20320140502004 2-3

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20320140502004 2-3

  1. 1. International Journal of Civil Engineering and OF CIVIL Technology (IJCIET), ISSN 0976 – 6308 INTERNATIONAL JOURNAL 2, February (2014),ENGINEERING (Print), ISSN 0976 – 6316(Online) Volume 5, Issue pp. 25-32 © IAEME AND TECHNOLOGY (IJCIET) ISSN 0976 – 6308 (Print) ISSN 0976 – 6316(Online) Volume 5, Issue 2, February (2014), pp. 25-32 © IAEME: www.iaeme.com/ijciet.asp Journal Impact Factor (2014): 3.7120 (Calculated by GISI) www.jifactor.com IJCIET ©IAEME STRENGTH OF FLY ASH MIXED WITH WASTE SLUDGE Dr. Malik Shoeb Ahmad Civil Engineering Department, Z.H. College of Engineering & Technology Aligarh Muslim University, Aligarh-India ABSTRACT The strength of fly ash-electroplating waste- cement mix were determined by undrained unconsolidated (UU) triaxial shear tests conducted on cylindrical specimens of diameter 39 mm and length 84 mm, prepared for fly ash and different combination of fly ash-waste sludge-cement mixes. The tests were carried out at different curing periods of 7, 28 and 90 days. The shear strength parameters and undrained shear strength of fly ash and mix blends were determined. The outcome of the test results was quite encouraging in terms of undrained shear strength and shear strength parameters. The maximum gain in shear strength was obtained at 90 days of curing for the mix 47%FA+45%S+8%C (2.48 MPa) as compared to fly ash (0.10 MPa) for the same curing period. KEYWORDS: Fly Ash; Shear Strength; Waste Sludge, Triaxial Shear Test. 1. INTRODUCTION The demand of power is increasing day by day. Major part of the power is supplied by Thermal Power Plants where coal is used as fuel and a large quantity of fly ash emerges in the process. Fly ash creates different environmental problems like leaching, dusting and takes huge disposal area. Transforming this waste material into a suitable construction material may minimize the cost of its disposal and in alleviating environmental problems. Fly ash has become an attractive construction material because of its self hardening character which depends on the availability of free lime in it. The variation of its properties depends on nature of coal, fineness of pulverization, type of furnace, and firing temperature. According to ASTM C 618[1] classification, fly ashes fall in two types; Class C and Class F. Class C fly ash high in calcium content undergoes high reactivity with water even without addition of lime [2]. Class F fly ash contains lower percentages of lime. It lacks adequate shear strength for use in geotechnical applications and requires stabilization with lime or cement and some admixtures to accelerate shear strength gain in short period. The fly ash studied in the present 25
  2. 2. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 5, Issue 2, February (2014), pp. 25-32 © IAEME investigation belongs to Class F. Various studies on application of fly ash as bulk fill material are available [3-5] which demonstrated the possibility of utilizing huge amount of fly ash in construction of embankments, dykes, and road subgrade. [6] demonstrated the use of fly ash as foundation medium reinforced with jute-geotextiles. They showed through unconfined compression test results that lime stabilization enhanced the strength of stabilized fly ash at elevated temperature or with long curing period. [7] reported the unconfined compressive strength and undrained triaxial strength for fly ash. Undrained shear strength parameters of solid waste incinerator fly ash stabilized with lime and cement were reported by [8]. The shear strength of geofibre reinforced fly ash was investigated by [9-10] but the strength characteristics of Class F fly ash mixed with waste sludge and cement have not received much attention by the previous researchers. 