Effects on p h behaviour of expansive and non expansive soils contaminated with acids and alkalis
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This document examines the effects of acidic and alkaline contamination on the pH behavior of expansive and non-expansive soils, specifically black cotton soil, red earth, and shedi soil. Results indicate that the addition of calcium carbonate and magnesium carbonate increases pH levels, while contamination with sulfuric and phosphoric acids significantly decreases pH, with sulfuric acid causing a greater reduction. The study highlights the importance of understanding soil chemistry for effective soil management, especially in contaminated environments.
![IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
__________________________________________________________________________________________
Volume: 03 Special Issue: 06 | May-2014 | RRDCE - 2014, Available @ http://www.ijret.org 61
EFFECTS ON pH BEHAVIOUR OF EXPANSIVE AND NON EXPANSIVE
SOILS CONTAMINATED WITH ACIDS AND ALKALIS
Venkataraja Mohan S.D1
, Ramesh H.N2
1
Professor Dept of Civil Engineering, Dr.Ambedkar Institute of Technology, Bangalore-56, India
2
Professor, Soil Mechanics and Foundation Division, Department of Civil Engineering, UVCE, Bangalore University,
Bangalore-56, India
Abstract
The acidic or alkaline characteristics of a soil sample can be quantitatively expressed by hydrogen ion-activity commonly designated
as pH. The hydrogen-ion concentration of soil water solution is of interest in problems involving grouting in weak rocks, soil
stabilization processes using lime and resinous materials, corrosion of metals in contact with soils and reclamation of marine soils.
The pH value also helps in interpreting some of the soil chemical tests. Several factors, soil-water ratio, soluble salts concentration,
Carbon dioxide pressure, exchangeable cations and temperature affect the pH value of a particular soil sample. With the dilution of
soil suspension, its pH increases. Increase in salt concentration, in general, decreases the pH. A definite relationship exists between
Carbon dioxide pressure of soil air and pH, for example, the pH of calcareous is reduced in proportion to the logarithm of Carbon
dioxide pressure of soil air. In alkaline soils, the pH is principally influenced by exchangeable cat ions. With increase in
temperature, pH decreases. In the present study Attempts were made to study the pH soils treated with optimum percent of alkalis and
contaminated with one normal acids. Expansive soil Black cotton soil and non expansive soils Red Earth and Shedi soil are treated
individually with optimum percent of alkalis CaCO3 and MgCO3 and contaminated with 1N H2SO4 and 1N H3PO4 separately. Results
of the study indicate that the evaluation factors associated with soil pH therefore are based on the full consideration of the soil
constituents and not on pH value alone.
Keywords: pH, Hydrogen ion concentration, alkalization, acidification and cation exchange.
-----------------------------------------------------------------------***-----------------------------------------------------------------------
1. INTRODUCTION
Expansive soils are found in arid and semiarid regions of the
world where the annual evaporation exceeds precipitation.
Hot climate and poor drainage conditions are usually
associated with the formation of these soils. The color of these
soils varies from deep black to grey and sometimes even
reddish to yellowish. In India, these soils are generally called
black cotton soil and covers 25% of total land mass. The
major mineral present is montmorillonite and composed of
units made of two silica tetrahedral sheets with a central
alumina octahedral sheet. The tetrahedral and octahedral
sheets are combined so that the tips of the tetrahedrons of each
silica sheet and one of the hydroxyl layers of the octahedral
sheet form a common layer. The atoms are common to both
the tetrahedral and octahedral layer become oxygens instead
of hydroxyls. The layers are continuous and are stacked one
above the other. Exchangeable cations occur between the
silicate layers. They tend to occur in equidimensional,
extremely thin flake-shaped units and are relatively readily
dispersible in water down to extremely small particle sizes.
Montmorillionites experience large volume changes upon
exposure to climatic change and chemical contamination; they
shrink upon drying accompanied by cracking and swell when
water comes in contact exerting enormous pressures on the
structure. Since black cotton soils cannot be avoided, their
properties are altered by many ways like mechanical, thermal,
chemical, Electrical or combined and other means to make
acceptable or rejected on contamination. The index and
engineering properties of the ground gets modified in the
vicinity of the industrial pants mainly as a result of
contamination by the industrial wastes disposed. The major
sources are the disposal of industrial water and accidental
spillage of chemicals during the course of industrial
operations. The leakage of industrial effluent in to subsoil
directly affects the use and stability of the supported structure.
Alkali at lower concentration can cause changes to changes in
the soil structure; Mitchel [1]. Also the presence of alumina
along with alkali on the clay alkali interaction is unknown.
