Soil Cement Bentonite Slurry Walls are a Stronger Selection of Slurry Walls

Soil Cement Bentonite Features higher Slurry Trench Stability

**SCB Mixing Box**

Soil-Cement-Bentonite (SCB) Slurry walls are a variation on the more common Soil Bentonite slurry walls. With this method, the materials excavated from the trench are generally blended with bentonite and cement to provide additional strength to the final backfill.

Advantages of Soil-Cement-Bentonite Slurry Walls

Most of the same advantages of SB slurry walls apply to SCB walls
The cementitious materials added to the backfill increase the strength of the backfill
Greater trench stability is possible because the SCB backfill creates a shorter backfill slope.
SCB is often preferred in levees for its resistant to erosion and burrowing animals.

Applications of SCB walls include levee repairs where internal erosion is a concern and other projects that need stronger backfill. SCB as a material has also been used to provide a protective encasement for critical foundations and as a replacement for compacted clay when construction must take place in wet and cold conditions. SCB is also closely related to roller compacted concrete and soil cement.

Construction Methods for Soil Cement Bentonite Slurry Walls

SCB walls are excavated using the same general methods as for a Soil Bentonite Slurry Wall. SCB backfilling requires some additional equipment for handling the cement and for making cement grout which is added to the backfill. Cement is added to the backfill most often as a grout, but also in dry powder form. A typical grout plant as used for SCB construction is shown below.

**Grout Plant for SCB Slurry Wall**

Because the grout must be added in small yet fairly precise ratios, mixing is often done in a mixing box rather than on the ground. Mixing is usually accomplished using an excavator, much the same as for an SB wall. Backfill can also be placed with the excavator. A picture of a backfill mixing box is shown below.

Properties of Soil Cement Bentonite Backfill

Adding the cement grout to the backfill generally means a higher (worse) permeability than would be obtained with the same material without the cement. This is because the Portland cement interferes with the bentonite and prevents it from achieving its full swelling potential. Typical permeabilities for SCB backfill are in the range of 10-7 cm/sec. Typical unconfined strengths are in the range of 30-150 psi (0.2 to 1 MPa). Unlike CB, SCB permeability usually remains unchanged over longer time intervals, however, SCB strength does continue to improve over time. Plots of short-term permeability and strength from a recent project are shown below.

**Short Term SCB Permeability**

**Short Term Strength of SCB**

Learn More about Slurry Cut-Off Walls

Geo-Solutions has authored and participated in over 50 different papers on slurry walls. View our library to read and download several slurry cut-off wall technical papers.
Learn more from case studies on slurry walls in our Section on Case Studies.
Learn more and view pictures of our slurry wall equipment in our Section on Equipment.

Slurry Wall Sample Specifications

Read and download Geo-Solutions sample specs for soil bentonite slurry cut-off walls, cement bentonite slurry walls, soil-cement-bentonite slurry walls, composite slurry walls, bio-polymer slurry groundwater collector trenches.

Call Us Today

For help with slurry cut-off walls utilizing various types of bentonite slurry mixes, call us at 724-335-7273.