2. TEST MATERIALS In this study, the materials used are Fly ash; Electroplating Waste Sludge; Lime and Cement. 2.1 FLY ASH Fly ash was procured from Harduaganj thermal power plant located at 16 km from Aligarh City, Uttar Pradesh, India. This power plant consist of 440 MW pulvarised coal units, producing 25 trucks of fly ash and bottom ash per day which is about 1500 tonnes fly ash and 500 tonnes of bottom ash. For the present investigation, dry fly ash from hoppers is collected in polythene bags. 2.1.1 Physical Properties Colour= Grey, Percent finer= 88%, Size of the particle= 0.002-0.30mm, Maximum dry density (MDD)= 9.30 kN/m3, OMC= 27.5%, Specific gravity = 2.02, Surface area= 3060 cm2/g Unburnt carbon= 11.80% and Classification = ML as per IS: 1498-1987. 2.1.2 Chemical Composition The chemical composition of fly ash are SiO2= 54.0, Al2O3= 24.0, Fe2O3= 12.0, CaO = 2.0, MgO= 1.0, SO3= 0.3 and Loss on Ignition (Percent by Weight) = 1.5 %. 2.2 ELECTROPLATING WASTE SLUDGE The electroplating waste sludge was collected in the form of filter cake, comprises of 70% solid waste and 30% waste water. The solid waste includes chemicals, heavy metals and metallic dust. Heavy metal analysis was carried out using GBC-902 atomic absorption spectrophotometer (AAS). The heavy metals concentration in the electroplating waste sludge was found as Nickel= 610, Chromium= 630, Zinc= 800, Cadmium= 025, Copper= 300 and Lead = 005 ppm. 2.3 Lime The finely powered white coloured lime was used as precipitator having the chemical composition such Assay= 95, Chloride = 0.01, Sulphate=0.2, Aluminium, iron and insoluble matters=1.0, Arsenic=0.0004 and Lead =0.001%. 2.3 Cement The cement used in this study was OPC-43 grade. The test on cement was conducted in accordance with IS: 269-1989. The physical properties of cement are Specific surface cm2/gm= 3175, Soundness in mm = 3.30, Compressive strength in MPa at 3 & 7 days = 14.3 & 23.5, Setting time (minutes) = 100(Initial) & 290(Final), Specific gravity = 3.13 and Normal consistency (water in % of cement by weight) = 27.5. 26
  3. 3. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 5, Issue 2, February (2014), pp. 25-32 © IAEME 3. PREPARATION AND TESTING OF SPECIMENS The preparation and testing of specimens for triaxial compression tests has been carried out in accordance with the IS: 2720 (Part 11–1993). The standard Proctor compaction tests were carried out using equipment and procedure as specified in IS: 2720 (Part 7–1987) equivalent to (ASTMD 698– 2000a) to obtain Maximum Dry Density (MDD) and Optimum Moisture Content (OMC) of fly ash and fly ash-waste sludge mixes. The OMC of the fly ash was obtained as 27.5% which also satisfies the IS: 456 (2000) requirements (i.e., 25% water by weight of cement is to be added to cement mortar for chemical reactions). First of all the lime precipitated electroplating waste sludge was dried in oven for 24 hours, pulverized and sieved through 425µ IS sieve. Fly ash was dried in oven for 24 hours and sieved through 425µ IS sieve. A known quantity of fly ash, fly ash–waste sludge, fly ash-cement and fly ash–waste sludge–cement mix were taken and water equal to OMC was added. The material was thoroughly mixed to achieve uniform mixing of water. The wet mix was then placed in split mould for casting the remolded cylindrical specimens having diameter as 39 mm and length 84 mm, for triaxial compression test as described in the IS: 2720 (Part 11–1993). 