Bentonite mud used in making excavations is deflocculated - chemically after use to improve backfilling by sand

摘要

To assist the backfilling with sand of an excavation made with the aid of a bentonite mud as support fluid, this mud is chemically deflocculated just before or during the backfilling. The deflocculation is pref. by addn. of sodium bicarbonate to ppte. the calcium ion previously added as quicklime to rigidify the mud. The mud is pref. more dil. than usual, having less than 40 (pref. 31-33) kg/cu.m of bentonite and an initial viscosity below 38 sec. Marsh; but it is then rigidified by quicklime, without passing the first rigidity peak. 500-1500 g/cu.m of quicklime is needed. Used in burying or embedding prefabricated piles or walls, tie-beams, sewers, pipes and caissons. The obstruction of the free flow of sand by the normally viscous bentonite mud is overcome. Filling is therefore more complete.