Specification Part 3 - Road & Bridge Works - Urban Administration ...

Physical requirements:
Weight e” 90 gm/sq. m, Width e” 90 mm and Thickness e” 5mm
Filter criterion requirement: The two key parameters that indicate the quality of filter are AOS
(Apparent opening size) and cross plane permeability of filter. It is recommended that the following
criteria be adopted for selection of PVDs.
O 95 d” (2-3) D 85 and O 50 d” ( 10-12) D 50
Where O 95 is AOS of filter, O 50 is size that is larger than 50% of fabric pores, D 85 and D 50
refer to sizes of 85 percent and 50 percent of passing of soil particles by weight.
Permeability Requirement: The permeability of filter is normally required to be at least one order of
magnitude higher than that of soil. The PVDs are generally used to accelerate the consolidation of very
soft saturated soils such as marine clay. The permeability of soils found in India generally have
permeability of the order of 10-7 to 10-10 m/s. Considering the clogging effect, a much higher
permeability is required. To avoid clogging it is recommended that the permeability of PVDs should at
least be of the order of 10-4 m/s.
701.2.6 Testing, handling, certification and acceptance: Geosynthetics shall be tested in
accordance with tests prescribed by ASTM/ BIS for respective applications. In absence of ASTM/BIS
Codes, tests prescribed either by British Standards or International Standards Organization, shall be
conducted. The supplier of the geotextile should provide to the Engineer, a certificate stating the name
of the manufacturer, product name, style number, roll number, chemical composition of the filaments or
yarns and other pertinent information regarding property values of individual roll to fully describe the
geosynthetics.
The manufacturer is responsible for establishing and maintaining a quality control programme to assure
compliance with the requirements of the specifications. Documentation describing the quality control
programme shall be made available upon request. The manufacturer certificate shall state that the
furnished geotextile meets MARV requirements of the specifications as evaluated under the
Manufacturer’s quality control programme and are in conformance as per ASTM D 4759. The certificate
shall be attested by a person having legal authority to bind the manufacturer.
702.2.6.1 Handling and Storage of Geosynthetics
Geosynthetics must be handled and stored properly to ensure that the specified physical properties are
retained to serve project needs. Geosynthetics rolls shall be furnished with suitable wrapping for
protection against moisture, and extended ultraviolet exposure to ultraviolet exposure prior to
placement. Each roll should be labeled or tagged to provide product identification sufficient for inventory
and quality control purposes. Rolls should be stored in manner which protects them for elements. If
stored outdoors, they shall be elevated and protected with water proof cover.The damages caused on
this account can significantly educe the geosynthetics ability to perform its intended function in some
applications.
The objective of geosynthetics handling and storage is to safely transport and store the geotextile rolls
at the project site without damaging the geosynthetics or unduly exposing it to sun light (ultraviolet
light), moisture or other contamination. The following are some of the general recommendations to be
followed while working with geosynthetics at site.
Site Handling
Rolls of geosynthetics should always be lifted off the ground surface prior to moving. Dragging the
geosynthetics and operating equipment on the geosynthetics, which results in physical damage, shall
be avoided at all times.
Site Storage
The geosynthetics rolls shall be adequately protected from ultraviolet light exposure during storage on
site. A protective wrapping shall be kept on rolls until the geosynthetics are installed. If stored outside,
the geotextile should be elevated from the ground surface and adequately covered to protect them from
site construction damage, precipitation, ultraviolet radiation including sun light, chemicals that are