Aggregate base and subbase are the important component of flexible pavement system. Wheel load imposed on the surface of pavement is transferred to the subgrade layer with the help of base and subbase. In this regard, load withstanding capacity of unbound aggregate base and subbase layers become the focus of study for several years. Amount of aggregate fines and plasticity are known to play great role in stiffness and deformation of base and subbase layers. In this study, the effect of plasticity index, fines content and dust ratio of unbound aggregate on permanent deformation and resilient modulus of base and subbase layers are investigated. Repeated load triaxial tests were conducted for two Illinois dense-graded standard gradations, i.e., CA 6 and CA 2, and two material types, i.e., crushed gravel and crushed limestone at optimum moisture content. From the study, higher plasticity index (i.e., 9%) was found to show high permanent deformation and low resilient modulus compared to aggregates with lower plasticity index (i.e., 5%). The effect of fines content on permanent deformation and resilient modulus was found dependent on dust ratio. Increasing dust ratio from 0.4 to 0.6 to 1.0 increased the permanent deformation and decreased the resilient modulus at fines content of 5%. However, an opposite behavior was observed when the dust ratio increased from 0.4 to 0.6 to 1.0 at fines content of 12%. Furthermore, based on the analysis of data, permanent deformation and resilient prediction models were proposed.
|Commitee:||Qi, Yan, Werner, Anne|
|School:||Southern Illinois University at Edwardsville|
|School Location:||United States -- Illinois|
|Source:||MAI 58/01M(E), Masters Abstracts International|
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