THE INFLUENCE OF POTASSIUM CHLORIDE ON THE REINFORCED MARINE CLAY FOR FOUNDATION SOIL BEDS Koteswara Rao. D J. Purna Chandra Rao Associate Professor Graduate Students-21 Department of Civil Engineering University College of Engineering KAKINADA- 533 3:: INDIA. ABSTRACT Weak marine soil deposits have been found both on the coast and in several offshore areas spread over many parts of the world. When clay particles precipitate in salt water, there is a tendency for the clay particles to flocculate and stick together giving rise to some sort of edge-to-face arrangement. As a result, clay, silt, and fine sand particles settle almost at the same rate and the final sediment formed consists of particles with a very loose card house-like structure. Hence the marine sediments can be considered loose sediments, usually formed with high void ratios. Problems are associated with these fine-grained soils deposited at a soft consistency. Fine-grained soils are very sensitive to changes in the stress system, moisture content and system chemistry of the pore fluid. In addition to these, the problems arising out of high compressibility and low shear strength of these weak marine deposits expose geotechnical engineers to considerable changes in the construction of various coastal and offshore structures. In this present investigation, the performance of the potassium chloride on the strength characteristics of the marine clay has been studied and also the reinforcement effect on the improvement of load bearing capacity of the KCl treated marine clay has been studied. KEY WORDS: OMC, MDD, FSC, KCl, Load Bearing Capacity, Strength Characteristics 1.1 INTRODUCTION The marine clay is available at fully saturated condition in the costal corridor and the natural water content of the marine clays is always greater than its liquid limit. The comprehensive review of literature shows that a considerable amount of work is related for the determination of deformation characteristics and strength characteristics of marine clay worldwide. From the various contributions, the investigations on strength characteristics of marine clay conducted by S. Narasimha Rao et.al (1987,1996), Shridharan et al.(1989), Mathew et al. (1997) and G. Rajasekaran et.al (22), Ali M.A. Abd-Allah(29) are worthy of note. Improving the strength of the marine clay by the stabilization technique was performed by Supakij Nontananandh et al. (24). Countable study on engineering properties of marine clays was performed by Basack et al (29). The effect of electrolytes on soft soils were explained by Sivanna, G.S (1976);Anandakrishnan et.al (1966); Saha et.al (1991); Rao, M.S et.al(1992);sivapullaiah, P.V. et al (1994); Bansal et.al(1996); S. Narasimha Rao et.al(1996); Appamma, P.,(1998); Chandrashekar et.al (1999);G. Rajasekaran et.al (2); J. Chu et.al (22);Matchala Suneel et.al (28). The effect of steel industrial wastes on soft soils were presented by Ashwani Kumar et.al (1998); Bhadra, T. K et.al (22); Dr. D. D. Higgins (25); Koteswara Rao (26), Marine clay deposits of Kakinada were used for the testing with the aim to investigate its strength characteristics and load bearing capacity and further make suitable for foundation constructions over it. The soil was collected at.4m to1.m depth from the Kakinada Sea Ports limited, Kakinada, A.P, India. ISSN : 975-5462 Vol. 3 No. 4 Apr 211 395
