Permeability and reactivity of cemented paste backfill with sodium silicate

Abstract

The key properties of sodium silicate-bearing cemented paste backfill (S-CPB) that have environmental impacts are investigated in this study. These properties include the permeability and reactivity of S-CPB. S-CPB consists of tailings, water and binder, along with the addition of sodium silicate, which is an alkali activator. The S-CPB samples are prepared and cured for 90 days. The reactivity of the S-CPB samples with sulphidic-tailings (45% wt. pyrite) is investigated by performing oxygen consumption (OC) tests, whereas the permeability of the S-CPB is evaluated through saturated hydraulic conductivity tests. The results of the OC tests show that the addition of 0.3% wt. of SS to CPB can reduce its reactivity due to an increase in the formation of cement hydration products in the CPB. Furthermore, the results show that SS reduces the hydraulic conductivity of the S-CPB by enhancing or refining its microstructure. The results obtained suggest that the addition of SS to CPB would reduce its environmental impacts.