Abstract
At the beginning of this century, due to well-established Brazilian recycling processes, geosynthetics’ manufacturers started to use recycled poly(ethylene) terephthalate (PET) yarns/filaments (from PET bottles) in geotextile production. Despite the fact that recycled products cannot act as reinforcement functions, geosynthetics are constantly under sustained tensile load and experiences evolutions of the axial strain (creep behaviour). Thus, this study aims to assess the influence of the structure of (needle-punched) non-woven geotextiles manufactured using recycled PET yarns on their creep behaviour. Two geotextiles with different fibre/filament production processes were investigated (short-staple fibres—GTXnwS—and continuous filaments—GTXnwC). Unconfined in-isolated conventional and accelerated (using the stepped isothermal method) creep tests were performed at 5%, 10%, 20%, 40% and 60% of geotextiles’ ultimate tensile strength. The geotextiles investigated provided similar creep behaviour to geotextiles manufactured with virgin PET material. The standard deviation of the axial strain tends to increase as the load level applied increase. The structure of the GTXnwS harms its tensile –strain behaviour, promoting axial deformation under sustained loads, at least 50% higher than GTXnwC for the same load level applied. The influence of the load level and geotextile structure in the initial axial strain is pointed out. Long-term predictions based on creep tests performed using the stepped isothermal method have proven to be conservative and they must be restricted for quality control of the investigated geotextiles.
Highlights
IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
The results, typically plotted in a semilogarithmic scale, exhibit three creep stages [13,14,15,16,17], and an almost linear relationship that can be represented by the best-fit Equation (1), where ε t is the creep strain at the specific time; Tα, is the creep strain rate; t, is a specific time; and b is the axial strain of the geotextile relative to the unity [18]
Comparison between the creep curves obtained using conventional creep tests and the master curves obtained by the accelerated creep tests for the non-woven needle-punched geotextile manufactured with continuous filament yarns (GTXnwC)
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Polymeric materials, such as geosynthetics, submitted to sustained axial tensile loads experience time-dependent elongation/strain, so-called ‘creep behaviour’, due to the polymers’ viscoelastic behaviour [1,2,3,4,5,6,7,8,9]. Geosynthetics’ creep behaviour is commonly evaluated in-isolation conditions and requires a series of creep tests performed at different load levels for a period that must exceed 1000 h and ideally achieve 10,000 h (NBR 15,226 [10]; EN ISO 13,431 [11]; ASTM D 5262-07 [12]).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
