Abstract:
The study sought to investigate the potential application of clay pozzolana as a supplement for cement in hydraulic backfill,
using classified tailings from AngloGold Ashanti, Obuasi Mine. The percentage of the Portland cement that could be
substituted with the clay pozzolana to produce backfill with best strength was determined. 10%, 25%, 30%, 35% and 40% of
the ordinary Portland cement were replaced with clay pozzolana and then mixed with tailings and water. The slurry produced
was cast into cylindrical specimen of 50mm diameter by 120mm high and tested for compressive strength after curing for 7,
14, 21, 28 and 56 days. The results indicate that, clay pozzolana-cement composite has potential for application in hydraulic
back fill production without increased risk to safety and dilution. It was noted that hydraulic backfill with 10%, 25%, 30%
and 35% of the ordinary portland cement replaced with clay pozzolana had strengths greater than those obtained for ordinary
portland cement alone. Ten percent (10%) pozzolana content gave the maximum strength followed by 25% pozzolana. It is
recommended that for safety and economic considerations, the cement content should be replaced by 25% pozzolana in the
production of backfills.