The sand or silty loam essentially forms the natural ground at
Bangalore, Karnataka State, India covers 10-15% of land mass
called as Red Earth. The non expansive soil has its kaolin
group of minerals in which the two layered kaolinite mineral
is present; however the major mineral present is quartz. The
basic structure unit consists of Gibbsite series (with aluminum
atoms at their centers) joined to the silica sheets through the
unbalanced oxygen atoms at the apexes of the silica. The
mineral thus is not readily dispersible in water into extremely
small units. In general, the poorly crystallized kaolinite occurs](https://image.slidesharecdn.com/effectsonphbehaviourofexpansiveandnonexpansivesoilscontaminatedwithacidsandalkalis-140824231317-phpapp01/85/Effects-on-p-h-behaviour-of-expansive-and-non-expansive-soils-contaminated-with-acids-and-alkalis-1-320.jpg)
![IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
_______________________________________________________________________________________
Volume: 03 Special Issue: 06 | May-2014 | RRDCE - 2014, Available @ http://www.ijret.org 62
in less distinct hexagonal flake-shaped masses than the will-
crystallized variety, and the particle sizes is generally smaller.
Laterites (Shedi soil deposits) are the ferruginous deposit of
vesicular unstratified structure, occurring not far below the
surface and have long been known in India where they occupy
large areas of Deccan Peninsula. They are the products of
intense sub aerial rock weathering whose Fe and /or Al
content is higher and Si content is lower than in many
kaolinised parent rocks. They consist predominantly of
mineral assemblage of goethite, aluminum hydroxide,
kaolinite minerals and quartz. Their upper stratum can be
converted into lateritic soils by soils forming process. A
laterite formation in general consists of top hardened vesicular
layer followed by Lithomarge clay layer over the weathered
residual soil and parent rock.
Extensive damage to the floors, pavements and foundations of
a light industrial building in a fertilizer plant in Kerala State
was reported by Sridharan [2], Rao and Sridharan [3]. Severe
damage occurred to the interconnecting pipes of a Phosphoric
acid tank in particular and also to the adjacent building due to
differential movements between pump and acid tank
foundations of fertilizer plant in Calgary, Canada was reported
by Joshi [4]. Decrease in shear strength of Black cotton soil on
account of reduction in diffuse layer thickness due to increase
in electrolyte concentration is reported by Sivapullaiah [5]. A
similar case of accidental spillage of highly concentrated
caustic soda solution as a result of spillage from cracked
drains in an industrial establishment in Tema, Ghana caused
considerable structural damage to a light industrial building in
the factory, in addition to localized subsidence of the affected
area is reported by Kumapley and Ishola [6]. The effect of
hydroxides on the properties some soils is well known: Ingles
[7] [10].
Anand J Puppala, [8] in his investigation on sulfate heave
mechanisms in chemical treated kaolinitc and illitic clay
observed that the increase in curing temperature enhanced the
unconfined compressive strength properties of lime and
cement treated soils. A strength decrement of 82% changing
the limestone rich soil into a weak soil due to splash from a
Sulphuric acid(pH<1) manufacturing factory in Al-Kaim of
North western Iraq was reported by Raid R. AL-Omari [9].
In this investigation an attempt is made to study the effect of
acids and alkalis separately on variation of pH behaviour of a
Black cotton soil, Red Earth and Shedi soil individually
contaminated with acids.
2. MATERIALS USED
The Black Cotton soil is obtained from Davanagere district in
Karnataka state of India. This is a residual soil and is
collected at a depth of one meter below the natural ground
surface. The soil was air dried and passed through IS sieve
425 microns and oven dried before being used for
investigation. It is classified as “CH” group as per IS
classification (1970). The physical and chemical properties of
Black Cotton soil have been listed in table 1 and 2
respectively.
Table -1 Physical Properties of Black Cotton Soil
Table -2: Chemical Analysis of Black Cotton soil
The Red Earth was collected at a depth of 1.5 meters at a test
pit dug for the proposed Bio-park at the Bangalore University
campus, Jnanabharathi. It was air dried and the soil sample for
the studies were taken from the collected soil by quartering to
ensure uniformity and pulverized and sieved through IS 425
micron sieve before using. The soil is a typical non-expansive
clayey soil. The Physical Properties of Red Earth are shown in
Table 3. Also the chemical composition of oven dried Red
earth was analyzed as per the standards methods and is
presented in table 4.
