International Journal of Engineering Trends and Technology (IJETT) Volume 35 Number 1 - May 16 Engineering Properties of Black cotton soil Modified with Fly ash and Cement Jaya Prakash Babu.V #1, Satyanarayana.P.V.V *2, Surya Manikantha #3 Abdul Moin #4 #1 PG Student, #2 Professor, #3,#4 PG students &Civil eng. department& Andhra University Visakhapatnam, India Abstract: Black cotton soil is a typical volume change soil which loses its strength on wetting due to increase in its volume and in absence of water it shows multiple cracks due to decrease in its volume. This volume change behavior causes distress when structures located on these soils and also these soils can be used as construction material.. Present paper describes the strength behavior of Black cotton soil treated with fly ash as stabilizer. Fly ash is a fine powder obtained from burning of coal during the production of electricity. Disposal of Fly ash is a big problem. To minimize the disposal of Fly ash onto large land areas, it can be used as a construction material in civil engineering works. In this an attempt is made for the utilization of Fly ash in bulk quantities by adding it to expansive soil at various percentages of cement and tests like plasticity, swell, compaction and tests were performed. From the test results it is identified that addition of Fly ash and cement decreases plasticity and improves strength characteristics. Addition 32-4 Fly ash and 6-8 cement attains higher values and improved swell characteristics. Key words: Expansive soil, Fly Ash, cement, 1. INTRODUCTION: Black cotton soils accounts about of land area in India and are predominantly located in the Deccan trap covering the states. Most Indian Black cotton soils are rich in Montmorillonate, this mineral is responsible for swell-shrink behavior of the soil. It is highly sensitive to moisture changes; Katti(1979) 2 has given properties of Black cotton soils which have Liquid limit 4-1, Plastic limit -6, Differential Free Swell index - 1.Structures located on these soils subjected to differential settlements due to moisture variations (Bala Subramanyam et.al 1989) 1. Hence the subgrade and its undesirable characteristics to be modified using a suitable stabilization technique. Stabilization involves the methods used for modifying the properties of a soil to improve its engineering performance. Keeping in this view investigation carried out with fly ash. In India, about 1 million tonns of coal ash is produced annually.coal-ash management poses a serious environmental problem for India and requires a mission-mode approach. Disposal of wastage requires costly land at thermal power plants and the transport of flyash to the ash ponds entail heavy expenditure. some researchers P.V.V.Satyanarayana et.al (13) 11 studied on the Strength characteristics of Expansive soil-fly ash mixes at various moulding water contents,kiran B.Biradar et.al (14) 3 studied the Influence of steel slag and Fly ash on Strength Properties of Clayey soil, Ramakrishnan, A.K. et.al(1) 1 Stabilization of Annamalainagar Clay with lime- Fly ash,nalbantoglu, Satyanarayana.P.V.V et.al (13) 12 studied the Bulk utilization of flyash lime sodium silicate mixes in geotechnical applications,satyanarayana.p.v.v et.al(16) 13 studied on the Engineering Properties of Expansive Soil Stabilized with Fly ash and Lime Mixes, Prabakar, J.et.al (3) 9 studied Influence of fly ash on strength behavior of typical soils,sridharan, A.et.al (1998)15 studied Use of Fly ash to improve the of soil, Pandian, N.S. et.al (2) 7 studied California bearing ratio behavior of cement stabilized fly ash-soil mixes, Kolias, S. et.al (5)4 studied Stabilization of Clayey soils with high calcium fly ash and cement, Phanikumar, B.R. et.al (7) 8 studied Volume changes Behaviour of fly ash-stabilized clay, Pandian, N.S. et.al (2) 6 studied The pozzolanic effect of fly ash on the behaviour of black cotton soil. In present investigation various percentages of Fly ash and cement mixes are added to expansive soils and effect of these mixes was studied in terms of plasticity, compaction, swell and strength characteristics. 2.. MATERIALS: To study the performance of Fly Ash and Cement mixes on expansive soil, which is obtained from delta areas of Godavari River in Bhimavaram, Andhra Pradesh, India and Fly Ash was collected from NPTC, Parawada of Visakhapatnam district,andhra Pradesh, India and cement of OPC 43 grade obtained from local markets. 2.1. Black cotton soil: ISSN: 2231-5381 http://www.ijettjournal.org Page 477
