Diaphragm walls are formed from cast-in-place reinforced concrete panels with interlocking vertical joints that provide a continuous watertight barrier. A shallow reinforced concrete guide wall is constructed along the line of the required wall to direct the excavation equipment. Alternating trenches are excavated using specialized equipment and utilizing bentonite slurry to support the vertical walls of the trough, preventing soil incursions. The bentonite slurry is continuously circulated and cleaned during excavation. Stop-end pipes are placed vertically at each end of the primary panel to form joints for adjacent secondary panels.
Upon completion of the excavation, a steel reinforcement cage is lowered into the trench. Concrete is continuously pumped starting at the bottom of the excavation using a tremie pipe, which is extracted as the concrete rises while its discharge end remains immersed in the fresh concrete. The poured concrete displaces the bentonite slurry, which is gradually pumped out, filtered and saved, to be reused.
An alternate construction method would be to use precast reinforced concrete panels. The panels are lowered into the trench filled with self-hardening bentonite slurry. The cement bentonite slurry sets adhering to the panels and thus forming the final composite wall panel.
Diaphragm walls are installed without dewatering in a vibration free, low noise process which makes them an ideal solution for congested areas. They can be installed in close proximity to existing structures with minimal disturbance to adjacent foundations.