Bentonite slurry is the name given to the mixture of sodium bentonite and slurry. This combination is often used to create a solid protective barrier in the ground. According to the Environmental Protection Agency, slurry walls are consistent and safe to shield the health of the population and the environment.
Sodium bentonite is a clay that grows and expands when wet. This expansion allows it to permeate cracks and crevices to form a solid barrier. However, according to the North Dakota State University Agriculture and University Extension, if the bentonite loses moisture from evaporation, it can shrink and revert back to the dry form.
A slurry is a watery mixture that cannot be dissolved. This runny substance can be made with many mixtures, but sodium bentonite is one of the most common materials used to create a slurry. The bentonite slurry will usually contain around 2 percent to 4 percent of bentonite by weight, according to the Virginia Tech Civil Engineering Department.
Bentonite slurry walls can be made using cement or soil. Soil bentonite walls are made by digging a trench and saving the soil from the hole. A bentonite slurry mix is poured into the hole and also mixed with the soil that was excavated. This soil is then poured into the slurry in the hole to create a barrier. Cement bentonite walls are similar, but instead of reintroducing the soil to the hole, cement is mixed with the slurry and that alone is poured into the hole.
Slurry walls act as a barrier against contaminated water. This allows a process that will keep contaminated waters away from other environmental sources in an attempt to isolate the polluted waters. Bentonite slurry is also used to plug abandoned wells. Slurry walls can also be used to help guide uncontaminated waters to channels where they are desired.
The benefit of a bentonite slurry wall is that it keeps the contaminated waters or hazardous materials contained. Groundwater often will mix with water that is consumed. If this water is contaminated, anyone who consumes it will be a risk for health problems.
- Portland Cement Association: Slurry Walls For Groundwater Control
- North Dakota State University Agriculture and University Extension: A Guide to Plugging Abandoned Wells
- Ecosystem Restoration: Groundwater Controls
- University of Washington Department of Construction Management: Slurry Trench / Diaphragm Walls