ANALYSIS OF COMBINED EFFECT OF POND ASH AND JUTE FIBER ON SOIL SUBGRADE CHARACTERISTICS

ANALYSIS OF COMBINED EFFECT OF POND ASH AND JUTE FIBER ON SOIL SUBGRADE CHARACTERISTICS Lokesh Gupta Assistant Professor,Civil Engg Dept, Sir Padampat Singhania University Udaipur, Rajasthan.India Abstract : The performance of a pavement is very quick to respond against any change in subgrade as it provides the base for the whole pavement structure. Therefore performance of pavements is need to be improved by adopting appropriate design and construction techniques. Burning of coal annually produce million tons of ash as a waste byproduct. Hence green disposal of ash is a issue of great concern. Characteristics of soil having low-bearing capacity can be improved economically by adopting various techniques like soil stabilization and reinforcement using fibers. In the present investigation an attempt has been made to explore the combined effect of pond ash and jute fiber to improve the poor soil subgrade characteristics. To achieve this, series of test such as standard proctor test, CBR and unconfined compressive strength test are conducted first on the soil samples partially replaced by pond ash with dosage 10%, 20%, 30%, 40% and then soil plus pond ash and different length (1cm, 2cm, 3cm) and content (0.5%, 1.0%, 1.5%) of jute fiber. Combination of "Soil + 30% Pond Ash + Jute fiber (L-1cm, 1.5%)" produces the best results and significant improvement than any other combination. It can be conclude that combination of jute fiber and pond ash has mutual effect of both pond ash stabilized soil and fiber reinforced soil. Therefore can be adopt successfully for the improvement of soil subgrade characteristics and also to reduce the design pavement thickness. Key words: MDD, OMC, CBR, UCS. I. INTRODUCTION Growing need of thermal power generation resulting in the production of million tons of ash or pond ash as combustion of coal. Green disposal of pond ash is a issue of great concern. Jute fiber is a long, soft, shiny fiber that can be spun into coarse, strong threads. It is one of the cheapest natural fibers. Black cotton soil contains a clay mineral called montmorillonite which is having a peculiar behaviour of swelling in the presence of moisture and developing shrinkage cracks in dry season. Because of volumetric change in behaviour the structure constructed on such soils will undergo differential settlements, cracks in structure or total destruction of the structure however the structures can be constructed on such a soil by treating the expansive soil with a non-expansive material. This can be done by using ground improvement technique like mechanical stabilization, chemical 79

stabilization, freezing and heating, reinforcing earth technique etc. II. OBJECTIVES OF THE PRESENT STUDY The prime objectives of the present investigation are- To study the physical properties of poor subgrade soil. To fix the optimum quantity of pond ash and analyze its effect as a stabilizing soil material. To study the effect of jute fiber on the pond ash stabilized soil. To quantify the length and optimum fiber content in order to improve soil subgrade characteristics. III. METHODOLOGY Soil stabilization can be defined as an valuable alternative for improving soil properties. Stabilization can be derived from chemical or mechanicalcal means. Mechanical stabilization, or compaction, is the densification of soil by application of mechanical energy. Chemical stabilization involves mixing or injecting soil with chemically active compounds such as ash, lime, cement, sodium or calcium chloride or with viscoelastic materials such as bitumen. Among these, the most extensively opt chemical additives are ash, cement and lime [1]. The established techniques of soil along with fly ash stabilization by adding cement, lime and reinforcement in form of discrete fibers cause significant modification and improvement in engineering behavior of soils. Fibers are simply added and mixed randomly with soil and fly ash [2]. Kumar and Tabor studied the strength behavior of silty clay with nylon fiber for varying degrees of compaction. Soil reinforcement is the practice of improving the engineering properties of the soil and thus making it more stable [3]. Addition of fiber results in considerable alteration and improvement in the engineering property of soils. Many of research has done studies on fiber-reinforced soils further followed by triaxial, unconfined compression, CBR [4] [5] [6]. Fig-1. Flow Chart of present study V. MATERIAL CHARACTERISATION A. Soil The soil used in the present investigation is collected from local sources. According to Indian Standard of soil classification (IS 1498:1970) the soil is classified as clayey. IV. LITERATURE REVIEW Table 1. Physical Properties of Expansive Soil 80