Finer Finer () International Journal of Engineering Trends and Technology (IJETT) Volume 35 Number 1 - May 16 Expansive soils in India are popularly known as Black cotton soils. Expansive soil under study was collected dried and pulverized into the required sizes and tested for properties like gradation,compaction, strength as per IS27 and the results are shown in table-1 and fig-1 Table.1.Geotechnical properties of Black cotton soil 1 1 8 6 4 Property.1.1.1.1 Grain size (mm) Values Gravel () Sand () 28 Fines () 72 a. Silt () 72 b. Clay() Liquid Limit () 28 Plastic Limit () NP Specific gravity 2.1 Optimum moisture content () () 21 Maximum dry density () (g/cc) 1.28 California bearing ratio () () 4 Coefficient of uniformity (Cu) 28.89 Coefficient of curvature (Cc) 2.13 Fig-1: Gradation curve of Black Cotton soil From the test results it is identified that it contains fines (less than 75µm) of 95.shows alluvial origin out of which 4 of silt and 55 as clay particles. The presence of fines contributed for high liquid limit ( w L ) of 74 and plasticity index of 45 can be classified as CH soil based on IS1498 197 It also exhibited high swelling characteristics with FIS as 1 and swell pressure as 9kpa and attained very low strength values under soaking in terms of as 1. 2.2Fly ash: Fly ash was collected from National Thermal Power Corporation (NTPC), which is located at Parawada, Visakhapatnam, Andhra Pradesh. The collected dried Fly Ash was subjected to various geo-technical characterizations such as gradation, compaction, strength, permeability etc., and the test Property Values Gravel () Sand () 4 Fines () 96 a) Silt 5 b) Clay 46 Liquid Limit () 74 Plastic Limit () 29 Plasticity Index (I P ) 45 IS Classification CH Optimum moisture content () () 26 Maximum dry density () (g/cc) 1.52 California bearing ratio () ( Soaked) 1. Angle of shearing resistance (Ø) 15 results are shown in table -2 and Fig 2(a),2(b) Table 2. Geotechnical Characterizations of Fly ash 1 1 8 6 4 Cohesion (t/m 2 ) 1.1.1.1 1 Particle size (mm) Fig-2: Gradation curve of Fly ash Table 3. Chemical Composition of Flyash Compound Formula Percentage SiO 2 59.83 Al 2 O 3 3.48 CaO 1.74 MgO.86 TiO 2 6.91 V2O 5.9 ZnO.9 From the test results it is identified that, it has 72 fine particles (<75µm) and all these particles are silt ranges. It is non-plastic and incompressible material. It has low specific Gravity and attained less dry Density with high Moisture Contents due to nature of Flyash particles. From the chemical composition it isd identified that it has less percentage of CaO (1.74<15) classified under ISSN: 2231-5381 http://www.ijettjournal.org Page 478
() Water content () (g/cc) International Journal of Engineering Trends and Technology (IJETT) Volume 35 Number 1 - May 16 class F flyash (ASTM) and presence of high percentages of sio 2 and Al 2 O 3 (9) make the Flyash Pozzolanic with addituion of Lime, Cement and other additives. 3. RESULTS AND DISCUSSIONS 3.1 Effect of Fly ash on Engineering Properties of Expansive Soils To study the effect of Fly ash on Expansive soil, various percentage of fly ash i.e.,, 5 by dry weight of soil were added and effectively mixed and tested for characteristics like consistency, compaction, and swell as per IS27,as the results are shown in table-4 and fig-3(a)-3(e) Table 2. Various characteristics of soil-fly ash mixes 1.54 1.52 1.5 1.48 1.46 1.44 1.42 1.4 1.38 Fig 3(b). Vs FLY ASH () 1 3 4 5 6 Fly ash () Fig 3. Vs FLY ASH () FLYASH 8 7 6 5 4 3 1 32 31 3 29 28 27 26 25 W L W P I P Liquid limit Plastic limit 1 3 Plasticity index 4 5 Fly ash () Fig 3(a).Consistency limits g/cc 1 3 4 5 6 Fly ash () 74 29 45 26 1.52 1 1 1 66 3 36 27 1.5 8 2.5 55 32 23 28 1.48 56 4 3 4 34 6 29 1.46 3 6 4 24 NP NP 3 1.43 15 7 5 NP NP NP 31 1.4 6.5 1 1 8 7 