Improvement in Physical and Mechanical Properties of Soils by the Addition of Lime for Paving Roads

This paper presents the results of a laboratory study of three expansive soil samples collected on the SC-112, an unpaved state road that connects the city of Rio Negrinho to Vila Volta Grande in Santa Catarina State, Brazil. The road's lack of pavement inhibits the development of the region by obstructing traffic during the rainy season. The study estimated the percentage of lime that would need to be added to the soil to minimize expansion of the soil and evaluated changes in the physical and mechanical characteristics of the soil. The study used the miniature, compacted, tropical (MCT) classification, which was developed in Brazil to study the properties and behavior of tropical soils. The following tests were used to study the physical and mechanical characteristics of the soil samples, soil–lime mixtures, and lime: Atterberg limits, grain size, compaction, California bearing ratio, MCT soil disk method, and chemical analysis of the lime. Lime requirements were estimated with the lime fixation point, pH, and MCT soil disk methods. The results of plasticity limit tests showed that the base exchange reactions of lime with the soil occur immediately after the addition of water to the soil–lime mixture. Use of the MCT methodology tests showed that the natural soil samples with the addition of lime changed their behavior from nonlateritic to lateritic. The addition of 3% lime to two soils and 2% to the third soil caused physical and mechanical changes in the soils that allow their use as subgrade of low-volume road pavement.