Bentonite Self-Hardening Slurry Mix Variations and Field Implementation Methods-Paper

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The paper examines mix design and field implementation of self-hardening slurry barrier walls, focusing on slag-cement-bentonite (SCCB) and comparing it with Portland cement-bentonite (CB). Self-hardening slurry both stabilizes the excavation during construction and cures in place as the final low-permeability barrier.<br /><br />Three mixing approaches are reviewed: combining dry ingredients in one mixer; hydrating bentonite separately before adding dry cementitious materials; and preparing bentonite and cementitious slurries separately before blending them. The more complex methods can improve hydration, mixing consistency, and field adjustment, but require additional equipment and quality control. Laboratory mix procedures should reflect the method planned for field use, including the order of ingredient additions and mixing energy.<br /><br />SCCB generally develops substantially greater strength and lower hydraulic conductivity than CB, while often using less cementitious material. Portland cement may still be preferred when it is more available, faster early strength is required, or site chemistry makes slag unsuitable.<br /><br />In the trench, sediment contamination, filtration, and consolidation change slurry volume and composition. Water loss can lower the water-to-cementitious ratio and increase strength, but may also make the wall less uniform. Higher bentonite-to-water ratios improve filtration control, reduce water loss and consolidation, and help produce a more uniform, ductile wall. Bentonite also retains considerably more water than cementitious materials. Fluidizers can help make higher-bentonite mixes workable.<br /><br />The paper emphasizes using suitable low-hardness, low-salinity make-up water, adequate mixing, and testing for site-specific soils and chemical contaminants. It recommends further research on consolidation, stress-strain behavior, and how bentonite concentration and suspended sediments affect the finished wall.

Keywords

self-hardening slurry

slurry barrier walls

slag-cement-bentonite

Portland cement-bentonite

mix design

bentonite hydration

hydraulic conductivity

field implementation

low-permeability barrier

fluidizers