6 5 4 3 2 1 8 6 4 1 3 4 5 6 Fly ash () Fig 3. Vs FLY ASH () Fig 3. Vs FLY ASH () From the consistency test data, it is identified that as the percentage of fly ash is increasing liquid limit and plasticity index values are decreasing and plastic limit values are increasing. This phenomenon is continued up to 3 after it became non-plastic. The decrease in liquid limit is due to the decrease in diffused double layer by replacement of clay particles by fly ash particles and increase in plastic limit is due to the development of shear resistance at inter particle level and the particles in soil-fly ash matrix require more water to mobilize for rolling. From the compaction test data it is identified that with increasing the percentage of fly ash values are increasing and values are decreasing. This increase in values are 1 3 4 5 6 Fly ash () ISSN: 2231-5381 http://www.ijettjournal.org Page 479
() International Journal of Engineering Trends and Technology (IJETT) Volume 35 Number 1 - May 16 due to the development of flocculated structure which resists the compaction effort and the particles in the soil-fly ash matrix requires more water to mobilize and less solids occupied in the given volume and low dry densities are also due to nature and low specific gravity of fly ash particles compared to clay particles. It is also observed that with increasing percentage of fly ash free swell values are decreasing. At a dosage of 4 it became low swelling and at 5 it is non-swelling. The decrease in swelling characteristics is due to decrease of the amount of repulsion between clay particles due to replacement of clay by fly ash particles. From the test results of it is identified that as the percentage of Fly ash is increasing values are also increasing up to 4 and then decreasing. Fly ash Clay blend offers more resistance compared to individual Fly ash particles and clay particles. 3.2 Effect of Cement on Fly ash Stabilized Expansive soil To study the effect of Cement on Fly ash stabilized expansive soil, various percentage of cement i.e. 2,4,6,.1 by dry weight of soil were added and effectively mixed and tested for characteristics like compaction, strength and swell as per IS27,and the results are shown in below. Table.5.Various Characteristics of Lime Stabilized Expansive soil fly ash mixes 6 5 4 3 1-1 4 35 3 25 Fly ash 3 Fly ash 4 Fly ash 2 4 6 8 1 CEMENT () Fig 4(a). () Vs CEMENT () Fly ash 3 Fly ash 4 Fly ash 2 4 6 8 1 CEMENT () Fig 4(a). () Vs CEMENT () CEMENT () () (g/cc) FLY ASH () 3 4 () (g/cc) () (g/cc) 28 1.48 56 4 29 1.46 3 5 3 1.43 15 6 2 28.5 1.47 4 1 35 1.48 1 12 31.5 1.45 15 4 29 1.46 15 32 1.5 26 33 1.47 3 6 29.8 1.45 34 33.5 1.52 48 34.5 1.49 54 8 31 1.44 52 35 1.54 68 36 1.51 8 1 32 1.43 74 37 1.55 84 37.5 1.53 9 ISSN: 2231-5381 http://www.ijettjournal.org Page 48
() (g/cc International Journal of Engineering Trends and Technology (IJETT) Volume 35 Number 1 - May 16 1.6 1.58 1.56 1.54 1.52 1.5 1.48 1.46 1.44 1.42 1.4 1 9 8 7 6 5 4 3 1 2 4 6 8 1 CEMENT () Fig 4(a). (g/cc) Vs CEMENT () Fig 4(a). () Vs CEMENT () Fly ash 3 Fly ash 4 Fly ash Fly ash 3 Fly ash 4 Fly ash 2 4 6 8 1 CEMENT () Compaction test data shows that with increasing the percentage of fly ash & cement values are increasing & values are decreasing. Increase in values are due to increase in cement concentration in pore water makes the particle further flocculate and more pore water is needed to mobilize the particle against compaction effort and hydration of cement is also responsible. Decrease in values are due to occupation of solids contributed less weight due to replacement of clay particles by Fly ash particles and acceleration of flocculated structure by cement particles. From the test results it is also identified that as the percentage of Fly ash and cement increases Differential Free Swell Index values decreases. At 4 dosage of cement with respective to all Fly ashes the soil became non-swelling. Addition of cement makes the soil-fly ash matrix move repultant against swelling due to absorption of calcium particles on to the surface of clay particles. test data shows the increase in percentage of cement increases the values of soil-fly ash matrix and attained high values at dosage of 8 of cement. Addition of cement to soil-fly ash blends offers more resistance against compression is due to development of cementitious compounds and became crystalline over a period of time. APPLICATIONS: 1. Addition of 4 Fly ash to Black cotton soil attained value of 7 with nonplastic and low swelling can be used as Sub-Grade material. 