EXPERIMENTAL STUDY ON SUBGRADE IMPROVEMENT FOR FLEXIBLE PAVEMENT CONSTRUCTION USING FLY ASH

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1 International Journal of Latest Research in Science and Technology Volume 6, Issue 4: Page No , July-August ISSN (Online): EXPERIMENTAL STUDY ON SUBGRADE IMPROVEMENT FOR FLEXIBLE PAVEMENT CONSTRUCTION USING FLY I Syedah Umul Mohasin, II Er. Munish Kumar I M.Tech Scholar, Civil Dept., SRMIET, Bhurewala, Ambala, Haryana, India II Assistant Professor, Dept. of Civil Engineering, SRMIET, Bhurewala, Ambala, Haryana, India Abstract The present research work has investigated the use of flyash (waste material of coal based thermal power plants) in Ground Improvement and to evaluate the effects of mixing of various percentages of flyash on the Bearing Capacity of saturated and unsaturated soil by conducting California Bearing Ratio test on the Sandy soil of poor gradation. All the tests were conducted at Optimum moisture content (OMC) and maximum dry density (MDD) of mixes. The results of California Bearing Ratio (CBR) tests have shown considerable improvement with the use of flyash. The maximum increase in CBR value with flyash was observed when 2 percentage (of total mixture) flyash was mixed with soil. The increment in the CBR value, under unsoaked condition was from.6.81% in virgin soil to 9.73% with use of flyash and under soaked conditions it was from 2.43% in virgin soil to 4.86% with use of flyash. Keywords: Pavement, flyash, OMC, MDD, CBR, Compaction. 1 INTRODUCTION Quality of life is rapidly improving with fast increasing urbanization in India, which has also demanded for the very fast growth of infrastructure such as buildings and reads on one hand and power plants on the other hand due to continuously increasing population, which has crossed over 1.33 billion.most of the roads in India are being constructed on the problematic soils, due to which many problems regarding the stability and the characteristics strength are faced. Problematic soils cause some engineering problems like differential settlement and failures under load. Roads that pass through expansive soil subgrade are subjected to heaving and shrinking settlementof these treacherous soils. India in its past did not allocate enough resources to build or maintain its road network. This has changed since 1995, with major efforts currently underway to modernize the country's road infrastructure. As of April 215, India had completed and placed in use over 24, kilometers of recently built 4 or 6-lane highways connecting many of its major manufacturing centers, commercial and cultural centers.due to urbanization, demand of electricity generation has vigorously. To meet this- demand, a number of coal based thermal power plants have been set up in the India. 2 OBJECTIVES The main objectives of this dissertation are: 1. Summarize the current knowledge about the problematic soils, ground improvement techniques and flyash. 2. Recommend test procedures for identifying and testing the soil sample for itsproperties and other characteristics. 3. Find out the CBR values of the soil sample after adding the required percentage of flyash to it. Table 1: Typical Properties of Fly ash(source:irc: SP: 58) Parameter Normal range Specific Gravity Plasticity Non-plastic Maximum Dry density(gm/cc) Optimum Moisture Content (%) Cohesion (KN/m 2 ) Negligible Angle of Internal friction 3-4 Coefficient consolidation(cm 2 /s) of 1.7x x1-3 Compression Index.5-.4 Permeability(cm/s) 8x x1-4 Particle size distribution (%of material) Clay size fraction(less than.2mm) 1-1 Silt size fraction(.75 to mm) Sand size fraction (4.75 to mm) Gravel size fraction(8 to mm) Coefficient of uniformity 3-11 Table 2: Chemical composition of flyash(source:irc:sp:58) Characteristics Composition SiO Al 2O Fe 2O CaO 3.1 MgO.91 ISSN:

