Correlation of resilient modulus of fine-grained soils with common soil parameters for use in design of flexible pavements

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Sandefur, Kealohi
thesis / dissertation description
This thesis describes research conducted at the University of Hawaiʻi at Manoa to evaluate the resilient modulus properties of tropical Hawaiian fine-grained soils for use in flexible pavement design. The objectives of this study were to: a) measure the resilient modulus of four fine-grained soils found on the island of O'ahu, and b) develop predictive equations for resilient modulus based on easily measured soil index properties. Each soil was tested at 100% and 95% relative compaction based on the Standard Proctor compaction test. At each relative compaction, the soils were compacted at three different water contents: at optimum, 2% above and 2% below optimum. Correlations were developed based on two resilient modulus stress-state models published by Uzan (1985) and Ni et al. (2002). Regression parameters obtained from the Uzan and Ni et al. models are correlated to soil index properties and physical-state conditions. A total of four regression models are proposed which correlate the resilient modulus to soil stress-state, physical-state, and soil index properties. Tropical soils may undergo irreversible changes upon drying, resulting in permanent alterations in soil properties. As a result, the resilient modulus of an MH soil was measured at three different stages of drying as follows: (1) at the in situ state; (2) after drying the soil to half the natural water content; and (3) after oven drying. In general, the resilient modulus was found to be more sensitive to changes in confining and deviatoric stresses upon increasing the degree of drying.