Percentage Finer, % Proceedings of 2nd International Conference on Structural Architectural and Civil Engineering, Held on Nature Exapnsive Particle Size Distribution: Gravel, % Sand, % Silt and Clay, % 0.00 43.66 56.34 Atterberg s Limits Liquid Limit, % Plastic Limit, % Plasticity Index, % 36.6 16.60 20.00 Standard Compaction Test Maximum Dry Density, (kn/m 3 ) Optimum Moisture Content, % 18.20 15.30 CBR, % (soaked) 3.54 Unconfined Compressive Strength (KPa) 95.36 To assess the physical properties of soil, the various test such as Particle Size Distribution, Atterberg s Limits, Standard Proctor Compaction Test, Unconfined Compressive Strength test are conducted on soil in the laboratory and the test results are presented in Fig-1, table-1 and table-2. Table 2. Sieve Analysis of Expansive Soil IS sieve size (mm) Percentage finer (%) 4.75 100.00 2.36 100.00 1.18 97.45 0.60 88.26 0.30 77.72 0.15 62.38 0.075 56.34 120 100 80 60 40 20 0 0.01 0.1 1 10 Sieve Size, mm Fig-2. Sieve Analysis of Soil B. Jute Fiber Jute fibers used for this study were procured from Karnataka State Coir Development Corporation Ltd. Jalahalli Bangalore. Jute fiber of length varing from 1cm, 2cm and 3cm are used as reinforcing material in this study along with different fiber content such as 0.5%, 1.0% and 1.5%. Physical properties of jute fiber are presented in table-3. Table 3. Physical properties of Jute Fiber Sl.No Properties Value 1 Cut Length 10mm -30 mm 2 Diameter 0.35 mm 3 Colour Light Brown Aspect Ratio 4 30-90 (L/D) C. Pond Ash The pond ash is a waste product obtained because of combustion of coal in thermal power plants. It is generally obtained from the wet disposal of fly ash. The fly ash gets mixed with bottom ash and disposed off in big pond or dykes as slurry. It is also known as as ponded fly ash and contains relatively coarse particles. It is generally collect at a depth of 0.3m from the ground surface level.physical properties of pond ash are presented in table-4. 81

OMC, % Proceedings of 2nd International Conference on Structural Architectural and Civil Engineering, Held on Table 4. Physical properties of Pond Ash Sl.No Properties Value 1 Specific Gravity 2.12 2 Liquid Limit ---- 3 Plastic Limit Non Plastics 4 Colour Light Grey 5 Shape Sub Rounded VI. RESULT AND DISCUSSION In order to investigate the effect of pond ash and jute fiber on the poor subgrade soil, series of test such as standard proctor test, California bearing ratio and unconfined compressive strength test are conducted first on the soil samples partially replaced by pond ash with dosage 10%, 20%, 30%, 40% and then soil plus pond ash and different length (1cm, 2cm, 3cm) and content (0.5%, 1.0%, 1.5%) of jute fiber. The results are presented in table-5 to table-8 and Fig-3 to Fig-9. Table 5. Standard Compaction Test Results of Soil Mixed With Pond Ash SN Particulars Maximum Dry Density (KN/m 3 ) Optimum moisture content (%) 1 Soil Alone 18.80 17.2 2 Soil + Pond Ash- 10% 18.30 17.6 3 Soil + Pond Ash- 20% 17.90 18.1 4 Soil + Pond Ash- 30% 17.60 18.4 5 Soil + Pond Ash- 40% 17.40 18.7 MDD, KN/m 3 Fig-3. MDD And OMC Values Of Soil Mixed With Different Dosage Of Pond Ash It can be observed from the fig-3 that as the amount of pond ash increases the optimum moisture content (OMC) of the soil increases. Addition of pond ash in soil increase the amount of finer material in the mix. Hence due to more specific surface area, mix requires more amount of water for proper packing and coating all particles. Similarly Maximum dry density (MDD) decreases with the increment in pond ash dosage in soil. This may be firstly due to the low specific gravity of pond ash than soil and secondly due to increasing order of OMC value with pond ash dosage. Table 6. CBR and Unconfined Compressive Strength Test Results of Soil Mixed with Pond Ash 19 18.5 18 17.5 17 S.N. Particulars CBR % (soaked) UCS (KPa) 1 Soil Alone 3.2 142.61 2 3 4 5 Soil + Pond Ash-10% Soil + Pond Ash-20% Soil + Pond Ash-30% Soil + Pond Ash-40% 19 18.5 18 17.5 17 16.5 16 MDD OMC 3.4 198.48 3.6 220.72 3.9 253.31 3.8 206.78 82

Fiber Length, cm Fiber Content, % MDD, OMC, % KN/m 3 0.5 17.47 18.1 1 1 17.21 18.4 1.5 17.10 18.5 0.5 17.31 18.3 2 1 17.11 18.5 Fig- 4. CBR Values of Soil Mixed with different 1.5 16.90 18.7 dosage of Pond Ash As the amount of pond ash increases, CBR value (Soaked) of pond ash soil mix also increases initially up to 30% replacement of soil and then 3 0.5 17.14 18.5 1 16.90 18.6 1.5 16.70 18.9 decreases. There is substantial increment in CBR value of about 18.75% at 30% replacement of soil by pond ash. Similar trend can be observe in case of 17.6 UCS results also(fig-5). There is substantial increment in UCS value of about 31% at 30% 17.4 replacement of soil by pond ash. MDD, KN/m 3 17.2 17 1cm 2cm 3cm 16.8 16.6 0 0.5 1 1.5 2 Fibre Content, % Fig-5. UCS Test Results of Soil Mixed with different dosage of Pond Ash Table 7. Standard Compaction Test Results of Soil Mixed With Pond Ash and Jute Fiber Fig-6. MDD of Soil Mixed With Pond Ash and Jute Fiber 83