2 SO 3.14 Ramezanianpour, (1994) [8]The terminology, 'highcalcium' K 2ONa 2O 1.1 and 'low calcium' have been used in this study, in Loss of Ignition 5 general, and Class C and Class F, while referring / reporting the type of fly ashes actual used by various researchers, in 3 LITERATURE REVIEW their investigations. Shashiprakash and Thomas (21) [9] investigated the use Weinheimer (1944) and Minnick (1959) [1] indicate that of high-calcium fly ash (Ca content 2 to 23 %) and silica specific gravity varies significantly for particles of different fume to improve the sulphate resistance of mortars. Three shape, color and chemical composition. Compositional Portland cements (with varying C3A contents), one ultra - fluctuations, especially of iron and carbon contents seem to fine fly ash with moderate CaO content (about 14%) were cause difference in density. also used and the binary and ternary blends were tested for assessing the sulphate resistance. Puri (1975)[2] has stated that fineness is one of the principal parameters to be considered for fly ash to be added to cement, as it influences the rate of development of mechanical strength and relative values to be attained. However, there is an optimal fineness above which the increase in strength becomes less significant, due to the increase in the specific surface. Chopra (1979)[3] grouped Indian fly ashes into two categories based on Blaine's fineness, however, no such classification was found to be possible, based on the residues of 9µm sieve. Most researchers agree about the influence of Blaine's fineness on reactivity and strength development at early ages. The fact that it also gives a good indication on the presence of finer particles makes it preferable for specifying characteristics of fly ash. Ravina (198) [4] showed that a linear relation was found to exist between the specific surface of pulverized fuel ash and its pozzolanic activity index. Manz and others (1982)[5] have suggested that highcalcium fly ashes (the so-called Class C ashes) are best distinguished from the low-calcium (Class F) ashes by their cementing properties. Thus, a general term 'mineral admixtures' has been suggested to describe all classes of slag, ashes, pozzolanaand other cement supplements, with a further distinction being drawn on the basis of their self-cementing capabilities. Sharma (199) based on his study of India fly ashes, has reported positive correlation between lime, reactivity strength and fineness. Sharma (199)[6] based on his study of 25 Indian fly ashes, has reported that specific gravity seems to have no direct influence on reactivity of fly ash, within the range of specific gravity values of ashes ( ) investigated by him. In general, it appears that specific gravity seems to have no direct influence on the reactivity of the ash, but, definitely helps in defining the ash quality in terms of the presence of carbon and iron contents, which are considered to be deleterious to concrete. Fraay.A, Bijen J.M (199) [7] various demonstration projects have been carried out in the Netherlands with cement-stabilized fly ash as a base course. Usually these courses were made of 1 parts by mass of fly ash; 1 parts by mass of cement; 2 to 3 parts by mass of watertests were carried out with different types of class-f fly ashes and with different NaOH concentration in the mixing water. The results show an increase in compressive strength of up to 3% depending on the type of fly ash, and a substantial decrease in the rate of water absorption. IRC:SP:2-22Rural Roads Manual ( ) [1] Introduction, Fly ash for Road construction, Design and construction of fly ash embankments, lime fly ash stabilized soil, lime and fly ash Bound Macadam, Roller and compacted fly ash concrete pavement, Dry lean fly ash concrete for base course, cement stabilized fly ash, other uses of fly ash in Road pavement. Pandian et.al. (22) [11] Studied the effect of two types of fly ashes Neyveli fly ash (Class C) and Raichur fly ash (Class F) on the CBR characteristics of the black cotton soil. The fly ash content was increased from to 1%.Generally the CBR/strength is contributed by its cohesion and friction. In Neyveli fly ash also there is an increase in strength with the increase in fly ash content, there by forming Cementitious compounds by additional pozzolanic reaction, which results in good binding between BC soil and fly ash particles. Patel et al. (27) [12] studied geotechnical properties of copper slag mixed with different percentages of fly ash (2, 25, 3, 35 and 4%) and reported the maximum CBR value of 32 for a mix of 8% slag and 2% fly ash. Havanagi et al. (27) [13] reported the maximum angle of friction of 41 and UCS of 5698 KPa for 28 days curing period for 75% copper slag and 25% fly ash mix stabilized with 3 to 9% cement. They recommended that the mix with minimum 3% cement can be used in the base course of road pavements. Singh et. al (28) [14]Detailed laboratory investigations were carried out on cement stabilized fly ash (GBFS) mixes in order to find out its suitability for road embankments, and for base and sub-base courses of highway pavements. 4 EXPERIMENTAL WORK The experimental work consists of the following steps: 1. Particle size distribution by sieve analysis 2. Determination of soil index properties (Atterberg s limits). i. Liquid limit ii. Plastic limit 3. Specific gravity of soil. 4. Determination of the maximum dry density (MDD) and the corresponding optimum moisture content (OMC) of the soil by proctor compaction test. 5. Preparation of reinforced soil samples 6. Determination of the bearing strength California Bearing Ratio (CBR) test. ISSN:

3 PARTICLE SIZE DISTRIBUTION According to the graph, corresponding to the 25 blowsliquid limit = 21.8 SPECIFIC GRAVITY Sample number Weight of soil (kg) w1 Weight of pycnometer (Kg) Weight of soil pycnometer water w2 Weight of pycnometer ,18 water w3 Weight of tasla Weight of dry soiltasla Weight of dry soil (Kg) w4 Specific gravity According to the above results, the soil is of coursegrained type soil because more than half the total soil by weight is larger than 75 micron. LIQUID LIMIT STANDARD PROCTOR COMPACTION TEST Standard Proctor Compaction SAMPLE NUMBER Number of blows Weight of porcelain dish (gm) Wt. of porcelain dish wet soil (gm) Wt. of porcelain dish dry soil (gm) Wt. of water (gm) Wt. of dry soil (gm) % water content Optimum moisture content = 15.62% ISSN:

