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Compaction and Shear behaviour of Low Plasticity Clayey Soils Treated by Crushed Lime Dr. Zahraa N. Rasheed Geotechnical Eng. Dept, Faculty of Eng, Koya University, Erbil, Iraq ABSTRACT Limestone is usually quarried for various constructional purposes. Cutting and dressing the stone generate huge amounts of by-product powder. The crushed limestone by-product creates serious environmental problems requiring an urgent solution to dispose of the huge quantities heaped in. This study aims to improve the shear behaviour of low plasticity clayey soils by the addition of different proportions of crushed lime as a soil stabilizer. Different percentages of the crushed limestone up to 20% by weight and passing sieve No.40, were added to the clay obtained from “Al-Fatha Formation - Koya, North of Iraq" to improve its characteristics for many earth work construction purposes. The results show increasing in the shear strength parameters, maximum dry density, and specific gravity with optimum lime percent of 10%. Furthermore, the results obtained from the standard compaction test show decreasing in the optimum moisture content in accordance to the optimum lime percent (10%). These results represent very important factor for improving the behaviour of low plasticity clayey soils that used as borrow materials for earth structure purposes. Keywords Compaction, Shear Behaviour, Clay Soils, Crushed Limestone, Cohesion, Angle of internal friction.

1. INTRODUCTION Modify the soil, expedite construction, and improve the strength and durability of the soil are the main purposes of stabilizing the soil to satisfy the engineering requirements (Attoh-Okine, 1995). Many types of stabilizers were used as soil additives to improve its engineering properties. A number of stabilizers depend on their chemical reactions with the soil elements in the presence of water such as lime, cement and fly ash (Azadegan et al., 2012; Ramadas et al., 2011). Other additives depend on their physical effects to improve soil properties such as geofiber and geogrid, (Alawaji, 2001). Adding to that stabilizer can be combined both of chemical and physical stabilization, for example, by using lime and geofiber or geotextile together (Chong and Kassim, 2014). Lime is the oldest traditional chemical stabilizer used for soil stabilization (Mallela et al., 2004). Addition of lime to expansive soils reduces swell potential and increases workability and strength (Bell, 1996). Lime columns or lime-soil columns were tried to stabilize expansive clays in situ (Rao 1984). It was reported that diffusion of lime is effective up to a radial distance of about 3 times the diameter of lime-soil column. Flocculation, cation exchange and pozzolonic action are responsible for the amelioration effects in lime-soil mixes. The lime content required to improve the physical properties of soils, which is the lime fixation point, varies between 3 to 10% depending on the type of soil. Lime-soil blends were reported to have developed substantial tensile strength also. B.R. Phanikumar, C. Amshumalini and R. Karthika, 2009 studied the effect of lime on engineering behaviour of expansive clays. The influence of lime on Free Swell Index (FSI), swell potential, swelling pressure, consolidation characteristics, compaction characteristics and strength behaviour were considered. Lime content was up to 6%. Swell potential and swelling pressure decreased with increase in lime content, but only up to 4% lime. Addition of lime beyond 4% resulted in increased swell potential and swelling pressure. Consolidation characteristics improved with increasing lime content as reflected in compression index, coefficient of consolidation and secondary consolidation. Compaction and strength characteristics improved up to 4% lime content. Al-Khashab and Al-Hayalee, 2008 studied the improvement of Mosul’s expansive clays, by the addition of crushed limestone. Different percentages of the crushed limestone were added up to 10% to the clay to reduce its expansiveness and improve its characteristics for many earth work construction. The test results showed reduction in the plasticity of the clay and significant decrease in the swelling properties.

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International Journal of Engineering Technology, Management and Applied Sciences

www.ijetmas.com June 2016, Volume 4, Issue 6, ISSN 2349-4476 This study represents an experimental assessment for the effect of different lime content up to 20% on the properties of a remolded low plasticity clayey soil predicted from Al-Fatha formation- Koya city in term of specific weight, compaction and shear strength. The obtained results represent very important factor for improving the behaviour of clayey soil as subsoil materials for foundations and roads, and as borrow materials in cases of embankment and dam core constructions. 2. TESTING PROGRAM Geotechnical laboratory tests were conducted at the soil mechanic laboratory, Koya University, according to ASTM "American Society for Testing and Materials". Grain size analysis of the tested soil was carried out according to ASTM D-422 for Particle-Size Analysis of Soils. Liquid Limit and Plastic Limit were carried out according to ASTM D-4138. Specific gravity test was carried out on virgin and contaminated soils according to ASTM D 854-00 – Standard Test for Specific Gravity of Soil Solids by Water Pycnometer. Compaction tests confirming ASTM D-698 for Laboratory Compaction Characteristics of Soil Using Standard Effort (600 KN-m/m3) for virgin and contaminated soils, while shear strength parameter was determined by direct shear tests on remolded samples obtained from compaction at optimum moisture content for each contamination percent in accordance with ASTM D-3080 for Direct Shear Test of Soils under Consolidated Drained Conditions.

