dr. s. k. ghosh, associate professor, djft, ijt, c.u. mr. m. m. mondal, srf, djft, ijt, c.u. mr. r....

Dr. S. K. Ghosh, Associate Professor, DJFT, IJT, C.U.

Mr. M. M. Mondal, SRF, DJFT, IJT, C.U.

Mr. R. Bhattacharyya, SRF, DJFT, IJT, C.U.

DEPT. OF JUTE AND FIBRE TECHNOLOGY, INSTITUTE OF JUTE TECHNOLOGY (IJT), UNIVERSITY OF CALCUTTA (FACILITATING AGENCY)

1

OPTIMIZATION OF PRORERTY PARAMETERS OF WOVEN JUTE GEOTEXTILES FOR POTENTIAL APPLICATIONS IN THE FIELD OF GEOTECHNICAL

CONSTRUCTIONS

The global growth of Geosynthetics for the last one decade or so has been substantially soaring @ 10% per annum.

Jute Geotextiles (JGT), a class of natural Technical Textiles, has carved out a niche in this emerging technology.

INTRODUCTION

The growth of JGT with respect to its man-made counterpart is not very far behind.

Effectiveness of JGT in addressing a host of geotechnical problems and more importantly its eco-compatibility is gaining increasing acceptability worldwide.

2

The use of JGT has extended rapidly into nearly all areas of civil, geotechnical, environmental, coastal and hydraulic engineering.

APPLICATIONS

Jute Geotextile has proved to be the most versatile in Separation, Filtration, Drainage, and Reinforcement besides providing a protective cover over soil.

JGT play a significant part in modern pavement design and maintenance techniques.

3

SCOPE AND AIM OF THE WORK

Several varieties of JGT – both woven and nonwoven have been developed for a number of geotechnical end uses e.g. improving pavement performance, soil erosion, embankment, drainage system etc.

All these available fabrics are not applicable as per the need of the different geotechnical constructions.

It is felt that there is an urgent need to design and engineer of such precise fabric for potential applications in emerging civil works.

4

In a recently concluded PMGSY Project and in other works on road constructions, in most of the cases traditional sacking quality jute woven fabrics (Plain Weave and Twill Weave) have been extensively used.

The previous studies and field applications carried out so far on rural road construction have confined the efficacy of the appropriate variety of jute material.

The applications, however, did not focus on engineering and manufacture of application specific and functions oriented varieties of JGT.

Added to this shortcoming is absence of appropriate standards in applications as well as in design and engineering of JGT in the rural road construction and river bank protection.

5

Use of conventional sacking fabrics being not application specific and function-oriented, deserves rethinking on adoption of the conventional jute fabrics used for flexible packaging in road construction.

It is in this context that development of potentially important JGT for strengthening rural roads assumes significance.

It was realized that such a JGT should be woven whose property parameters should be functionally apt for serving the purpose.

6

Optimization of the fabric property parameters of DW plain weave JGT of different gsms alongwith that of Open Weave JGT samples (soil savers) with respect to different geotechnical applications like road construction for strengthening of sub grade and river bank protection to control erosion of the river bank as well as Hill Slope protection.

Comparative Analysis (CA) of the results of different tests carried out with JGT samples supplied by the different Jute Mills of West Bengal and zeroing on the two types of woven JGT on the basis of evaluated property parameters for rural road construction and three types of soil savers for hill slope protection.

Determination of the tolerance limit of the prime property parameters of the optimized and selected DW JGT samples alongwith that of Open Weave JGT samples (soil savers) by statistical interpretation for formulation of the specification by relevant national and international statutory bodies for global acceptance of the said fabric.

OBJECTIVES

7

In order to achieve the objectives of this work DW Plain Weave JGT Fabrics of different GSMs were produced by varying yarn and fabric parameters followed by conventional jute processing system in different commercial jute mills.

Different tests were carried out in the laboratory for assessing the physical, mechanical and hydraulic property parameters and the effect of change in yarn parameters and yarn density on the produced fabric properties before actual field trial on roads and river banks.

8

The following fabric property parameters were tested as per relevant ASTM standards in the laboratory-

Subsequently on the basis of test results optimization of the fabric samples were carried out by Simple Average Weighted Ranking Procedure (SAWRP).

9

FABRIC SAMPLES PREPARATION

10

Three different counts of warp yarns viz., 9, 11 and 13 lbs/ spyndle and weft yarns viz., 24, 26, 28 lbs/ spyndle were produced in conventional slip draft spinning machine.

Twelve double warp plain weave fabrics of three GSM ranges, (600 -700), (700 – 800) and (800 – 900) were produced by using warp and weft count (9 X 24) lbs / spyndle, (11 X 26) lbs / spyndle and (13 X 28) lbs / spyndle, respectively in a conventional Jute loom.

11

The entire range of produced Jute based Woven DW Fabric Samples were conditioned according to ASTM standard using standard Temperature and humidity for 24 hours before commencement of testing work.

CONDITIONING OF FABRIC SAMPLES

12

From the actual application point of view of Technical Textiles / Geotextiles, conventional testing parameters along with sample specifications for normal textile testing cannot generally be regarded as appropriate for Technical Textile/ Geotextile Testing.

Conventional textile testing methodology has only a limited usefulness in assessing the properties of a fabric relative to its engineering end use.

TESTING OF FABRIC SAMPLES

Test samples were selected in such a way that it could represent the whole population of the fabric and the piece of fabric cut out for the laboratory test was one meter long with full width of the fabric.

No samples have been taken from nearer than 50 mm to the selvedge of the fabric sample. Fabric samples were tested according to ASTM Standard Testing Methods.

13

Testing Parameters for Woven and Open Weave JGT samples for application on Rural Road Construction and Hill Slope Management

Testing Parameters Woven JGT Open Weave JGT

Construction : Design of Weave √ XConverted Mass: GSM [at 20% M.R.] √ √Ends / dm & Picks / dm √ √Thickness (mm) √ √

Wide – width Tensile strength (kN/m)(Warp X

Weft)

Elongation at Break (%) (Warp X Weft)

√√

√√

Index Puncture Resistance (kN) √ XBursting Strength (kg/cm2) √ XFlow Rate (l/m2/sec) at 50 mm. Constant Water Head Pressure.

