Slurry walls are below-grade walls that restrict groundwater flow (cutoff/barrier) or support excavations and structures (structural diaphragm), using soil-bentonite or cement-bentonite.
For structural diaphragm slurry walls, a clam-shell bucket is typically used to excavate individual panels that will compose the wall, to design depth. During excavation, soil-bentonite slurry is placed to prevent caving. After design depth is reached, the slurry is displaced with concrete pumped through a tremie pipe to the bottom of the panel, and steel reinforcement is inserted. The finished walls can simultaneously function as a ground water cut-off and soil retention system during the excavation phase of the project, and then as permanent underground walls with load-carrying capabilities for the finished structure.
For traditional barrier walls, the trench is excavated through bentonite slurry or cement-bentonite (CB) slurry to prevent collapse of the trench during excavation. In the case of CB walls, the CB hardens in the trench to form the wall. When bentonite slurry alone is used, the excavated soil is mixed with bentonite and then placed back into the trench to form a soil-bentonite wall. The finished wall results in a groundwater barrier with low permeability.
Non-traditional methods of slurry cutoff wall construction include the vibrating beam method. A vibratory hammer is used to drive special steel beams to design depth along the wall alignment. Cement-bentonite slurry is injected during penetration and withdrawal of the beam. The penetrations are overlapped to construct a continuous barrier. The finished wall results in a thin groundwater barrier with low permeability.
This technique is available in most areas through either Hayward Baker or sister Keller companies. Contact your local Hayward Baker office for more information.