% Finer

3. MATERIALS 3.1 Soil For the purpose of predicting the effect of adding of crushed lime on the behaviour of the clayey soil, the clayey soil samples were predicted from location belong to Al-Fatha formation-Koya, North Iraq especially from Haibat Sultan Mountain with coordinate (Latitude & Longitude lines) 36° 06′ 15″ North & 44° 39′ 25″ East. The soil samples were obtained at a depth (0.5-1.0) meter from ground surface. The analysis showed that the tested soil samples have specific gravity of 2.56. The grain size distribution of the soil based on the sieve and hydrometer analysis is shown in Figure 1. The percent of gravel was 4%, and the percent of sand was 20% while percent passing from sieve #200 was 76% (52.8% silt and 23.2% clay). 100.0 90.0 80.0 70.0 60.0 50.0 40.0 30.0 20.0 10.0 0.0 1.0000

0.1000

0.0100

0.0010

0.0001

Particle Dia. (mm)

Figure (1) Grain Size analysis of the tested soil (0% of lime) 3.2 Limestone Limestone is the most widely rock in Iraq and particularly in Kurdistan area, where it can be extensively used in constructional activities. Limestones are sedimentary bedded rocks, often containing many fossils. They are classed as organically and chemically formed, but the most abundant is usually of organic origin (Blyth, 1963). Shelly limestone is an organically formed rock in which fossil shell form a large part of its bulk. Limestone consists essentially of Calcium Carbonate, with which there is generally some magnesium carbonate and siliceous matter such as quartz grains. The limestone may be composed of four minerals, Calcite (CaC03) Aragonite, Dolomite (CaMg (C03)2) and Magnetite (MgC03) (Boynton, 1980). The chief

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www.ijetmas.com June 2016, Volume 4, Issue 6, ISSN 2349-4476 constituent of limestone is that the Calcium Carbonate (CaC03) has cleavage faces, well developed in three planes of 75° with each other. The hardness is effervesces with cold dilute hydrochloric acid (HC1). It has variable colours but the colour becomes white when it is pure (Field, 1955). The crushed limestone powder used through this study obtained from the waste of masonry factories. The grain size analysis for the crushed lime (Figure 2) show that about 100% of the crushed lime pass from sieve No.40 while 5% pass from sieve No.200, that mean the added lime fall within the grain size for the medium to fine sand. 99.6 99.4

% Finer

99.2 99 98.8 98.6 98.4 98.2 0.5

0.05 Particle Dia. (mm)

Figure (2) Grain Size analysis of lime 3.3 Soil classification In order to specify the type of the soil that used for the evaluation of the effect of crushed lime on the behaviour of the clayey soil, the soil sample were classified using the Unified Soil Classification System (USCS). The results obtained from the testing of untreated soil were used for the classification purpose. The liquid (Casgrande device) and plastic limit test for the untreated soil were developed in accordance to ASTM D 4138. The average plastic limits was 24% and the liquid limit for 25 blows were found to be equal to 42%, while the plasticity index was 18%. According to results obtained from grain size analysis, percent passing from sieve No. 200 = 76% which is more than 50% and that means it is a fine grain soil. Using the plasticity chart (Figure 3), the soil is classified as low plasticity clay “CL”.

Figure (3) Plasticity chart.

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www.ijetmas.com June 2016, Volume 4, Issue 6, ISSN 2349-4476 4. RESULTS 4.1 Specific gravity Specific gravity is the ratio of the mass of unit volume of soil at a stated temperature to the mass of the same volume of gas-free distilled water at a stated temperature. In order to predict the effect of adding different percent of lime on the behaviour of the treated soil, different percent of lime were added as percent of dry soil weight ranged from 0%-20%. Figure (4) shows the variation of specific gravity for treated soil, It can be noticed that the specific gravity Gs increases with the amount of crushed stone added up to 10%. It is believed that these changes in the physical properties of the clay partly resemble the same effect of clay stabilization by sand addition as the increase of sand in certain amount of soil, the percentage of clay within this amount will be reduced, and consequently, the properties will be changed (Al-Ashou et al, 1993). Furthermore at the adding of small amount of lime cause of change in the properties because of the effect of the presence of Ca++ ions. These ions initially combined with, or absorbed by clay, creating an increase in the flocculation tendency of the soil fluid (Bell, 1996). 3 2.95 2.9 2.85

