InTrans / May 29, 2020

CP Tech Center releases Guide to Cement-Stabilized Subgrade Soils

A new guide developed by the National Concrete Pavement Technology Center (CP Tech Center) in collaboration with the Portland Cement Association (PCA) offers the latest advances in cement-stabilized subgrade (CSS) soil, a compacted, engineered mixture of pulverized in situ soil, water, and moderate proportions of portland cement that results in a semi-bound to bound material.

The Guide to Cement-Stabilized Subgrade Soils, completed in May 2020, updates and expands on the information presented in the PCA’s 2008 publication Guide to Cement-Modified Soil (CMS).

CMS and CSS typically describe soils treated with a relatively small proportion of cement to provide improved characteristics, such as reduced plasticity and volume change. While CMS and CSS are similar, CSS has all the benefits of CMS and also substantially increases soil stiffness and strength to the point where the treatment can provide structural benefits to pavement and building foundations.

The guide describes the characteristics, uses, and benefits of cement-stabilized subgrade and presents methods for geotechnical evaluation, mix design, construction, and field testing that will help to produce a satisfactory final project.

“CSS is a more economical and sustainable alternative than removing and replacing unstable or expansive untreated soils. It reduces not only costs but also construction time,” said Jerod Gross, of Snyder & Associates and one of the lead authors on the project.

“CSS aids in extending the service life of a pavement system by providing a non-expansive and stable subgrade that will last under different climactic conditions. The increased service life of the pavement minimizes the costs and materials that would otherwise be consumed to rehabilitate or reconstruct the pavement system,” added Wayne Adaska, of the PCA and the other lead author on the guide.

While CSS has applications beyond stabilizing problematic soils, the guide focuses on the use of cement to enhance the engineering properties of subgrade soils beneath both rigid and flexible pavements, as well as building floor slabs.

The guide’s intended audiences include design engineers, testing laboratory personnel, contractors, and owners. Readers can use the document to determine which applications are appropriate for CSS and the proper steps for its uses in a pavement system project.

More information about the latest in concrete pavement technologies can be found at the CP Tech Center’s website here.