Stability Analysis of Kuttanad Clay Reinforced with PET Bottle Strips

Stability Analysis of Kuttanad Clay Reinforced with PET Bottle Strips

Meera Manuel

1. ech. Geomechanics and Structures, SAINTGITS College of Engineering, Kottayam, Kerala, India.

   Shyla Joseph A

   Assistant Professor, Dept. of Civil Engg, SAINTGITS College of Engineering, Kottayam, Kerala, India.

   AbstractKuttanad clay spread over the Kuttanad region in the state of Kerala, India. These clays are characterized by high compressibility, low shear strength and high percentage of organic matter, which are unfavorable from the geotechnical point of view. Reinforced earth technique is considered as an effective ground improvement technique because of its cost effectiveness, easy adaptability and reproducibility. In this context, a detailed study is undertaken to study the effect of using waste plastic bottle (PET bottle) strips/chips as a reinforcement material in kuttanad clay. To study the effect of stabilization, on load- settlement properties of Kuttanad clay, analysis of foundation is done using PLAXIS software.

   KeywordsPET; Stabilization.

   1. INTRODUCTION

      Kuttanad clays are dark brown colored medium sensitive alluvial deposits spread over the Kuttanad region in the state of Kerala in India. This area lies 0.6-2.2 m below mean sea level and a major portion of the region is in submerged condition during the monsoon season in every year. These clays are characterized by high compressibility, low shear strength and high percentage of organic matter, which are unfavorable from the geotechnical point of view. A large number of embankment failures and foundation failures have been reported in this soil due to its poor shear strength and compressibility characteristics. Reinforced earth technique is considered as an effective ground improvement method because of its cost effectiveness, easy adaptability and reproducibility. Fibre selected must not be hazardous to the environment, and it should be easily available and less expensive.

      The bottled water is the fastest growing beverage industry in the world. Recycling plastic wastes formed due to use of water bottles has become one of the challenges worldwide. The use of plastic waste in engineering applications reduces the problem of disposal of this non- biodegradable waste in the most environmental friendly way and it can be converted into a resource.

      In this context, a detailed study is undertaken to evaluate the effect of using waste plastic bottle (PET bottle) strips/chips as a reinforcement material in kuttanad clay. To study the effect of stabilization, on load- settlement properties of Kuttanad clay, analysis of foundation is to be done using PLAXIS software.

   2. MATERIALS

      1. Reinforcement

         For the present study, plastic strips were obtained from PET water bottles. The strips were cut into pieces of length

         25 mm having average width 10mm. Strips are randomly mixed with soil in varying percentages (0, 0.25, 0.5, 0.6, 0.75, and 1) by dry weight of soil.

      2. Soil

      In this study, Kuttanad clay collected from Nedumudy, Alappuzha district, Kerala, India is used. Samples were collected from a depth of 1m from the surface. The properties of soil were determined by standard test procedures and tabulated as per provision of IS codes of practice. The properties of kuttanad clay are given in Table I.

      SL NO	Property	Value
      1	Specific gravity	2.56
      2	Particle size distribution
      	Sand (%)	11.57
      	Clay (%)	21
      	Silt (%)	67.43
      3	Atterbergs Limits
      	Liquid Limit (w ) L	171 %
      	Plastic Limit (w ) P	45 %
      	Shrinkage Limit (w ) S	30%
      	Plasticity Index (I ) p	126 %
      	Soil classification	MH or CH
      4	Unconfined compressive strength (kN/m2)	5

      TABLE I. PROPERTIES OF KUTTANAD CLAY

      	Cohesion(kN/m2)	2.5
      5	Triaxial test
      	Cohesion(kN/m2)	5
      	Angle of internal friction, Ø	3o
      6	Standard Proctor compaction test
      	Maximum dry density (g/cm3 )	1.31
      	Optimum moisture content (%)	32
      7	CBR Value (%)	2.97
      8	Coefficient of consolidation, Cv (cm2/s)	1.58 X 10-4
      	Coefficient of volume change, mv (cm2/kg)	0.0112

      TABLE II

      SL NO	Property	Clay + PET (0.6%)
      1	Standard Proctor compaction test
      	Maximum dry density (g/cm3 )	1.323
      	Optimum moisture content (%)	32.1
      2	CBR Value (%)	8.92
      3	Unconfined compressive strength (kN/m2)	24.69
      	Cohesion(kN/m2)	12.345
      4	Triaxial test
      	Cohesion(kN/m2)	17.5
      	Angle of internal friction, Ø	19o

      Properties of Kuttanad clay reinforced with PET bottle strips

   3. TEST ON REINFORCED SOIL

      A. Preparation of Soil Fiber Mix

      For the present study, plastic strips were obtained from PET water bottle. The strips were cut into pieces of length 25mm having average width 10mm. It is to be noted the that the mould diameter would be at least 4 times the maximum strip length, which ensures the sufficient room for the strip to behave freely and independent of mould confinement. Strips are randomly mixed with soil in varying percentages (0, 0.25, 0.5, 0.6, 0.75, and 1) by dry weight of soil.

