Permanent Deformation Response of Polymer-Treated Pavement Foundation Material under Transmitted Stress Pulses

Abstract

An understanding of the response of pavement materials under repeat loading is required for the mechanistic approach to pavement design. In this study, the response of granular subbase materials for a flexible pavement under simulated traffic loading has been investigated using repeat load triaxial (RLT) testing. Three types of granular materials treated with polyacrylamide (PAM) have been tested to assess changes in engineering performance and response to simulated traffic. Untreated materials have been also tested for comparison. In addition, these samples have been prepared using different compaction efforts to assess the effect of compaction level on performance and response of these materials. The engineering performance of these materials (treated and untreated) in terms of strength and deformation is assessed by conducting unconfined compressive strength (UCS) and RLT tests. Data related to their response under simulated loads have been also collected and used to calibrate an existing plastic strain model to predict the permanent strain response of each soil type from its physical properties. Results indicate that samples treated with PAM yielded higher UCS values and lower deformation characteristics than the untreated samples, with plastic strain magnitude being dependent on the compaction effort used. Furthermore, the model adopted for determining plastic strain has been found to satisfactorily describe the plastic strain response of the RLT experimental test data.