Color Black
Specific gravity 2.64
Fine sand 9%
Silt 31%
Clay 60%
Liquid limit 77%
Plastic limit 30.75%
Plasticity Index 49.85%
Shrinkage Limit 8.3%
Optimum moisture Content 33.7%
Maximum dry density 13.8 kPa
Unconfined Compressive strength 299 kPa
Coefficient of permeability 1.796X10-9
m/sec
Free swell Index 86%
Coefficient of Consolidation Cv 1.2X10-2
mm2
/sec
Compression Index Cc 0.09 cm2
/kg
Chemical composition Percentage
Silica (SiO2) 52.85
Alumina(Al2O3) 12.24
Ferric Oxide(Fe2O3) 8.04
Calcium Oxide(CaO) 6.01
Magnesium Oxide(Mgo) 2.94
Titanium Dioxide(Ti O2) 0.24
Potassium Oxide (K2O) 0.48
Sodium Oxide (N2O) 0.26
Loss of ignition 16.18](https://image.slidesharecdn.com/effectsonphbehaviourofexpansiveandnonexpansivesoilscontaminatedwithacidsandalkalis-140824231317-phpapp01/85/Effects-on-p-h-behaviour-of-expansive-and-non-expansive-soils-contaminated-with-acids-and-alkalis-2-320.jpg)
![IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
__________________________________________________________________________________________
Volume: 03 Special Issue: 06 | May-2014 | RRDCE - 2014, Available @ http://www.ijret.org 65
3.5 Effect of CaCO3 and MgCO3 on Shedi soil
Increase with the various percentages of Calcium Carbonate
and Magnesium Carbonate has successively increased the pH
of the Shed soil. However the increase in pH with the increase
in percentage Magnesium Carbonate is more compared to
increase in pH with percentage Calcium Carbonate due to soil
alkali interaction in the presence of water in which hydrogen
ion concentration increases significantly. The variations are
shown in figures 5 and 6.
Chart 5 Variation of pH with % of CaCO3 and 1N acids
3.6 Effect of 1N H2SO4 and 1N H3PO4 on Shedi soil
Alkalis treated soils contaminated with 1N H3PO4 and 1N
H2SO4 respectively showed drastic decrease in pH. However
the decrease in pH by 1N H2SO4 for CaCO3 treated soil is
observed more than that for MgCO3 treated Shedi soil
contaminated with1N H3PO4. The decrease in pH indicates the
higher acidification of soil due to increase in Hydrogen ion
concentration in soil- alkali-acid mixture followed with
immediate soil-alkali-acid interaction in which formation of
sulphate compounds takes the role of increasing the Hydrogen
ion concentration. Shedi soil alone contaminated with 1N
H2SO4 and1N H3PO4 showed significant decrease in pH. The
decrease with 1N H2SO4 more is compared to decrease in pH
with 1N H3PO4. 1N H2SO4 is the strong acid compared to 1N
H3PO4 and hence the maximum decrease in pH is noticed. The
variations are shown in figures 5 and 6.
Chart 6 Variation of pH with % of MgCO3 and 1N acids
4. CONCLUSIONS
1. Magnesium carbonate has resulted in more alkalization of
Black cotton soil and Shedi soil equally, compared to
alkalization of Red Earth indicating high pH.
2. The cation exchange phenomena is more with increase in
Magnesium Carbonate at all percentages compared to increase
in Calcium Carbonate at all percentages for all the three soils
inferring more hydrogen ion activity .
3. The increase or decrease in pH for soil alone treated with
CaCO3 and MgCO3 separately and again for the soil alone
contaminated with 1N H2SO4 and 1N H3PO4 are due to
Physical properties and chemical analysis of the individual
soil
4. Significant acidification is resulted in all the three soils due
to 1N H2SO4 contamination rather than contamination due to
1N H3PO4 indicating sudden low pH.
5. Acidic Soils showing the pH value between 1 to 2 in pH
Scale determines the amount of lime to be added to raise its
pH for any Engineering applications.
ACKNOWLEDGEMENTS
The authors acknowledge the PVP welfare Trust, Bangalore,
for carrying out the research work at PhD level at Bangalore
University.
RFERENCES
[1]. Mitchell,J.K. (1993) Fundamentals of Soil Behavior, John
Wiley, New York.
[2]. Sridharan A, Nagaraj T.S and Shivapullaiah P.V (1981)
Heaving of Soil due to Acid Contamination, Proceedings of
XI ICSMFE, Stockholm, Vol.2:.383-386.
[3]. Rao, S.M. and Sridharan,A.(1985) Mechanism controlling
the volume change behaviour of kaolinite, Clays and Clay
Minerals, 33(4), 323-328.
