Development of an Improved Test Setup for Measuring the Resilient Modulus of Stabilized Pavement Materials

Abstract

In a recent study to develop mechanistic empirical relationships for full depth reclamation (FDR) in California, it was determined that the commonly used triaxial testing setup detailed in American Association of State Highway and Transportation Officials (AASHTO) T 307 was not suitable for testing stabilized materials. This paper investigates different testing setups, based on a comprehensive literature review, to determine an appropriate approach for measuring strains on both laboratory-compacted and field-cored specimens. Five different test setups were evaluated, ranging from measurements on the top cap of the triaxial cell, to third-point measurements on the specimen. This study also investigated methods of mounting transducer gauge points on the specimen in a repeatable and accurate manner, and for preparing the specimen ends to mitigate point loads. Two field cores, one sampled from an FDR project with cement stabilization (FDR-PC) and the other from an FDR project with foamed asphalt stabilization (FDR-FA), were subjected to unconfined, low stress cyclic triaxial testing using different deviatoric and seating stresses using each of the five test setups. The effects of non-linear strain distribution on the cyclic stress strain curves were compared. Based on these results, the recommended test setup for determining the resilient modulus of the stabilized material is the third point on-specimen setup for measuring strain. This approach was minimally influenced by the non-linear strain distribution, and provided resilient moduli that closely correlated with stiffnesses back calculated from the falling weight deflectometer deflections measured close to the core locations.