Abstract:
Jute geotextiles (JGTs) are used in many civil engineering applications. JGTs are applied under various loading conditions for different time duration. Similar to geosynthetics, JGTs also show different load-strain-time responses under different loading regime at isothermal conditions. To determine the response of JGT at different loading and time, an approach called strain envelope, which is already being applied for geosynthetics, was considered. The study was carried out on selected JGT samples to evaluate the strain components (i.e., recoverable strain (ƐR) and locked strain (ƐL) through isochronous curve in order to develop strain envelop in isothermal conditions. To assess the strain components of selected JGTs, creep tests were conducted following ASTM specifications for geosynthetics. Four types of JGTs, untreated and additive treated with two different mass combinations(627gsm and 724gsm) which are commonly used in Bangladesh for different geotechnical purposes, were selected for this investigation,.
To determine loads for creep test, wide-width tensile strength test was performed for all type of samples. The test was conducted at three different strain rates: (10±3)%/min, (50±5)%/min and (100±10)%/min. Test results revealed that, unlike the synthetic geotextiles, strain rate is insignificant on the strength of JGTs in machine direction as well as in cross machine direction.
Isochronous curves were developed from creep test results. From isochronous curves of selected JGTs, the possible design life for a particular load or the load carrying capacity at the End of Design Life (EDL) can be predicted for a limit strain under isothermal conditions. Strain envelops of selected JGTs show that locked strain (ƐL) increases and the recoverable strain(ƐR) decreases with the increase in loading time. Results also indicate that when a particular strain is developed within a shorter duration, larger value of ƐR and smaller value of ƐL are found. On the other hand, when relatively longer duration is taken to generate the same amount of strain, comparatively smaller value of ƐR and larger value of ƐL can be seen.
It is expected that the findings and observations of the study will be useful for the application of JGTs in various civil engineering works, as well as for the standardization of JGTs.
