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Abstract:
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The nonwoven industry has experienced significant growth over the past 25
years. As of 1992, approximately 17.2 billion square yards of nonwoven fabrics had
been consumed. Nonwovens hold the largest share of the geotextile market over knit
and woven fabrics, and the most commonly fiber utilized in this industry is
polypropylene.
The most common form of nonwoven geotextiles are produced by needlepunching
fibers together and then thermally bonding the web. A needlepunched nonwoven
fabric primarily achieves its strength through fiber entanglement and fiber-to-fiber
friction. The inherent loose construction of a needlepunched nonwoven can become
compact under compression, increasing the fiber-to-fiber contact, with increased fiberto-
fiber friction, compressed geotextiles exhibit different physical properties than non-
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confined geotextiles. The purpose of this thesis was to develop an index test method
for evaluating nonwoven geotextiles under compressed conditions.
A total of 216 conditions were utilized to determine the "best" set-up for testing
nonwoven geotextiles under confined conditions. Sample shape, compressive force,
compressive plate covers, and fabric style were evaluated during the optimization.
Following the optimization process, a total of 24 fabric conditions were produced to
determine if certain levels of fabric properties are detectable under confined
conditions. The fabrics produced had various levels of needlepunch density, fiber
tenacity, calendering, and fabric weight. The results indicated that the confined tensile test produced significantly higher
tensile strengths than the standard grab test. The trends of various fabric properties
could be clearly seen and were more apparent when utilizing the confined tensile test.
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