1.2 OBJECTIVES This investigation has been carried with the following objects. To study influence of KCl on the Marine Clay + GBFS mix for the foundation Soil beds. To investigate the efficiency of geotextile as a reinforcement and separator in the treated marine clay foundation soil bed. To indentify the improvement in the load carrying capacity of the untreated and treated marine clay foundation soil bed at OMC & FSC. 1.3 MATERIALS USED Marine clay: The marine clay used for this study was collected from the Kakinada Sea Ports Limited, Kakinada, A.P, India and the soil was air dried prior to the laboratory investigation. The various geotechnical properties were determined and tabulated in the table 1. Geotextile: PP woven Geotextile-GWF-4-22, manufactured by GARWARE WALL ROPES LTD, Pune, India, is used in this investigation. The tensile strength of woven geotextile is 6. kn /m for warp and 45. kn / m for weft. Potassium Chloride: Laboratory grade potassium chloride consisting of 98% KCl was used in this work. The amount potassium chloride was varied between to 2.% by dry weight of soil. Table 1: Properties of Untreated and Treated Marine Clay Sl. Property Marine Clay (MC) Marine clay 1% KCl + 2% No +2% GBFS GBFS + M.C 1 Gravel % ------ ----- 2 Sand 14% ------ ----- Silt 3% ------ ----- 3 Fines Clay 56% ------- ------ 4 Liquid Limit 74.5 % 64.7 % 55.3 5 Plastic Limit 26.9 % 28.9 % 26.75 6 Plastic Index 47.6 % 35.8 % 28.55 7 Shrinkage limit 1.678 % 15.45% 18.15 8 Soil Classification CH CH CH 9 Specific Gravity 2.35 2.45 2.52 1 D FS (%) 8 45 3 11 O M C 35% 23.5% 15.6 12 M D D 1.27 gm / cc 1.635 gm / cc 1.81 13 Cohesion 12.2 t /m 2 9.12 t /m 2 7.5 14 Angle of Internal Friction 2 7 1 15 CBR Value ( %).754 3.58 5.37 16 NMC % 86.15 ------ ------ Granulated Blast Furnace Slag: Granulated blast furnace slag used for this study was brought from Vizag steel plant, Visakhapatnam, Andhra Pradesh, A.P,India. Various laboratory tests were conducted to determine the properties of GBFS as per IS codes of practice.the physical properties of GBFS were given in the table 2. Gravel: Locally available gravel has been used as cushion on the treated marine clay soil for conducting static plate load test. The physical properties of gravel were presented in the table 3. 1.4 LABORATORY EXPERIMENTATION Index properties: The atterberg limits of the untreated and treated marine clay were determined as per the procedures laid down in IS 272(Part V), 197. It was observed that the liquid limit and the plasticity index of the treated marine clay have been decreasing when compared with the untreated marine clay as shown in the table 1. Compaction properties of treated marine clay with GBFS and Potassium Chloride: It was noticed from the results that the marine clay has exhibited the maximum dry density (MDD) up to the addition of 2% GBFS as presented in the table 4& Fig 1& 2 and further the MDD of the 2%GBFS + marine ISSN : 975-5462 Vol. 3 No. 4 Apr 211 396
clay mix has been increased with addition of KCl up to 1% and beyond the addition of 1% KCl, the MDD values of the 2%GBFS + marine clay mix has been decreased as presented in the table 5 & Fig 5&6. Table 2: Physical Properties of GBFS Sl.No PROPERTY VALUE 1 Specific Gravity 2.116 2 Grain Size Distribution Gravel Size (%) (>4.75mm) Sand Size (%) (4.75-.75mm) 98.44 Silt Size (%) (.75-.2mm) 1.56 3 OMC (%) MDD(g/cc) 12 1.42 4 Cohesion(kN/m2) Angle of internal friction(φ) 4 5 C BR (%) 15 Table 3: Physical Properties of Gravel Sl.No Property Value 1 Gravel (%) 61.54 2 Sand(%) 29.58 3 Silt & Clay (%) 8.88 4 Maximum Dry Density kn/m 3 19.94 5 OMC (%) 11.51 6 Liquid limit (%) 23.14 7 Plastic limit (%) 17.11 8 Plasticity Index 6.3 9 CBR % 16.42 Table 4: OMC and MDD Values of Marine Clays and GBFS Sl. NO Mix Proportion OMC (%) M D D(g/cc) CBR (%) 1 1% soil 35 1.27.74 2 85%Soil+15%GBFS 21.5 1.621 1.19 3 82%Soil+18%GBFS 23 1.628 1.34 4 8%Soil+2%GBFS 23.5 1.635 3.58 5 78%Soil+22%GBFS 21.5 1.598 2.39 6 76%Soil+24%GBFS 22.8 1.597 1.34 It was observed that the CBR values of marine clay has been increased with addition of GBFS up to 2% and beyond the addition of % 2 GBFS, the CBR values of the marine clay has been decreased as presented in the table 4 & Fig 3and 4. Further the CBR value of the 2%GBFS + marine clay mix has been increased with addition of KCl up to 1% and beyond the addition of 1% KCl, the CBR values of the 2%GBFS + marine clay mix has been decreased as presented in the table 5 & Fig 7 and 8. ISSN : 975-5462 Vol. 3 No. 4 Apr 211 397
