Strength And Stiffness Characteristics Of Lime Stabilized Soil In A Flexible Pavement Design

Abstract

Lime treatment has proven to be a useful tool for stabilizing expansive soils. Expansive soils cause major damage to flexible and rigid pavements every year, since seasonal changes in soil moisture creates cyclical changes in the forces acting on a pavement. The use of lime to stabilize soil can reduce the soil's swell potential and add strength and stiffness to a pavement's subgrade. Due to the improved physical properties, lime stabilized soil (LSS) can be considered as part of the structural pavement layers. Utilizing LSS as a subbase in the pavement structure can reduce the thickness of the more expensive pavement layers. In the North Tarrant Expressway (NTE) Segment 1 project, the results of the geotechnical investigation and quality assurance (QA) programs were used to verify the increase in strength and stiffness of the LSS with time. Unconfined compression strength (UCS) and resilient modulus tests were used, during the design phase, to determine if the reactions between the soil and lime would increase the strength and stiffness of the soil. Eight groups of soils from the NTE Segment 1 project were treated with lime and tested in the lab to confirm a 25,000 psi design assumption for the LSS layer resilient modulus. During construction, as part of the QA program, UCS and Falling Weight Deflectometer (FWD) tests were conducted to further confirm the design assumption. The design, quality control, and QA processes along with testing results are reviewed and summarized in this thesis to demonstrate that LSS can be considered a pavement subbase, if the proper precautions are taken.