4. RESULTS AND DISCUSSION The results of triaxial compression tests (UU-test) on aged/cured specimens of fly ash, fly ash-waste sludge, fly ash–8% cement and fly ash–waste sludge–8% cement are shown in Table. The tests were conducted under confining pressures of 0.05, 0.10 and 0.15 MPa at 7 and 28 days of curing. The results show that: (i) (ii) (iii) (iv) (v) (vi) (vii) (viii) (ix) The confining pressures have a significant effect on deviator stresses. The deviator stresses at failure after 90 days of aging are 0.171 MPa, 0.235 MPa and 0.253 MPa at confining pressures of 0.05 MPa, 0.10 MPa and 0.15 MPa respectively. The shear strength of fly ash improves on aging. The improvement in shear strength is of the order of 12.5% and 25% at 28 and 90 days of aging respectively (Fig. 1). The average undrained cohesion values have been observed as 0.04 MPa and 0.043 MPa at 28 and 90 days of aging respectively. The gain in the cohesion due to aging is 33% and 43% respectively, when compared with 7 days of aging. The shear strength of the mix increases with increase in the waste sludge content and curing periods. Amongst all the combinations of mixes, 60%FA+40%S mix exhibits highest shear strength of 1.53 MPa at 28 days of curing, which is 17 times more than the shear strength of fly ash at the same curing period. The average peak friction angle (¢) for the mix 60%FA+40%S has been increased significantly from 150 (fly ash) to 330 at 7 days of curing. The similar trend has also been observed at 28 days of curing i.e., the value of average peak friction angle (¢) increased from 15.20 (fly ash) to 410 of this mix. The value of average undrained cohesion (c) of this mix has been observed as 1.13 MPa at 28 days of curing, which is 2725% more than the value of cohesion of fly ash for the similar curing period. The increase in the shear parameters of this mix, clearly demonstrates the existence of an interaction effect that involves the confining pressure and curing periods on the peak strengths. Amongst all combinations of the mixes, mix 50%FA+50%S has the lowest shear strength 0.74 MPa at 28 days of curing. 27
  4. 4. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 5, Issue 2, February (2014), pp. 25-32 © IAEME (x) (xi) (xii) (xiii) (xiv) (xv) (xvi) (xvii) (xviii) (xix) The addition of cement has increased the deviator stress and shear strength parameters due to availability of cement for pozzolanic reaction. The rate of gain of shear strength of the mix 92%FA+8%C is 0.59 MPa which is 556% more than the fly ash (0.09 MPa) at 28 days of curing. The gain in the shear strength continues further at 90 days of curing (Fig. 2). The average peak friction angle (¢) of the mix has been increasing significantly from 15.20 (fly ash) to 390 at 28 days of curing. The gain in the ¢ value is observed as 157%. The value of average undrained cohesion (c) of the mix has been observed as 0.41 MPa at 28 days of curing, which is 925% more than that of fly ash. The gain in the average values of peak friction angle and undrained cohesion has been continued further at 90 days of curing as well. It is envisaged from the test results that the contribution of waste sludge with cement in fly ash at longer periods of curing is significant. Amongst all the combinations of mixes, 47%FA+45%S+8%C mix exhibits maximum shear strength of 2.15 MPa at 28 days of curing, which is 24 times more than the fly ash. The shear strength of this mix at 90 days of curing has been observed as 2.48 MPa, which is 25 times more than the fly ash at 90 days of curing (Fig. 3). The percent gain in average undrained cohesion (c) of this mix with respect to fly ash at 28 days of curing is 3350%. Whereas, the increase in c value at 90 days is 4272%. The average peak friction angle (¢) of this mix has been increased significantly from 15.20 (fly ash) to 420 at 28 days of curing. The gain in the (¢) value observed as 176%. The improvement in the (¢) value continues at 90 days (500), which is 190% more than fly ash. The decrease in the shear strength of this mix might also be attributed due to the presence of excess amount of sulphate and lime added with the waste sludge in the mix, causing development of shrinkage cracks due to formation of ettringite and progressive carbonation reaction which eventually leads to depletion of portlandite. Subsequently decalcification of C-S-H results in deterioration in the strength of the mix. The failure pattern of the samples is shown in Fig. 4. 1.6 0.30 0.05 MPa 0.25 0.05 MPa 0.10 MPa 1.4 0.10 MPa 0.15 MPa 0.15 MPa Deviator Stress (MPa) Deviator Stress (MPa) 1.2 0.20 0.15 0.10 0.05 1.0 0.8 0.6 0.4 0.2 0.0 0.00 0.00 1.00 2.00 3.00 4.00 5.00 0.0 2.0 4.0 6.0 Axial Strain (%) Axial Strain (%) Fig. 1: Stress-Strain Behaviour of Fly ash at 90 days of Curing Fig. 2: Stress-Strain Behaviour of 92%FA+8%C at 90 days of Curing 28 8.0
  5. 5. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 5, Issue 2, February (2014), pp. 25-32 © IAEME 4.0 0.05 MPa 3.5 0.10 MPa 0.15 MPa Deviator Stress (MPa) 3.0 2.5 2.0 1.5 1.0 0.5 0.0 0.0 1.0 2.0 3.0 4.0 Axial Strain (%) 5.0 Fig. 3:Stress-Strain Behaviour of 47%FA+45%S+8%C at 90 days of Curing Fig. 4: Specimen after Failure Table: Shear Strength Behaviour of Fly ash, Fly ash-Waste Sludge, Fly ash-Cement and Fly ash-Waste Sludge-Cement Mix Mix Curin g Period (days) (1) (2) 7 Fly ash 28 90 7 70%FA+30%S 28 7 65%FA+35%S 28 Confin ing Pressu re (MPa) (3) 0.05 0.10 0.15 0.05 0.10 0.15 0.05 0.10 0.15 0.05 0.10 0.15 0.05 0.10 0.15 0.05 0.10 Failur e Load (N) Deviator Stress (MPa) Average Angle of Shearing Resistance (degree) Average Undrained Cohesion (MPa) Average Shear Strength (MPa) (4) 99 155 187 202 272 287 214 294 316 1422 1488 1567 1676 1845 1910 2012 2165 (5) 0.081 0.125 0.150 0.161 0.217 0.230 0.171 0.235 0.253 1.105 1.156 1.218 1.302 1.434 1.484 1.563 1.682 (6) (7) (8) 15.1 0.03 0.08 15.2 0.04 0.09 17.2 0.043 0.10 21.2 0.57 0.76 28.9 0.66 0.92 28.0 0.85 1.14 0.15 0.05 0.10 0.15 2234 2535 2616 2765 1.736 1.970 2.033 2.149 29.4 0.97 1.32 29
  6. 6. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 5, Issue 2, February (2014), pp. 25-32 © IAEME (1) (2) 7 60%FA+40%S 28 7 55%FA+45%S 28 7 50%FA+50%S 28 7 92%FA+08%C 28 90 7 62%FA+08%C+ 30%S 28 90 (3) (4) (5) 0.05 0.10 0.15 0.05 0.10 0.15 0.05 0.10 2295 2378 2605 2408 2714 2876 2324 2409 1.783 1.848 2.024 1.871 2.109 2.235 1.806 1.872 0.15 0.05 0.10 0.15 0.05 0.10 0.15 0.05 0.10 0.15 0.05 0.10 0.15 0.05 0.10 0.15 0.05 0.10 0.15 0.05 0.10 0.15 0.05 0.10 0.15 0.05 2458 2587 2603 2713 1479 1544 1596 1270 1356 1378 763 1003 1107 1134 1426 1578 1270 1569 1736 1780 1987 2132 2430 2690 2860 3120 1.910 2.010 2.023 2.108 1.158 1.209 1.259 1.010 1.083 1.101 0.593 0.779 0.860 0.881 1.109 1.226 0.987 1.220 1.349 1.383 1.544 1.657 1.888 2.090 2.222 2.424 0.10 3456 2.686 0.15 57%FA+08%C+ 35%S 7 28 90 3786 2278 2378 2634 3462 3552 3894 3506 4067 4319 1.775 1.848 2.052 2.690 2.760 3.026 2.766 3.160 3.356 (7) (8) 33.7 1.00 1.35 40.5 1.13 1.53 20.1 0.93 1.19 19.9 0.98 1.26 18.7 0.52 0.69 19.6 0.57 0.74 35.3 0.34 0.50 39.0 0.41 0.59 41.0 0.45 0.71 35.4 0.67 0.97 38.8 0.87 1.26 46.2 1.04 1.53 36.2 0.90 1.26 40.0 1.20 1.71 48.8 1.41 1.96 2.942 0.05 0.10 0.15 0.05 0.10 0.15 0.05 0.10 0.15 (6) 30
  7. 7. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 5, Issue 2, February (2014), pp. 25-32 © IAEME (1) (2) 7 52%FA+08%C+ 40%S 28 90 7 47%FA+08%C+ 45%S 28 90 7 42%FA+08%C+ 50%S 28 90 5. (3) (4) (5) 0.05 0.10 0.15 0.05 0.10 0.15 0.05 0.10 0.15 0.05 0.10 0.15 0.05 0.10 0.15 0.05 0.10 0.15 0.05 0.10 0.15 0.05 0.10 0.15 0.05 0.10 0.15 3053 3281 3441 4136 4237 4612 4356 4788 5198 3218 3357 3678 3489 3716 3978 3819 4387 4578 718 805 961 922 1194 1287 1067 1269 1339 2.372 2.550 2.674 3.214 3.292 3.602 3.385 3.720 4.039 2.584 2.729 2.939 2.829 3.028 3.234 3.051 3.505 3.658 0.588 0.658 0.787 0.766 0.978 0.973 0.880 1.037 0.973 (6) (7) (8) 