Characterization of a Northeast Brazilian Swelling Soil in the Natural Condition and Treated with Lime

The volume variation of expansive soils due to alterations in water content causes socioeconomic and environmental damages to geotechnical engineering works. The expansiveness of a soil is determined by intrinsic (mineralogical composition, texture, and structure) and extrinsic (groundwater movement, vegetation, and anthropic occupation) characteristics. The addition of lime to a swelling soil improves its geotechnical properties through physical-chemical interactions capable of stabilizing the volume variation. This paper investigates the effects of lime treatment on the properties of Paulista's swelling soil, comparing the natural soil's behavior with 1, 3, 5, and 7% dry weight soil-lime mixtures. Physical, chemical, mineralogical, and swelling characterization tests were performed and the natural soil presented high expansiveness. The determination of expansion pressure was influenced by the stress trajectory followed during the test. The addition of lime to the soil caused the aggregation of particles or flocculation, and reduced the plasticity index. The addition of 5% hydrated lime content to Paulista's soil stabilized both free and pressure swelling tests.