Contaminated sites and cement solidification/ stabilization

S/S, which involves mixing portland cement into contaminated material, protects human health and the environment by immobilizing hazardous constituents within the treated material. The cement reacts chemically with water in the material being treated, creating changes in the physical and chemical properties of the treated materials preventing the escape of hazardous constituents into the environment. Solidification refers to changes in the physical properties of the waste, including an increase in its compressive strength that enables it to support more weight, a decrease in its permeability that reduces water infiltration, and encapsulation of hazardous constituents. Stabilization refers to chemical changes in the hazardous constituents in the waste, that convert them into a less soluble, mobile or toxic form.

The popularity of S/S is due to the fact that it can be used for a wide variety of contaminants in many types of contaminated material. Soil, sediment and sludge impacted with an array of organic and inorganic contaminants have been treated successfully using this versatile technology. There are two distinct methods for the treatment of contaminated material. Cement may be mixed directly into hazardous material on-site or it may be excavated and transported off-site for treatment. Afterwards, the treated material may be safely reused on-site or disposed in a landfill.

S/S provides an economically viable means of treating contaminated sites. Because this technology can treat and contain contaminated soil on site, it often reduces the need for landfill disposal. It protects surrounding communities and water resources by preventing leaching of contaminants into groundwater.

S/S with portland cement has benefits that make it more economical and easier to use than other methods:

• Cement is manufactured under strict CSA and ASTM Standards, ensuring uniformity of quality and performance
• Cement’s success in S/S is supported by more than 50 years of use in a variety of projects
• Cement has a long-term performance record
• Cement usage can minimize volume increase compared with other reagents
• Cement is a non-proprietary manufactured product, readily available across the country in bag or bulk quantities

A set of complementary concrete pavement resources are highlighted in the links below: