1. GEOSYNTHETICS IN ROAD CONSTRUCTION
S.Jaswant Kumar
Chief General Manager (Planning and Quality)
National Highways Authority Of India

2. Introduction Geosynthetic-Overview Geosynthetics Applications Impediments Suggestions

3. Geosynthetics Modern civil engineering construction materials
Modify/Improve soil/geologic material behaviour
Developed/Synthesized for specific function or application in construction
More than 1billion sq m annual use

4. Geosynthetics –The wide variety
Geotextiles –Woven, non-woven Filter fabrics
Geogrids
Geomembranes
Geocomposites
Geonets, Geofibres,mesh mattings, Geopipes, Geotubes.

5. Woven or Knitted Geotextiles

6. Non-woven Geotextile

7. Uniaxial Geogrid

8. BIAXIAL GEO GRID

9. Woven or Welded Geogrids

10. Geonets

11. Geocomposites

12. Geosynthetics – composition
Polypropylene
H D P E
Polyester
PVC
Synthetic Rubber
Natural fibres – Jute, coir

13. COIR GEOTEXTILES

14. Geosynthetics – the functions
Separation
Drainage
Filtration
Reinforcement
Moisture barrier
Cushion

15. Separation function

16. Drainage function

17. Filtration function

18. Reinforcement function

19. REINFORCEMENT FUNCTION

20. Geomembrane Seepage Barrier

21. Lateral Restraint

22. Bearing Capacity Increase

23. Membrane Tension Support

24. GEOCELL MATRESS UNDER EMBANKMENT ON SOFT SOIL

25. Geocell in the making

26. Geotextile wrapping of Geocell

27. Concrete Facia Panels for GRS Wall

28. Erosion Control Blanket

29. Design Requirements for Asphalt Pavements
Before dealing with the individual failure modes, it is appropriate to summarise the design requirements for an asphalt pavement.
The surfacing is essentially cosmetic and provides skid resistance and, sometimes, waterproofing.
The dense asphaltic materials provide the main structural layer which must have the properties shown.
Composite construction can be used in which the lower part of this layer is made from cement treated material. This generates shrinkage cracks which can ‘reflect’ through the asphalt and measures are needed to deal with this problem. Geosynthetics can be applied.
The term ‘durability’ has a special meaning in asphalt technology; it refers to resistance to effects of the environment, principally air and water, which can cause ageing and stripping of binder from aggregate respectively.
The pavement foundation has to carry construction traffic in the short term (a small number of high stress applications) and provide good support in the long term (a large number of low stress applications).

30. Grid Locations for Asphalt reinforcement
This slide shows the preferred locations for geogrid reinforcement of asphalt.
One layer at the bottom of the asphalt deals with fatigue cracking, while the additional layer nearer the surface will be effective for rutting.
These mechanisms have been demonstrated in research at Nottingham using the Pavement Test Facility.

31. Reflection Cracking Locate near to existing discontinuity
Mechanistic design method still evolving
Stiff geogrid best
Geotextile can waterproof
This slide sets out the principles for reinforcing an overlay to reduce reflection cracking.

32. Rutting in Overlays Locate where strains are largest; mid-depth
Increase in life to critical rut of three times
Requires stiff geogrid
This slide sets out the principles for reinforcing asphalt overlays to reduce rutting.

33. GLASS GRID UNDER OVER LAY

34. ROAD WIDENING
Overlay
GLASS GRID
bitumen emulsion layer
ROAD WIDENING

35. Other Applications in Highways
Geosynthetic Reinforced Soil Walls
Reinforced soil slopes
Subsurface Drainage systems-trench drains, strip drains
Stabilising canal road systems in expansive soil regions.
PVD.

36. Geosynthetic Reinforced Soil Wall

37. Geosynthetic Band drains

38. Impediments Most of the Geosynthetics are imported.
Test Methodology they adopt is from country of origin.
Test could be of:-
International standards (ISO TC221 Geosynthetics).
European Standards (CFN TC Geosynthetics).
German Standards DIN textiles norms.
British Standards BS
American Standards ASTM.
Very few Indian Standards.

39. specifications Specifications are from international organizations.
AASHO.
British Textile Technology Group - BTTG.
DGGT- EBGEO, Germany.
Geosynthetics Research Institute, USA
Presence of large number of test methods & specifications are a matter of concern and confusion.

40. Need for Testing Index Testing-Basic Properties of Products
Quality control tests- Rapid testing to assure continuity of equality.
Performance testing- Testing of Geosynthetics in contact with soil under standard conditions in the lab to provide better simulation of site conditions. Also in full scale on site.

41. R&D FACILITIES Available R&D facilities:-
IITs, Delhi, Chennai, Mumbai.
BTRA
CRRI
CCRI, Coir Board
SASMIRA
Manufacturers Lab.

42. R&D FACILITIES The existing Labs may have excellent facilities but
May not necessarily have all relevant facilities for test house.
May not maintain ambient temperature and humidity as required by ISO (21± 2°C &65%).
May not have necessary Grips for all varieties of Geosynthetics.
May not have skilled/Trained Technicians.
Not accredited.

43. SUGGESTIONS
Need for establishing national organisation to address the problems.
Role:-
Functions as a Geosynthetics test house.
QC checking at the place of manufacturer.
Property assessment of the product for the designer.
3rd party quality control testing of product.
Testing & evaluation for product certifications.
Testing for R&D needs.

44. SUGGESTIONS Render advice to the industry & Govt.
Organise short refresher & training programs.
Develop laison with all specifying dept. like BIS, IRC & International institutions.
Immediate Standardization of specifications, test procedures.
Code on the lines of BS 8006.

45. THANK YOU