Presentation on theme: "Development & Application of Potentially Important Jute Geotextiles (CFC/IJSG/21) A Presentation by P K Choudhury & Koushik Das Indian Jute Industries’"— Presentation transcript:
Development & Application of Potentially Important Jute Geotextiles (CFC/IJSG/21) A Presentation by P K Choudhury & Koushik Das Indian Jute Industries’ Research Association (IJIRA) Kolkata
NATIONAL JUTE BOARD ( NJB), THE PROJECT IMPLEMENTATION AGENCY ENTRUSTED IJIRA AS A FACILITATING AGENCY ( FA ) FOR THE FOLLOWING ACTIVITIES : - To design and develop potentially important JGTs optimally to meet specific technical requirements for the three specified end uses like rural road construction, river bank erosion control and hill slope stabilization To provide installation guidance to the end users for all the above three types of field applications ASSIGNED ACTIVITIES FOR IJIRA AS A FACILATATING AGENCY FOR THE PROJECT
Identification of Potentially important JGT on the basis of previous performance evaluation jointly by NJB / BESUS / BUET / PwC / IJIRA Types of JGT primarily chosen were – 20, 25 & 30 kN/m woven, 500 gsm non-woven & 500 gsm open weave. Additionally, 5 new varieties of woven DW plain weave JGT (627,665,724,760 & 810 gsm) & 4 new varieties of open weave JGT (365,500,600 &700 gsm) were also planned to design and develop ACTIVITIES UNDERTAKEN
woven JGT s are used for road construction and river bank erosion control while for slope protection works open weave JGTs are used. In the past DW Twill weave JGTs with varied tensile strengths & weight like, 15kN- 643 gsm,20kN-760 gsm,30kN - 810gsm & 40 kN/m -900 gsm were developed by IJIRA having two specific widths like, 76 cm and 200 cm. These fabrics were being popularly used so long in river bank, road construction & railway works Deficiencies observed in the exhisting fabrics:- a)76 cm wide fabric is too narrow as it entails wastages on overlaps and leaves planes of weakness on laps b)200 cm wide fabric are manufactured by a very few jute mills because of non availability of wider looms ( 90 inches). Moreover, heavier unit weight ( gsm) of the fabric leads to higher cost of product TYPES OF WOVEN JGT AVAILABLE OFF THE SHELF
FABRIC ENGINEERING : Need base development of Potentially Important JGTs was mooted for the project. Procedure for development of the targeted fabric was based on “design by experience” followed by “design by approach” to ensure - a) Effectiveness in performing the basic geotechnical functions like, separation, filtration, drainage and initial reinforcement b) Facility of manufacturing new varieties of JGT by any jute mills c) Economy & ease of availability d) Selection of the appropriate cost effective jute batch for meeting the tensile strength requirements Careful assessment of tensile strength & porometry requirements for the 3 specified end-uses was carried out. And the fabric design was optimized meeting the technical needs as well as economy
FACTORS CONSIDERED FOR DEVELOPMENT OF THE FABRICS – A)TENSILE STRENGTH B)POROMETRY C)WEIGHT OF FABRIC / COST OF PRODUCT / BATCH COMPOSITION D)TYPE OF WEAVE & EASE OF MANUFACTURE BY ANY JUTE MILLS FOLLOWING EMPERICAL RELATIONSHIP WERE ADOPTED FOR CALCULATING WEIGHT AND TENSILE STRENGTH OF FABRICS – Weight of Fabric ( gsm) = 1.425 ( N 1 G 1 + N 2 G 2 ), where, N 1 = Ends /inch & N 2 = Picks / inch and G 1 = Warp count in lbs & G 2 =Weft count in lbs. Tensile strength ( MD ), F S ( kgf) = C x QR x N’ 1 X U% 2.204 where F S is Tensile Strength of Fabric in warp way (MD), C is warp count, N 1 for ends / inch & QR is a factor derived by dividing tensile strength with warp count of yarn & expressed in percentage & U stands for utilization %, Tensile strength ( CD ), F’ S ( kgf) = C’ x QR x N’ 2 X U% 2.204 Where F’ S is Tensile Strength of Fabric in weft way (CD),C’ is weft count, N 2 for picks / inch & QR is a factor derived by dividing tensile strength with weft count of yarn & expressed in percentage & U stands for utilization DEVELOPMENT OF POTENTIALLY IMPORTANT JGTs