√ X

Permittivity (/sec) at 50 mm. Constant Water Head Pressure.

√ X

Permeability (cm/sec) at 50 mm. Constant Water Head Pressure.

√ X

Apparent Opening Size (micron), O95 √ XOpen Area (%) X √Width (cm) X √

14

RESULTS AND DISCUSSIONS (Part-1)

For

DW PLAIN WEAVE JGT SAMPLES

15

Table (1): Physical and Mechanical Properties of the Fabric Samples

Param-eters

Sl. No.

Physical Mechanical

Converted Mass @ 20%

M.R.

Ends/dmX

Picks /dm

Thickness (mm)

Tensile Strength (kN/m),[Warp X

Weft]

Elongation (%)

[Warp X Weft]

Index Puncture

(kN)

Bursting Strength (kg/cm2)

01. 605.00 86 X 34 1.51 20.24 X 22.50

9.0 X 9.0 0.41 23.10

02. 626.44 92 X 36 1.65 21.88 X 22.79

9.0 X 6.0 0.45 24.27

03. 657.00 92 X 40 1.73 22.32 X 23.98

11.0 X 7.0 0.50 26.60

04. 680.00 94 X 42 1.77 22.70 X 25.00

9.0 X 7.0 0.55 28.07

16

Fig. 1 Fig. 2 Fig. 3

Fig. 4

Graphical representation of the effect of GSM (600 – 700 ) on Tensile Strength (Warp Way and Weft Way),Index Puncture Resistance and Bursting Strength of JGT.

Fig. 1 Fig. 2 Fig. 3

17

DISCUSSIONS

It was observed from the Table (1) and Fig.1, Fig.2, Fig.3 and Fig.4 that the fabric samples with higher GSM had shown higher tensile properties (tensile strength, index puncture resistance and bursting strength, etc.).

This can be accounted for by the fact that an increase in GSM in the fabric indicated an increase in the number of load bearing elements per unit length in the warp as well as weft directions leading to an increase in the tensile strength of the fabric.

18


Param-eters

Sl. No.

Physical Mechanical

Converted

Mass @ 20% M.R.

Ends/dmX

Picks /dm

Thickness (mm)


Weft]

Elongation (%)

[Warp X Weft]

Index Puncture

(kN)


05. 716.00 92 X 36 1.68 21.88 X 26.62

11.0 X 7.0 0.48 26.50

06. 724.00 96 X 36 1.78 25.25 X 27.77

11.0 X 11.0 0.52 27.08

07. 758.00 98 X 38 1.81 25.00 X 29.90

15.0 X 13.0 0.53 29.70

08. 780.00 100X40 1.87 24.76 X 32.64

16.0 X 13.0 0.57 28.10

19

Graphical presentation of the effect of GSM (700-800) on the Tensile Strength (Warp Way & Weft Way), Index Puncture Resistance and Bursting Strength of JGT.

Fig. 5 Fig. 6 Fig.7

Fig. 6 Fig. 7

Fig. 8

Fig. 5

20

DISCUSSIONS



21


Param-eters

Sl. No.

Physical Mechanical

Converted

Mass @ 20% M.R.

Ends/dmX

Picks /dm

Thickness (mm)


Weft]

Elongation (%)

[Warp X Weft]

Index Puncture

(kN)


01. 809.00 92 X 35 1.44 22.39 X 28.32

12.0 X 7.0 0.59 24.82

02. 826.00 95 X 36 1.51 25.59 X 29.00

12.0 X 8.0 0.61 31.42

03. 853.00 97 X 38 1.63 25.12 X 30.90

13.0 X 8.0 0.64 32.70

04. 891.00 100X41 2.11 26.50 X 32.90

19.0 X 8.0 0.62 30.40

22

Graphical presentation of the effect of GSM (800-900) on the Tensile Strength (Warp Way & Weft Way) , Index Puncture Resistance and Bursting Strength of JGT.

Fig. 9

Fig.10

Fig. 11

Fig. 10Fig. 9

Fig. 12

Fig. 11

23

DISCUSSIONS



24

Table (4): Hydraulic Properties of the Fabric Samples

25

Fig. 13 Fig.14 Fig. 15

Graphical presentation of the effect of different GSMs on Apparent Opening Size (AOS) of JGT.

Fig. 13 Fig. 14Fig. 15

26

Table No.(4) and Fig. 13, Fig. 14, Fig. 15 shows that, the values of AOS had decreased within a particular GSM range and between the GSM ranges.

This is due to the fact that the increase in the GSM with the increase in yarn density results in decrease in the percentage open area of the fabric causing reduction in average pore dimension of the fabric samples.

DISCUSSIONS

27

Apart from this, it was also observed that there is a decrease in AOS values in the produced fabric samples of different GSM ranges because of the increase in the count of the warp and weft yarns respectively.

Consequently, the water permeability and permittivity of fabric samples had shown a decreasing trend with the increase in fabric GSM, which is self explanatory from the results of Apparent Opening Size (AOS) of different produced fabric samples.

DISCUSSIONS

28

Values of all the dimensional and geotechnical (physical, mechanical and hydraulic properties etc.) property parameters obtained for all the jute woven fabric samples produced in this work by varying process parameters and machine parameters are compared by the method of Simple Average Weighted Ranking Procedure for three categories (600 – 700 gsm, 700 – 800 gsm and 800 – 900 gsm) of such woven JGT fabric samples separately for optimization of different fabric property parameters.

RANKING OF FABRIC SAMPLES

29

For ranking within the specified range of fabric area

density, each property parameter of each sample is

proportionately weighted as compared to the best

values obtained in that property parameter to award

ten (10) point and rest of the obtained values lower than

the best value were weighted proportionately.

Finally considering all the property parameters

together simple average were determined to get the

rank within that class.

30

Sl. No.

GSMEnd/dm

Picks/dm

Thickness

(mm)

Tensile Strength in Warp (kN/m)

Rank

Tensile Strengt

h in Weft

(kN/m)

RankPuncture

Resistance (kN)

RankBursting Strength (kg/cm2)

Rank

AOSO95, (Micron)

Rank

Permittivity

(/sec)

Rank

Total Rank

Average Ran

k

01.

605.00 86 34

1.51

20.24 8.9 22.50 9 0.41 7.45

23.10

8.22

720

4.37

3.2

3.31 41.29 6.88

02.

626.44 92 361.65

21.88 9.63 22.79 9.11 0.45 8.18

24.27

8.64

480

6.56

1.79

5.92 48.07 8.01

03.

657.00 92 40

1.73

22.32 9.83 23.98 9.59 0.50 9.09

26.60

9.47

355

8.87

1.13

9.38 56.25 9.37

04.

680.00 94 42

1.77

22.70 10 25.00 10 0.55 10

28.07

10

315

10

1.06

10 60.00 10.0

Table (5): Ranking of Fabric Samples in GSM Range 600 to 700

31

Sl. No.

GSMEnd/dm

Picks/dm

Thickness

(mm)


Rank

Tensile Strength in Weft (kN/m)

Rank

Puncture

Resistance (kN)


Rank

AOS, O95, (Micr

on)

Rank

Permittivity

(/sec)

RankTotal Rank

Average

Rank

05.

716.00

92 36

1.68

21.88 8.752 26.62 8.156

0.48

8.42

26.50

8.92

300

7.90

1.07

6.355 48.51 8.08

06.

724.00

96 36

1.78

23.25 9.300 27.77 8.508

0.52

9.12

27.08

9.11

270

8.7

0.82

8.293 53.12 8.85

07.

758.00

98 38

1.81

25.00 10 29.90 9.161

0.53

9.29

29.70

10

237

10

0.81

8.395 56.85 9.48

08.

780.00

100 40

1.87

24.76 9.904 32.64 10

0.57

10

28.10

9.46

240

9.87

0.68

10 59.24 9.87


32

Sl. No.

GSMEnds/dm

Picks/dm

Thickness

(mm)


Rank

Tensile Strength in Weft (kN/m)

Rank

Puncture

Resistance

(kN)


Rank

AOSO95, (Micron)

RankPermittivity (/sec)

RankTotal Rank

Average

Rank

09.

809.00

92 35

1.44

22.39 8.44 28.32 8.60

0.59

9.21

24.82

7.59

245

5.3061

1.1

4.455 43.63 7.27

10.

826.00

95 36

1.51

24.59 9.27 29.00 8.81

0.61

9.53

31.42

9.60

207

6.2802

0.99

4.949 48.46 8.08

11.

853.00

97 38

1.63

25.12 9.4 30.90 9.39

0.64

10

32.7

1

167

7.7844

0.72

6.806 53.46 8.91

12.

891.00

100 41

2.11

26.50 10 32.90 10

0.62

9.68

30.4

9.29

130

10

0.49

10 58.98 9.83


33

It has been observed from the ranking method that by optimizing mechanical, hydraulic and fabric area density (gsm) properties the fabric sample no. 4 within gsm Range 600 – 700, sample no. 8 within gsm range 700 – 800 and sample no. 12 within gsm range 800 – 900 have secured the highest rank mainly due to their higher gsm property parameters.

But considering the techno-economic aspect such a fabric was desperately needed to be selected which would not only confirm with the optimum requirement as per the design as well as end use with its satisfactory test results during its period of performance.

34

35

Therefore, keeping that in mind, sample no. 2 was found to be the best amongst the other fabric samples in the gsm category 600-700 both in terms of its test results, particularly in tensile and porometry properties, as well as cost-effective since its gsm was found to be lying near the lower value of its gsm category.

Similarly, it has been also observed for sample no.6 in the gsm category 700-800 that the sample depicts optimum test results of its property parameters best fitting to the end use requirements alongwith comparatively lower gsm, nearing the lower value of its gsm category thereby proving its economic benefit.

Hence, sample nos. 2 and 6 have been standardized for the application in roads as underlay for strengthening of sub-grades. Moreover, sample No.2 has undergone suitable rot resistant treatment for the application in river bank protection to enhance its durability and simultaneously paving the way for comparing the performance of both the grey and treated fabric.

36

Considering techno-economic viability no sample in the higher gsm range 800-900 has not been selected for the same since higher gsm values lead to higher expenditure both during bulk production as well as application on site.

After optimization and selection of the two fabric samples of gsm 626.44 (627 gsm approximately) and 724 respectively, their test results have been placed before the relevant Fabric Design and Engineering Committee, entrusted under the purview of this work, to furnish a full-scale specification to the different Jute Mills of West Bengal, India as well as in Bangladesh for the purpose of manufacturing of the several woven JGT samples as per the mentioned specifications (provided in next slide) for carrying out different field trial applications in both the case studies like road construction and river bank protection.

37

The specifications of the Jute Geotextile samples which have been optimized for rural road construction as well as for river bank protection are furnished in the Table (8) below -

ConstructionDouble Warp Plain Weave for

application in river bank** as well as in road construction

Double Warp Plain Weave for application in rural

road construction

Width (cm) ≥ 200 cm* ≥ 200 cm*

Weight (gsm) at 20% MR 627 (±5%) 724 (±5%) (Untreated)

Ends X Picks / dm ≥ 85 X 32 ≥ 94 X 39

Thickness (mm) 1.70 (± 10%) 1.85 (± 10%)

Wide width Tensile strength (kN/m) MD X CD

≥ 20 X 20 ≥ 25 X 25

Elongation at break (%)MD X CD

≤ 12 X 12 ≤ 12 X 12

Puncture Resistance (kN) 0.400 (± 10%) 0.500 (± 10%)

Burst Strength (KPa) 3100 (± 10%) 3500 (± 10%)

Permittivity at 100 mm constant head (/s)

0.35 (± 10%) 0.35 (± 10%)

A.O.S. (Micron) O95 150 - 400 150 - 400

Open Area (%) X X

Water Holding Capacity (%) on dry weight

X X

N.B.: *Width of the Woven JGT may be fixed as agreed between buyer and seller, subject to a lower limit of 100 cm. **To be treated with a suitable additive

38

DETERMINATION OF TOLERANCE LIMIT OF THE PRIME PROPERTY PARAMETERS OF DW PLAIN WEAVE JGT SAMPLES

39

1. Population Size: Population is the whole bulk of the material available for testing and that the sample is a relatively small fraction of that population.

