Document Type

Thesis - Open Access

Award Date

2022

Degree Name

Master of Science (MS)

Department / School

Civil and Environmental Engineering

First Advisor

Rouzbeh Ghabchi

Abstract

Improving the engineering properties of the subgrade soil by means of chemical stabilization is known to enhance the construction conditions in plastic soils and result in a reduction in design thickness requirements of the base, subbase, and wearing course in a layered pavement structure. This can also potentially lead to an increase in pavement life. This study was undertaken to study the effect of hydrated lime and Portland cement used as a stabilizing agents on the strength properties and the cracking resistance of a clayey soil collected from South Dakota. Hydrated lime was mixed with the collected soil by 2%, 3% and 5% and Portland cement was blended at 7%, 9% and 11% by the weight of the soil. Different tests, namely Particle size distribution, Atterberg limits, pH, Proctor test, freeze-thaw (F-T) cycles, unconfined compressive strength, and semicircular bend test were conducted before and after treatment with hydrated lime and Portland cement. The results indicated that use of 1% cement was more effective than 1% lime in improving soil’s shear strength. In general, shear strength of the natural soil was found to become more sensitive to F-T cycles with increasing both Portland cement and hydrated lime contents. The flexural stiffness and fracture energy of the natural soil were found to improve by stabilizing it with both lime and cement. This improvement was more pronounced when Portland cement was used. Reduction in the flexural stiffness and fracture energy of the lime-stabilized soil was found to be more sensitive to F-T cycles than cement-stabilized soil. The only stabilizing agent found to be capable of improving the flexibility index of the natural soil was hydrated lime. Cement-stabilized soil was concluded to be highly brittle and may result in instantaneous propagation of the crack in the whole section after reaching the peak load. Therefore, the use of cement stabilization should be carried out more cautiously to avoid premature crack.

Number of Pages

74

Publisher

South Dakota State University

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Rights Statement

In Copyright