Tensile creep behavior of polyester geogrids by conventional and accelerated test methods

Abstract

Five different types of polyester geogrids whose nominal tensile strengths vary from 100 to 400 kN/m were investigated. Series of conventional long-term (ASTM D5262) and stepped isothermal method (SIM, ASTM D6992) tests were performed to evaluate the long-tern creep strain of these geogrids. The conventional long-term creep strains for 10,000 hours varied from 1.32 % and 0.53 %. Knitted geogrids showed higher creep strains than those associated with woven geogrids. The results of SIM tests showed that a minimum of 6 to 8 steps should be used in order to predict the creep behavior beyond 75-year design life. SIM tests showed good match with the results obtained from long-term creep tests for woven geogrids. Based upon SIM test results obtained from the test geogrids, the creep reduction factor of 1.50 is a reasonable value for 75-year design life.