No. of Specimens: n = 0.15 r²; Where r = co-efficient of variation (%) of the parameter under test.

2.Sampling Distribution: Suppose we took a large a no. of samples, each of ‘n’ individuals, from a population which has a normal or nearly normal distribution and in each case the sample mean is calculated. We could then make a frequency distribution of the sample means.

3. Calculation of standard Deviation of the Test Results. (S.D.)4. Estimation of Standard Error of the mean: (S.E.) S.E. = (S.D. / √n); n = sample size 5. Significance testing of Means : (i) Physical Significance of ‘t’ (tolerance limit) t = (Nominal Mean- Sample Mean) / Standard Error (ii) The value ‘t’ has a SD of its own which is not normal even though the

population from which the samples have been drawn has a normal distribution.

6. Determination of Tolerance limit: First Method: To calculate Sample mean, S.D. and S.E. Nominal Mean = {Sample Mean ± (t × S.E.)}, where, S.E. = (S.D. / √n) The value of ‘t’ may be found from table of Significant Limit where ‘t’ has

sampling distribution of its own which is not regular.

Second Method: Nominal Mean = Sample Mean ± 1.96 × б where 1.96 lies in 95 % level of confidence and б = S.D. and the sampling

distribution is normal.mal.

To Determine the Tolerance Limit of a Textile Testing Parameter along with its Statistical Significance (Statistical Interpretation)

40

The tolerance limit for the above stated parameters of the developed fabric has been calculated by using the

following method :

•Usually all population values are not available that is why we take samples and express Standard Error (S.E.) as Standard Deviation (S.D.) /√n, where n is the population size.

• In this case we take a sample and calculated the S.D. (gsm) of the same sample.

•As per Statistical calculation Standard Error (S.E.) of Mean will be S.D./√n. The average value of the determined fabric weights produced by the different Jute Mills is tabulated in Table 1. ……(contd.)

41

Fabric Wt.(gsm)

642.66 626.44 632.20 612.00 605.00 634.00 614.00 618.00 640.34 615.50

Jute Mills 1 2 3 4 5 6 7 8 9 10

SINo.

x xC x-xC (x-xC)2

S.D.= √Σ(x-xC)2 / (n-1)= 12.81

1. 642.66

624.12

18.59 343.73

2. 626.44 2.32 5.38

3. 632.20 7.08 50.12

4. 612.00 -12.12 146.89

5. 605.00 -19.12 365.57

6. 634.00 9.88 96.82

7. 614.00 -9.62 92.54

8. 618.00 -5.52 30.47

9. 640.34 16.22 263.80

10. 615.50 -9.12 84.27

Standard Error (S.E.) = S.D. / √n = 4.05, t = Nominal Mean — Sample Mean / S.E. for degree of freedom, v = n-l = 9, t = 2.262 at 5% significant level (obtained from table of significant limit, “t” has sampling distribution of its own which is not regular). Nominal Mean = Sample Mean ± t × S.E., i.e., Nominal Mean = 627 ± 2.262 × 4.05 = 627 ± 9.16.Nominal Mean = Sample Mean ± 1.5 %.Considering Normal Distribution of Sample, Nominal Mean = 627 ± 1.96 × 12.81, Nominal Mean = Sample Mean ± 4.0%.

Table 9 - gsm values of the JGT samples (626.44 gsm) produced by the different Jute Mills

The S.D. of the samples have been determined, using the following mathematical correlation-S.D. = √∑(x- x ̅) 2/ (n-1) where (x-x ̅) = Deviation of the observation from the Specified value and the values have been depicted in Table 10.

Table 10- Different gsm values and calculation of S.D.

42


28.07 27.75 24.46 23.10 28.30 25.68 26.20 28.00 25.15 24.40

Jute Mills 1 2 3 4 5 6 7 8 9 10

SINo.

x xC x-xC (x-xC)2

S.D.= √Σ(x-xC)2 / (n-1)= 0.62

1. 28.07

26.11

1.96 3.842. 27.75 1.64 2.693. 24.46 -1.65 2.724. 23.10 -3.01 9.065. 28.30 2.19 4.796. 25.68 -0.43 0.187. 26.20 0.09 0.00088. 28.00 1.89 3.579. 25.15 -0.96 0.9210. 24.40 -1.71 2.92


Table 11 - Bursting Strength values of the JGT samples (626.44 gsm) produced by the different Jute Mills

t = Nominal Mean — Sample Mean / S.E. For degree of freedom, v = n-l = 9, t = 2.262 at 5% significant level (obtained from table of significant limit, t has sampling distribution of its own which is not regular).Nominal Mean = Sample Mean ± t × S.E., = 627 ± 2.262 × 0.196. Nominal Mean = Sample Mean ± 0.07 %. Considering Normal Distribution of Sample, Nominal Mean = Sample Mean ± 1.96 × 0.62 = 627 ± 1.22 .Nominal Mean = Sample Mean ± 0.19 %.

Table 12- Different Bursting Strength values and calculation of S.D.

43

AOS(O95)

micron280 500 460 520 720 385 770 450 500 760

Jute Mills 1 2 3 4 5 6 7 8 9 10

SINo.

x xC x-xC (x-xC)2

S.D.= √Σ(x-xC)2 / (n-1)=54.79

1. 280

534.5

-254.5 64770.252. 500 -34.5 1190.253. 460 -74.5 5550.254. 520 -14.5 210.255. 720 185.5 34410.256. 385 -149.5 22350.257. 770 235.5 55460.258. 450 -84.5 7140.259. 500 -34.5 1190.25

10. 760 225.5 50850.25

The S.D. of the samples have been determined, using the following mathematical correlation S.D. = √∑(x- x[ ) 2/ (n- 1) where (x-x[ ) = Deviation of the observation from the Specified value and the values have been depicted in Table 14.

