specifications for geotextiles in india by r. p. indoria secretary general, indian roads congress 19...
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Specifications for Geotextiles in India
byR. P. Indoria
Secretary General, Indian Roads Congress
19 November 2010
ABOUT IRC
Indian Roads Congress is a Society of Highways Engineers established in 1934
Frames Codes of Practice , Standards, Guidelines, Manuals etc. on various subjects for Roads and Bridges
Identification of research topics and Institutions Collection of data on research done and
utilization there of
(Cont…)
ABOUT IRC
Dissemination of Research findings for revision of IRC Codes and Special Publications
Holding Workshops and Seminars on Crucial Topics for dissemination of knowldge
Promoting Usages of New Materials and Technologies
IMPORTANCE AND USAGES OF GEOTEXTILE IN ROAD SECTOR
Use as Separator to Improve Pavement Performance
Use as reinforcement and drainage layer Use for Ground Improvement Use for drainage of ground (PVD/piped drains) Jute Geogrid for Erosion Control of Denuded
Slopes Jute Geotextile for Drainage and Filtration
Application Jute is low cost, renewable, biodegradable and
eco-friendly natural product (Cont…)
IMPORTANCE AND USAGES OF GEOTEXTILE IN ROAD SECTOR
Construction of road embankments in water logged area
Soil Nailing River Bank Protection Embankment slope protection
TYPES OF GEOTEXTILES
Geotextile: Non Biodegradable Synthetics Woven / Non Woven Fiber and perform discrete function i.e. separation, reinforcement, filtration, drainage and moisture barrier (when impregnated).
Geogrids :Open, grid like configuration, i.e., they have large apertures and used for the purpose of separation, but invariably they are being used in some form of reinforcement.
( Cont…)
TYPES OF GEOTEXTILES Geonets: another specialized segment of Geosynthetics
and Geonets are used for the purpose of drainage. It is to be noted that geonets are always used with a geotextile. Geonets used in protective works for highway structures
Geocomposite: A geocomposite consists of a combination of geotextile and/or geogrid and/or geomembrane or any of these three materials with another material in laminated or composite form and used for accelerating the consolidation of soft soils.
(Cont…)
TYPES OF GEOTEXTILES
Geomembranes : Geomembranes are also synthetic materials but they are impervious and made of thin sheets of rubber or plastic materials used primarily for lining and cover of liquid-or solid-storage facilities
Geocell : A three dimensional structure with interconnected cells which can be filled with soil/granular material forming a mattress for increased bearing capacity and manoeuvrability on loose or compressible subsoil of base or sub-base in pavements and slope protection
(Cont…)
TYPES OF GEOTEXTILES
Natural Geotextiles: Natural fibres are extracted from plants and are then converted into yarns by spinning. These fabrics are sometimes treated with rot resistance materials or reinforced with synthetic fibres to enhance their durability under different soil conditions without affecting its strength and other properties. Natural fibres such as jute, coconut and coir fabrics are used to improve soil erosion control and drainage applications.
USE OF GEOTEXTILE FOR IMPROVING PERFORMANCE OF
ROADS
Geosynthetics for Highway Pavements Geosynthetics Over Existing Bituminous Surface Provision of Geotextiles Against Subgrade and
Embankment Erosion Geotextiles In Sub-surface and Composite Drains Geogrid Applications For Reinforced Soil Slope
Protection
USE OF GEOTEXTILE FOR IMPROVING PERFORMANCE OF
ROADS
Road pavement as a drainage layer, Bioengineering measure for shoulders and earthen slopes, Improving the pavement performance and Reducing the pavement crust (?)
• Construction of road embankments in water logged area
• Soil Nailing , Soil Stabilization
IRC DOCUMENTS ON GEOTEXTILES
IRC has one document titled “State of the Art: Application of Geotextiles in Highway Engineering” published by IRC in 1994
It is a compilation of available literature (at the time of preparation of the report)
Since then a lot of developments have taken place in manufacturing and preparation of geotextiles, their usage and applications etc.