2. Addition of 4 cement and 3-4 Fly ash to the Black cotton soil attained values 26-3 can be used as Sub-Base material. 3. Addition of 8-1 cement and 32-4 of Fly ash to the Black cotton soil attained value 8 can be used as Base course material. CONCLUSIONS: High Expansive Black cotton soil can be effectively utilized as a Geo technical material by addition of 3-4 fly ash and 6-1 cement. At these dosage of admixtures the Black cotton soil can be behaves non-plastic and non-swelling can reduce the problems of volume change. Bulk utilization of Fly ash reduces its deposal problem. REFERENCES: [1] Balasubramaniam, A. S., Bergado, D. T., Buensuceso Jr, B. Rand Yong, W. C. (1989). Strength and deformation Characteristics of lime-treated soft clays. Geotech. Eng. [2] Katti,R.k.(1979), Search for solutions to problems in black cotton soils, First TGS annual lecture, Indian Geotech.Journal,No.1,vol.95 [3] Kiran B.Biradar, Arun Kumar.U, Satyanarayana.P.V.V. (14) Influence of steel slag and Fly ash on Strenth Properties of Clayey soil:a comparative study International Journal of Engineering Trends and Technology (IJETT).e-ISSN:2231-5381, p-issn:2349-918 Volume 14, No.2,August 14,Page No.61-64 [4] Kolias, S., Rigopoulou, V.K. and karahalios, A. (5), Stabilization of Clayey soils with high calcium fly ash and cement, Cement and Concrete Composites, 27, 31-313. [5] KRISHNA RAO.C.V, SATYANARAYANA.P.V.V, RAMA RAO.R (2) Fly ash - a construction material in rural roads Conference 4th International conference on Ground Improvement Techniques Volume 2 Issue 1 Pages 645-648 [6] Pandian, N.S. and K.C. Krishna. (2). The pozzolanic effect of fly ash on the behaviour of black cotton soil. J. of testing and Evaluation, ASTM, 31(6), 479-485. [7] Pandian, N.S. and Krishna, K.C. (2), California bearing ratio behavior of cement stabilized fly ash-soil mixes, Journal of testing and evaluation, 3(6), 1-5. [8] Phanikumar, B.R. and Sharma, R.S. (7), Volume changes Behaviour of fly ash-stabilized clays, Journal of materials in Civil Engineering, 19(1), 67-64. [9] Prabakar, J., Dendorkar, n., and Morchhale, R.K (3), Influence of fly ash on strength behavior of typical soils. Construction and building material, pp. 263-267. [1] Ramakrishnan, A.K., Natarajan, K., and Ravichandran, K. (1), Stabilization of Annamalainagar Clay with lime- Fly ash, Indian Geotechnical Conference, Dec. 14-16, 1, pp. 251-254. [11] Satyanarayana.P.V.V, Hemanth kumar.s, Praveen.D, Suresh kumar.b.v(13). A study on Strength ISSN: 2231-5381 http://www.ijettjournal.org Page 481
International Journal of Engineering Trends and Technology (IJETT) Volume 35 Number 1 - May 16 characteristics of Expansive soil-fly ash mixes at various moulding water contents, International Journal of Recent Technology and Engineering(IJRTE). ISSN:2277-3878,Vol-2,Issue-5,pp-145-149. [12] Satyanarayana.P.V.V K.Prasadarao, U.Arunkumar and K. Sivaramakrishna Bulk utilization of flyash lime sodium silicate mixes in geotechnical applications Publication date 13/8 Journal Pollution Research Volume 32 Issue Impact factor: ISSn No:257-85 [13] Satyanarayana.P.V.V, Vijaya Sree.K, Mohan Rao.G, Jaya Prakash Babu.V(16)A Study on the Engineering Properties of Expansive Soil Stabilized with Fly ash and Lime Mixes, International Journal of Emerging Technology and Advanced Engineering,ISSN 225-2459, Volume 6, Issue 4, pp-54-58. [14] Satyanarayana.P.V.V, Krishna rao.c.v, Rama Rao.R (4) Utilization of Lime fly Ash Stabilized Expansive Soil in Roads and Embankments Indian Geotechnical Conference Volume 1 Issue 1 Pages 465-467 [15] Sridharan, A., Pandian, N.S. and Srinivas, S. (1998), Use of Fly ash to improve the of soil, Indian Geotechnical Conference, Vol. 2, 261-264 ISSN: 2231-5381 http://www.ijettjournal.org Page 482