Determination of porometry of woven JGT – Calculation of pore size and pore diameter of JGT ; Method 1: Particulars of Warp and WeftMethod of calculation Warp/dm102Weft/dm39 Count of warp in ld/spyndle9.75Count of weft28 Diameter of yarn in inch0.035Diameter of yarn in inch0.059(√ count)/90 Diameter of yarn in cm0.088Diameter of yarn in cm0.149 Distance covered by the warp yarns in one dm (cm) (L1) 8.988 Distance covered by the weft yarns per dm (cm) 5.824 L1 = (Threads/dm) X diameter of the yarn (cm) Gap (Open area) left by the warp yarns in one dm (cm) (L2) 1.011 Open distance left by the weft yarns per dm (cm) 4.176L2 = 10 – L1 Open distance between the warp yarns (mm) 0.100 Open distance between the weft yarns (mm) 1.099 L3 = L2 X 10 / (no of threads – 1) Area of each open space (pore) in the fabric (Sq mm) (L3) 0.110L3 of warp X L3 of Weft Diameter of the pore (mm)0.332 Assuming shape of the pore as square, the side of the square will be the pore diameter. Diameter of the pore (micron) 332
End s / dm Pic ks / dm Count threads (Warp X Weft) (lb/spindle) Warp cover (K 1 ) Weft cover (K 2 ) Fabric cover (K c ) (%) Ope n area (%) No of mesh in one squar e dm Open area in one square dm (sq mm) Open area/ mesh (sq mm ) (A) Diam eter of one pore (mm) * (√ A) Diam eter of one pore (micr on) 1023910 X 2781.9351.4798.261.743978174.110.044 0.209 209.2 11 943910 X 2775.5051.4794.595.413666541.060.148 0.384 384.1 73 Calculation of pore size and pore diameter of JGT ; Method 2 : Established equations for calculation of cover factors of Jute fabric are : Warp cover : K 1 = No of warp / inch X √ (Count of warp in ld/spyndle) Weft cover : K 2 = No of weft / inch X √ (Count of weft in ld/spyndle) Fabric Cover : K c = K 1 + K 2 – (K 1 K 2 / 120)
Indicative batch composition of raw jute used to prepare yarns for developing the targeted fabric Tensile strength (KN/m) / Weight (gsm) 20/62725/724 WarpWeftWarpWeft Yarn count in lbs/ tex10 / 34528 / 96510 / 34527 / 930 TD43 6.5--36.5-- TD563.51063.520 TD646 Rope & Habijaby10 Cuttings2215 Thread Waste109 Gunny cuttings1- Caddies1- Total100. NB: Presently, due to non availability of good quality raw jute, batch composition of weft yarn for 25 kN/m fabric has marginally been modified to achieve desired tensile strength.
Based on the above concept five varieties of DW Plain weave JGT of 100 cm width having varied tensile strength with a porometric range from 150 to 400 micron were developed, tested and evaluated ConstructionDouble Warp Plain Weave (DW Plain) for application in rural road and river bank Open weave jute geotextile ( soil saver) for hill slope management Width (cm) Min100 cm122 cm Tensile strength (kN/m) MDx MD 20 - 30 Fabric weight (gsm)62 7 665724760810365 (with thicker weft / thinner warp yarn) 500 (with thicker wft & thinner wp yarn) 600700 Ends X Picks / dm85 X 32 77 X 35 94 X 39 102 X 39 102 X 41 5 X 46.5 X 4.5 7 X 6 7 X 7 Thickness (mm) 2 - 4 Elongation at break(%)Min MD x CD 8 - 12 A.O.S.Micron O 95 150 - 400
The fabrics developed were tested at IJFT & IJIRA geotextile testing laboratory and the results were found technically suitable for application under the project However, PIA has zeroed in on 2 types of woven JGT (20 kN/m- 627 gsm & 25 kN/m - 724 gsm and 3 types of open weave JGT (500, 600 & 700 gsm) for meeting end-use requirements, ease of manufacture and economizing cost of production
NomenclatureWoven JGT 20 kN/mWoven JGT 25 kN/m Construction1/1 DW Plain Weave Weight (gsm)627724 Width (cm)100 Ends x Picks / dm85 x 3294 x 39 Thickness, (mm at 2 kPa)1.71.85 Tensile Strength (kN/m), MD x CD20 x 2025 x 25 Elongation at break (%), MDx CD8 x 810 x 10 Puncture Resistance(kN)0.4000.500 Burst Strength (KPa)31003500 Permittivity at 50mm constant head (/sec)350 x 10 -3 A O S ( micron ) O 95 150 - 400 Specifications of two newly developed DW Plain Weave Jute Geotextiles.