[4]. Joshi R.C., Pan X and Lohita P. (1994) Volume Change in
Calcareous Soils due to Phosphoric Acid Contamination,](https://image.slidesharecdn.com/effectsonphbehaviourofexpansiveandnonexpansivesoilscontaminatedwithacidsandalkalis-140824231317-phpapp01/85/Effects-on-p-h-behaviour-of-expansive-and-non-expansive-soils-contaminated-with-acids-and-alkalis-5-320.jpg)
![IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
_______________________________________________________________________________________
Volume: 03 Special Issue: 06 | May-2014 | RRDCE - 2014, Available @ http://www.ijret.org 66
Proceedings of the XII ICSMFE, New Delhi, Vol.4: 1569-
1574.
[5]. Sivapullaiah P.V., Sridharan A. and Vijaya Bhaskar Raju
K. (1994) Role of Electrolytes on the Shear Strength of Clayey
Soil, Proceedings of IGC, Warangal: 199-202.
[6]. Kumpaley N. K. and Ishol A. (1985) The effect of
Chemical Contamination on Soil Strength, Proceedings of XI
ICSMFE, Sanfransicso, and Vol.3: 1199-1201.
[7]. Ingles, O.G. (1970) Mechanisms of Clay Stabilization
with inorganic acids and alkalis, Australian Journal of Soil
Research., 8, 81-95.
[8]. Anand J Puppala, (2006), “Sulfate Heave Mechanisms in
Chemical Treated Clay” Proceedings of Indian Geotechnical
Conference-2006, Vol: 1, pp.95-104.
[9]. Raid, R., Al-Omari Waleed K. Mohammed., Isam H.
Nashaat., and Oday M. Kaseer, (2007), “Effect of Sulphuric
and Phophoric Acids on the Behaviour of a Limestone
Foundation,” Indian Geotechnical Journal, Vol. 37, pp. 263-
282.
[10]. Zhao, H., Low, P.F., and Bradford, J.M. (1991), “Effect
of pH and Electrolyte concentration on particle interaction in
three Homoionic Sodium soil Clay Suspensions,” Soil
Science, Vol.151, No.3, pp.196-207.](https://image.slidesharecdn.com/effectsonphbehaviourofexpansiveandnonexpansivesoilscontaminatedwithacidsandalkalis-140824231317-phpapp01/85/Effects-on-p-h-behaviour-of-expansive-and-non-expansive-soils-contaminated-with-acids-and-alkalis-6-320.jpg)
Effects on p h behaviour of expansive and non expansive soils contaminated with acids and alkalis
- 1. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308 __________________________________________________________________________________________ Volume: 03 Special Issue: 06 | May-2014 | RRDCE - 2014, Available @ http://www.ijret.org 61 EFFECTS ON pH BEHAVIOUR OF EXPANSIVE AND NON EXPANSIVE SOILS CONTAMINATED WITH ACIDS AND ALKALIS Venkataraja Mohan S.D1 , Ramesh H.N2 1 Professor Dept of Civil Engineering, Dr.Ambedkar Institute of Technology, Bangalore-56, India 2 Professor, Soil Mechanics and Foundation Division, Department of Civil Engineering, UVCE, Bangalore University, Bangalore-56, India Abstract The acidic or alkaline characteristics of a soil sample can be quantitatively expressed by hydrogen ion-activity commonly designated as pH. The hydrogen-ion concentration of soil water solution is of interest in problems involving grouting in weak rocks, soil stabilization processes using lime and resinous materials, corrosion of metals in contact with soils and reclamation of marine soils. The pH value also helps in interpreting some of the soil chemical tests. Several factors, soil-water ratio, soluble salts concentration, Carbon dioxide pressure, exchangeable cations and temperature affect the pH value of a particular soil sample. With the dilution of soil suspension, its pH increases. Increase in salt concentration, in general, decreases the pH. A definite relationship exists between Carbon dioxide pressure of soil air and pH, for example, the pH of calcareous is reduced in proportion to the logarithm of Carbon dioxide pressure of soil air. In alkaline soils, the pH is principally influenced by exchangeable cat ions. With increase in temperature, pH decreases. In the present study Attempts were made to study the pH soils treated with optimum percent of alkalis and contaminated with one normal acids. Expansive soil Black cotton soil and non expansive soils Red Earth and Shedi soil are treated individually with optimum percent of alkalis CaCO3 and MgCO3 and contaminated with 1N H2SO4 and 1N H3PO4 separately. Results of the study indicate that the evaluation factors associated with soil pH therefore are based on the full consideration of the soil constituents and not on pH value alone. Keywords: pH, Hydrogen ion concentration, alkalization, acidification and cation