Gs

2.8 2.75 2.7 2.65 2.6 2.55 2.5 0

5

10

15

% lime

20

Figure (4) Variation of Specific gravity with added % of lime

14.8 14.6 14.4 14.2 14 13.8 13.6 13.4

Max. Dry density (kg/cm3)

O.M.C %

4.2 Compaction The effect of the adding of crushed lime on the compaction behaviour of treated soil were predicted for two purposes, the first one is to follow the behaviour of the treated soil at different percent of treatment while the second one is to specify the optimum moisture content for each lime percent to be used for the purpose of evaluation of the shear strength parameters. Figures (5) and (6) show the variation of the optimum moisture content “O.M.C.” and maximum dry density at different lime percent ranged from 0% - 20%. The results show that the maximum dry density obtained at lime percent of 10 and the minimum moisture content predicted at the same percent of lime.

0

5

10

15

20

% lime

Figure (5) Variation of O.M.C with % lime.

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1730 1720 1710 1700 1690 1680 1670 1660 0

5

10

15

20

% lime

Figure (6) Variation of Max. Dry Density with % Lime.

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150

Horizontal Force (N)

Horizontal Force (N)

4.3 Direct Shear Test The direct shear device used to determine the shear strength parameter of treated compacted soil with different percent of crushed lime up to 15%. (i.e. angle of internal friction and cohesion). From the plot of the shear stress versus the horizontal displacement, the maximum shear stress is obtained for a specific vertical confining stress as shown in figures 7, 8, 9 and 10. After the test is run several times for various verticalconfining stresses (70 kN/m2, 138 kN/m2, 206 kN/m2), a plot of the maximum shear stresses versus the vertical (normal) confining stresses for each crushed lime percent were produced. From the plot, a straightline approximation of the Mohr-Coulomb failure envelope curve can be drawn, as a result the angle of friction and cohesion were obtained for added crushed lime percent up to 15% as shown in figures 11, 12, 13 and 14. As a conclusion from the predicated results from the direct shear test for the treated clay according to adding of different percent of crushed lime up to 15%, Figure (15) show the variation of soil cohesion verse the increase in the percent of crushed lime, while figure (16) show the variation of the angle of friction of the soil with percent of crushed lime. The results show increase in the soil cohesion and friction with optimum value of added crushed lime of 10%.

100 50 0

0

2

4

6

8

400 300 200 100 0

10

0

Horizontal Displacement 70 kPa

138 kPa

2

4

6

8

10

Horizantal Displacement (mm)

206 kPa

70 kPa

138 kPa

206 kPa

Figure (7) Variation of Horizontal Force with

Figure (8) Variation of Horizontal Force with

horizontal Displacement 0% of lime

horizontal Displacement 5% of lime

Horizontal Force (N)

Horizontal Force (N)

600 500 400 300 200 100 0 0

2

4

6

8

10

150 100 50 0 0

Horizantal Displacement (mm) 70 kPa

138 kPa

206 kPa

2

4

6

8

10

Horizantal Displacement (mm) 70 kPa

138 kPa

206 kPa

Figure (9) Variation of Horizontal Force with

Figure (10) Variation of Horizontal Force with

horizontal Displacement 10% of lime

horizontal Displacement 15% of lime

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International Journal of Engineering Technology, Management and Applied Sciences

30 25 20 15 10 5 0

y = 0.066x + 13.68

5

55

105

155

205

255

Shear Stress (kN/m2)

Shear Stress (kN/m2)

www.ijetmas.com June 2016, Volume 4, Issue 6, ISSN 2349-4476 40 30 y = 0.081x + 18.70

20 10 0 5

55

Normal Stress (kN/m2) 0% Lime

105

155

205

255

Normal Stress (kN/m2)

Linear (0% Lime)

% lime =5

Linear (% lime =5)

and Cohesion of Soil (0% lime)

and Cohesion of Soil (5% lime)

200 150

y = 0.603x + 24.36

100 50 0 5

55

105

155

205

255

Shear Stress (kN/m2)

Figure (12) Evaluation of Angle of Friction

Shear Stress (kN/m2)

Figure (11) Evaluation of Angle of Friction

50 40 y = 0.155x + 5.337

30 20 10 0 5

Normal Stress (kN/m2) % lime =10

55

105

155

205

255

Normal Stress (kN/m2)

Linear (% lime =10)

