INTERNATIONAL JOURNAL OF CIVIL AND STRUCTURAL ENGINEERING Volume 1, No 4, 2011

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1 Effect of marble dust on strength and durability of Rice husk ash stabilised expansive soil Akshaya Kumar Sabat 1, Radhikesh P. Nanda 2 1- Associate Professor, Department of Civil Engineering, ITER, SOA University, Bhubaneswar , India 2- Associate Professor, Department of Civil Engineering, NIT Durgapur, Durgapur , India akshayasabat@yahoo.co.in doi: /ijcser ABSTRACT This paper presents the results of a laboratory study undertaken to investigate the effect of Marble dusts on strength and durability of an expansive soil stabilized with optimum percentage of Rice Husk ash (RHA). The optimum percentage of RHA was found out be 10% based on Unconfined Compressive Strength (UCS) tests. Marble dust was added to RHA stabilized expansive soil up to 30%, by dry weight of the soil, at an increment of 5%. Compaction tests, UCS tests, Soaked California Bearing Ratio (CBR) tests, Swelling pressure tests and Durability tests were conducted on these samples after 7 days of curing. The UCS, and Soaked CBR of RHA-stabilized expansive soil increased up to 20% addition of Marble dust. Further addition of Marble dust had negative effects on these properties. The Maximum Dry Density(MDD) and Swelling pressure of expansive soil goes on decreasing and Optimum Moisture Content (OMC) goes on increasing irrespective of the percentage of addition of Marble dust to RHA stabilized expansive soil. From the Durability test results it was found that the addition of Marble dust had made the RHA stabilized expansive soil durable. For best stabilization effect the optimum proportion of Soil: Rice husk ash: Marble dust was found to be 70: 10: 20. Keywords: Rice husk ash, Marble dust, OMC, MDD, UCS, Soaked CBR, Durability. 1. Introduction Construction on expansive soil always creates a problem for civil engineers because of its peculiar cyclic swell shrink behavior. This type of soil swells when it comes in contact with water and shrinks when the water evaporates out. Because of this movement lightly loaded structures such as foundations, pavements, canal beds and linings and residential buildings founded on them are severely damaged (Chen, 1988). It has been estimated that the annual damage to civil engineering structures on expansive soil are $1000 million in USA, 150 million in UK and many billion pounds worldwide (Gourley et al., 1993).This soil occupies more than 20% of total soils of India. The clay mineral montmorillonite is mostly responsible for this type of nature of the soil. There are different methods of altering the nature of this soil to make it fit for construction, stabilization using industrial wastes is one of them. 939

2 Rice husks are the shells produced during de-husking operation of paddy, which varies from 20% (Mehta, 1986) to 23% (Della et al., 2002) by weight of the paddy. The rice husk is considered as a waste material and is being generally disposed of by dumping or burning in the boiler for processing paddy. The burning of rice husk generates about 20% of its weight as ash (Mehta, 1986). Silica is the main constituent of rice husk ash (RHA) and the quality (% of amorphous and unburnt carbon) depends upon the burning process (Nair et al., 2006). The RHA is defined as a pozzlanic material (ASTM C 168, ASTM 1997) due to its high amorphous silica content (Mehta, 1986). In India, the annual production of paddy is about 100 million tones, thereby generating more than 4 million tonnes of RHA (Ramakrishna and Kumar, 2008). Rice husk ash cannot be used alone for stabilization of soil due to lack of cementitious properties (Haji Ali et al., 1992). So it is used along with a binder like Lime, cement, lime sludge, Calcium chloride etc. for stabilization of soil (Muntohar and Hantoro, 2000; Haji Ali et al., 1992; Rama Krishna and Kumar, 2006; Basha et al., 2003; Chandra et al., 2005; Sharma et al., 2008). Marble dust are the wastes generated during marble cutting and polishing. Swami, 2002; Baser, 2009 and Palaniappan and Stalin, 2009 had studied the stabilizing effect of marble dust on engineering properties of expansive soil and has found varied success. The objective of this paper is to study the effect of Marble dust on Compaction, UCS, Soaked CBR, Swelling pressure and durability characteristics of an expansive soil stabilized with optimum percentage of Rice husk ash. 2. Materials The materials used in the experiments are expansive soil, Rice Husk Ash and Marble dust 2.1. Expansive Soil. The expansive soil used in the experimental work was brought from a place 10 km away from Bhubaneswar. The geotechnical properties of the expansive soil are: Sand size -18%, Silt size -26%, Clay size -56%, Specific Gravity Liquid Limit -60%, Plastic Limit-32%, Plasticity Index -28%, Shrinkage Limit- 11%,, OMC -21%, MDD- 16.1kN /m³, UCS- 60KN/m², Un-Soaked CBR =4.82%, Soaked CBR =1.98%, Swelling Pressure-128 kn/m Rice Husk Ash Processed Rice husk ash (RHA) was procured from a plant located at Odisha, India. It had SiO %, Al 2 O %, Fe 2 O 3-1 %, CaO %, and Specific Gravity-2.3 etc Marble dust 940