exchange. -----------------------------------------------------------------------***----------------------------------------------------------------------- 1. INTRODUCTION Expansive soils are found in arid and semiarid regions of the world where the annual evaporation exceeds precipitation. Hot climate and poor drainage conditions are usually associated with the formation of these soils. The color of these soils varies from deep black to grey and sometimes even reddish to yellowish. In India, these soils are generally called black cotton soil and covers 25% of total land mass. The major mineral present is montmorillonite and composed of units made of two silica tetrahedral sheets with a central alumina octahedral sheet. The tetrahedral and octahedral sheets are combined so that the tips of the tetrahedrons of each silica sheet and one of the hydroxyl layers of the octahedral sheet form a common layer. The atoms are common to both the tetrahedral and octahedral layer become oxygens instead of hydroxyls. The layers are continuous and are stacked one above the other. Exchangeable cations occur between the silicate layers. They tend to occur in equidimensional, extremely thin flake-shaped units and are relatively readily dispersible in water down to extremely small particle sizes. Montmorillionites experience large volume changes upon exposure to climatic change and chemical contamination; they shrink upon drying accompanied by cracking and swell when water comes in contact exerting enormous pressures on the structure. Since black cotton soils cannot be avoided, their properties are altered by many ways like mechanical, thermal, chemical, Electrical or combined and other means to make acceptable or rejected on contamination. The index and engineering properties of the ground gets modified in the vicinity of the industrial pants mainly as a result of contamination by the industrial wastes disposed. The major sources are the disposal of industrial water and accidental spillage of chemicals during the course of industrial operations. The leakage of industrial effluent in to subsoil directly affects the use and stability of the supported structure. Alkali at lower concentration can cause changes to changes in the soil structure; Mitchel [1]. Also the presence of alumina along with alkali on the clay alkali interaction is unknown. The sand or silty loam essentially forms the natural ground at Bangalore, Karnataka State, India covers 10-15% of land mass called as Red Earth. The non expansive soil has its kaolin group of minerals in which the two layered kaolinite mineral is present; however the major mineral present is quartz. The basic structure unit consists of Gibbsite series (with aluminum atoms at their centers) joined to the silica sheets through the unbalanced oxygen atoms at the apexes of the silica. The mineral thus is not readily dispersible in water into extremely small units. In general, the poorly crystallized kaolinite occurs
- 2. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308 _______________________________________________________________________________________ Volume: 03 Special Issue: 06 | May-2014 | RRDCE - 2014, Available @ http://www.ijret.org 62 in less distinct hexagonal flake-shaped masses than the will- crystallized variety, and the particle sizes is generally smaller. Laterites (Shedi soil deposits) are the ferruginous deposit of vesicular unstratified structure, occurring not far below the surface and have long been known in India where they occupy large areas of Deccan Peninsula. They are the products of intense sub aerial rock weathering whose Fe and /or Al content is higher and Si content is lower than in many kaolinised parent rocks. They consist predominantly of mineral assemblage of goethite, aluminum hydroxide, kaolinite minerals and quartz. Their upper stratum can be converted into lateritic soils by soils forming process. A laterite formation in general consists of top hardened vesicular layer followed by Lithomarge clay layer over the weathered residual soil and parent rock. Extensive damage to the floors, pavements and foundations of a light industrial building in a fertilizer plant in Kerala State was reported by Sridharan [2], Rao and Sridharan [3]. Severe damage occurred to the interconnecting pipes of a Phosphoric acid tank in particular and also to the adjacent building due to differential movements between pump and acid tank foundations