Conventional and accelerated creep tests on nonwoven needle-punched geotextiles

Nonwoven needle-punched geotextiles are prone to creep deformations when subjected to sustained tensile loads. Creep characterization of these materials is particularly relevant in countries such as Brazil, where nonwoven geotextiles are often used in soil reinforcement applications. However, creep testing is time consuming and requires rigorous quality control. Consequently, a research effort was conducted to develop reliable test methods suitable for expeditious determination of creep curves. Creep tests at elevated temperatures are a promising alternative in polymer engineering to accelerate creep deformations. However, only limited information is currently available on the suitability of temperature-accelerated methods for nonwoven needle-punched geotextiles. In particular, this paper presents the results of a creep study on polyester and polypropylene nonwoven needle-punched geotextiles conducted using the stepped isothermal method (SIM) to accelerate the creep process. Not only axial strains, but also lateral strains (necking) were monitored using photographic techniques. The results obtained using temperature- accelerated methods were compared with those obtained using conventional creep tests. The experimental results indicate that the accelerated creep tests can accurately characterize both axial and lateral creep phenomena in nonwoven needle-punched geotextiles.