Table 13 - Apparent opening size values of the JGT samples (626.44 gsm) produced by the different Jute Mills

t = Nominal Mean — Sample Mean / S.E. For degree of freedom, v = n-l = 9, t = 2.262 at 5% significant level (obtained from table of significant limit, t has sampling distribution of its own which is not regular)Nominal Mean = Sample Mean ± t × S.E., = 627 ± 2.262 ×17.34. Nominal Mean = Sample Mean ± 6.26 %. Considering Normal Distribution of Sample, Nominal Mean = Sample Mean ± 1.96 ×54.79 = 627 ± 107.39. Nominal Mean = Sample Mean ± 17.13%.

Table 14 - Different Apparent opening size values and calculation of S.D.

44

Fabric Wt.(gsm)

716.88 752.00 716.20 795.00 768.00 672.00 758.00 733.16 697.50 710.85

Jute Mills 1 2 3 4 5 6 7 8 9 10

SINo.

x xC x-xC (x-xC)2

S.D.= √Σ(x-xC)2 / (n-1)= 12.20

1. 716.88

731.96

-15.08 227.412. 752.00 20.04 401.603. 716.20 -15.76 248.384. 795.00 63.04 3974.045. 768.00 36.04 1298.886. 672.00 -59.96 3595.207. 758.00 26.04 678.088. 733.16 01.20 01.449. 697.50 -34.46 1187.49

10. 710.85 -21.11 445.63


Table 15 - gsm values of the JGT samples (724 gsm) produced by the different Jute Mills


Standard Error (S.E.) = (S.D. / √n) = 3.86, t = Nominal Mean — Sample Mean / S.E. for degree of freedom, v = n-l = 9, t = 2.262 at 5% significant level (obtained from table of significant limit, t has sampling distribution of its own which is not regular). Nominal Mean = Sample Mean ± t × S.E., Nominal Mean = 724 ± 2.262 × 3.86, Nominal Mean = Sample Mean ± 1.21%.Considering Normal Distribution of Sample, Nominal Mean = Sample Mean ± 1.96 × б, 724 ± 1.96 × 12.20 = 724 ± 23.91. Nominal Mean = Sample Mean ± 3.30%.

45


26.50 33.30 21.02 22.24 25.00 30.45 28.42 30.40 27.20 29.70

Jute Mills 1 2 3 4 5 6 7 8 9 10

SINo.

x xC x-xC (x-xC)2

S.D.= √Σ(x-xC)2 / (n-1)=1.28

1. 26.50

27.42

-0.92 0.852. 33.30 5.88 34.573. 21.02 -6.40 40.964. 22.24 -5.18 26.835. 25.00 -2.42 5.866. 30.45 3.03 9.187. 28.42 1.00 1.008. 30.40 2.98 8.889. 27.20 -0.22 0.0510. 29.70 2.28 5.19

Table 18 - Different Bursting Strength values and calculation of S.D.

Table 17 – Bursting Strength values of the JGT samples (724 gsm) produced by the different Jute Mills


Standard Error (S.E.) = (S.D. / √n) = 0.4, t = Nominal Mean — Sample Mean / S.E., for degree of freedom, v = n-l = 9, t = 2.262 at 5% significant level (obtained from table of significant limit, t has sampling distribution of its own which is not regular). Nominal Mean = Sample Mean ± t × S.E. Nominal Mean = 724 ± 2.262 × 0.41, 724± 0.93, Nominal Mean = Sample Mean ± 0.13 %.Considering Normal Distribution of Sample, Nominal Mean = Sample Mean ± 1.96 × б, 724 ± 1.96 × 1.28 ,724 ± 2.51. Nominal Mean = Sample Mean ± 0.35 %.

46

AOS(O95)

micron195 260 240 200 175 175 245 237 195 250

Jute Mills 1 2 3 4 5 6 7 8 9 10

SINo.

x xC x-xC (x-xC)2

S.D.= √Σ(x-xC)2 / (n-1)= 10.79

1. 195

217.2

-22.2 492.842. 260 42.8 1831.843. 240 22.8 519.844. 200 -17.2 295.845. 175 -42.2 1780.846. 175 -42.2 1780.847. 245 27.8 772.848. 237 19.8 392.049. 195 -22.2 492.8410. 250 32.8 1075.84

Standard Error (S.E.) = (S.D. / √n) =3.41, t = Nominal Mean — Sample Mean / S.E., for degree of freedom, v = n-l = 9, t = 2.262 at 5% significant level (obtained from table of significant limit, t has sampling distribution of its own which is not regular).Nominal Mean = Sample Mean ± t × S.E. Nominal Mean = 724 ± 2.262 × 3.41,7 24± 7.71. Nominal Mean = Sample Mean ±1.06 %.Considering Normal Distribution of Sample, Nominal Mean = Sample Mean ± 1.96 × б, 724 ± 1.96 × 10.79, 724 ± 21.15. Nominal Mean = Sample Mean ± 2.92 %.

Table 19. Apparent opening size values of the JGT samples (724 gsm) produced by the different Jute Mills


Table 20. Different Apparent opening size values and calculation of S.D.

RESULTS AND DISCUSSIONS (Part-2)

For

OPEN WEAVE JGT SAMPLES (SOIL SAVER)

47

48

Para-meters

Physical Property Mechanical and Porometry Properties

Width

(cm)

Converted

Mass @ 20% M.R.

Ends /dmX

Picks /dm

Thicknes

s (mm

)


Weft]

Elongation (%)

[Warp X Weft]

Open Area

(%)Sample No.

01. 122.0

467.00 7.0 X 5.0 3.81 7.00 X 4.66 10.0 X 8.0

51.11

02. 122.0

482.22 7.0 X 5.0

4.62 6.34 X 5.74 11.0 X 12.0

55.87

03. 122.0

536.00 7.0 X 5.0 4.96 4.85 X 5.55 16.0 X 16.0

51.10

Table 20–Physical, mechanical and porometry properties of the open weave JGT Samples within the GSM range 450-550

49

DISCUSSIONS

•Among all of the supplied samples by the different Jute Mills, the Sample No. 02 of GSM 482.22 is found to be closely matching with the specified GSM 500 (range considered 450-550 GSM)along with its physical and mechanical properties .