37.0 1.19 1.65 42.6 1.38 1.97 50.0 1.65 2.29 39.0 1.30 1.80 42.0 1.61 2.15 50.0 1.88 2.48 30.0 0.30 0.46 33.4 1.19 1.43 25.2 0.38 0.56 CONCLUSIONS The following conclusions may be drawn from the test results of these studies. (i) (ii) (iii) (iv) (v) The mix containing 70%-55% fly ash and 30%-45% waste sludge has been showing good shear and bearing strength characteristics. Addition of small percentage of cement (8%) along with waste sludge to fly ash enhances the shear and bearing strengths at early stage of curing. The shear and bearing strengths of fly ash were increased to manifolds on addition of waste sludge and cement to it. The shear strength parameters ‘c’ and ‘φ’ of fly ash have been increased to 4272% and 191% respectively, for 47%FA+45%S+8%C mix at 90 days of curing. Amongst all combinations of mixes, mix 42%FA+50%S+8%C exhibits lowest shear strength of 1.43 and 0.56 MPa at 28 and 90 days of curing respectively. 31
  8. 8. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 5, Issue 2, February (2014), pp. 25-32 © IAEME REFERENCES [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] ASTM C 618 (2003). “Specification for fly ash and raw or calcined natural pozzolana for use as a mineral admixture in Portland cement concrete.” Philadelphia, U.S.A. Raymond, S., and Smith, P. H. (1966). “Shear strength, settlement and consolidation characteristics of pulverized fuel ash.” Civil Engineering and Public Works Review, London, 61, 1107–1113. DiGioia, A. M., and Nuzzo, W. L. (1972). “Fly ash as structural fill.” Journal of Power Division, 98(1), 77–92. Gray, D. H., and Lin, Y. (1972). “Engineering properties of compacted fly ash.” Journal of Soil Mechanics and Foundation Division, 98 (9), 361–380. Joshi, R. C., and Nagraj, T. S. (1987). “Fly ash utilization for soil improvement.” Environmental Geotechnics and Problematic Soils and Rocks, Balkema, Rotterdam, 15–24. Bera, A. K., Ghosh, A., and Ghosh, A. (2005). “Regression model for bearing capacity of a square footing on reinforced pond ash.” Geotextile and Geomembrane, 23(3), 261–285. Indraratna, B., Nutalaya, P., Koo, K. S., and Kuganenthira, N. (1991). “Engineering behaviour of low carbon, pozzolanic fly ash and its potential as a construction fill.” Canadian Geotechnical Journal, 28, 542–555. Poran, C. J., and Ahtchi-Ali, F. (1989). “Properties of solid waste incinerator fly ash.” Journal of Geotechnical Engineering, 115(8), 1118–1133. Anniamma C., Andrew Farnans, and Lovely, K.M. (2013). “Effect of fly ash on the strength characteristics of soil.” International J. of Engineering Research, 6, 61-64. Kayser, C., Larkin, T., and Singhal, N. (2011). “Enhancement of the shear strength of wastewater residuals using industrial waste by-products.” J. Environ. Eng., 137(11), 1002–1011. N. Krishna Murthy, N. Aruna, A.V.Narasimha Rao, I.V.Ramana Reddy and M.Vijaya Sekhar Reddy, “Self Compacting Mortars of Binary and Ternary Cementitious Blending with Metakaolin and Fly Ash”, International Journal of Civil Engineering & Technology (IJCIET), Volume 4, Issue 2, 2013, pp. 369 - 384, ISSN Print: 0976 – 6308, ISSN Online: 0976 – 6316. Rushabh A. Shah and Jayeshkumar R. Pitroda, “Assessment of Sorptivity and Water Absorption of Mortar with Partial Replacement of Cement by Fly Ash (Class-F)”, International Journal of Civil Engineering & Technology (IJCIET), Volume 4, Issue 5, 2013, pp. 15 - 21, ISSN Print: 0976 – 6308, ISSN Online: 0976 – 6316. P.A. Ganeshwaran, Suji and S. Deepashri, “Evaluation of Mechanical Properties of Self Compacting Concrete with Manufactured Sand and Fly Ash” International Journal of Civil Engineering & Technology (IJCIET), Volume 3, Issue 2, 2012, pp. 60 - 69, ISSN Print: 0976 – 6308, ISSN Online: 0976 – 6316. 32

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