4 Maximum dry density = 1.873gm/cc Load (KN) CBR % Unsoaked 25 % 2 % 15 % 1 % Penetration (mm) CBR SOAKED % FLY 1% FLY 15% FLY 2% FLY 25% FLY PENETRAT ION (mm) LOAD (KN) Optimum moisture content = 15.62% Maximum dry density = 1.873gm/cc CBR UNSOAKED CBR % Soaked Load (kn) % 2 % 15 % Penetration (mm) ISSN:

5 COMPARISON CBR VALUE RESULTS OF VARIOUS SAMPLES AT 1% % 9% 1% 85% 15% 8% 2% 75% 25% 2.5mm mm International Journal of Latest Research in Science and Technology..6 and.28 with the addition of 1%, 15%, 2% and 25% flyash respectively. 3. The results from the California Bearing Ratio test is also similar up to a certain extent, with the increase in flyash the CBR value of both soaked and unsoaked samples increases upto a certain level of flyash after that the value of CBR start decreasing, therefore indicating us the optimum level of flyash content. 4. The increment in the value of unsoaked CBR was observed to be 1.46%,.73%,.73% and.7% at 2.5 mm penetration with 1%, 15%, 2% and 25% addition of fly ash respectively. And it was an increment of.97%,.49%, 1.46% and.97% at 5 mm penetration with 1%, 15%, 2% and 25% addition of flyash respectively. SOAKED CBR AT 1% % 9% 1% 85% 15% 8% 2% 75% 25% 2.5mm mm % CBR Soaked CBR % Comparion % 2.5 mm 5 CONCLUSIONS 1. Based on the test results of the Standard Proctor Compaction test of the soil sample with the flyash content 1%, 15%, 2% and 25%, this is observed that the Optimum Moisture Content (OMC) increases with the increase in flyash and the Maximum Dry Density (MDD) decreases with the increase in flyash. 2. The increase in the OMC was found to be 2.7%, 1.6%, 2.3% and 1.5% with the addition of 1%, 15%, 2% and 25% flyash respectively. The decrease in MDD was observed to be.18,.65, REFERENCES 1. C. M. Weinheimer. Evaluating importance of the Physical and Chemical Properties of in Creating Commercial Outlets for the Material. Transaction of the American Society of Mechanical Engineers, Vol. 66, No. 6, Aug. 1944, pp Teoreanu, M. Gerogesu and A. Puri, (1975). Hydrated Phases in Slag-Water-Activator Systems, Proceedings, 7th ICCC, Paris, II, pp Chopra. Utilization of rice husk for making cement and cement like binders. In Proc. UNIDO/ESCAP/RCTT Workshop on Rice Husk Ash Cement. Peshawar, Pakistan, 1979, pp Ravina,D (198) Optimized Determination of PFA (flyash) finesses with reference to Pozzolanic activity Cement and concrete research vol 1 pp Manz, O. E., Ash production and utilization in the world. Paper No. EP-SEM71R.51, United Nations Economic Commission for Europe, Geneva, May Sharma,B.M.Aggarwal,R.K. and Kumar,P. (199) Study of Different Fly ash A study in Vitro arid soil research and rehabilitation Vol 4(1), Fraay A., Bijen J.M. and Vogelaar P. (199). Cement stabilized fly ash base courses, Journal of cement and concrete composites, 12(4), pp RAMEZANIANPOUR et. All Backscattered Electron image of a Polished Section of the Dispersed Sample, Concrete Construction Engineering Handbook, 1994, 4/97-4/ M.D.A. Thomas, M.H. Shehata, S.G. Shashiprakash, The use of fly ash in concrete: classification by composition, Cement, Concrete, and Aggregates, 21 (2) (1999). 1. IRC: SP: 2-22 Rural Roads Manual ( ). 11. Pandian, N.S., et. al (22), Effect of Fly-ash on the CBR behavior of Soils, Indian Geotechnical Conference, Allahabad, Vol.1, pp Patel, S., et. al (27), Use of Copper Slag and Mix as Subgrade and embankment fill material, Journal of Indian Highways, 11, pp Havanagi, V. G., et. al (27), Feasibility of copper slag-fly ash-soil mix as a road construction material. Journal of Transportation Research Board, Washington, D.C., No. 1989, 2, pp Singh S.P., et. al (28), Performance evaluation of cement stabilized fly ash GBFA mixes as a highway construction material. Journal of waste management, 28, pp ISSN: