Monitoring of strength and microstructure evolution characteristics of cemented paste backfill incorporating potable and non-potable water using real-time sensors

Global water scarcity has heightened the need for alternative sources in industry, making non-potable water such as seawater vital for resource conservation and sustainability. This study explores replacing potable water with seawater or process water in cemented paste backfill (CPB) to enhance sustainability. CPBs were produced with different water mix ratios (tap/sea/process: 0/100, 25/75, 50/50, 75/25), using a constant solid/cement ratio (75/5 wt%) and cement type (CEM I 42.5 R). Tests included strength, microstructure, thermal analysis, and real-time monitoring for up to 180 days. Strength increased reaching 1.47 MPa until 56 days but declined afterward. Seawater-based samples showed higher early-age strength (0.57 MPa) due to elevated alkalinity, which enhanced hydration. However, at 180 days, CPBs with seawater or process water showed faster strength loss (up to 33 %) than tap water mixes, due to harmful ions and salts. Still, seawater presents a viable alternative for CPB production in coastal, water-scarce mining areas. • Seawater and process water can replace potable water in CPB sustainably. • CPBs containing seawater reached higher UCS value (∼1.5 MPa) up to 56 days. • Strength declined after 56 days in CPBs including sea or process water. • Non-potable water use enables sustainable CPB in coastal/water-stressed mines. • Real-time sensors effectively monitor performance of CPB on-site conditions.