Alternative Materials for the Modification and Stabilization of Unstable SubgradeSoils. Laboratory Testing

摘要

This study examines two lime by-products and two fly ashes for treatment ofunstable (CBR<6) subgrade soils. The treatment methods include both modification and stabilization. Modification is temporarily enhancing subgrade stability to improve constructability. Stabilization is the construction of a permanent, high strength base material which is considered a part of the pavement structure. The alternative materials include a dried lime kiln sludge (DLKS), a hydrated lime by-product (HLB), an ASTM C 618 Type C fly ash (TCFA), and a fly ash (FA) that does not meet the requirements of ASTM C 618. The performance of soils treated with these materials was compared to that of the corresponding soils treated with the control material, a high calcium lime kiln dust (LKD). Test results presented in this study include the moisture-density relationships, bearing values, compressive strengths, swell potential, and plasticity index for treated soils and untreated soils. The results do not provide enough data to comprehensively evaluate the performance of FA. However, the results do indicate that the suitability of DLKS, HLB, and TCFA depends on soil type, moisture contents, and expected performance.