3 The Marble dust was obtained from a locally available marble cutting and polishing industry. The Marble dust contains SiO 2-6.2%, Fe 2 O 3-0.8%, Al 2 O 3-4.8% CaO-30.1% 3. Testing Procedure To find optimum percentage of RHA, for stabilization of expansive soil, RHA was varied from 5 percent to 20 percent by dry weight of soil in steps of 5 percent.standard Proctor Compaction tests, UCS tests, were conducted on these samples/mixes after 1 day of curing according to the relevant Indian Standard codes. For studying, the effect of Marble dust on expansive soil stabilized with optimum percentage of RHA, the Marble dust was added from 0 to 30% at an increment of 5%. After 7 days of curing periods in Humidity chamber at 34º C temperature and 97% humidity.standard Proctor tests, UCS tests, Soaked CBR tests, and Swelling Pressure tests were conducted on these samples according to relevant Indian Standard Codes. The durability of the mixes was investigated as per the following procedure. Three samples of UCS were cured for 7 days. After curing their height and weight were measured then immersed in water for 5 hours. After 5 hours of immersion, the samples were surface dried and their weight and height was recorded again. These samples were then dried in oven for 42 hours at 70 o C. Then they were cooled for one hour and weight and height of the samples were recorded, which constitutes one cycle. The samples survived after 12 cycles were tested for UCS. The durability was measured in terms of a ratio (strength ratio) of UCS of soil after 12 cycles of wetting and drying to that of original sample without any cycle of wetting and drying. 4. Analysis of Test Results Figure 1 shows the variation of MDD of expansive soil with addition of different percentage of Rice husk ash. MDD goes on decreasing irrespective of the increase in percentage of addition of RHA. MDD of soil decreases to 15.5 kn/m 3 from 16.1 kn/m 3 when 20% RHA was added to expansive soil, which is attributed to the lower value of specific gravity(2.3) of Rice Husk Ash as compared to higher specific gravity(2.61) of expansive soil (Haji Ali et al.1992 ) 941

4 Figure 1: Variation of MDD with % of RHA The OMC goes on increasing irrespective of percentage addition of RHA. The OMC increases to a value of 23 % from 21% when 20% RHA was added to expansive soil. The increase in the optimum moisture content may be caused by the absorption of water by the RHA (Haji Ali et al., 1992). Figure 2: Variation of OMC with % of RHA The results of UCS tests on expansive soil treated with different percentage of RHA have been shown in Fig. 2. By increasing the percentage of addition of RHA the UCS of soil goes on increasing up to 10% addition of RHA, further addition of RHA, decreases the UCS of the expansive soil. The UCS of soil increases to 72kN/m² from 60 kn/m² of neat soil, when 10 per cent RHA was added, this is because of the frictional resistance from RHA in addition to the cohesion from expansive soil. Reduction in UCS occurs due to reduction in cohesion because of the reduction in expansive soil content. 942

5 Figure 3: Variation of UCS with % of RHA Figure 4: Variation of MDD of RHA stabilized soil with % of Marble Dust Figure 5: Variation of OMC of RHA stabilized soil with % of Marble Dust 943

