What is soil-cement? Why have millions of cubic yards been used for slope protection, seepage control, foundation stabilization and pipe bedding?


Broadly defined, soil-cement is a mixture of natural soils, portland cement and water. In its moist-compacted state it forms a durable, strong, economical and virtually impermeable material with properties similar to concrete and natural rock. A typical mixture contains about 10 percent cement and 10 percent moisture by weight of the dry soil.


The best demonstration of soil-cement durability has been the satisfactory performance of a test section built by the U.S. Bureau of Reclamation on the southeast shore of the Bonny Reservoir in eastern Colorado. This test section has endured severe wave action, countless cycles of wetting and drying and more than 100 cycles of freezing and thawing each year for 31 years. Other projects have shown soil-cement to be durable to seawater, domestic and industrial wastewater, coal ash slurries, brine solution and water flow up to 10 to 15 feet per second.


Soil-cement for energy and water resource projects falls into four categories:

  • Slope protection--Soil-cement is widely used for constructing channels, canals and ditches to control erosion.
  • Seepage control--The low permeability of soil-cement leads to its use to prevent water seepage by lining water facilities such as recreational development lakes, water storage reservoirs and ash settling ponds.
  • Foundation stabilization--Soil-cement has been used as a massive fill to provide foundation strength and uniform support under large principal structures.
  • Pipe bedding--A type of fluid or plastic soil-cement has been used as a backfilling material around pipes and adjacent to structural walls.