Utilizing accelerated stress relaxation techniques to predict long-term creep behavior of a HDPE geogrid

Understanding the creep behavior of polymer geosynthetic reinforcements is crucial for designing
geosynthetic-reinforced soil (GRS) structures. Traditionally, determining the creep reduction factor (RFCR) for a specified design lifetime involves lengthy conventional creep tests to derive the creep rupture curve. To expedite this process, techniques employing increased temperature to accelerate creep straining, such as time-temperature superposition (TTS) and stepped isothermal method (SIM), have been introduced. Additionally, creep and stress relaxation behaviors are attributed to a material’s viscous properties. Stress relaxation occurs much faster than creep for the same irreversible strain rate under a given tensile load. An empirical framework has been established to correlate stress relaxation time history with creep strain, enabling successful prediction of long-term creep strain from short-term stress relaxation. This study applies temperature-acceleration techniques to short-term creep and stress relaxation tests on a high-density polyethylene (HDPE) geogrid. Analysis yields long-term time histories of creep strain and stress relaxation, with the duration increased by a factor of 250. An empirical linkage between these time histories is developed, resulting in a more efficient prediction of long-term creep behavior by multiplying the time factor of both methods, approximately 1,635-fold. This approach offers a streamlined and effective means of predicting the long-term creep behavior of HDPE geogrids.