Pore Structure Evolution and Its Effect on Strength Development of Sulfate-Containing Cemented Paste Backfill

Abstract

In this study, the effects of the initial sulfate content on the properties of cemented paste backfill (CPB) made from coarse tailings has been investigated via mercury intrusion porosimetry. The combined effects of the sulfate content and curing time on the total porosity, pore size distribution, and unconfined compressive strength of the produced material were discussed. It was found that the specimens with an initial sulfate content of 5000 and 35,000 ppm exhibited higher unconfined compressive strength, while the resulting fine porous structures characterized by pore radii of 10–400 and 1–10 μm significantly improved the mechanical properties of the CPB. In addition, an increase in the curing time decreased the overall pore volume in the radius range of 1–400 μm but increased the pore volume at pore radii less than 1 μm.

Keywords

• sulfate attack
• mercury porosimetry
• pore size distribution
• hydration products
• compressive strength