TENSILE CREEP BEHAVIOR OF A PVC COATED POLYESTER GEOGRID AT DIFFERENT TEMPERATURES

Abstract

This study investigates the tensile creep behavior of a PVC coated polyester geogrid at different temperatures. The ultimate tensile strength of the test geogrid is 128(MD)/115(CD) kN/m. The geogrid was fabricated using knitting and woven techniques. A series of tensile tests (ASTM D6637) and conventional long-term (ASTM D5262) creep tests were performed to evaluate the tensile strength, elongation at rupture and long-term creep strains of the geogrid. The test results indicated that the ultimate tensile strength of the PET geogrid linearly decreased as the test temperature increased up to 60°C. The tensile strength decreasing rate is about −0.33% per degree of Celsius. The elongation at break is about 11% for the tested conditions varied from 0°C to 60°C. The tensile strength and elongation at break for the 80°C test condition was inconsistent with the results from other test conditions. It is believed that the phenomenon of glass formation might have some effects on the engineering behavior of the test geogrid at around 80°C. The creep strain rate also increased as the test temperature was increased under same tensile load condition. Linear creep strain rates were observed from a series of conventional long-term test product creep tests. Under conditions with same creep tensile load or same percentage UTS tensile load under higher temperature conditions presented higher total creep strain and associated creep strain rate. The creep modulus decreased as the test temperature was increased. The creep strain rate increase could be up to 80% for temperature condition changes from 20°C to 40°C. The required rupture time linearly decreases as creep load increased on a log time scale. The decreasing rate of rupture time increases as test temperature increased.