Study On Mechanical Properties Of Cemented Paste Backfill Using Fly-Ash-Based Cementitious Materials

Abstract

In Mongolia, the Ulan lead-zinc mine is now struggling with high backfill operating costs and poor Cemented Paste Backfill (CPB) mechanical performance after curing. To solve this problem, BGRIMM Technology Group has investigated an activator that could mix with fly ash from Choibalsan Power Plant in Mongolia as a supplementary cementitious material for backfill. In this study, the mechanical performance of CPB samples prepared with various fly ash content and activator types were studied to provide a basis for the industrial application of fly ash-based supplementary cementitious materials. The research results indicate that partially replacing cement with fly ash reduces the uniaxial compressive strength (UCS) of CPB samples. Compared with the CPB sample prepared with pure cement, when the fly ash substitution rate is 10%, 20%, and 30%, the UCS reduced by 15.66%, 18.69%, and 32.83%, respectively. With the use of chemical activators, the UCS of CPB samples could be significantly improved. Among them, CPB samples prepared by the activator sodium sulfate+ sodium chloride+ TEA have achieved the highest UCS. Overall, this study shows that the synergistic effect of fly ash and chemical activators could effectively enhance the mechanical performance of CPB, which is beneficial for mine backfill cost reduction and could provide a basis for the further industrial application of fly ash-based cementitious materials in mine backfill.