IRC DOCUMENTS ON GEOTEXTILES
IRC has another document titled SP:59 – 2002 `Guidelines for use of Geotextiles in road pavements and associated works`
Being a Special Publication, this document does not have the status of a ‘Code of Practice” per se but nevertheless covers the following:
Scope
Raw Material and types of Geotextiles
Functions of Geotextiles
IRC DOCUMENTS ON GEOTEXTILES
Handling and storage of geotextiles
Geotextiles properties and test methods
Geotextiles property requirements for various applications
Construction guidelines for use of geotextiles in various applications
References have been made to ASTM standards for test methods
GEOTEXTILES SPECIFICATIONS More comprehensive specifications are included
in the Ministry of Road Transport and Highways book of Specifications, popularly known as the “Orange Book”
The current edition of this book is also very old (2001) and a revision of the book has been almost finalised and is likely to be published soon
GEOTEXTILES SPECIFICATIONS The proposed specifications(section 700) cover
the following:
1 GEOSYNTHETICS IN ROAD AND BRIDGE WORKS
Scope
Testing, handling, certification, and acceptance
Minimum Geotextile strength property requirements
Installation condition
Type Strength property requirement (MARV)*
Grab Strength in
N as per ASTMD 4632
Tear Strength in
N as perASTMD 4533
Puncture Strength in N as per ASTM
D 4833
Burst Strength in N as per
ASTMD 3786
Elongation at Failure
<50%
>50%
<50%
>50%
<50%
>50%
<50%
>50%
Harsh installation
Type 1 1400 900 500 350 500 350 3500 1700
Moderate Installation condition
Type II 1100 700 400 250 400 250 2700 1300
Less Severe Installation condition
Type III 800 500 300 180 300 180 2100 950
Geotextile Requirements for Ultra Violet Light Degradation
S.No Properties of Fabric Test Methods
Units Requirements(Retained Strength)
1 Grab Strength ASTMD 4632 N Not lessthan 70%after 500 hrs of exposure
2 Tear Strength ASTMD 4533 N
3 Puncture Strength ASTMD 4833 N
4 Burst Strength ASTMD 3786 N
Properties for Prefabricated Vertical Drains
Unit
Minimum Value Test Method
Physical Requirements
Weight gm/sq. m 90 -
Width mm 90 -
Thickness mm 5 -
Strength Requirements
Tensile Strength kN ≥ 1 at 10% elongation ASTM D4632
Puncture Strength N 150 ASTM D 4833
Tear Strength N 200 ASTM D 4533
Discharge Capacity
Index text using deformable foam layers
m3/sec 60x10-6 (300kPa)40x10-6 (500kPa)
ASTM D- 4716
Straight – embedded in bentonite
m3/sec 90x10-6 (300kPa ASTM D- 4716
Buckled – embedded in bentonite
m3/sec 80x10-6 (300kPa ASTM D- 4716
Typical Specifications for Geocells
Property Min. Required Value Test method
Density 0.935gm/cm3 ASTM D1505
Environmental Stress crack resistance (ESCR)
5000 Hrs. ASTM D1693
Carbon Black Content 1.5 to 2% by Weight
Strip / Cell Wall thickness 1.27mm, -5% +10% ASTM D5199
Seam Peel-Strength Test Min. 355 N per 25mm of cell depth. ASTM E41
Creep Rupture Strength Creep Rupture Load at 10,000 hours shall be 95 kg minimum obtained from the 95% prediction interval at 10,000 hours considering a logarithmic time/creep rupture model.
ASTM D2990
Typical Specifications of Natural Geotextile
Type of Fibre
Weight Width Thickness Open Area
Tensile Strength(KN/m)
Water Holding Capacity
Porometry (O95)
(gsm) (cm) (mm) (%) MD CD (%) micron
Open Mesh
500 120 4.0 50 10 7.5 - -
Woven Geotextile
1)Ordinary 700 75 2.0 - 20 20 - 3002) Rot Resistance
700 75 2.0 - 20 20 - 300
3)Bitumen treated
1200 75 2.0 - 20 20 - 150
Non- woven Fibre
500 150 4.0 - 5 2.5 300 -
2 GEOTEXTILES IN SUB SURFACE DRAINS
Scope
Materials
Construction requirements
Measurement for payment
Rate
Geotextile Requirements for Subsurface Drainage
Per cent in-situ passing 0.075 mm
sieve
Geotextile drainage property requirement
Recommended geotextile *
Permittivity, per sec ASTM D 4491 (Minimum ARV)
Apparent opening size, mm ASTM D 4751 (Maximum ARV
< 15 0.5 0.43 Type II from Table 700-1
15 to 50 0.2 0.25
> 50 0.1 0.22
Recommended Permittivity for Different Soils
Soil type Typical Permeability, Ks (cm/sec)Range of
Soil
Minimum Recommended Geotextile Filter
Permittivity, Y(per second)
Sandy Gravel 1 X 10-1 to 1 X 10-2 0.5 to 0.1
Clean Sand 1X10-2 to 1 X 10-3 0.1 to 0.01
Silty Sand 1X10-3 to 1 X 10-4 0.01
Silt 1X10-4 to 1X10-5 0.01
Clay 1X10-5 0.01
3 USE OF GEOSYNTHETICS IN COMPOSITE DRAINS
Scope
Material
Installation
Measurement for payment
Rate
Apparent Opening Size for Geo-composite Drains
Test Method Units Requirements Percent in-situ
soil passing 0.075 mm
ASTM D 4751 mm <15 15 to 50 >50
0.43 0.25 0.22**
4 GEOTEXTILES FOR EROSION CONTROL
Scope
Materials
Construction requirements
Slope protection placement
Seams
Repair
Measurement for payment
Rates
Erosion Control Geotextile Requirements
Percent in-situ passing
0.075 mm sieve
Geotextile drainage property requirement
Recommended geotextile
Permittivity, per sec ASTM D
4491 (Min. ARV)
Apparent opening size, mm ASTM D
4751 (Max. ARV)
<15 0.7 0.43 Type I from table 701
15 to 50 0.2 0.25
>50 0.1 0.22
5 GEOGRID APPLICATIONS FOR REINFORCED SOIL SLOPE PROTECTION
Description
Material
Installation
Measurement and basis for payment
Rates
6 GEOSYNTHETICS FOR HIGHWAY PAVEMENTS
Scope
Materials
Certification
Installation
Measurement for payment
Rate
Separation/Filtration Property Requirement for subgrade Soil with LL < 35 (such as ML, CL, CL-ML etc) **
** The soil classification shall be as per BIS-1498 – 1970 (Re-affirmed 1987)
Sl. No. Geotextile Property RequirementRecommended
Geotextile
1.Permittivity* as per
ASTM D 4491
0.02 sec -1 (per sec) (Minimum average
roll value)Type II from Table:
701
2.Apparent Opening
Size as per ASTM D 4751
0.06 mm (Maximum average roll value)
Separation/Filtration Property Requirement for subgrade Soil with LL > 35 (such as CL, CH, MH etc)**
** The soil classification shall be as per BIS-1498 – 1970 (Re-affirmed 1987)
Sl. No.Geotextile Property
RequirementRecommended
Geotextile
1.Permittivity* as
per ASTM D 4491
0.05 sec -1 (per sec) (Minimum
average roll value) Type I from
Table: 701
2.
