Long-term creep estimation of HDPE geogrid using temperature-accelerated stress relaxation techniques

This study integrates temperature-accelerated techniques with a framework for predicting creep (CP) behavior from stress relaxation (SR) to enhance the efficiency of long-term creep strain predictions for a high-density polyethylene (HDPE) geogrid. Short-term CP tests using the stepped isothermal method (CP-SIM) and SR tests employing the time-temperature superposition technique (SR-TTS), each lasting four hours across four temperature stages, produced master creep and stress relaxation curves, extending the observable time by a factor of 250. The nonlinear three-component (NTC) model was used to analyze the time for CP (Δt_CP), irreversible strain increment during CP (Δe^ir_CP), and corresponding SR parameters (Δt_SR and Δe^ir_SR). At the same irreversible strain rate (), Δt_CP and Δe^ir_CP were significantly larger than Δt_SR and Δe^ir_SR, demonstrating that SR data can effectively extend to predict CP. Relationships between Δt_CP and Δt_SR and between Δe^ir_CP and Δe^ir_SR formed the SR-to-CP prediction framework, enabling the prediction of Δe^ir_CP vs. Δt_CP relationships from Δe^ir_SR vs. Δt_SR data. This framework extended Δt_CP by a factor of 6.55 compared to Δt_SR. Overall, combining temperature-accelerated techniques with the SR-to-CP framework resulted in a total time extension factor of 1,637, significantly enhancing the practicality and accuracy of long-term creep predictions compared to using temperature-accelerated techniques alone.