6 The variation of MDD of the RHA stabilized expansive soil treated with different percentage of Marble dust has been shown in Fig.4.It is observed that by addition of 10% of RHA, the MDD of soil decreases to kn/m 3 from 16.1 kn/m 3. With increase in percentage of Marble dust the MDD of soil further goes on decreasing, decreases to 14.9 kn/m 3 from 15.85kN/m 3 when 30 % Marble dust was added. The variation of OMC of the RHA stabilized expansive soil treated with different percentage of Marble dust has been shown in Fig.5. The OMC increases to 21.8% when 10% RHA was added to expansive soil. With increase in different percentage of Marble dust the OMC goes on increasing, increases to a value of 24.6% when 30% Marble dust was added to expansive soil stabilized with 10% Rice husk ash. Figure 6: Variation of UCS of RHA stabilized soil with % of Marble Dust The results of UCS tests on RHA stabilized expansive soil treated with different percentage of Marble dust has been shown in Fig.6.It is observed that by addition of 10% RHA the UCS of soil increases to 72 kn/m 2. Addition of different percentage of Marble dust has considerable effects on the UCS of the RHA stabilized expansive soil. With increase in percentage of Marble dust the UCS of soil further goes on increasing, increases to 197 kn/m 2 from 72kN/m 2 when 20 % Marble dust was added, further addition of Marble dust decreases the UCS of the soil. The UCS of the soil decreases to 168kN/m 2 when 30% Marble dust was added to expansive soil stabilized with 10% Rice husk ash. The UCS had the highest value when the percentage of Marble dust was 20%. There is a 228 % increase in UCS of the virgin soil by the combined effect of RHA and Marble dust. The reason of this effect is the pozzolanic reactions of Lime present in Marble dust with the amorphous silica and Alumina present in soil and RHA. After 20% addition of Marble dust,the strength decreases because of the availability of extra Lime to react with the insufficient amorphous silica and Alumina present in soil and RHA, which results in carbonation reaction and strength decreases. 944

7 Figure 7: Variation of Soaked CBR of RHA stabilized soil with % of Marble Dust The results of soaked CBR tests on RHA stabilized expansive soil treated with different percentage of Marble dust has been shown in Fig.7.It is observed that by addition of 10% RHA the soaked CBR of soil increases to 2.6% from 1.98%. With increase in different percentage of Marble dust the soaked CBR of soil further goes on increasing, increases to 7.8% from 2.6% when 20% Marble dust was added, further addition of Marble dust decreases the soaked CBR of the soil. The soaked CBR of the soil decreases to 6.5% when 30 % Marble dust was added to expansive soil stabilized with 10% Rice husk ash. The soaked CBR attains the highest value when the percentage of Marble dust was 20%. There is a 293% increase in Soaked CBR of the virgin soil by the combined effect of RHA and Marble dust.the reasons are same as discussed in UCS test results. Figure 8: Variation of Swelling pressure of RHA stabilized soil with % of Marble Dust 945

8 The results of swelling pressure tests on RHA stabilized expansive soil treated with different percentage of Marble dust has been shown in Fig.8.It is observed that by addition of 10% RHA, the swelling pressure of soil decreases to112 kn/m 2. The reason of which is the decrease in plasticity characteristics of soil due to reduction in clay content of soil because of replacement of clay with RHA. By the addition of different percentage of Marble dust the swelling pressure of soil goes on decreasing, decreases to zero from 112kN/m 2 when 25 % Marble dust was added. The swelling pressure of the soil decreases to 19kN/m 2 when 20% Marble dust was added to expansive soil stabilized with 10% Rice husk ash, the swelling pressure which will not create any problem with the structures to be founded on it. Because of the pozzolanic reaction of lime present in Marble dust with the amorphous silica and Alumina present in soil and RHA a strong inter-particle bond develops, this cementing bond offers great resistance to swelling and also does not allow the water to escape from soil to induce shrinkage. The effects of marble dust on durability of different samples of RHA stabilized expansive soil are summarized in Table 1 given below. The soil: RHA mix of 90:10 could not survive the 12 Wet-Dry cycles due to lack of any binder. The other samples survived. The samples were not much affected by wet-dry cycle by addition of marble dust because of the strong bond developed by the pozzolanic reaction between lime present in Marble dust with the amorphous silica and Alumina present in soil and RHA. The strength ratio was highest (0.98) with the sample having Soil : RHA : Marble dust ::70:10:20 which is the optimum proportion. Table 1: Durability characteristics of RHA and RHA-Marble dust stabilized expansive soil Mix Mix Proportion A B A/B REMARKS No. 1 90S+10R+0M Could not survived 12 Wet Dry Cycle 2 85S+10R+5M S+10R+10M S+10R+15M S+10R+20M S+10R+25M S+10R+30M S = Expansive soil ( %,) R = RHA ( % )and M = Marble dust( %) A= UCS of specimen moist cured for 7 days and subjected to 12 Wet-Dry cycles B= UCS of specimen moist cured for 7 days 5. Conclusions Following conclusions are drawn from the study 946