Table 5 : O M C and MDD Values of 2% GBFS + Marine Clay Mix with % Variation of Potassium Chloride Sl. No Mix Proportion OMC MDD(g/cc) CBR(%) (%) 1 1% soil 35 1.27.74 2 8% soil+2%gbfs 23.5 1.635 3.8 3 8% soil+2%gbfs+.25%kcl 22 1.611 3.88 4 8% soil+2%gbfs+.5% KCl 21.5 1.664 4.18 5 8%Soil+2%GBFS+1% KCl 19 1.751 5.37 6 8% soil+2%gbfs+1.5% KCl 2.5 1.71 4.78 7 8% soil+2%gbfs+2% KCl 23.5 1.651 4.48 COMPACTION CURVES 1.7 1.6 DRY DENSITY(g/cc 1.5 1.4 1.3 1% SOIL 85% SOIL+15% GBFS 82% SOIL+18% GBFS 8% SOIL+2% GBFS 78% SOIL+22% GBFS 76% SOIL+24% GBFS 1.2 1.1 1 2 3 4 5 WATER CONTENT(%) Fig 1: Variation in MDD Values of Marine Clay with Different % of GBFS OMC g/cc 1.64 1.63 1.62 1.61 1.6 1.59 Fig 2: Effect of % Variation of GBFS on the MDD Values of Marine Clay 15, 1.614 2, 1.635 18, 1.622 22, 1.625 24, 1.61 1 12 14 16 18 2 22 24 26 % GBFS OMC ISSN : 975-5462 Vol. 3 No. 4 Apr 211 398
SOAKED CBR TEST RESULTS 1 9 8 7 LOAD(kg) 6 5 4 Series1 85%SOIL+15%GBFS 82%SOIL+18%GBFS 8%SOIL+2%GBFS 78%GBFS+22%GBFS 76%SOIL+2%GBFS 3 2 1 1 2 DEFLECTION(mm) Fig3: Load Vs Deflections of Marine Clay with Different % of GBFS CBR (%) 4 3 2 1 Fig4 : Variation in CBR Values of Marine Clay with Different % of GBFS 15, 1.19 18, 1.34 2, 3.8 22, 2.39 24, 1.34 14 16 18 2 22 24 26 % GBFS ISSN : 975-5462 Vol. 3 No. 4 Apr 211 399
COMPACTION CURVES 1.8 1.7 DRY DENSITY 1.6 8%SOIL+2%GBFS 8%SOIL+2%GBFS+.25%kcl 8%SOIL+2%GBFS+.5%kcl 8%SOIL+2%GBFS+1%kcl 8%SOIL+2%GBFS+1.5%kcl 8%SOIL+2%GBFS+2%kcl 1.5 1.4 15 2 25 3 35 WATER CONTENT Fig 5: Compaction Curves of 2% GBFS+ Marine Clay Mix with % Variation of Potassium Chloride MDD g/cc 1.76 1.74 1.72 1.7 1.68 1.66 1.64 1.62 1.6 Fig 6 : Effect of % Variation of KCl on the MDD Values of 2% GBFS + Marine Clay Mix.25, 1.611.5, 1.664 1, 1.751 1.5, 1.71 2, 1.651.5 1 % KCl 1.5 2 2.5 ISSN : 975-5462 Vol. 3 No. 4 Apr 211 31
SOAKED CBR TEST RESULTS 2 18 16 14 LOAD(kg) 12 1 8 8%SOIL+2%GBFS 8%SOIL+2%GBFS+.25%kcl 8%SOIL+2%GBFS+.5%kcl 8%SOIL+2%GBFS+1%kcl 8%SOIL+2%GBFS+1.5%kcl 8%SOIL+2%GBFS+2%kcl 6 4 2 5 1 15 DEFLECTION(mm) Fig 7: CBR Curves of 2% GBFS + Marine Clay Mix with % Variation of KCl CBR % 5.5 5 4.5 4 3.5 3 Fig 8 : Effect of % Variation of KCl on the CBR Values of 2% GBFS + Marine Clay Mix.5, 4.18.25, 3.88 1, 5.37 1.5, 4.78 2, 4.21.5 1 1.5 2 2.5 % KCl 1.4 PLATE LOAD TESTS ON MODEL FOUNDATION SOIL BED General: Four model foundation soil beds were prepared in the laboratory by using 6cm diameter mild steel tank with different alternatives as presented in table 6 for this investigation. The gravel was used as cushion in the four models and was laid uniformly on the untreated and treated & reinforced marine clay foundation soil bed. The tests were conducted at OMC and fully saturated condition (FSC). Preparation of Foundation Soil Bed: The untreated and treated marine clay was compacted in layers of 5cm thickness at its OMC and MDD to a total compacted thickness of 3cm. In case of preparing untreated marine clay and marine clay + GBFS mix, the OMC of the natural marine clay and marine clay + GBFS mix were used respectively and the required quantity of chemical(1%kcl) was dissolved in marine clay first and then ISSN : 975-5462 Vol. 3 No. 4 Apr 211 311
