Characterization of Bases and Subbases for AASHTO ME Pavement Design
The characteristics of base and subbase layers play a very important role in pavement performance under the complex conditions of traffic loading and environment. Unreasonable and inaccurate base design parameters can result in poor pavement performance as well as higher construction and maintenance costs. This study was conducted to develop material input databases for several common types of base and subbase layers in South Carolina including Graded Aggregate Base (GAB), Cement Stabilized Aggregate Base (CSAB), Cement Modified Recycled Base (CMRB), and Soil-Cement (S-C). Seven South Carolina aggregate sources were used to evaluate GAB. Five of these sources were used to evaluate CSAB. Two subgrade sources (clay soil and sandy soil) and one RAP source were utilized to evaluate CMRB. The same two subgrade sources were also used to evaluate S-C. One GAB source was also utilized in a laboratory test pit to simulate field conditions and correlate with other testing. Compressive strength, elastic modulus, dry shrinkage, resilient modulus, and other properties were characterized through laboratory testing. Optimum mathematical resilient modulus models and material coefficients were recommended for the different kinds of base layers. A database was compiled, which considers the effect of moisture content, cement content, material type, curing period, and so on.