9 The optimum percentage of RHA in stabilization of expansive soil is found out be 10%. The MDD goes on decreasing and OMC goes on increasing irrespective of the percentage of addition of Marble dust to RHA stabilized expansive soil. The UCS of the RHA stabilized expansive soil increased up to 20% addition of Marble dust. Further addition of Marble dust decreased the UCS of the expansive soil. There is 228 % increase in UCS of the virgin soil. The Soaked CBR of the RHA stabilized expansive soil increased up to 20% addition of Marble dust. Further addition of Marble dust decreased the soaked CBR of the expansive soil. There is 293% increase in Soaked CBR of the virgin soil. The swelling pressure of the expansive soil goes on decreasing irrespective of the percentage of addition of Marble dust to RHA stabilized expansive soil. The swelling pressure was 112kN/m 2 when the percentage of Marble dust was 0 % and Zero when Marble dust was 25%. The Swelling Pressure of the soil decreased to 19 kn/m 2 when 20% Marble dust was added to expansive soil stabilized with 10% Rice husk ash, the swelling pressure which will not create any problem with the structures to be founded on it. The RHA stabilized expansive soil could not survived the durability test. Addition of Marble dust makes the RHA stabilized expansive soil a durable one, the RHA stabilized soil is least affected by wet-dry cycle when 20% Marble dust was added. For best stabilization effect, the optimum proportion of Soil: Rice husk ash: Marble dust was found to be 70: 10: References 1. Başer, O., 2009, Stabilization of expansive soils using waste marble dust, Master of Science thesis submitted to Civil Engineering Department, Middle East,Technical University 2. Basha, A. M., Hashim, R. and Muntohar, A. S., 2003, Effect of cement - rice husk ash on the plasticity and compaction of soil, Electronic J. Geotechnical Engineering. Vol.8, Bundle A. 3. Chandra, S., Kumar, S. and Anand, R. K., 2005 Soil stabilization with rice husk ash and lime sludge. Indian Highways,.33(5), pp., Chen, F. H., 1988, Foundations on expansive soils, Chen & Associates, Elsevier Publications, U.S.A. 5. Della, V.P., Ku hn, I., and Hotza, D., 2002 Rice husk ash as an alternate source for active silica production, Materials Letters, 57, pp

10 6. Gourley, C. S., Newill, D., and Shreiner, H. D., 1993, Expansive soils: TRL s research strategy. Proc., 1st Int. Symp. on Engineering Characteristics of Arid Soils 7. Haji Ali, F., Adnan, A. and Choy, C. K., 1992, Geotechnical properties of a chemically stabilized soil from Malaysia with rice husk ash as an additive, Geotechnical and Geological Engineering,10, pp Mehta, P. K., 1986, Concrete structure, properties and materials, Prentice- Hall, Englewood Cliffs, N.J. 9. Muntohar, A. S. and Hantoro, G., Influence of Rice Husk Ash and lime on engineering properties of a clayey subgrade, Electronic Journal of Geotechnical engineering, 5, pp Nair, D. G., Jagadish, K. S. and Fraaim, A., 2006,. Reactive pozzolanas from rice husk ash: An alternative to cement for rural housing. Cement and Concrete Research, 36, pp Nelson, J. D. and Miller, D. J., 1992, Expansive Soils: Problem and Practice in Foundation and Pavement Engineering, Wiley, New York, 12. Palaniappan, K. A. and Stalin, V. K., 2009, Utility effect of solid wastes in problematic soils International Journal of Engineering Research and Industrial. Applications. 2(1), pp Payá, J., Monzó, J., Borrachero, M. V., Mellado, A. and Ordoñez, L. M., 2001, Determination of amorphous silica in rice husk ash by rapid analytical method. Cement and Concrete Research, 31, pp Ramakrishna, A.N. and Pradeep Kumar, A.V., 2006, Stabilisation of black cotton soil using rice husk ash and cement, National conference on Civil Engineering meeting the challenges of tomorrow, GND Engineering college, Ludhiana, pp Ramakrishna, A.N. and Pradeep Kumar, A.V., 2008, Effect of moisture content on strength behaviour of BC soil-rice husk-lime mixes. Indian Highways, 36(1), pp Sharma, S.R., Phani Kumar, B.R. and Rao B.V., 2008, Engineering behaviour of a remolded expansive clay blended with lime, calcium chloride and Rice- husk ash. ASCE Journal of Materials in Civil Engineering, 20( 8), pp Swami, B. L., 2002, Feasibility study of marble dust in highway sector, Highway Research Bulletin, 67, December, pp