Combined influence of sulphate and temperature on the saturated hydraulic conductivity of hardened cemented paste backfill

This paper presents an experimental study that focuses on the investigation of the coupled effects of temperature and sulphate on the permeability of hardened cemented paste backfill (CPB). Hydraulic conductivity tests and a microstructural analysis are conducted on mature CPBs prepared with various amounts of sulphate (0, 5000, 15,000, and 25,000 ppm) and cured at various temperatures (2 °C, 20 °C, 35 °C, and 50 °C). Important findings and valuable results are gained. It is found that the coupled effects of sulphate and temperature can lead to decrease (i.e. improvement of the environmental performance of CPBs) or increase of the hydraulic conductivity of CPBs. There is competition between the permeability decreasing and increasing factors. The dominant influencing factors depend on the curing temperature and initial sulphate content.