Influences of Moisture Content on Resilient Modulus of Unbound Crushed Limestone

Abstract

The design method of pavement structure is evolving to the new Mechanistic-Empirical (M-E) approach. A major benefit of M-E approach is being able to identify the distress patterns and the progress rate of a given pavement structure. This is possible by the knowledge of mechanistic characteristics of pavement materials responding to the repeated loads and environmental changes. Resilient modulus of the unbound granular material is the fundamental parameter needed in the mechanistic analysis of pavement structure. The resilient modulus behavior responding to moisture changes is the key contribution to the structural strength of conventional pavement in Thailand.  This study investigated the resilient modulus of the road base materials for the M-E approach. In this research, a set of laboratory tests were conducted on unbound crushed limestone. Two gradations of the limestone were selected to determine the resilient modulus using the repeated-load tri-axial test according to AASHTO T307. Test results revealed that water content played a significant influence to the resilient modulus value. The resilient modulus characteristic of limestone UGM observed from these tests can be employed in Mechanistic-Empirical Pavement Design.