Slurry Cut Off Walls
Pictures
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Contact information
- Dr Dan Adams
- 01937 541118
- geotechnique@keller-ge.co.uk
Keller Slurry Walls are formed by using a specially formulated mix of cementitious and bentonite based materials together with proprietory additives to provide a plastic structure that offers extremely low permeability with a degree of flexibility.
Demanding current specifications have been proven in practice by the Keller mix design. These generally require permeability in the range of 10-8 to 10-9m/s, strains in excess of 5% without failure, and strengths typically of 100-300kN/m2.
The wall can form a barrier to the passage of leachates and ground water flows, to prevent the contamination of adjacent ground and water courses.
Construction
Excavation of the wall is normally carried out using a Keller long reach excavator, currently with depth capabilities up to 12 metres. For deeper walls, grabbing techniques similar to those used for constructing diaphragm walls are used.
A bentonite/cement slurry is prepared at a central mixing and batching station using Keller high shear colloidal mixing techniques. Precise batching and monitoring of the mix constituents is essential for uniformity of the final product. Automated electronic controls are used throughout the process as part of on-site quality control measures.
As excavation proceeds the slurry is pumped from the mixing station to the excavation.
The bentonite/cement slurry mix maintains the sides of the excavation to provide temporary stability until a set occurs and the mix hardens insitu to form the permanent wall.
