Role of standards in Promotion
of Technical Textiles
Presentation on Use of Geotextiles in highway sector
On behalf of
Indian Roads Congress
By
A.V.Sinha,
Former DG(RD) & Spl Secretary,
Ministry of Road Transport & Highways
Geosynthetics and their varieties
• Geotextiles
– Synthetic fibres (Polypropylene, Polyester, Polyvinyl Chloride,
Polyamide, or Polyethyleyne) converted into fabric by (a) weaving
(woven), or (b) bonding of random fibres (non-woven), or (c) knitting
– Good drainage property
• Geogrids
– Extruded sheets of Polypropylene and Polyethyelne punched to form
a grid pattern having large apertures
– Good strength properties
• Geonets
– Polymer strands crossing one another at an angle (usually acute angle
to give a diamond pattern aperture) and bonded at joints by thermal
bonding
– Used in combination with Geotextile or Geomembrane for drainage
– Not used for strength
Geosynthetics and their varieties
(..contd)
• Geocomposites
– A composite material of usually three out of geotextile, geogrid,
geonet, and geomembrane in laminated or other form.
– Good drainage property and used for Prefabricated Vertical
Drain
• Geomembranes
– An impervious geosyntheitc material
– Used for checking migration of water(e.g lining of drains/ canals)
• Geomats
– A three dimensional (as opposed to two dimensional geotextile
and geogrid) open mat
– Good drainage property, suitable for draining filling behind
bridge abutment
Geosynthetics and their varieties
(..contd)
• Geocells
– These are formed by connecting HDPE strips in series
to form a pattern of grid in three dimensions, the
width of strips forming the walls of the cells which are
filled with soil/gravel/stones etc
– The confinement provided by cell walls gives strength
– Improves the bearing capacity of weak foundations
• Natural geotextiles
– Naturally growing fibres (like jute) and their strands
form these geotextiles
– Usually biodegradable and used for slope protection
by vegetation
Areas of Application of Geo Synthetics
and predominant properties
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•
•
Retaining Wall: Strength
Embankment in soft soil: Strength, drainage
Repairs of damaged Pavement: Strength
Slope protection and Erosion Control:
Separation, filtration, aperture size
• Drainage of embankment, subgrade, fill
behind abutment, and surface drains:
Separation, filtration, drainage
Standardization of Geotextile
applications
• Indian efforts:
– 1994: Indian Roads Congress published a State-of-the-Art
Report: Application of Geotextile in Highway Engineering
(IRC:SP12)
– 2001: Ministry of Road Transport and Highways included a
chapter in its Specifications (MORTH Specficification for Roads
and Bridges)
– 2002:Indian Roads Congress published Guidelines for use of
Geotextiles in Road Pavements and associated works
– 2011: MORTH Specifications including chapter on Geptextile
under revision
– 2011: IRC Council approved for publication the State-0f-the-Art
Report on use of Jute Geo textile (under print)
– 2011: IRC Council approved for publication Guidelines for the
Deesign and Construction of Geosynthetic reinforced
embankment on soft soils
Standardization of Geotextile
applications (..contd)
• International efforts
– 1995/2010: British Standard BS 8006 Code of
Practice for Strengthened/ Reinforced soils and
other fills was published
– 1998/2001: Federal Highway Administration of US
published a document (Publication No. FHWANHI-00-43) on reinforced soils
General Specifications for Geosynthetic Systems
• Material properties: These are generally specified and accepted if the
material tests are as per standard procedures specified by
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–
–
–
American Society for Testing of Materials (ASTM)
International Standardization Organization (ISO)
British Standards (BS)
Accredited laboratories
• Design: This required to be done as per BS or FHWA procedure
• Certification: A certification by the system supplier about conformity
with
– ISO for manufacturing process
– BBA (British Board of Agreement, AASHTO (American Association of
State Highway and Officials)
– Accredited laboratories
• Warranty:Client seeks a warranty from the supplier
– The warranty can be for as long as for 50 years
Typical geotextile properties
Property
Requirement
Unit
Test Method
Minimum Average Roll Value (MARV) at more than 50% elongation under different
installation conditions
Grab strength
500-900
Newton (N) ASTM D 4932
Tear Strength
180-350
N
ASTM D 4533
Puncture strength
300-500
N
ASTM D 6241
Burst strength
180-350
N
ASTM D 3786
Ultraviolet Stability: Not less than 70 % of the above values after 500 hrs exposure
Filtration and separation
Apparent Opening Size (AOS)
<0.3
mm
ASTM D 4533
Permittivity
> 0.5
per sec
EN ISO 11058
Tensile strength (MD/CMD)
>60/>45
kN/m
ISO10319
Strain at max strength(MD/CMD)
30/20
%
ISO10319
Reinforcement
Indian Test Procedures
• IS 13162 (part2): Test Method for deterioration of
Geotextile for exposure to Ultraviolet Light and
Water
• IS 14324: Test methods for Water Permeability of
Geotextile by Permittivity
• IS 14294: Test Method for Detrming Apparent
Opening Size for Geotextiles
• IS 13162 (Part 4):Test Method for Index Puncture
Resistance of Geotextiles and related products
(Source : IRC SP 59:2002)
Gaps in Design Procedures
• Indian standards on Geotextiles are practically
absent
– One Guideline recently approved by IRC Council
and will be released shortly
• Design, particularly where strength is the main
concern ( like retaining walls, embankment,
pavement rehabiltation) is an involved process
– Design Approach particularly for internal stability
of structures (i.e where geotextiles come into
play) has to be standardized
Gaps in Design Procedures
• Design (..contd)
– Factors of safety, reduction factors, partial factors
etc used in the British and US standards have to
be evolved for our national codes and Guiodelines
• Testing Standards
– There is huge gap in the requirement and
availability of national testing procedures
– An indicative list of subjects on which test
procedures need to be developed are as follows:
Gaps in Design Procedures
• Indicative list of tests
– Determination of friction between the soil and geotextile
reinforcement at different levels of strain
– Determination of vulnerability of geotextiles to chemicals and
microbiological substances present in soil and water
– Detrmination of the effects of creep and long term stability
– Determination of relationship between ultimate strength and design
strength
– Suggesting reduction factors (or partial factors or factors of safety on
the basis of
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Tests
Manufacturing Process
Serviceability conditions
Installation factors
Temperature variations
Durabilty factors
Construction imperfections
Thank You for your attention