CBR, % Proceedings of 2nd International Conference on Structural Architectural and Civil Engineering, Held on 6.2 5.8 5.4 5 4.6 4.2 0 0.5 1 1.5 2 Fibre Content, % 1cm 2cm 3cm Fig-7. OMC of Soil Mixed With Pond Ash and Jute Fiber Fig-8. CBR Values of Soil Mixed With Pond Ash and Jute Fiber As the length and amount of fiber increases the OMC value of the pond ash soil mix also increases. Combination of soil plus 30% pond ash and jute fiber of 3cm length (1.5% by weight) is showing maximum OMC i.e. 18.9%. Addition of Jute fiber in Pond ash mix is causing the absorption of water. This may be resulting in the increment of OMC. MDD value decreases as the length and amount of fiber increases. This may be due to low specific gravity of fiber. Table 8. CBR and UCS Test Results of Soil Mixed with Pond Ash and Jute Fiber Fiber Length, Fiber Content, CBR, % UCS, KPa cm % 0.5 5.2 353.61 1 1 5.61 381.42 1.5 5.89 396.41 0.5 4.89 304.58 2 1 5.20 343.63 1.5 5.32 357.8 0.5 4.42 275.22 3 1 4.81 283.84 1.5 5.00 297.14 Fig-9. CBR Values of Soil Mixed With Pond Ash and Jute Fiber As the fiber content increases (Irrespective of fiber length), the CBR and UCS value of pond ash soil mix also increases. Combination of "Soil + 30% Pond Ash + Jute fiber (L-1cm, 1.5%)" is showing maximum CBR and UCS values i.e. 5.89% and 396.41KPa respectively. This particular combination produces substantial increase of about 45.67% and 64% in CBR and UCS values respectively when compared with results of soil alone. But further increase in fiber length causes the reduction of CBR and UCS value. This may be due to localization and improper mixing (Accumulation of fiber at one place ). VII. CONCLUSION The addition of Jute fiber to the pond ash soil mix exhibits the substantial improvement in soil subgrade characteristics. Pons ash stabilized black 84

cotton soil followed by the reinforcement from jute fiber also shows the significant improvement in CBR and UCS values. The prime conclusion drawn from the present investigation are- 1. Jute fiber acts as reinforcing material in pond ash soil mix. It binds the soil particles together and helps in reduction in drastic change in volumetric properties. 2. Addition of fiber improve the interaction between jute and pond ash soil mix, which improves the ductility behavior, CBR value and UCS value. 3. The best results are obtained for the combination of "Soil + 30% Pond Ash + Jute fiber (L-1cm, 1.5%)". This particular combination shows the significant improvement than any other combination. It can be conclude at last that combination of jute fiber and pond ash has mutual effect of both pond ash stabilized soil and fiber reinforced soil. Therefore can be adopt successfully or the improvement of soil subgrade characteristics and also to reduce the design pavement thickness. ACKNOWLEDGEMENT It is a great pleasure for author to acknowledge and express his gratitude to Dr. Shubham Goswami, (Assistant Professor, School of Management, Sir Padampat Singhania University, Udaipur) for his immense help, valuable suggestion, understanding and unstinted support throughout the study. REFERENCES [1] Petry, T.M. and Little, D.N, Review of Stabilization of Clays and Expansive Soils in Pavement and Lightly Loaded Structures- History, Practice and Future, Journal of Materials in Civil Engineering, 2002, Vol. 14, No. 6. [2] Sharma R.K. Subgrade characteristics of locally available soil mixed with fly ash and randomly distributed fibers, International Conference on Chemical, Ecology and Environmental Sciences (ICEES'2012), Bangkok, pp.25-30. [3] Kumar S, Tabor E. Strength characteristics of silty clay reinforced with randomly oriented nylon fibers, Electronic Journal of Geotechnical Engineering, EJGE, 2003. [4] Consoli N.C, Prietto P.D.M, Pasa G.S. Engineering behavior of a sand reinforced with plastic waste, Journal of Geotechnical and environmental Engineering, ASCE, 2002, No. 6, Vol. 128, pp.462-472. [5] Kumar A, Singh B, Asheet B. Influence of fly ash, lime, and polyester fibers on compaction and strength properties of expansive soil, Journal of Materials in Civil Engineering, 2007, No. 3, Vol. 19, pp. 242 8. [6] Diambra A, Ibraim E, Muir Wood D, Russell A.R. Fiber reinforced sands: experiments and modeling, Geotextiles and Geomembranes, 2010, No. 3, Vol. 28, pp. 238-250. [7] Santoni R.L, Tingle J.S, Webster S. Engineering properties of sand fiber mixtures for road construction, Journal of Geotechnical and Geoenvironmental Engineering, 2001, No. 3, Vol. 127, pp. 258 268. [8] Kumar, A., Walia, B.S. and Bajaj, A. (2008) Influence of Fly ash, Lime and Polyester Fibres on compaction and Strength Properties of Expansive Soil Journal of Materials in Civil Engineering, Vol.19(3),:pp.242-248 85

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