mercury intrusion porosimetry, X-ray diffraction, and thermogravimetric analyses were also carried out to have a better understanding of the reactive mechanisms. The results obtained show that the addition of PCSP leads to a proportionate reduction of reactivity. The admixture causes the refinement of the pore structure of the CPB by mainly improving binder hydration and self-consolidation. It was also observed that less pyrite crystals were present in the CPB containing the superplasticizer. High curing temperature was also found to improve binder hydration, leading to a decrease in reactivity of CPB with PCSP. Due to the micro-filer effects on the CPB pore structure, partial replacement of cement with fly ash and blast furnace slag also decreases the reactivity of CPB. These research findings will be valuable for the design of cost-effective, more environmentally friendly and sustainable CPB structures.

超塑化剂用于制备胶结膏体回填 (CPB) 以改善其流变性能。含硫化物尾矿生产的 CPB 会产生酸性矿山排水 (AMD)，对环境产生负面影响。AMD 潜力可以根据暴露于大气时 CPB 的反应性来评估。然而，高效减水剂对 CPB 反应性的影响尚不清楚。本文介绍了聚羧酸减水剂 (PCSP) 对含黄铁矿CPB 反应性影响的实验研究结果。. 固化 CPB 样品的反应性是通过监测封闭室中的耗氧率来确定的。还进行了微观结构测试，即压汞法、X 射线衍射和热重分析，以更好地了解反应机理。获得的结果表明，添加 PCSP 会导致反应性成比例地降低。该外加剂主要通过改善粘合剂的水合和自固结来细化 CPB 的孔结构。还观察到含有减水剂的 CPB 中存在较少的黄铁矿晶体。还发现高固化温度可以改善粘合剂的水合，导致 CPB 与 PCSP 的反应性降低。由于微过滤器对 CPB 孔结构的影响，用粉煤灰和高炉渣部分替代水泥也会降低 CPB 的反应性。这些研究结果对于设计具有成本效益、更环保和可持续的 CPB 结构具有重要价值。