Get the entire paper (pdf) - Ejge.com

Effect of Geotextile on CBR Strength of
Unpaved Road with Soft Subgrade
Dr. P. Senthil Kumar
Associate Professor, Department of Civil Engineering,
PSG College of Technology, Coimbatore, India
e-mail: psk@civ.psgtech.ac.in
R. Rajkumar
Graduate Student, Master of Engineering (Infrastructure),
Department of Civil Engineering,
PSG College of Technology, Coimbatore, India
ABSTRACT
Successful use of geosynthetics is ensured in a given geotechnical application, as it is not only
compatible but effective in improving the soil properties when appropriately placed. In this
study the performance of woven and nonwoven geotextile, interfaced between soft subgrade
and unbound gravel in an unpaved flexible pavement system, is carried out experimentally,
utilising the California Bearing Ratio (CBR) testing arrangement. In order to evaluate the
performance, the reinforcement ratio is obtained based on the CBR load – penetration relation
of both soft subgrade-gravel and soft subgrade-geotextile-gravel, separately, for woven and
nonwoven geotextile. Comparison of reinforcement ratio determined using the CBR strength
test shows that the performance is improved with the inclusion of woven and nonwoven
geotextile.
KEYWORDS: Unpaved road, Geotextile, CBR test, Reinforcement ratio.
INTRODUCTION
The economical development of a country is closely related to its road transport infrastructure
facilities available. Especially in an under developing country, the rural roads connecting
agricultural villages is vital in improving the rural economy. It is known that the option of
unpaved roads are economical for low traffic volume in such areas, however, when unpaved
roads laid on soft subgrade undergoes large deformations, where the periodical maintenance of
the rural road is limited due to cost considerations, which may disrupt the service and affect the
function of the road. In such situations, comparing various other methods, geosynthetics can be
- 1355 -

Vol. 17 [2012], Bund. J 1356
utilized to improve not only the performance of the unpaved road by increasing the life time, but
also, minimizing the maintenance cost as well as reducing the thickness of the road.
Extensive analytical and experimental studies relating geosynthetic interfaced aggregate –
soil as unpaved road (Giroud and Noiray, 1981; Giroud et al., 1985; Love et al., 1987; Jacobsen,
1989; Espinoza and Bray, 1995; Burd, 1995; Fannin and Sigurdsson, 1996; Oloo et al., 1997;
Som and Sahu, 1999; Raymond and Ismail, 2003; Watts and Blackman, 2004; Giroud and Han,
2004; Chew et al., 2005; Retzlaff et al., 2006; Lyons and Fannin, 2006; Kazimierowicz-
Frankowska, 2007; Aggarwal et al., 2007; Hu and Zhang, 2007; Ghosh and Dey, 2009; and Basu
et al., 2009) are available.
Full-scale field tests and large scale laboratory tests (Elvidge and Raymond, 1999; Bergado et
al., 2001; Hufenus et al., 2006; Bhosale and Kambale, 2008; Subaida et al., 2009; Palmeria and
Antunes, 2010) are carried out to investigate the performance of unpaved roads. Laboratory CBR
tests are performed to study the use of natural coir and jute geotextile (Michael and Vinod, 2009;
Senthil Kumar and Pandiammal Devi, 2011; and Babu et al., 2011). CBR tests are also conducted
by introducing geotextiles and geogrid in granular soil (Naeini and Mirzakhanlari, 2008; Duncan-
Williams and Attoh-Okine, 2008; and Dhule et al., 2011). Further, based on CBR test, the
influence of geotextile, geogrid and geonet are investigated in clay with low or medium
compressibility (Srivastava et al., 1995; Naeini and Moayed, 2009; Nair and Latha, 2010;
Moayed and Nazari, 2011; and Nair and Latha 2011) as soft subgrade in an unpaved road system.
Hence, in this study the effect woven and non-woven geotextiles on the CBR strength of the
aggregate – soil system is carried out considering the clay with high compressibility as soft
subgrade.
MATERIALS USED
Soil
Soil sample obtained locally is used for the present experimental investigations. The required
properties of the soil were determined and are presented Table 1.
Table 1: Properties of Soil
Particulars
Soil
Specific Gravity 2.71
Liquid Limit (%) 54
Plastic Limit (%) 35
Plasticity Index (%) 19
BIS Classification
CH
Optimum Moisture Content (%) 15
Maximum Dry Density (g/cm 3 ) 1.562
California Bearing Ratio (%) 0.9

