Study on short- and long-term creep behavior of plastics geogrid

A geogrid is subjected to a long-term, steady load when it is used in civil constructions, and that will result in creep. Obviously, creep properties of geogrids are important for their engineering applications. The creep behavior of geogrids was studied by experiment and analysis of the results. Strain-time curves of geogrid specimens were plotted directly from the test records. These curves showed that the process of geogrid creep was greatly influenced by the stress (or load level). Under lower load levels, strain-time curves showed a gentle slope, while under higher load levels, the strain increased and the curves became steep, and then the specimens may fracture. Sherby-Dorn and isochronous load-strain plots could be constructed, and they are useful for prediction of long-term creep behaviors of the geogrid. From kinetic model theory of the creep tensile strength of polymeric materials, a linear extrapolation method was used to predict the long-term creep limited strength and the time to failure at the temperature of the experiment. The time-temperature equivalence principle was also used to predict these relations at other temperatures.