of fertilizer plant in Calgary, Canada was reported by Joshi [4]. Decrease in shear strength of Black cotton soil on account of reduction in diffuse layer thickness due to increase in electrolyte concentration is reported by Sivapullaiah [5]. A similar case of accidental spillage of highly concentrated caustic soda solution as a result of spillage from cracked drains in an industrial establishment in Tema, Ghana caused considerable structural damage to a light industrial building in the factory, in addition to localized subsidence of the affected area is reported by Kumapley and Ishola [6]. The effect of hydroxides on the properties some soils is well known: Ingles [7] [10]. Anand J Puppala, [8] in his investigation on sulfate heave mechanisms in chemical treated kaolinitc and illitic clay observed that the increase in curing temperature enhanced the unconfined compressive strength properties of lime and cement treated soils. A strength decrement of 82% changing the limestone rich soil into a weak soil due to splash from a Sulphuric acid(pH<1) manufacturing factory in Al-Kaim of North western Iraq was reported by Raid R. AL-Omari [9]. In this investigation an attempt is made to study the effect of acids and alkalis separately on variation of pH behaviour of a Black cotton soil, Red Earth and Shedi soil individually contaminated with acids. 2. MATERIALS USED The Black Cotton soil is obtained from Davanagere district in Karnataka state of India. This is a residual soil and is collected at a depth of one meter below the natural ground surface. The soil was air dried and passed through IS sieve 425 microns and oven dried before being used for investigation. It is classified as “CH” group as per IS classification (1970). The physical and chemical properties of Black Cotton soil have been listed in table 1 and 2 respectively. Table -1 Physical Properties of Black Cotton Soil Table -2: Chemical Analysis of Black Cotton soil The Red Earth was collected at a depth of 1.5 meters at a test pit dug for the proposed Bio-park at the Bangalore University campus, Jnanabharathi. It was air dried and the soil sample for the studies were taken from the collected soil by quartering to ensure uniformity and pulverized and sieved through IS 425 micron sieve before using. The soil is a typical non-expansive clayey soil. The Physical Properties of Red Earth are shown in Table 3. Also the chemical composition of oven dried Red earth was analyzed as per the standards methods and is presented in table 4. Color Black Specific gravity 2.64 Fine sand 9% Silt 31% Clay 60% Liquid limit 77% Plastic limit 30.75% Plasticity Index 49.85% Shrinkage Limit 8.3% Optimum moisture Content 33.7% Maximum dry density 13.8 kPa Unconfined Compressive strength 299 kPa Coefficient of permeability 1.796X10-9 m/sec Free swell Index 86% Coefficient of Consolidation Cv 1.2X10-2 mm2 /sec Compression Index Cc 0.09 cm2 /kg Chemical composition Percentage Silica (SiO2) 52.85 Alumina(Al2O3) 12.24 Ferric Oxide(Fe2O3) 8.04 Calcium Oxide(CaO) 6.01 Magnesium Oxide(Mgo) 2.94 Titanium Dioxide(Ti O2) 0.24 Potassium Oxide (K2O) 0.48 Sodium Oxide (N2O) 0.26 Loss of ignition 16.18
- 3. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308 __________________________________________________________________________________________ Volume: 03 Special Issue: 06 | May-2014 | RRDCE - 2014, Available @ http://www.ijret.org 63 Table -3: Physical Properties of Red Earth Table -4 Chemical analysis of Red Earth Table -5: Physical Properties of Shedi Soil Table -6 Chemical analysis of Shedi Soil The Shedi soil used for the present study has been obtained from shedi gudda from a depth of 2 meter below natural ground level, Mangalore, Karnataka state, India. It was dried and sieved through a sieve of 4.75 mm to eliminate grave fraction if any. Chemicals used in the study are Calcium Carbonate (CaCO3), Magnesium Carbonate (MgCO3), Sulphuric acid (H2SO4) and Orthophosporic acid (H3PO4).These chemicals have been obtained from Qualigens Fine Chemicals and Sd Fine Chemicals Pvt. Limited, Mumbai India. The Calcium Carbonate and Magnesium Carbonate are in white powder form and insoluble in water but reacts with constituents of any soil. The strength of the acids was reduced to one normal solution. Properties of CaCO3 and MgCO3 are listed table 7. 