Cost Benefit factor of Newly Designed Woven JGT Cost of JGT is mainly governed by its weight. Hence, 627 gsm ( 20 kN/m) JGT is 17.5 % cheaper as compared to earlier 760 gsm JGT. & 724 gsm ( 25kN/m) is about 5.0 % cheaper than its earlier variety.
Woven JGT of DW Twill construction as developed earlier are now being widely used in road construction, river bank protection and also in railway track improvement. Incidentally, the type of construction i.e. twill or plain practically is hardly of significance. On the other hand jute looms of 46.5"(118cm) R.S. are basically designed for plain weave construction and set with 2 leaf wyper ( tappet ). Further, plain weave is more convenient than twill weave from operational point of view. Hence, the manufacturers are in favor of plain weave construction which is also acceptable to the end users. TWILL or PLAIN WEAVE ?
Methodology followed to produce desired JGT To develop the targeted fabric, conventional 46.5"(118cm) R.S. loom was utilized Modifications/adjustment in shedding, raising the back rest as well as use of single denting in place double. Appropriate & standard batch composition of jute fibre were chosen to minimize the cost and to achieve desired tensile strength. Targeted porometry was achieved by judicial selection of yarn count ( dia) and yarn density in the fabric
DEVELOPMENT OF OPEN WEAVE JGTs 292 gsm,500 gsm & 730 gsm Open Weave ( OW ) JGT available off the shelf are being widely used world wide mainly for stabilizing the slopes of earthen embankment. CSWCRTI, who is one of the PEUs recommended to develop three new varieties of OW JGTs viz, 500 gsm,600 gsm & 700 gsm for use in hill slope stabiliztion. Accordingly, the products were developed by IJIRA. In designing the newer variety of 500 gsm fabric 170 lbs weft yarn was used instead of conventional 124 lbs for higher yarn dia. in anticipation of getting better effect in controlling surface run- off. As there is no significant role of warp yarn in entrapping the soil particles as well as to keep the weight of the fabric at lower side lighter warp count of 70 lbs was used which also controlled the cost The fabrics were tested at IJFT & IJIRA laboratories prior to put them to use in hill slope stabilization works by CSWCRTI at three different hill sites.
SPECIFICATIONS OF NEWLY DEVELOPED OW JGTs TYPE PROPERTIES 123 Weight (g/m 2 ) at 20% M.R.500600700 Threads/dm (MD x CD)6.5 x 4.58 x 78 x 8 Thickness (mm)18.104.22.168 Width (cm)122 Open area (%)554840 Strength (kN/m) [MD x CD]6.5 x 612 x 614 x 7 Water holding capacity (%) on dry weight 500 600
Construction Double Warp Plain Weave (DW Plain) for application in rural road Double Warp Plain Weave (DW Plain) for application in river bank Open weave jute geotextile for hill slope management Width (cm) at 20 % MR ≥ 200 cm* ≥ 122 cm Weight (gsm) 724 (- 5%, + 10%) 627 (- 5%, + 10%) (To be treated with Bitumen / any other additives) 500 (- 5%, + 10%) 600 (- 5%, + 10%) 700 (- 5%, + 10%) Tensile strength (kN/m) MD X CD ≥ 25 X 25≥ 20 X 20≥ 6.5 X 6 ≥ 12 X 6 ≥ 14 X 7 Ends X Picks / dm ≥ 94 X 39≥ 85 X 32≥ 6.5 X 4.5≥ 8 X 7 ≥ 8 X 8 Thickness (mm) 1.85 (± 10%)1.70 (± 10%) 4.50 (± 10%)5.25 (± 10%)5.50 (± 10%) Elongation at break (%) MD X CD ≤ 12 X 12 ≤ 14 X 14 Puncture Resistance (kN) 0.500 (± 10%)0.400 (± 10%) --- Burst Strengnth (KPa) 3500 (± 10%)3100 (± 10%) --- Permittivity at 50 mm constant head (/sec) 350 x 10 -3 (± 10%) --- A.O.S. (Micron) O95 150 - 400 --- Open Area (%) --50 - 6545 - 5040 - 45 Water Holding Capacity (%) on dry weight --450 - 500 550 – 600 CONSOLIDATED SPECIFICATIONS OF ALL THE JGTS DEVELOPED 724 gsm also appears to be an better alternative to earlier 760 gsm JGT for application in railways
Special care was taken for maintaining the quality of JGT during its manufacture by adopting strict process & quality control measures to ensure that fabrics would also be free from the following faults that can affect the specified porometry (O95) and tensile strength causing impairment of the expected geotechnical functions – Missing warp/weft,Multiple warp breakage,Gaw, Smash,Shuttle),Inserted Cop,Reed mark / dent mark As FA as well as a part & parcel of the project IJIRA also provided technical guidance to the mills for manufacturing right type of JGT. IJIRA also provided installation guidance to all the end users in India. PHOTOGRAPHIC VIEW OF FEW M/Cs, FABRIC SAMPLES AND APPLICATIONS ARE SHOWN IN NEXT FEW SLIDES ….