Vol. 17 [2012], Bund. J 1357
Aggregate
The gravel aggregate used for the base course is subjected to the sieve analysis. The
uniformity co-efficient and co-efficient of curvature of the aggregate is 4.5 and 2 respectively.
Hence, the aggregate used in the CBR test is classified as well graded gravel.
Geosynthetic Material
A woven and nonwoven geotextile produced from polypropylene were interfaced between the
soil and the aggregate. The properties provided by the manufacturers are given in Table 2.
Table 2: Properties of geotextiles
Particulars Woven geotextile Nonwoven geotextile
Mass per unit area (g/m 2 ) 136 203
Grab Tensile Strength (N) 900 710
Puncture Resistance (N) 3120 1820
CBR TEST PROCEDURE
The subgrade soil was compacted in the CBR mould for 125mm height to its maximum dry
density at the optimum moisture content found from Standard Proctor test and remaining 50mm
with well graded gravel, as shown in Figure 1. CBR tests were carried out with 50mm plunger for
soil-aggregate, soil-woven geotextile-aggregate and soil-nonwoven geotextile-aggregate systems
separately.
Figure 1: Schematic arrangement and photograph of the Soil-Aggregate in the CBR Mould

Vol. 17 [2012], Bund.
J
1358
RESULTS AND DISCUSSION
The results obtained by taking the average of three trails for each, are plotted as load
versus penetration. The variation of load-penetration curve forr soil-aggregate and soil-
woven geotextile-aggregate is shown in Figure 2.
240
220
200
180
160
Soil-Aggregate
Soil-Woven Geotextile-
Aggregate
Load(kg)
140
120
100
80
60
40
20
0
0
2 4
6 8 10 12 14 16
18 20 22
Penetration(mm)
The variation of load-penetration curve for soil-aggregatee and soilgeotextile
-aggregate are shown in Figure
3.
Figure 2: Comparison between Soil-Aggregat
te and Soil-Woven geotextile-
Aggregate
non woven

Vol. 17 [2012], Bund. J 1359
200
180
160
140
Soil-Aggregate
Soil-Nonwoven
geotextile-Aggregate
Load (kg)
120
100
80
60
40
20
0
0 2 4 6 8 10 12 14 16 18 20 22
Penetration(mm)
Figure 3: Comparison between Soil-Aggregate and Soil-Nonwoven geotextile-
Aggregate
From the load-penetration curve of Figure 2 and 3, it is clearly observed that there is an
increase in resistance to penetration, when the woven geotextile as well as nonwoven geotextile
interfaced between soft subgrade and base aggregate.
Further, in order to quantify the amount of increase in the penetration resistance, the
reinforcement ratio is taken into consideration. The reinforcement ratio (Koerner, 2005) at a
particular penetration is,
=
h
h
Based on the reinforcement ratio obtained for both soil-woven geotextile-aggregate and soilnonwoven
geotextile-aggregate, the reinforcement ratio versus penetration curve is plotted, as
shown in Figure 4.

Vol. 17 [2012], Bund. J 1360
2.20
2.00
1.80
1.60
Reinforcement Ratio
1.40
1.20
1.00
0.80
0.60
0.40
0.20
0.00
Woven geotextile
Nonwoven geotextile
0 2 4 6 8 10 12 14 16 18 20
Penetration(mm)
Figure 4: Variation of Reinforcement Ratio for Woven geotextile and Nonwoven
geotextile
From the Figure 4, it shows that the reinforcement ratio is more than one throughout the test,
which indicates that the introduction of geotextile offers good resistance even to lower
penetration. Further, the reinforcement ratio increases with an increase in penetration. Hence the
use of geotextile is most advantage in an unpaved road with soft subgrade at higher penetration.
CONCLUSIONS
Interfacing of both woven geotextile as well as nonwoven geotextile in an unpaved road
especially with soft subgrade, increases the penetration resistance and hence the CBR strength.
Therefore, the performance of the unpaved road is better with the inclusion of both the geotextiles
and improves further at larger depth of penetration.
REFERENCES
1. Babu, K.K., K.S. Beena and A.K. Raji (2011) “Estimation of CBR of Coir Geotextile
Reinforced Subgrade,” Highway Research Journal, Vol. 4, No. 2, 41-47.
2. Basu, G., A.N. Roy, S.K. Bhattacharyya and S.K. Ghosh (2009) “Construction of
Unpaved Rural Road using Jute-Synthetic Blended Woven Geotextile – A Case
Study,” Geotextiles and Geomembranes, Vol. 27, 506-512.