•For other samples the GSM values are not matching with the specified GSM as well as their tensile properties are not compatible with that of the specifications of the Sample No.02.

•Specifications of the sample of GSM 482.22 supplied by Sample No.02 can be considered nearest to the specified GSM.

50

Para-meters


Width(cm)

Converted

Mass @ 20% M.R.

Ends /dmX

Picks /dm

Thickness (mm)


Weft]

Elongation (%)

[Warp X Weft]

Open Area

(%)Sample No.

01. 122.0 593.11 8.0 X 7.0

5.47 11.76 X 6.19 7.0 X 12.0 48.00

02. 122.0 606.00 7.5 X 6.5

4.52 9.23 X 6.00 10.0 X 10.0

51.50

03. 122.0 633.00 8.0 X 6.5

4.69 14.07 X 8.37 9.0 X 11.0 41.00

Table 21 –Physical, mechanical and porometry properties of the open weave JGT Samples within the GSM range 551-650

51

DISCUSSIONS

• The Sample No. 02 supplied by the Jute Mill having GSM value 606.00 is found to be closely compatible with the specified GSM along with its thread density and open area value.

• While for the other supplied samples it is observed that neither their physical properties (GSM, thread density) nor their mechanical properties (tensile properties) are in agreement with the specifications.

• Specifications of the sample supplied by Mill No. 02 can be considered nearest to the specified GSM.

52

Para-meters


Width(cm)

Converted

Mass @ 20% M.R.

Ends /dmX

Picks /dm

Thickness (mm)


Weft]

Elongation (%)

[Warp X Weft]

Open Area

(%)Sample No.

01. 122.0 699.00 7.5 X 8.0 4.66 16.86 X 9.98

9.0 X 10.0 41.50

02. 122.0 713.30 8.0 X 8.0

5.30 14.38 X 6.98

8.0 X 13.0 40.30

03. 122.0 660.00 7.5 X 7.5 5.47 9.05 X 9.92 13.0 X 16.0

49.00

Table 22 –Physical, mechanical and porometry properties of the open weave JGT Samples within the GSM range 651-750

53

DISCUSSIONS

•The Sample No. 01 supplied by Mill No. 01 is found to be in close approximation with the specified GSM as well as with the specified thread density.

•For the samples supplied by the other Jute Mills it is found that though their thread density and tensile properties are matching with the specified thread density and tensile properties to some extent yet their GSM values are not at all matching with the specified GSM leading to a greater cost factor.

•Specifications of the Sample No. 01 can be considered nearest to the specified GSM.

54

After optimization and selection of the three fabric samples of

gsm 482.22, 606.00 and 699.00 respectively, their test results have

been placed before the relevant Fabric Design and Engineering

Committee, entrusted under the purview of this work, to furnish

a full-scale specification to the different Jute Mills of West

Bengal, India as well as in Bangladesh for the purpose of

manufacturing of the several open weave JGT (soil saver)samples

as per the mentioned specifications (provided in next slide) for

carrying out different field trial applications in both the case

studies like road construction and river bank protection.

55

Construction Open weave jute soil saver for hill slope management

Width (cm) Minimum 122 cm (± 5%)Tensile strength (kN/m) MD X CD

6.5 (+4%, -2%)

4.5(+4%, -2%)

8 (+4%, -2%) 7 (+4%, -2%)

8 (+4%, -2%) 8 (+4%, -2%)

Untreated Fabric weight (gsm) 500 (± 10%) (with

thicker weft & thinner

warp yarn)

600 (± 10%) 700 (± 10%)

Ends X Picks / dm6.5 (+4, -2) x 4.5 (+2, -

1)

7 (+4, -2) x 6 (+2, -1)

7 (+4, -2) x 7 (+2, -1)

Thickness (mm) 4.50 (± 10%)

5.25 (± 10%) 5.50 (± 10%)

Elongation at break (%) Minimum MD X CD

≤10 x 12 ≤ 10 x 10 ≤ 9 x 10

Open Area Percentage 50-65 45-50 40-45 Water Holding Capacity(%) on dry wt.

450-500 450-500 550-600

Table 23- Full-Scale Specifications of the Open Weave JGT (Soil Saver) samples identified for field trial

56

DETERMINATION OF TOLERANCE LIMIT OF THE PRIME PROPERTY PARAMETERS OF OPEN WEAVE JGT (SOIL SAVER SAMPLES)

57

Fabric Wt.(gsm)

467.00 482.22 536.00 558.00 627.55 583.00 495.70 512.30 500.08 521.00

Jute Mills 1 2 3 4 5 6 7 8 9 10

SINo.

x xC x-xC (x-xC)2

S.D.= √Σ(x-xC)2 / (n-1)= 16.42

1. 467.00

528.29

-61.29 3756.462. 482.22 -46.07 2122.443. 536.00 07.71 59.444. 558.00 29.71 882.685. 627.55 99.26 9852.556. 583.00 54.71 2993.187. 495.70 -32.59 1062.118. 512.30 -15.99 255.689. 500.08 -28.21 795.8010. 521.00 -07.29 53.14

Standard Error (S.E.) = (S.D. / √n) = 5.20, t = Nominal Mean — Sample Mean / S.E. For degree of freedom, v = n-l = 9, t = 2.262 at 5% significant level (obtained from table of significant limit, t has sampling distribution of its own which is not regular). Nominal Mean = Sample Mean ± t × S.E. Nominal Mean = 500 ± 2.262 × 5.20, 500 ± 11.76, Nominal Mean = Sample Mean ± 2.35%.Considering Normal Distribution of Sample, Nominal Mean = Sample Mean ± 1.96 × б, 500 ± 1.96 × 16.42, 500 ± 32.18, Nominal Mean = Sample Mean ± 6.44%

Table 24 - gsm values of the open weave JGT samples (500 gsm) produced by the different Jute Mills

The S.D. of the samples have been determined, using the following mathematical correlation-S.D. = √∑(x- x[ ) 2/ (n-1) where (x-x[ ) = Deviation of the observation from the Specified value and the values have been depicted in Table 25.


