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Load-strain-time behaviours of a PP geogrid affected by temperature change histories

Polymer geosynthetic reinforcements are presently widely adopted in the constructions of reinforced-soil (GRS) structures. The reason may attribute to their high performance-to-cost ratio. How-ever, it is revealed in the literature that their tensile strength and deformation properties are significantly dependent on strain rate and ambient temperature. Namely, the rupture tensile strength typically increases with an increase in the strain rate, while decreases with an increase in the ambient temperature. Moreover, they also exhibit significant creep deformation upon sustained loading, and this creep deformation in-creases with an increase in the ambient temperature. This research explores further into the effects of temperature change history on the strength and deformation properties of a polypropylene (PP) geogrid. The study is carried out by performing tensile loading tests under different temperature and loading con-ditions. It is found that, under the conditions in which the ambient temperature is kept constant, or in-creased, or decreased during creep, the instantaneous tensile load of PP geogrid is rather a unique func-tion of the current tensile strain, its rate, and the current temperature. The residual tensile strength is rather a unique function of strain rate and temperature at rupture. However, by cyclical change of temper-ature during creep, creep strain is repeatedly accelerated and decelerated, which results in a large creep strain and reduction of residual tensile strength.