Polymer support fluids: use and misuse of innovative fluids in geotechnical works

Bentonite slurries have been used for over sixty years for the temporary support of excavations such as bored piles and diaphragm walls. At intervals over this time polymer products have been tried in place of bentonite but not always successfully. Recently it has become clear that, if used properly, polymer fluids offer many advantages over their bentonite counterparts, including improved foundation performance, lower environmental impacts, smaller site footprint and also simpler preparation, mixing and final disposal as they are used at much lower concentrations. They are also more easily managed than bentonite. However, successful use requires that the some specific characteristics of polymers are respected, in particular, it must be recognised that they are sorbed onto soils so that the polymer concentration in solution drops during use.