58

Open Area(%)

51.11 55.87 51.10 51.32 51.00 47.50 50.50 49.60 47.00 48.60

Jute Mills 1 2 3 4 5 6 7 8 9 10

SINo.

x xC x-xC (x-xC)2

S.D.= √Σ(x-xC)2 / (n-1)= 0.83

1. 51.11

50.36

0.75 0.562. 55.87 5.51 30.363. 51.10 0.74 0.554. 51.32 0.96 0.925. 51.00 0.64 0.416. 47.50 -2.86 8.187. 50.50 0.14 0.028. 49.60 -0.76 0.589. 47.00 -3.36 11.29

10. 48.60 -1.76 3.09

Standard Error (S.E.) = (S.D. / √n) = 0.26, t = Nominal Mean — Sample Mean / S.E. For degree of freedom, v = n-l = 9, t = 2.262 at 5% significant level (obtained from table of significant limit, t has sampling distribution of its own which is not regular). Nominal Mean = Sample Mean ± t × S.E., 500 ± 2.262 × 0.26, 500 ± 0.59. Nominal Mean = Sample Mean ± 0.12%. Considering Normal Distribution of Sample, Nominal Mean = Sample Mean ± 1.96 × б, 500 ± 1.96 × 0.83, 500 ± 1.63, Nominal Mean = Sample Mean ± 0.33 %.

Table 26 – Open Area Percentage values of the open weave JGT samples (500 gsm) produced by the different Jute Mills


Table 27- Different Open Area Percentage values and calculation of S.D.

59

Fabric Wt.(gsm)

601.07 593.11 606.00 675.00 672.50 633.00 614.30 611.00 597.85 600.08

Jute Mills 1 2 3 4 5 6 7 8 9 10

SINo.

x xC x-xC (x-xC)2

S.D.= √Σ(x-xC)2 / (n-1)= 10.08

1. 601.07

620.39

-19.32 373.262. 593.11 -27.28 744.193. 606.00 -14.39 207.074. 675.00 54.61 2982.255. 672.50 52.11 2715.456. 633.00 12.61 159.017. 614.30 -6.09 37.098. 611.00 -9.39 88.179. 597.85 -22.54 508.0510. 600.08 -20.31 412.49

Standard Error (S.E.) = (S.D. / √n) = 3.19, t = Nominal Mean — Sample Mean / S.E. For degree of freedom, v = n-l = 9, t = 2.262 at 5% significant level (obtained from table of significant limit, t has sampling distribution of its own which is not regular). Nominal Mean = Sample Mean ± t × S.E., Nominal Mean = 600 ± 2.262 × 3.19, 600 ± 7.22, Nominal Mean = Sample Mean ± 1.20%.Considering Normal Distribution of Sample, Nominal Mean = Sample Mean ± 1.96 × б, 600 ± 1.96 × 10.08, 600 ± 19.76, Nominal Mean = Sample Mean ± 3.29%.




60

Open Area(%)

47.50 48.00 51.50 52.91 47.00 41.00 43.50 44.00 51.00 46.00

Jute Mills 1 2 3 4 5 6 7 8 9 10

SINo.

x xC x-xC (x-xC)2

S.D.= √Σ(x-xC)2 / (n-1)

=1.27

1. 47.50

47.24

0.26 0.072. 48.00 0.76 0.583. 51.50 4.26 18.154. 52.91 5.67 32.155. 47.00 -0.24 0.066. 41.00 -6.24 38.947. 43.50 -3.74 13.998. 44.00 -3.24 10.499. 51.00 3.76 14.14

10. 46.00 -1.24 1.54

Standard Error (S.E.) = (S.D. / √n) = 0.40, t = Nominal Mean — Sample Mean / S.E., For degree of freedom, v = n-l = 9, t = 2.262 at 5% significant level (obtained from table of significant limit, t has sampling distribution of its own which is not regular) Nominal Mean = Sample Mean ± t × S.E., Nominal Mean = 600 ± 2.262 × 0.40, Nominal Mean = Sample Mean ± 0.15% •Considering Normal Distribution of Sample, Nominal Mean = Sample Mean ± 1.96 × б 600 ± 1.96 × 1.27, 600 ± 2.49, Nominal Mean = Sample Mean ± 0.42%

Table 30 – Open Area % values of the open weave JGT samples (600 gsm) produced by the different Jute Mills


Table 31- Different Open Area % values and calculation of S.D.

61


Fabric Wt.(gsm)

699.00713.3

3660.00 780.00 673.33 773.00 734.45 744.20 765.00 693.5

Jute Mills 1 2 3 4 5 6 7 8 9 10

SINo.

x xC x-xC (x-xC)2

S.D.= √Σ(x-xC)2 / (n-1)

= 14.08

1. 699.00

723.58

-24.58 604.182. 713.33 -10.25 105.063. 660.00 -63.58 4042.424. 780.00 56.42 3183.225. 673.33 -50.25 2525.066. 773.00 49.42 2442.347. 734.45 10.87 118.168. 744.20 20.62 425.189. 765.00 41.42 1715.62

10. 693.50 -30.08 904.81

Standard Error (S.E.) = (S.D. / √n) = 4.46,t = Nominal Mean — Sample Mean / S.E. ,For degree of freedom, v = n-l = 9, t = 2.262 at 5% significant level (obtained from table of significant limit, t has sampling distribution of its own which is not regular) Nominal Mean = Sample Mean ± t × S.E., Nominal Mean = 700 ± 2.262 × 4.46, = 700 ± 4.46, Nominal Mean = Sample Mean ± 0.64%Considering Normal Distribution of Sample, Nominal Mean = Sample Mean ± 1.96 × б, 700 ± 1.96 × 14.0, 700 ± 27.6 Nominal Mean = Sample Mean ± 3.94%



62

Table 34 – Open Area % values of the open weave JGT samples (700 gsm) produced by the different Jute Mills

Open Area(%)

41.50 40.30 49.00 51.70 41.00 38.00 42.50 50.00 47.50 42.00

Jute Mills 1 2 3 4 5 6 7 8 9 10

SINo.

x xC x-xC (x-xC)2

S.D.= √Σ(x-xC)2 / (n-1)

