Effects of temperature on the rupture strength and elastic stiffness of geogrids

ABSTRACT: An automated tensile loading system that can accurately control histories of both loading and temperature was developed. A series of unconventional tensile loading tests were performed on polypropylene (PP), high-density polyethylene (HDPE) and polyester (PET) geogrids using this system. The following was found. The temperature significantly affects the elasto-viscoplastic stress–strain properties of the tested polymer geogrids. The inviscid stress–viscoplastic strain relation changes with temperature. The tensile rupture strength decreases by 9.2%, 26.7% and 4.5% when the temperature rises from 30°C to 50°C with PP, HDPE and PET geogrids, respectively. The elastic stiffness of the geogrid was evaluated by applying small-strain-amplitude unload–reload cycles after a certain period of sustained loading during otherwise monotonic loading at a constant load rate. The value increases with an increase in the tensile load level at a fixed temperature, and decreases with an increase in the temperature at a fixed load level. A set of mathematical expressions are proposed to describe these trends of tensile rupture strength and elastic behaviour.