% lime =15

Linear (% lime =15)

and Cohesion of Soil (10% lime)

and Cohesion of Soil (15% lime)

30

35 30 25 20 15 10 5 0

ang;e of friction in degree

Figure (14) Evaluation of Angle of Friction

Cohesion kN/m2

Figure (13) Evaluation of Angle of Friction

25 20 15 10 5 0 0

5

10

15

% Lime

0

5

10

15

% Lime

Figure (15) Variation of the soil cohesion with

Figure (16) Variation of the friction angle with

% lime

% lime

5. CONCLUSION: 1. The results showed pronounced increase in the maximum dry density as the percent of crushed lime increase with optimum value of 10%, while the optimum moisture content decrease as the percent of lime increase, the behaviour represent important conclusion as the required amount of water decreased and the predicted dry density increase.

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Furthermore, results showed an increase in the parameters of shear strength (angle of friction and soil cohesion) with optimum crushed lime percent of 10%. The results show that the adding percent of lime has to be with improper amount in order to get the perfect improvement to the behaviour of the clayey soil. The behaviour of the treated clay effected by the grain size of the crushed lime and the presence of free Ca++ ions. The results withdrawn from this study represent very important factor for improving the behaviour of low plasticity clayey soils that used as borrow materials for earth structure purposes.

3. 4. 5.

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[15] [16] [17]

Al-Khashab, Mohammad Natheer, and Al-Hayalee, Mohammed Thafer, (2008) “Treatment of Expansive Clayey Soil with Crushed Limestone”, Uni of Technology, Tec Magaz, Vol. 26, No 3. Al-Ashou, M.O. and Al-Khashab, M.N. (1993) "Treatment of Expansive Clay with Potassium Chloride". Rafidian Engg. Journal, Mosul University, Vol. 2, pp.17-30. ASTM, (2004) “Annual Book of American Standards for Testing and Materials”, Part 8, Vol. 4. Bell, F.G. (1996) "Lime Stabilization of Clay Minerals and Soil", Engineering Geology 42, Dept. of Geology and Applied Geology, University of Natal, South Africa, pp. 223-237. Blyth, F.G.H (1963), "A Geology for Engineers". London, the English Language Book Society and Edward Arnold (Publishers) L.T.D. Field, R.M. (1955) "Geology", Collage Outline Series-Barnes and Noble Inc. New York 4th Edition. Kenneth A. Gutschick (1967), “Lime Stabilizes Poor Soils”, publication #C670163, the aberdeen group, all rights reserved. Roa, B.R. (1984), “A Study of Swelling Characteristics of and GPA Foundation Technique In Expansive Soils”, PhD Thesis Submitted to JN Technological University, Hyderabad, India. B.R. Phanikumar, C. Amshumalini and R. Karthika (2009), “Effect of Lime on Engineering Behaviour of Expansive Clays”, Indian Geotechnical Conference, IGC, Vol. 1, Guntur, India. Attoh-Okine, N.O., (1995), “Lime Treatment of Laterite Soils and Gravels-Revisited”, Constr. Build. Mater, 9(5): pp. 283-287. Azadegan, O., S.H. Jafari and J. Li, (2012), “Compaction Characteristics and Mechanical Properties of Lime/Cement Treated Granular Soils”, Electron. Journal Geotech. Eng., Vol. 17, pp. 2275-2284. Ramadas, T., N.D. Kumar and G. Yesuratnam, (2011), “Geotechnical Characteristics of Three Expansive Soils Treated with Lime and Flyash” Int. Journal of Earth Sci. Eng., 4: pp. 46-49. Alawaji, H.A., (2001), “Settlement and Bearing Capacity of Geogrid-Reinforced Sand over Collapsible Soil”, Geotext. Geomembranes, 19(2): pp. 75-88. Chong, S.Y. and K.A. Kassim, (2014), “Consolidation Characteristics of Lime Column and Geotextile Encapsulated Lime Column (GELC) Stabilized Pontian Marine Clay”, Electron. J. Geotech. Eng., 19A: pp. 129141. Mallela, J, P. Harold Von Quintus, K.L Smith and E. Consultants, (2004), “Consideration of Lime-Stabilized Layers in Mechanistic-Empirical Pavement Design”, The National Lime Association, Arlington, Virginia, USA. Boynton, R.S. (1980) "Chemistry and Technology of Lime and Limestone" .New York, Wiley-Interscience Publishers. Al-Ashou, M.O. and Al-Khashab, M.N. (1993) "Treatment of Expansive Clay with Potassium Chloride". Rafidian Engg. Journal, Mosul University, Vol. 2, pp.17-30.

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