Road Construction with Jute Geotextiles (JGT)

1. Road Construction with Jute Geotextiles (JGT) A NATIONAL JUTE BOARD PRESENTATION Presenter-T Sanyal Chief Consultant, National Jute Board

2. What are Geotextiles? • Geotextiles- more aptly Geosynthetics –belong to the class of Technical Textiles under GEOTECH category. • Geotextiles are generically of two varieties—one variety is made of synthetic polymers (petrochemical derivatives) and the other of natural fibres (such as jute, coir) • Geotextiles are intended to improve engineering performance of soil on or in which it is laid

3. Jute Geotextiles • Jute Geotextiles (JGT)-as the name suggests –is made of bast fibres of jute plants—a renewable agri-resource under cultivation in the Ganga-Brahmaputra delta for centuries. Presently under cultivation in other areas/countries as well • The British were the first to discover the potential of jute fibre for flexible packaging (sacks) after elaborate tests • The features of jute fibre conform to technical requirements of geotextiles, besides its added advantage of being eco-concordant, abundant availability, the back-up R & D support and industry-expertise to make customized JGT • Use of JGT helps reduce carbon foot-print in road construction

4. USP OF JUTE • High moisture absorbing capacity • Excellent drapability (the best of all GTs) • High modulus • Low extension-at-break • High roughness co-efficient • Excellent spinnability • Bio-degradability with mulching & soil-nourishing properties • Annually renewable resource with abundant availability • Economical & • Eco-concordant

5. JGT - THE FORERUNNER OF MAN-MADE GT Jute fabric was used in road construction long before the concept of geotextiles with man-made fibres emerged Jute hessian was applied successfully on Strand Road at Kolkata as early as in 1934 and in Myanmar during the 2nd World War First concerted effort to promote use of Jute Geotextiles took off in 1980s with the support of UNDP Extensive R & D on JGT over the years have helped understand the mechanism of its functioning and develop improved varieties for its application in roads & other areas.

6. JGT – Basic Functions • JGTmatches its man-made counterpart in the three basic functions of a geotextile viz Separation, Filtration, Drainage. Besides, • Along-plane drainage capability (i.e. transmissivity) of JGT is higher than its man-made counterpart. • Fineness of jute fibre enables manufacture of JGT according to the specified porometric features • High Roughness Co-efficient of jute ensures better load transference & confining action on soil • JGT has far greater water absorbency than all other GTs –a quality which enables sustained release of the absorbed water, thus creating a congenial micro-climate for better growth of vegetation

7. Role of JGT in Filter-cake formation in soil FILTER CAKE FORMATION IN SOIL IS AN OPTIMAL STATE OF SOIL CONSOLIDATION TRIGGERING GRADUAL DEVELOPMENT OF EFFECTIVE STRESS WITHIN A SOIL MASS, THUS ENABLING IT TO BEAR GREATER LOAD.

8. Civil engineering Applicationsof JGT • Strengthening of road by improving CBR • Slope management • Protection of river bank against erosion • Stabilizing embankments • Prevention of railway track settlement • Consolidation of soft soil • Control of surface soil detachment

9. 1. JGT in Road Construction Causes of failure of roads : • Inadequate pavement thickness • Higher-than-design traffic load & intensity • Low bearing capacity of sub grade • Intermixing of sub-base and sub grade • Insufficient drainage of surface and sub-surface water • Leading to “mud pumping” • Permeable wearing course • Besides the distress /failure of road pavement, stability of a road also depends on the stability of the embankment on which it is built and slope stability the causes of distress/failure of which are different.

10. Design parameters • Road pavements are usually designed on the basis of traffic load & its intensity or equivalent single axle load (ESAL), sub-grade CBR and allowable rut-depth • There are other design parameters followed in some of the overseas countries. USA, for instance, follows the concept of Structural Number.

11. JGT in Road Construction • How can JGT help? • Enhances the CBR of the sub-grade by • -inducing membrane effect, exerting confining action on sub-grade, • preventing soil migration & facilitating water-dissipation along & • across its plane (essentially ‘filtration’ function) leading to generation • of effective stress within sub-grade • -preventing intermixing of sub-grade and sub-base (“separation” • function) • -facilitating drainage in the sub-surface zone • In fact all GTs act as change agents to the soil by concurrent • functioning of separation, filtration & drainage at the formative phase

12. Membrane & confining effect of JGT

13. JGT in Road Construction • Rough Guidelines for designing a new road with JGT based on field trial results & lab. findings • CBR to be taken as 1.5 times the control value of CBR. • Woven JGT should be selected in conformity with the • average particle size distribution • Sub-surface drainage may be facilitated with suitable use of • non-woven JGT concurrently. • N.BPrecise design guidelines are being finalised under an international project on JGT sponsored by the Common Fund for Commodities, a financial institution of the UN.

