Regular cement based suspension grout used for mine backfilling operations have low cohesion values and migrate downwards through the shotrock for the duration of a backfilling operation. The upper portion of the backfill zone has a much higher percentage of voids than the lower portion.
Cement foam with the proper additives will not sag and provides a uniform distribution of the grout throughout the backfill, reducing dilution during pillar recovery.
The benefits of using cement foam over regular cement based suspension grouts are:
· Fine cellular structure has greater impact absorption during blasting operations
· Greater contact surface between the grout and the rock surfaces because of non-sag characteristics.
· Greater volumes of cement foam grout can be produced per kilogram of cement (compared with regular cement based suspension grouts).
· Cement foam can be mixed in-line with the cement based suspension grout and does not require additional equipment near the backfill zone.
· Provides a higher void filling ratio than regular cement based suspension grouts.