only the GBFS was mixed. On the prepared foundation soil a sand layer of 1. cm thickness is provided and then the geotextile was placed. The geotextile was anchored to create the tensile force to offer max load carrying capacity and distributed equally over the stabilized foundation soil. Preparation of Gravel Cushion for Foundation Soil Bed: On the prepared untreated and treated & reinforced marine clay foundation bed, uniformly mixed gravel at OMC was laid in each layer of 5cm compacted thickness for a total thickness of 15.cm. The gravel cushion layer was compacted to its MDD and OMC and the Plate.1 presents a prepared marine clay model foundation soil bed. Static Plate Load Test: Static plate load tests were conducted in a model tank of circular in shape, having 6 cm diameter and 45 cm height as shown in the plate 2. The load was applied through the circular plate of 15cm diameter on to the untreated and treated & reinforced marine clay foundation soil bed at OMC and FSC. Plate 1: Prepared Model Foundation Soil Bed Plate 2: Static Plate Load Test Setup (Second Author is Conducting the Test) A 15cm diameter circular metal plate with extension rod was placed centrally over the prepared model foundation soil bed (Plate 2) and a hydraulic jack of 5kN capacity was centrally placed over the circular plate for conducting the static plate load test. Two dial gauges were placed on the metal plate welded to the extension rod on opposite sides to measure the deformation. The static Plate load tests were carried out to determine the ultimate load carrying capacity of the untreated and treated & reinforced marine clay foundation soil bed. Each pressure increment was placed only till, no significant change in deformation was observed between consecutive load increments. The testing was further continued till the failure for knowing the ultimate load bearing capacity of the untreated and treated & reinforced marine clay foundation soil bed and the results are presented in the table 6 and Fig 9. ISSN : 975-5462 Vol. 3 No. 4 Apr 211 312
Table 6: Load Carrying Capacity of the Marine Clay Foundation Soil bed with Various mix Proportions and their Settlements at OMC and FSC Ultimate Load Gravel Carrying Capacity in Settlement in Cushion kn/m 2 mm Sl No Foundation Soil bed At OMC At FSC At OMC At FSC 1 Marine Clay Gravel 146.5 35.1 2.21 2.95 2. Marine Clay +2%GBFS Gravel 44.256 159.7 1.6 1.9 3 MC+2%GBFS+1% KCl Gravel 5.17 177.9 1.4 1.8 4 MC+2%GBFS+1% KCl + Geotextile as reinforcement & separator between stabilized marine clay soil and gravel cushion Gravel 1385.93 59.17 1.11 1.51 Settlement in mm.3.6.9 1.2 1.5 1.8 2.1 2.4 2.7 3 3.3 3.6 Fig 9 :Static Plate Load Test Results on Treated Marine Clay Foundation Soil Bed with 2%GBFS +1% KCl+ Geotextile as Reinforcement at OMC & FSC 59.17, 1.51 424.256, 2.1 Load in kn/ m 2 2 4 6 8 1 12 14 16 537.391, 2.88 565.674, 3.25 FSC OMC 1385.93, 1.11 1414.187, 1.88 1.5 CONCLUSIONS The following conclusions were drawn based on the laboratory studies carried out on this work. It was observed that the MDD and CBR values of marine clay has been improved by 28.74% and 383.78% respectively with the addition of 2% BGFS Further, it was noticed that the MDD and CBR values of Marine clay +2% GBFS mix has been increased by 37.87% and 625.67% respectively with the addition of 1% KCl It was investigated that the load carrying capacity of the marine clay foundation soil bed has been improved by 175.94%, 241.36% and 846.1% with the addition of 2%GBFS, 1% KCl +2%GBFS and 1% KCl +2%GBFS+ with the provision of geotextile as reinforcement & separator respectively at OMC It was investigated that the load carrying capacity of the marine clay foundation soil bed has been improved by 354.98%, 46.83% and 135.44% with the addition of 2%GBFS, 1% KCl +2%GBFS and 1% KCl+2%GBFS+ with the provision of geotextile as reinforcement & separator respectively at FSC. It was observed that the total