= 1.58

1. 41.50

44.35

-2.85 8.122. 40.30 -4.05 16.403. 49.00 4.65 21.624. 51.70 7.35 54.025. 41.00 -3.35 11.226. 38.00 -6.35 40.327. 42.50 -1.85 3.428. 50.00 5.65 31.929. 47.50 3.15 9.92

10. 42.00 -2.35 5.52

Standard Error (S.E.) = (S.D. / √n) = 0.5,t = Nominal Mean — Sample Mean / S.E. ,For degree of freedom, v = n-l = 9, t = 2.262 at 5% significant level (obtained from table of significant limit, t has sampling distribution of its own which is not regular) Nominal Mean = Sample Mean ± t × S.E., Nominal Mean = 700 ± 2.262 × 0.5, 700 ± 0.5 Nominal Mean = Sample Mean ± 0.07%

•Considering Normal Distribution of Sample, Nominal Mean = Sample Mean ± 1.96 × б, 700 ± 1.96 × 1.58 = 700 ± 3.1 Nominal Mean = Sample Mean ± 0.44%


Table 35- Different Open Area % values and calculation of S.D.

63

During testing and after testing of supplied Jute Geotextile (JGT) samples from different Jute Mills it has been observed that the test results of majority of the samples are not conforming to the specified property parameters which were supplied to the Jute Mills by the Project Executing Agency NJB, MoT, GoI.

The Probable Causes for not confirming the required property parameters with the test results may be summarized as follows:

1.After testing it has been found that many of the supplied JGT samples are not belonging in the range of specified GSM after converting the GSM at 20% Moisture Regain (M.R.), rather their GSM values are quite high than that of the specified GSM value. Probable reasons for this notable difference in GSM values may be attributed to the fact that either during the calculation of GSM, moisture content of the fabric was not measured properly or the amount of Moisture Regain (M.R.) of the JGT samples was not kept as per standard / requirement. Therefore these supplied JGT samples from different Jute Mills of higher GSM values than the specified GSM, will enhance the overall cost factor including raw material cost (batch cost).

Observations and Comments

64

2. The test results of the Thread Density (Ends/dm and Picks/dm) of the supplied DW Plain Weave JGT samples show a wide variation from the specified Thread density value. This wide variation in spacing of threads for DW Plain Weave JGT samples has led to considerable variation in Flow Rate along with Apparent Opening Size (AOS) in the JGT samples. On the other hand the Thread Density values of the Open Weave JGT samples are well within the specified range of Thread Density (Ends/dm and Picks/dm).

3. After proper investigation through different property parameters of Warp and Weft yarns it has been observed that there is no gross variation of Warp Count (lb/spyndle) whereas there is a wide variation of the Weft Count (lb/spyndle) as well as batch variation which cause an effective variation of the tensile properties of the JGT fabrics.

…………….(contd.)

65

4. The tested Tensile Strength values in the machine direction of most of the supplied DW Plain Weave JGT samples supplied by the different Jute Mills are found to be on the lower side of the specified Tensile Strength value. One probable reason may be ascribed to the fact that instead of double warp yarns to be taken through the mail eye during preparation of DW Plain Weave JGT samples; sometimes single end might have been taken causing thereby faulty fabrics as well as low tensile properties. Moreover this phenomenon has also affected overall resistance of warp yarns during cloth formation which have caused variation of other property of the fabric samples.

5. It has also been found after testing of Yarn Strength, Twist and other properties that there is a wide variation in the Yarn Strength and Twist. Warp and Weft Yarn Quality Ratios have also been checked and the calculated Yarn Quality Ratio does not match with the specified Yarn Quality Ratio which ultimately affects the Tensile Properties of the fabric.

6. Few samples are also found over calendered, which affect

the Fabric Porometry significantly as well as Flow Rate.

Observations and Comments (contd.)

66

CONCLUSIONS

CONCLUSIONS

67

Double Warp (DW) Plain Weave JGT Fabric sample, prepared and analyzed in this work, with a gsm range of 600-900 and Open Weave JGT samples in the gsm range of 450-750 have shown the following advantages from design and engineering aspects-

Cost Effectiveness Techno-Economic Viability Dimensional Stability Improved Mechanical Properties [tensile strength, index puncture, bursting strength) comparable to

that of the conventional Twill JGT Fabrics of higher gsm (760 and above)]

Greater Strength Greater Cover Factorensuring restricted number of materials to pass through across its plane.

Hence it is suitable to be used as a Geotextile fabric for filtration and drainage applications.

CONCLUSION (contd.)

68

Amongst all of the woven JGT samples manufactured by the different Jute Mills, the gsm of the sample supplied by M/s. Cheviot Company Limited and M/s. Gloster Limited are closely matching with the following property parameters- specified gsm value, belonging to the gsm category 600-700 and the gsm category 700-800.

While for all of the open weave JGT samples supplied by the different Jute Mills, the samples supplied by M/s. Reliance Jute Mill International Ltd. and M/s. Naffar Chandra Jute Mills Ltd. are in close association with specified gsm value, belonging to the gsm category 450-550, 551-650 and 651-750 respectively.

69

Mechanical and Hydraulic properties Mechanical and Hydraulic Properties of the produced

fabric samples are in well concurrent with the requirements of river bank protection.

Compatibility with the required parameters of rural road pavement construction and hill slope protection.

Higher GSM values of the JGT samples JGT samples supplied by other Jute Mills enhancing

the overall cost factor including raw material cost (batch cost).

CONCLUSION (contd.)

70

CONCLUSION (contd.)

The PI has made a critical review on statistical significance of setting tolerance limit for the specific property parameter of the Jute Geotextile samples (both DW Plain Weave JGT as well as Open Weave JGT samples) which is very much essential for acceptance of the material within the specified tolerance limit.

The review has been shared with the PEA (NJB) to justify the tolerance limits which have been set for the different property parameters of the developed Jute Geotextiles.

71

Thank you for your patient hearing

dr. s. k. ghosh, associate professor, djft, ijt, c.u. mr. m. m. mondal, srf, djft, ijt, c.u. mr. r....

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