Heaving Mechanisms in High Sulfate Soils

Pavement distress caused by chemically treated sulfate soils are considered as major maintenance problems to highway agencies. In view of this, researchers across the world have conducted studies on heave mechanisms in chemically treated sulfate soils. Many of these studies are focused on soils with soluble sulfate contents below 10,000 parts per million (ppm). Heave mechanisms in soils with sulfate contents above 10,000 ppm still need to be understood as sulfate measurements indicate that the soil sulfate levels of certain regions are well above 10,000 ppm and may exceed 50,000 ppm in some cases. In order to understand the behavior of treated soils containing sulfates above 10,000 ppm, a research study was initiated. Two soils with different soil classification are studied. Lime is used as a chemical stabilizer for these soils. Chemical and mineralogical tests as well as engineering swell tests were conducted to compare the changes in swelling, mineralogical and chemical compositions of the soils from the limesulfate reactions. Results will explain the need to look for replace the classical treatments by alternate ones for these high sulfate soils for civil infrastructure projects.