deformation values of the marine clay foundation soil bed has been improved by 27.6%, 36.65% and 49.77% with the addition of 2%GBFS, 1% KCl +2%GBFS and 1%KCl +2%GBFS+ with the provision of geotextile as reinforcement & separator respectively at OMC. It was observed that the total deformation values of the marine clay foundation soil bed has been improved by 35.59%, 38.98% and 48.81% with the addition of 2%GBFS, 1% KCl +2%GBFS and 1% KCL +2%GBFS+ with the provision of geotextile as reinforcement & separator respectively at FSC. ISSN : 975-5462 Vol. 3 No. 4 Apr 211 313
1.6 DISCUSSIONS The reductions in deformation values were due to the chemical reactions between the added chemical and the replacement of clay mineralogy by GBFS. Further, an increase in the load carrying capacity was observed by introducing the geotextile as reinforcement & separator. The reason for appreciable improvement in the load carrying capcity of the treated marine clay foundation soil bed was that the load was equally distributed on treated marine clay foundation soil by providing the geotextile as separator & reinforcement. Form the results it was clearly observed that the efficiency of the geotextile as a reinforcement & separator. References [1] A, Rao SM, Chandrasekaran S (1989), Engineering Properties of Cochin and Mangalore Marine Clays, Indian Geotech, J.1:265-278. [2] Anandakrishnan, M. and Dhaliwal, S.S.(1966), Effect of various concentrations of Sodium Chloride and Calcium Chloride on the pore pressure parameters and on strength parameters of Black Cotton Soil, Research Report, Dept. of Civil Engg., IIT, Kanpur, India, 1966. [3] Appamma, P (1998), Strength characteristics of Ca -Rice husk ash stabilized soil mixes, M.Tech., thesis, Department of Civil Engg. JNTU, Kakinada, 1998. [4] Ashwani Kumar and H.S. Mehta (1998), Laboratory Investigations on Use of Stabilized Granulated Blast Furnace Slag in Roads, Indian Highways, December 1998. [5] Basack and Purkayastha (29). Engineering properties of Marine Clays from the eastern coast of India. Journal of Engineering and Technology Research Vol.1(6),pp.19-114,September, Shridharan 29. [6] Bhadra, T. K and Sandhawar, R. R (22), Design of roads using waste products from steel plants, Indian Highways. [7] Chandrashekar, B.P., Prasada Raju, G.V.R (1999), Relative Performance of Lime and Calcium Chloride on Properties of Expansive Soil For Pavement Subgrades, Proc. Of IGC-99, Calcutta, 1999, pp 279-282. [8] Guram, D., Marienfelf, M. and Hayes, C (1994), Evaluation of Non Woven Geotextile versus Lime-Treated Subgrade in Atoka Country, Oklahoma, TRR-1439,TRB, 1994, pp.7-11. [9] Higgins D. D. (25), Soil Stabilization with Ground Granulated Blast Furnace Slag, UK Cementitious Slag Makers Association (CSMA), September 25. [1] Koteswara Rao,D (26), Laboratory investigations on GBFS-CH soil mixes for the utilization of foundation beds, CONCEPTS- 26, J.N.T. University College of Engineering, Kakinada, July 26. [11] Prasada Raju,G.V.R (21), Evaluation of Flexible Pavement Performance with Reinforcement and Chemical Stabilization of Expansive Soil Subgrade, a Ph.D. thesis, Kakathiya University, Warangal,(A.P). [12] Saha and Saha, P (1991), Improvement of Soils by Use of Chemicals,IGC-91. [13] Sivanna, G.S (1976), Strength and consolidation characteristics of black cotton soil with chemical additives- &, Report prepared by Karnataka Engg. Research Station, Krishnarajasagar, India, 1976. [14] Sivapullaiah, P.V. et al (1994), Role of Electrolytes on the Shear Strength of clayey soil, Proc. of IGC-94, Warangal, 1994, pp. 199-22. [15] Slate, F.O. and Johnson, A.W (1958), Stabilization of Soil with calcium chloride, HRB, Bibliography-24, 1958, pp. 1-9. ISSN : 975-5462 Vol. 3 No. 4 Apr 211 314