Apparent Opening Size as
per ASTM D 4751
0.43 mm (Maximum
average roll value)
Requirements for Geogrid for Sub-Base/base of Flexible Pavements
Note 1) All numerical values in the Table represent MARV in the specified direction.
2) All geogrids shall be placed along machine direction parallel to the centre line of roadway alignment.
3) Junction strength is required to maintain dimensional stability of the geogrid during deployment. It is not applicable to geogrid/geotextile composite products.
Property
Test Method
Required
value , kN/m
Machine Direction
Cross Direction
Tensile strength@1% strain ASTM D6637 4.3 6.6
Tensile strength@2% strain ASTM D6637 7.3 10.9
Tensile strength@5% strain ASTM D6637 13.4 19.7
Tensile modulus @5% strain ASTM D4355 437 656
Junction Efficiency, % of rib ultimate tensile strength
90 90
Ultraviolet stability (after 500 hrs) ASTM D4355 70 %
7 GEOSYNTHETICS OVER EXISTING BITUMENOUS SURFACE
Scope
Paving Fabrics
Material Requirement
Specifications for bitumen coated fiber glass fabric
Placement
Measurement
Rate
Physical Requirements for Paving Fabrics
Property Units Standard Requirements
Test Method
Tensile Strength KN/m 9KN/m ASTM D 4632
Elongation % ≥50 ASTM D 4632
Mass per unit area
Gm/m2 140 ASTM D 3776
Asphalt Retention
Kg/10 sq.m 10 Texas DOT 3099
Melting Point °C 150 ASTM D 276
Surface Texture - Heat bonded on One side only
Visual Inspection
Properties for Glass Grid Fiber
Property Test Method Grid
Tensile strength
MD (kN/m) ASTM 6637/ ISO
13439
≥50
CMD (kN/m) ≥50
Elongation at break (%)
>5
Minimum Mesh size (mm)
12.5 x 12.5
Melting point 0C - >218
Framework for promoting usages of Geotextile
Majority of the National Highway Development Programme to be implemented on PPP mode on BOT basis
The use of geotextile for road structure i.e. part of new or existing pavement does not bring the desired reduction in crust thickness since the pavement has to be designed as per IRC:37
There is a strong need to establish relationship between use of a type of geosynthetic and corresponding reduction in crust thickness
Framework for promoting usages of Geotextile
This can only be achieved by concerted research (may be industry sponsored) with the involvement of research institutes and academia
This could lead to formulation of definitive specifications and design methods using geotextiles/ geosynthetics
For the interim, the Government has created an enabling environment for the Concessionaire to use any material / technology / equipment as long as it meets any of the established international standards
Framework for promoting usages of Geotextile
The Manuals for four and six laning of highways, which form part of the Concession agreement, have been published by IRC containing this provision
Industry need to come out with ways and means to demonstrate to the prospective users (Concessionaires) the cost effectiveness (short term and long term) of the use of geotextiles
Industry also to come out with other innovative usage of geosynthetics besides the existing ones
Framework for promoting usages of Geotextile
On our part in IRC we have started a process of accreditation of new material / technologies / equipment etc. for use in the design and construction of highways
The proposals are examined by an Accreditation Committee constituted within IRC and comprising of experts from public as well as private sector
Upon satisfaction, the Committee issues an Accreditation Certificate which acts as a confidence measure with the prospective buyers
Framework for promoting usages of Geotextile
We also insist on field trial / usage reports from clients
In case of satisfactory performance reports, the new material, technology or equipment will then be suitably incorporated in Codes of Practices / Specifications
Conclusion
Need to establish relationship with cost (crust) reduction with usage of geosynthetics
Concerted research to have road crust design methods and formulate specifications
Concessionaires to be apprised of benefits of geosynthetics
Thank You for your kind attention
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