   4. ANALYSIS OF FOUNDATION USING PLAXIS SOFTWARE

      1. Before stabilization

         Plastic reinforced soils were prepared manually by hand mixing. Oven dried soil after passing through 4.75 mm sieve was taken and water added and mixed uniformly. For a particular percentage of fiber content, the 1/3 rd of total amount of plastic strips were distributed evenly and mixed thoroughly with wet soil. After mixing the 1/3rd amount, another 1/3rd amount were mixed in the same way. Lastly the rest 1/3rd amount was mixed with the wet soil. The wet plastic-mixed soils were then used for various tests.

         Standard Proctor test, CBR test, Unconfined compression test and Triaxial compression test were done in the laboratory to study the effect of fiber reinforcement on Kuttanad clay.

         The properties of soil were determined by standard test procedures and tabulated as per provision of IS codes of practice. The properties of kuttanad clay reinforced with PET bottle strips are given in Table II.

         Settlement of a simple square footing placed on pure clay layer is done by using PLAXIS software. Size of footing 2m x 2m. Depth of footing is taken as 0.5 m. Distributed load is applied on the plate placed on pure clay layer of 10 m thickness and 20 m width and the displacement caused by the applied load is calculated.

         Fig.1. Plaxis 2d Model Of Pure Clay

         Fig. 2.Total displacement diagram of Pure Clay

         Total displacement of Pure Clay at a load of 45kN/m2 is found to be 0.2984 m.

      2. After stabilization

         Settlement of a simple square footing placed on reinforced clay layer is done by using PLAXIS software distributed load of 45kN/m2 is applied on the plate placed on reinforced clay layer of 1 m thickness and the displacement caused by the applied load is calculated. Analysis result shows that the total displacement is 0.093 m. The procedure is repeated by increasing the thickness of reinforced clay layer by 0.5m and the displacement caused by the applied load is calculated.

         Fig.3. PLAXIS 2D Model of clay reinforced upto 1m depth

         Fig. 4.Total displacement diagram of clay reinforced upto 1m depth

         Total displacement of clay reinforced upto 1m depth, at a load of 45kN/m2 is found to be 0.0935m.

   5. CONCLUSION.

The following conclusions may be drawn from the present study:

1. Analysis of foundation using PLAXIS software show that the total displacement of foundation decreases from 0.2984m (before stabilization) to 0.0935m after stabilizing soil upto 1m depth at a load of 45kN/m2

2. The maximum dry density increase with the increase in the strip content upto optimum strip content and then decreases.

3. CBR value increases with the increase in the strip content upto optimum strip content and then decreases. The optimum strip content corresponding to maximum improvement in CBR value is found to be 0.6%.

4. The unconfined compressive strength of the sample increase from 5 kN/m2 (pure clay) to 24.69 kN/m2, cohesion of the sample increase from 5 kN/m2 (pure clay) to 17.5 kN /m2 and the angle of internal friction (Ø) of the sample increase from 30 (pure clay) to 190.

REFERENCES

1. Pragyan Bhattarai, A. V. A Bharat Kumar, K. Santosh, T. C. Manikanta &K. Tejeswini (2013), Engineering behavior of soil reinforced with waste plastic strips, International Journal of Civil, Structural, Environmental and Infrastructure Engineering Research and Development (IJCSEIERD) ISSN 2249-6866, Vol. 3, Issue 2, Jun 2013, Pages .83-88.

2. G. L. Sivakumar Babu and Sandeep Kumar Chouksey , (2012), Analytical Model for Stress-Strain Response of Plastic Waste Mixed Soil, Journal Of Hazardous, Toxic, And Radioactive Waste © Asce , July 2012 , Pages. 219-228.

3. A.K. Choudhary, J.N. Jha and K.S. Gill, (2010), A study on CBR behavior of waste plastic strip reinforced soil, Emirates Journal for Engineering Research, 15 (1), 51-57.

4. K.Shyam Chamberlin, (2012), Stabilization of soil by using plastic wastes, International Journal of Emerging trends in Engineering and Development ISSN, 2249-6149 Issue 2, Vol.2 .

5. Nilo Cesar Consoli, Julio Portella Montardo, Pedro Domingos Marques Prietto and Giovana Savitri Pasa, (2002), Engineering behavior of sand reinforced with plastic waste, Journal of Geotechnical and Geoenvironmental Engineering, 128:462-472.

6. R. K. Dutta, G. Venkatappa Rao, (2007), Regression models for predicting the behavior of sand reinforced with waste plastic, Turkish J. Eng. Env. Sci.31, 119 126.

7. Agus Setyo Muntohar, Anita Widianti, Edi Hartono and Wilis Diana, (2013), Engineering properties of silty soil stabilized with lime and rice husk ash and reinforced with waste plastic fiber, Journal of materials in Civil Engineering © ASCE ,25:1260-1270.