Vol. 17 [2012], Bund. J 1361
3. Bergado, D.T., S. Youwai, C.N. Hai and P. Voottipruex (2001) “Interaction of
Nonwoven Needle-Punched Geotextiles under Axisymmetric Loading Conditions,”
Geotextiles and Geomembranes, Vol. 19, 299-328.
4. Bhosale, S.S. and B.R. Kambale (2008) “Laboratory Study on Evaluation of
Membrane Effect of Geotextile in Unpaved Road,” The 12th International
Conference of International Association for Computer Methods and Advances in
Geomechanics, Goa, India, 4385-4391.
5. Burd, H.J (1995) “Analysis of Membrane Action in Reinforced Unpaved Raods,”
Canadian Geotechnical Journal, Vol. 32, 946-956.
6. Chew, S.H., S.A. Tan and K.W. Leong (2005) “Performance of Geotextiles
Stabilized Unpaved Road Systems Subjected to Pretensioning,” Geo-Frontiers-2005,
Annual ASCE Conference Proceedings, Austin, Taxes, USA, Vol. 155, 405-412.
7. Dhule, S.B., S.S. Valunjkar, S.D. Sarkate and S.S. Korrane (2011) “Improvement of
Flexible Pavement with Use of Geogrid,” Electronic Journal of Geotechnical
Engineering, Vol. 16, Bundle C, 269-279.
8. Duncan-Williams, E. and N.O. Attoh-Okine (2008) “Effect of Geogrid in Granular
Base Strength – An Experimental Investigation,” Construction and Building
Materials, Vol. 22, 2180-2184.
9. Elvidge, C.B. and G.P. Raymond (1999) “Laboratory Survivability of Nonwoven
Geotextiles on Open-Graded Crushed Aggregate,” Geosynthetics International, Vol.
6, No. 2, 93-117.
10. Espinoza, R.D. and J.D. Bray (1995) “An Integrated Approach to Evaluating Single-
Layer Reinforced Soils,” Geosynthetics International, Vol. 2, No. 4, 723-739.
11. Fannin, R.J. and O. Singurdsson (1996) “Field Observations on Stabilization of
Unpaved Roads with Geosynthetics,” Journal of Geotechnical Engineering, ASCE,
Vol. 122, No. 7, 544-553.
12. Ghosh, A. and U. Dey (2009) “Bearing Ratio of Reinforced Fly Ash Overlying Soft
Soil and Deformation Modulus of Fly Ash,” Geotextiles and Geomembranes, Vol.
27, 313-320.
13. Giroud, J.P. and J. Han (2004) “Design Method for Geogrid-Reinforced Unpaved
Roads. I. Development of Design Method,” Journal of Geotechnical and
Geoenvironmental Engineering, ASCE, Vol. 130, No. 8, 775-786.
14. Giroud, J.P. and J. Han (2004) “Design Method for Geogrid-Reinforced Unpaved
Roads. II. Calibration and Applications,” Journal of Geotechnical and
Geoenvironmental Engineering, ASCE, Vol. 130, No. 8, 787-797.
15. Giroud, J.P. and L. Noiray (1981) “Geotextile-Reinforced Unpaved Road Design,”
Journal of Geotechnical Division, ASCE, Vol. 107, No. GT9, 1233-1254.
16. Giroud, J.P., C. Ah-Line and R. Bonaparte (1985) “Design of Unpaved Road and
Trafficked Areas with Geogrids,” Proceedings of conference on Polymer Grid
Reinforcement, Thomas Telford Limited, London, 116-127.