14. JGT in Road Construction • Note : • Choice of JGT also depends on the allowable rut depth which is a factor of the level of service expected of a road vis-à-vis the level of its maintenance • Porometry range: 150 to 400 microns depending on the average grain size of the sub-grade • Tensile strength: 25 kN/m is considered adequate for most of the roads [Recommended by the CFGG Manual (France) for SGT.]

15. JGT in Road Construction • Some Salient Findings of studies • Percentage elongation at break of JGT is significantly lower than that of synthetic geotextiles (maximum 15% against more than 50 % of SGT) (Ramaswamy & Aziz – 1989) • Substantial reduction (more than 50%) in rut depth under dynamic load tests with JGT (Ramaswamy & Aziz – 1989) • Loss of strength of JGT after a year is not a deterrent as, by that time, JGT is seen to have helped in providing a self sustaining sub-grade for most type of soils (Ramaswamy & Aziz – 1989) • The gain in strength of the sub-grade with time is compensated against the loss of strength of JGT within the same time frame (ibid & JU 2005)

18. Effect of Jute Fabric on Compaction Characteristics of Subgrade Soil

19. a) Water Content (%) 25 30 35 b) Undefined Compressive Strength (kN/m2) i) without JGT ii) with JGT 110 330 45 115 36 65 c) Strain at failure (%) i) without JGT ii) with JGT 8 26 10 30 22 42 a) Water Content (%) 20 25 30 35 b) CBR (%) i) without JGT ii) with JGT 5.0 8 4.7 6.8 3.5 5.2 2.6 4.5 Studies by Ramaswamy & Aziz (1989) onClayey Subgrade Table - I Table - II

20. 2. Slope Management with JGT Roads built on high embankments require preventive measures to control erosion of slope surface. Slopes erode due to: • Detachment of top soil by K E of rain drops • Flow of rain water (surface run-off) • Severe wind Surficial soil erosion can be controlled by reducing the velocity of surface run-off & entrapping detached soil particles. Wind-induced soil erosion can be controlled by suitable JGT- cover

21. 2. Slope Management with JGT • Remedial Concept • Universal Hydrological Equation in its simplest form states • precipitation  surface flow + through flow ( sub-surface flow ) + storage • If through-flow and on-land storage can be increased, surface run-off gets reduced • Through-flow depends on hydraulic conductivity of the soil. Storage can be facilitated by creating micro-barriers on the slope. Such micro-barriers also curb the velocity of surface flow • JGT is the ideal material that fulfills the requirements, besides facilitating fast growth of vegetation on its bio-degradation as a result of its mulching properties and by increasing the hydraulic conductivity of soil

22. RAIN D d overlandflow a material in suspension XC belt of no erosion e b’ b active erosion FLOW c’ c - - - - - - - deposition of sediments - - Soil Erosion Process on a Slope

23. D Storage - - - - Weft of open mesh JGT - - - - - Storage ) β - - - - - - - - - L Dam Storage 2.87 litres / sq.m. of water on a 1:2 slope can be impounded when an open weave JGT having 45 wefts in a metre, and dia of 4mm in weft with an overall weight of 500 gsm. JGT is laid

24. Direction of laying + Grass plant Graded slope 150 Fixing nail Shoulder anchor (150 mm x 150mm) Jute Geotextile 50 mm 150 mm Fixing nail (II Gauge wire) Toe anchor (150 mm x 150mm) Installation of JGT on slope

25. 3. Stability of Embankments • Embankment is an essential component of a road. • Almost all roads are built on embankments. • Expansive or compressive soils used as fills in • embankments may lead to: • Vertical settlement • Lateral dispersion • Downslope migration • Rotational slides (slip circle failure)

26. Stability of Embankments • JGT • absorbs stress and strain induced due to moving loads on embankments • high soil - JGT interfacial friction acts as a good medium of transference of the induced stress and strain • can directly reinforce the soil mass in an embankment during its useful lifespan • Soil is otherwise stabilized due to separation, filtration and drainage effects acting concurrently

27. Basal Reinforcement with JGT for anynew embankment is effective • JGT can also be used in successive layers of an embankment and may be folded at the fringes asside restraint for protection against rotational slide • In new embankments woven JGT may be used as basal reinforcement to avert settlement • PRECAUTION • Prevent ingress of water into an embankment • Drain out entrapped water from an embankment for which installation of JGT- encapsulated concealed drains and, in more severe cases, prefabricated vertical jute drains (PVJD) deserves consideration.

