3.3.2
Sewn Seams
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NOTE: The plans and/or specifications should
indicate which seams must be sewn.
Seam strength can be specified based on ASTM D 4632
for applications where the geotextile will not be
placed in tension. In this case, seam strength is
typically measured in accordance with ASTM D 4632
and is typically specified to be equal to or greater
than 85 to 90 percent of the grab strength of the
geotextile. If seam strength testing will be
required, add seam strength requirements to Table 1.
The need for quality assurance testing needs to be
determined on a site specific basis and should be
based on how critical the project is and the
consequences of failure.
If the geotextile is designed to be in tension,
strength testing should be required and ASTM D 4884
should be used to determine seam strength. Quality
assurance and quality control testing should be
performed on all seams that are designed to be in
tension.
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Factory and field seams shall be continuously sewn [on all slopes steeper
than 1 vertical on [4][_____] horizontal] [at the locations shown on the
drawings.] The stitch type used shall be a 401 locking chain stitch or as
recommended by the manufacturer. [For field and factory seams which are
sewn, the Contractor shall provide at least a 2-meter sample of sewn seam
before the geotextile is installed. For seams that are field sewn, the
seams shall be sewn using the same equipment and procedures as will be used
for the production seams. If seams are sewn in both the machine and cross
machine direction, samples of seams from both directions shall be
provided.] [Quality Assurance seam samples shall be provided to the
Government at the request of the Contracting Officer]. Seam strength shall
meet the minimum requirements specified in Table 1. The thread at the end
of each seam run shall be tied off to prevent unraveling. Skipped stitches
or discontinuities shall be sewn with an extra line of stitching with a
minimum of 450 mm 18 inches of overlap.
3.4
PROTECTION
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NOTE: The use of staples or pins to hold
geotextiles in place should not be allowed in
applications where the geotextile will be located
adjacent to other geosynthetic layers which could be
damaged.
The purpose of limiting exposure time prior to
covering geotextiles is to minimize damage due to UV
radiation and to prevent direct contact by vehicles,
humans, and animals. To prevent UV degradation,
exposure time of polypropylene geotextile should be
limited to 14 to 28 days. Polyester geotextile is
SECTION 02373
Page 12
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