Vol. 17 [2012], Bund. J 1362
17. Hu, Y.C. and Y.M. Zhang (2007) “Analysis of Load-Settlement Relationship for
Unpaved Road Reinforced with Geogrid,” First International Symposium on
Geotechnical Safety and Risk, Tongji University, Shanghai, China, 609-615.
18. Hufenus, R., R.Rueegger, R. Banjac, P. Mayor, S.M. Springman and R. Bronnimann
(2006) “Full-Scale Field Tests on Geosynthetic Reinforced Unpaved Roads on Soft
Subgrade,” Geotextiles and Geomembrane, Vol. 24, 21-37.
19. Jacobsen, H.M (1989) “In-situ Study of Road Reinforced by Geotextiles,” XII
ICFMFE, Rio De Janeiro, 1-17.
20. Kazimierowiicz-Frankowska, K (2007) “Influence of Geosynthetic Reinforcement on
the Load-Settlement Characteristics of Two-Layer Subgarde,” Geotextiles and
Geomembrane, Vol. 25, 366-376.
21. Koerner, R.M. (2005) “Designing with Geosynthetics,” Fifth Edition, Prentice Hall,
New Jersey, pp.184-186.
22. Love, J.P., H.J. Burd, G.W.E. Milligan and G.T. Houlsby (1987) “Analytical and
Model Studies of Reinforcement of a Layer of Granular Fill on a Soft Clay
Subgrade,” Canadian Geotechnical Journal, Vol. 24, 611-622.
23. Lyons, C.K. and J. Fannin (2006) “A Comparison of Two Design Methods for
Unpaved Roads Reinforced with Geogrids,” Canadian Geotechnical Journal, Vol. 43,
1389-1394.
24. Michael, M. and P. Vinod (2009) “California Bearing Ratio of Coir Geotextile
Reinforced Subgrade,” 10th National Conference on Technological Trends, College
of
Engineering, Trivandram, India, 63-67.
25. Moayed, R.Z. and M. Nazari (2011) “Effect of Utilization of Geosynthetic on
Reducing the Required Thickness of Subbase Layer of a Two Layered Soil,” World
Academy of Science, Engineering and Technology, Issue 49, Article 175, 963-967.
26. Naeini, S.A. and M. Mirzakhanlari (2008) “The Effect of Geotextile and Grading on
the Bearing Ratio of Granular Soils,” Electronic Journal of Geotechnical
Engineering, Vol. 13, Bundle J, Paper 0891.
27. Naeini, S.A. and R. Z. Moayed (2009) “Effect of Plasticity Index and Reinforcement
on the CBR Value of Soft Clay,” International Journal of Civil Engineering, Vol. 7,
No. 2, 124- 130.
28. Nair, A.M. and G.M. Latha (2010) “Bearing Resistance of Geosynthetic Reinforced
Soil-Aggregate Systems,” Proceedings of International Conference on Advances in
Materials, Mechanics and Management, College of Engineering, Trivandram, India,
Vol. I, 457-463.
29. Nair, A.M. and G.M. Latha (2011) “Bearing Resistance of Reinforced Soil-
Aggregate Systems,” Ground Improvement, Vol. 164, No. 2, 83-95.
30. Oloo, S.Y., D.G. Fredlund and J.K-M. Gan (1997) “Bearing Capacity of Unpaved
Road,” Canadian Geotechnical Journal, Vol. 34, 398-407.

Vol. 17 [2012], Bund. J 1363
31. Palmeira, E.M. and L.G.S. Antunes (2010) “Large Scale Tests on Geosynthetic
Reinforced Unpaved Roads Subjected to Surface Maintenance,” Geotextiles and
Geomembranes, Vol. 28, 547-558.
32. Praveen Aggarwal, K.G. Sharma and K.K. Gupta (2007) “Modeling of Unreinforced
and Reinforced Pavement Composite Material using HISS Model,” IJE Transactions
B: Applications, Vol. 20, No. 1, 13-22.
33. Raymond, G. and I. Ismail (2003) “The Effect of Geogrid Reinforcement on
Unbound Aggregates,” Geotextiles and Geomembranes, Vol. 21, 355-380.
34. Retzlaff, J., U. Turezynski and S. Schwerdt (2006) “The Effect of Geogrids under
Unbound Sub-base Layers,” Proceedings of the 8th International Conference on
Geosynthetics, Yokohama, Japan, Vol. 3, 825-830.
35. Senthil Kumar, P. and S. Pandiammal Devi (2011) “Effect of Needle Punched
Nonwoven Coir and Jute Geotextiles on CBR Strength of Soft Subgrade,” ARPN
Journal of Engineering and Applied Sciences, Vol. 6, No. 11, 114-116.
36. Som, N. and R.B. Sahu (1999) “Bearing Capacity of a Geotextile-Reinforced
Unpaved Road as a Function of Deformation: A Model Study,” Geosynthetics
International, Vol. 6, No. 1, 1-17.
37. Srivastava, R.K., A.V. Jalota and R. Singh (1995) “Model Studies on Geotextile
Reinforced Pavements,” Indian Highways, Vol. 23, No. 9, 31-39.
38. Subaida, E.A., S. Chandrakaran and N. Sankar (2009) “Laboratory Performance of
Unpaved Roads Reinforced with Woven Coir Geotextils,” Geotextiles and
Geomembranes, Vol. 27, 204-210.
39. Watts, G.R.A. and D.I. Blackman (2004) “The Performance of Reinforced Unpaved
Sub-Bases Subjected to Trafficking,” Third Europen Geosynthetics Conference,
German Geotechnical Society and Zentrum Geotechnick, 261-266.
© 2012 ejge