28. Durability of JGT • As already indicated • Loss of strength of JGT after a year is NOT a deterrent– for, by that time, JGT provides a self-sustaining sub-grade for most soils • The gain in strength of the sub-grade compensates the loss of strength of JGT within the same time frame • With the passage of time dependence on JGT for soil stability continues to decrease However there is need to ensure JGT-durability ranging from 2 to 4 years (depending on the application-type) by special treatment. Eco-friendly durability treatments have been developed by IIT, KgP & IJIRA

29. Is Bio-degradability of JGT a Technical Disadvantage? • The answer is NO. Optimal consolidation • (development of effective stress) is seen to take place • within the effective life of JGT • N.B. Effective life of JGT may be enhanced by specially • developed eco-friendly water-repellent treatment (developed by IIT Kgp & IJIRA • Necessity of JGT or, for that matter, of any GT ceases after • filter-cake formation. • Bio-degradability of JGT is thus not a technical disadvantage. Additionally JGT lends environmental advantage to road construction

30. ENVIRONMENTAL ASPECTS • Jute fibres are eco-friendly, soil-friendly, biodegradable, annually renewable resource Following points are relevant in context of eco-concordance and socio-economic value of jute • During 100 days of jute growing period, 1 hectare of jute plant can absorb about 15 MT of CO2 from atmosphere and liberate about 11 MT of O2. Studies reveal that CO2 assimilation rate of jute is higher than trees (Inagaki, 2000; IJSG 2003). In fact jute helps in carbon sequestration.

31. (contd.) • Main use of jute sticks (a retting output) is as fuel and household uses. Yield of jute sticks is 2.5times the fibre by weight. Jute sticks annually saves 5.06 million tons of forest wood(in India and Bangladesh) and help in preserving ecological balance. • Leaves left in the field are good manures and increase fertility of land. Increases hydraulic conductivity of soil

32. Field Experience with JGT • Experience in India & elsewhere with JGT in geotechnical engineering applications numbering more than 150 in India alone corroborates its effectiveness in road construction and erosion control of diverse nature • In road construction enhancement of CBR value is minim 1.5 times and in some cases the increase has been even 3-5 times after 4 years! • Soil continues to consolidate even after bio-degradation of JGT. In fact JGT triggers the process of consolidation thru’ development of effective stress. The process continues for a protracted period.

33. Some salient properties of woven JGT • JGT has a high initial tangent modulus (comparable • JGT offers a greater interfacial friction than SGT • JGT has greater transmissivity than SGT • Permittivity of JGT is comparable to that of SGT

34. Advantages Of JGT – in summary • Economical • Easily available • Can be tailor made to meet the criteria of retention and permeability. • Precise control on quality and workmanship possible. • Quicker execution time. • Better drapability than any other geo-textile. • Provides a sustainable and eco-compatible solution. • Conducive natural protection against erosion through quick growth of vegetation cover.

35. Newly developed products • Several new products have been developed recently based on Jute for highway applications • JGT in asphaltic overlay for prevention of reflection cracks. (developed by IIT Delhi)—not tried • Paving fabric for wearing course as alternative to mastic asphalt • (developed by IJT & CRRI (under the JTM sponsored by MoT with • NJB as the collaborating/facilitating organization) -under field trial • Development of durable & water-repellent JGT (recently developed by IIT, KgP under the JTM) -under field trial • ‘Jutecrete’-Jute-fibre reinforced concrete (developed by IIT, KgP) • under the JTM sponsored project by MoT with NJB as the • collaborating/facilitating organization) -under field trial • Pre-fabricated vertical jute drain (PVJD) developed by IIT Delhi & • Singapore Sate University (Prof R D Ramaswamy)-already tried

36. Standards/Normative References • IS 14986:2001— -Guidelines for application of Jute Geo-textiles for rain water erosion control in road & railway embankment and hill slope -2 BIS guidelines on rural road constn & river bank protection with JGT have recently been approved- under print • RDSO, Ministry of Railways & Rly Board– • -Specs for Open weave JGT in slope protection • -Guideline no GE:G1 (July 2003)— • -Guidelines for earthwork in railway projects • -Included as an item in the unified SoR of Railways 2011 • Indian Roads Congress— • -State-of-the-art report on use of jute Geotextiles in Road • Constn & Prevention of Soil Erosion/Landslides (2012) • -Specifications for road & bridge works (2001) & • -Recommended practice for treatment of • embankment slope & erosion control (1991) • I & W Deptt & PW(Roads) of GoWB have included JGT items in • their SoRs

