Investigation of the utility of the waste brick and marble powders on the paste backfill

In this study, effect of usage of grinded waste marble and brick as replacement and additive at a given rate instead of Portland cement on the strength and stability properties of paste backfill prepared from tailings having high sulphur content was investigated. At the end of 7-180 days of curing period, paste backfill samples produced at different mixture properties were subjected to unconfined compressive strength test. To ascertain the loss of stability in the paste backfill samples at long-term, acid formation based on pyrite oxidation in tailings was monitored depending on curing period. The results of strength and stability obtained were associated with physical, chemical, mineralogical and pozzolanic properties of additives (marble and brick) used. It was observed that usage of grinded brick dust having pozzolanic character at 15% by weight instead of Portland cement increase the strength and stability of paste backfill. Usage of grinded marble and brick powders at the rates of 15 and 45% in addition to Portland cement used as a binder in paste backfill provided an increase of 15-65% on the strength of paste backfill. It was also seen that usage of grinded marble dust powders increased the neutralization potential of paste backfill on the long-term by comparison control sample. From the short and long-term tests, it was observed that usages of grinded marble dust at the rate of 25% and grinded brick dust at the rate of 25% in addition to Portland cement made a positive impact on the strength and stability of paste backfill.