3. RESULTS AND DISCUSSIONS 3.1 Effect of CaCO3 and MgCO3 on Black Cotton Soil Increase with the various percentages of Calcium Carbonate and Magnesium Carbonate has successively increased the pH of the Black Cotton soil. However the increase in pH with the increase in percentage Magnesium Carbonate is more compared to increase with percentage Calcium Carbonate due to soil alkali interaction in the presence of water in which hydrogen ion concentration increases significantly. The variations are shown in figures 1 and 2. Table -7 Properties of Chemicals used Color Brick Red Specific gravity 2.39 Fine sand () 29 % Silt () 23 % Clay ( 48 % Liquid limit 44.1% Plastic limit 20.69 % Plasticity Index 23.41% Shrinkage Limit (%) 14.3% Optimum moisture Content 22..5% Maximum dry density 16.6kPa Unconfined Compressive strength 237.35kPa Coefficient of permeability 2.4X10-7 cm/sec Free swell Index (modified) 1.2cc/g Coefficient of Consolidation Cv 0.001887mm2/sec Compression Index Cc 0.0029 m2/KN Chemical composition Percentage Silicon dioxide 60.4 Alumina 15.05 Iron –oxide 6.6 Titanium dioxide 0.2 Calcium oxide 6.9 Magnesium oxide 1.7 Potassium oxide 0.4 Loss on ignition 8.4 Sodium oxide 0.3 Color Light Pink Specific gravity 2.43 Gravel fraction (%) 0.00 Sand fraction (%) 85.00 Silt and Clay fraction (%) 15.00 Liquid Limit 26.5 Plastic Limit 16.7 Shrinkage Limit 21.19 Optimum Moisture content (%) 14.5 Maximum Dry Density (KN/cum) 17.7 Free swell Index (cc/g) 0.00 Coe-efficient Permeability (mm/s) 3.652X10-6 Coefficient of Consolidation Cv (mm2 /s) 70.8 X10-3 Compression Index Cc (mm2 /s) 1.69 X10-3 Unconfined Compressive Strength (kPa) 220.78 Chemical Parameters Percentage % pH 5.42 Calcium (%) 0.002 Sodium (%) 0.039 Potassium (%) 0.000 Chloride (%) 0.008 Sulphate As SO4 0.004 As SO3 0.003 Properties CaCO3 MgCO3 Molecular Weight 100.1 84.3 Color White White Crystal Symmetry Rhombic Trigonal Refractive Index nD 1.681 1.51 Density 2.71g/cc 3.05g/cc Melting Point 825◦ C 990◦ C Solubility in 100 parts solvent 0.013g/100ml@ 20◦ C,soluble in acids 0.01g/100ml@ 20◦ C,soluble in acids Assay 85% 95%
- 4. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308 _______________________________________________________________________________________ Volume: 03 Special Issue: 06 | May-2014 | RRDCE - 2014, Available @ http://www.ijret.org 64 3.2 Effect of 1N H2SO4 and 1N H3PO4 on Black Cotton soil Alkalis treated soils contaminated with 1N H2SO4 and1N H3PO4 showed drastic decrease in pH. However the decrease in pH by 1N H2SO4 is observed more than that with1N H3PO4. The decrease in pH indicates the higher acidification of soil and due to increase in Hydrogen ion concentration in soil- alkali-acid mixture followed with immediate soil-alkali-acid interaction. Black Cotton soil alone contaminated with 1N H2SO4 and1N H3PO4 showed further decrease in pH. The decrease with 1N H2SO4 more compared to decrease in pH with 1N H3PO4 the variations are shown in figure 3. 3.3 Effect of CaCO3 and MgCO3 on Red Earth Increase with the various percentages of Calcium Carbonate and Magnesium Carbonate has successively increased the pH of the Red Earth. However the increase in pH with the increase in percentage Magnesium Carbonate is more compared to increase with percentage Calcium Carbonate due to soil alkali interaction in the presence of water in which hydrogen ion concentration increases significantly. The variations are shown in figures 3 and 4. Chart 1 Variation of pH with % of CaCO3 and 1N acids Chart 2 Variation of pH with % of MgCO3 and 1N acids Chart 3 Variation of pH with % of CaCO3 and 1N acids Chart 4 Variation of pH with % of MgCO3 and 1N acids 3.4 Effect of 1N H2SO4 and 1N H3PO4 on Red Earth Alkalis treated Red Earth contaminated with 1N H2SO4 and1N H3PO4 showed drastic decrease in pH. However the decrease in pH by 1N H2SO4 is observed more than that with1N H3PO4. The decrease in pH indicates the higher acidification of soil due to increase in Hydrogen ion concentration in soil-alkali- acid mixture followed with immediate soil-alkali-acid interaction in which formation of sulphate compounds takes the role of increasing the Hydrogen ion concentration. Red Earth alone contaminated with 1N H2SO4 and1N H3PO4 showed further decrease in pH. The decrease with 1N H2SO4 more compared to decrease in pH with 1N H3PO4. 1N H2SO4 is the strong acid compared to 1N H3PO4 and hence the highest decrease in pH is noticed. The variations are shown in figures 3 and 4.