37. Illustrative Case Studies Case Studies in road & slope erosion control

38. Some Case Studies in Road with JGT • Re-construction of damaged highway on soft marine soil using JGT at Kakinada Port – Andhra Pradesh • 2. Strengthening of UT Road - Jorabari with JGT(Assam) • Strengthening of Chatumary - MDR14 road with JGT (Odisha) • 4. Widening and strengthening of Munshirhat – Rajpur Road with JGT (West Bengal). • 5. Strengthening of Andulia – Boyratola Road with JGT (West Bengal)

39. Re-construction of damaged highway on soft marine soil using JGT at Kakinada Port – Andhra Pradesh

40. LOCATION :Kakinada Port Area, Andhra Pradesh • SITE CONDITION: The subsoil is soft clay up to 4m depth and water table is about 0.5m below G.L. • SOLUTION: Woven JGT was used to re-build & strengthen the damaged carriageway on the existing soft soil • CLIENT NAME: CRRI and Kakinada Municipality • YEAR OF APPLICATION: 1996 Condition of Damaged Road Leveling of the damaged road with earth

41. PAVEMENT COMPOSITION JGT on prepared sub-grade overlain by compacted sand of 1.2 m as sub-base & 10 cm thick compacted gravel as base. 1m deep side drains on either side • PROPERTIES OF SUBGRADE SOIL: Plasticity Index: 32 Soil type: CH • PROPERTIES OF JUTE GEOTEXTILE USED: Weight : 760 gsm Tensile Strength : 20 kN/m Pore Size (O90) : 300 micron Type of JGT : Woven (Rot-proof) Laying of JGT over sand Finished road after 7 years of construction

42. CBR VALUES OF SUB-GRADE SOIL BEFORE AND AFTER LAYING OF JGT * Test was performed after 30 months of laying JGT

44. Strengthening of UT Road - Jorabari (Assam) with JGT

45. LOCATION : The road (UT Road to Jorabari) is located at Udalguri in Darrang district, Assam • SITE CONDITIONS: This was an earthen road under PMGSY Pilot project. Flash flooding of the area occurs occasionally. Deep ruts had formed at some locations. Average annual rainfall is 1600 – 1700 mm. The water table is 3 to 4 m below G.L during summer and 1.5 to 2 m during monsoon. • SOLUTION: Jute Geotextile was used on sub-grade to strengthen the road. • ROAD LENGTH: 4.6 Km Before construction Pavement composition Woven JGT sandwiched bet. sand layers (100) & overlain by GSB (100), gravel (100) & WBM Gr III (75) with bituminous overlay

46. CLIENT NAME: • Chief Engineer PWD, Rural Road Works, Assam • YEAR OF APPLICATION: 2007 • PROPERTIES OF SUBGRADE SOIL: Liquid Limit: 24% Plastic Limit: Non-plastic CBR of soaked specimen: 4% Soil type: ML • PROPERTIES OF JGT USED: Weight : 643/760/810 gsm Tensile Strength : 15/20/30 kN/m Pore Size (O90) : 150 – 200 micron Type of JGT : Woven (Rot-proof) Laying of Jute Geo-textile Finished Road

47. CBR VALUES OF SUB-GRADE SOIL BEFORE AND AFTER LAYING OF JGT *after 3 years

48. FINDING: • The CBR values increased by more than 3.5 times with decrease in moisture content. • The blacktop pavement surface was distress-free in all the sub-sections during the entire period of performance monitoring • Shoulders as well as side slope was in shape without any rain-cut or settlement with green grass over it.

49. Strengthening of Chatumary – MDR-14 road, Odisha with JGT

50. LOCATION : The road (Chatumari to MDR 14) is located under Tehsil – Bari in Jajpur district,Odisha. • SITE CONDITIONS: This was an earthen road under PMGSY Pilot project. Deep ruts had formed at some locations. Average annual rainfall is 1400 mm. The water table is at a depth of 1.5 to 3 m. • SOLUTION: Jute Geotextile was used on sub-grade to add to stability of the road. • ROAD LENGTH: 2.67 Km Before construction Pavement composition Woven JGT sandwiched bet. sand layers (100) & overlain by GSB (100), gravel (100) & WBM Gr III (75) with bituminous overlay