500gsm 600 gsm 700 gsm DIFFERENT TYPES OF OW JGT DEVELOPED
JGT-Acceptance at site Check the name of the supplier-mill, brand-mark if any, type of JGT supplied vis-à-vis specifications stated in the contract document, test certificate (whether by the mill or by any independent testing outfit), whether the material recommended for laying by the competent authority and the quantity in the consignment Note: One set of tests for each consignment of 16,000 sqm of JGT or as specified shall be carried out. Any palpable shortcoming in JGT-construction should be brought to the notice of the Engineer
JGT-Storage & handling JGT to be kept in a covered shed without removing the protective pack- sheet & not to be kept directly on ground/floor JGT not to be stored normally beyond 1 month JGT to be carried by inserting a bamboo or similar pole into the central hole of the roll when the fabrics come in the form of roll Check that the fabric does not get damaged during handling
JGT-Installation For slope protection work prepare the slope & dress properly Demarcate the entire area to be covered by JGT & measure the area Ascertain how JGT is to be placed considering the size (especially width) with the specified overlaps Decide on cutting the fabric supplied in rolls considering the length & width to be covered including the length needed inside anchoring trenches and ensuring minimum wastage Stitching of JGT is discouraged as it is difficult to achieve seam-strength of the order of 90%. Overlapping is advised usually. Ensure anchoring of JGT at the beginning and the end of a roll. In road construction, anchoring is done by pinning staples spaced @ 150 mm along the length and the width In slopes & river-banks, JGT shall be secured in anchor-trenches invariably at the top of the slope. The usual dimension of such a trench of rectangular section is 250 mm (base) x 500 mm (ht).
JGT-Installation Ensure that JGT touches the base and the two sides of the anchor trench uniformly at all points There shall be at least 2 staples at the bottom of the trench & 3 at the two sides Longitudinal spacing of staples within the trench shall be @150 mm usually. All trenches shall be filled with brick bats /stones after stapling is complete In river-bank erosion control, JGT is to be taken to the LWL. A sand-filled toe-beam is to be made by folding the end-fringe of the JGT-roll with river sand inside and sewing it. Alternatively, a bevel at the lower end of the bank could be made. In other slope protection works (embankment slope, hill slope etc), it is advisable to construct a rubble-filled drain at the toe that will serve both as anchor and drain. The shape of the drain-cum-anchor could be similar to the top anchor trench in shape & size.
JGT-Installation Usual overlap is 150 mm. JGT should be stapled by inserting U-shaped or broad-headed nails or fork-shaped wooden pegs. May have closer staples in case of roads with CBR 30°, eroding river banks with eddies at the toe, large water-level fluctuation (>3 m) and flow velocity > 1 m/sec Ensure that the overlaps of successive JGT rolls do not fall along the same line. Ensure that the fabric touches ground at all points, staples are firmly embedded in the ground Installed fabric shall not be left uncovered except in case of slopes. Heavy granular overlay over JGT should be placed softly to avoid puncturing of the fabric
JGT-Installation Usually a thin cushion of sand (15 mm to 25 mm) is spread over and under JGT to avoid direct contact with the sharp aggregates and soil. Note that JGT is more durable when sandwiched between sand-layers JGT should not be placed directly over soil-slurry or mud. It is advisable to level off the ground, remove the muddy portion & place a thin cushion of sand before placing JGT Find from the drawing the position of JGT in the pavement-structure i.e. whether it is placed over sub-grade or over sub-base or over the base- course. Similarly, follow the working drawing in case of a river bank erosion control and ensure placement of JGT at the right place.
Direction of laying Jute Geotextile Fixing nail Graded slope Grass plant Toe anchor (150 mm x 150mm) INSTALLATION METHOD OF JUTE GEOTEXTILE 150 Shoulder anchor (150 mm x 150mm) 150 mm 50 mm Fixing nail (II Gauge wire) +
ROAD CONSTRUCTION- Preparation of Road Sub-grade, Nihinagar to Hajratpur, Balurghat, WB