- 5. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308 __________________________________________________________________________________________ Volume: 03 Special Issue: 06 | May-2014 | RRDCE - 2014, Available @ http://www.ijret.org 65 3.5 Effect of CaCO3 and MgCO3 on Shedi soil Increase with the various percentages of Calcium Carbonate and Magnesium Carbonate has successively increased the pH of the Shed soil. However the increase in pH with the increase in percentage Magnesium Carbonate is more compared to increase in pH with percentage Calcium Carbonate due to soil alkali interaction in the presence of water in which hydrogen ion concentration increases significantly. The variations are shown in figures 5 and 6. Chart 5 Variation of pH with % of CaCO3 and 1N acids 3.6 Effect of 1N H2SO4 and 1N H3PO4 on Shedi soil Alkalis treated soils contaminated with 1N H3PO4 and 1N H2SO4 respectively showed drastic decrease in pH. However the decrease in pH by 1N H2SO4 for CaCO3 treated soil is observed more than that for MgCO3 treated Shedi soil contaminated with1N H3PO4. The decrease in pH indicates the higher acidification of soil due to increase in Hydrogen ion concentration in soil- alkali-acid mixture followed with immediate soil-alkali-acid interaction in which formation of sulphate compounds takes the role of increasing the Hydrogen ion concentration. Shedi soil alone contaminated with 1N H2SO4 and1N H3PO4 showed significant decrease in pH. The decrease with 1N H2SO4 more is compared to decrease in pH with 1N H3PO4. 1N H2SO4 is the strong acid compared to 1N H3PO4 and hence the maximum decrease in pH is noticed. The variations are shown in figures 5 and 6. Chart 6 Variation of pH with % of MgCO3 and 1N acids 4. CONCLUSIONS 1. Magnesium carbonate has resulted in more alkalization of Black cotton soil and Shedi soil equally, compared to alkalization of Red Earth indicating high pH. 2. The cation exchange phenomena is more with increase in Magnesium Carbonate at all percentages compared to increase in Calcium Carbonate at all percentages for all the three soils inferring more hydrogen ion activity . 3. The increase or decrease in pH for soil alone treated with CaCO3 and MgCO3 separately and again for the soil alone contaminated with 1N H2SO4 and 1N H3PO4 are due to Physical properties and chemical analysis of the individual soil 4. Significant acidification is resulted in all the three soils due to 1N H2SO4 contamination rather than contamination due to 1N H3PO4 indicating sudden low pH. 5. Acidic Soils showing the pH value between 1 to 2 in pH Scale determines the amount of lime to be added to raise its pH for any Engineering applications. ACKNOWLEDGEMENTS The authors acknowledge the PVP welfare Trust, Bangalore, for carrying out the research work at PhD level at Bangalore University. RFERENCES [1]. Mitchell,J.K. (1993) Fundamentals of Soil Behavior, John Wiley, New York. [2]. Sridharan A, Nagaraj T.S and Shivapullaiah P.V (1981) Heaving of Soil due to Acid Contamination, Proceedings of XI ICSMFE, Stockholm, Vol.2:.383-386. [3]. Rao, S.M. and Sridharan,A.(1985) Mechanism controlling the volume change behaviour of kaolinite, Clays and Clay Minerals, 33(4), 323-328. [4]. Joshi R.C., Pan X and Lohita P. (1994) Volume Change in Calcareous Soils due to Phosphoric Acid Contamination,
- 6. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308 _______________________________________________________________________________________ Volume: 03 Special Issue: 06 | May-2014 | RRDCE - 2014, Available @ http://www.ijret.org 66 Proceedings of the XII ICSMFE, New Delhi, Vol.4: 1569- 1574. [5]. Sivapullaiah P.V., Sridharan A. and Vijaya Bhaskar Raju K. (1994) Role of Electrolytes on the Shear Strength of Clayey Soil, Proceedings of IGC, Warangal: 199-202. [6]. Kumpaley N. K. and Ishol A. (1985) The effect of Chemical Contamination on Soil Strength, Proceedings of XI ICSMFE, Sanfransicso, and Vol.3: 1199-1201. [7]. Ingles, O.G. (1970) Mechanisms of Clay Stabilization with inorganic acids and alkalis, Australian Journal of Soil Research., 8, 81-95. [8]. Anand J Puppala, (2006), “Sulfate Heave Mechanisms in Chemical Treated Clay” Proceedings of Indian Geotechnical Conference-2006, Vol: 1, pp.95-104. [9]. Raid, R., Al-Omari Waleed K. Mohammed., Isam H. Nashaat., and Oday M. Kaseer, (2007), “Effect of Sulphuric and Phophoric Acids on the Behaviour of a Limestone Foundation,” Indian Geotechnical Journal, Vol. 37, pp. 263- 282. [10]. Zhao, H., Low, P.F., and Bradford, J.M. (1991), “Effect of pH and Electrolyte concentration on particle interaction in three Homoionic Sodium soil Clay Suspensions,” Soil Science, Vol.151, No.3, pp.196-207.