geotechnical properties of oil contaminated soil

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GEOTECHNICAL PROPERTIES OF OIL CONTAMINATED SOIL

A thesis submitted to The University of Manchester for the degree of

Master of Philosophy

in the Faculty of Engineering and Physical Sciences

2015

Miebaka Ransome Daka

School of Mechanical, Aerospace and Civil Engineering

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CONTENTS CONTENTS 2

LIST OF ABBREVIATIONS 24

LIST OF SYMBOLS 25

ABSTRACT 28

DEDICATION 29

DECLARATION 30

COPYRIGHT STATEMENT 31

ACKNOWLEDGEMENT 32

CHAPTER 1 INTRODUCTION 33

1.1 Background 33

1.2 Problem statement 33

1.3 Aim and objectives 35

1.4 Scope of the study 36

1.5 Limitations of the study 37

1.6 Structure of the thesis 38

CHAPTER 2 LITERATURE REVIEW 39

2.1 Geotechnical properties of oil contaminated soils 39

2.1.1 Aggregate size distribution of oil contaminated soils 40

2.1.1.1 Summary on aggregate size distribution of oil contaminated soils 41

2.1.2 Atterberg limits of oil contaminated soils 41

2.1.2.1 Oil contamination increases the Atterberg limits 41

2.1.2.2 Oil contamination decreases Atterberg limits 42

2.1.2.3 Summary on Atterberg limits of oil contaminated soils 46

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2.1.3 Compaction of oil contaminated soils 47

2.1.3.1 Oil contamination, increase in maximum dry density and

decrease in optimum water content 47

2.1.3.2 Oil contamination, decrease in maximum dry density and

decrease in optimum water content 49

2.1.3.3 Summary on compaction of oil contaminated soils 55

2.1.4 Hydraulic conductivity of oil contaminated soils 55

2.1.4.1 Oil contamination decreases hydraulic conductivity 56

2.1.4.2 Summary on hydraulic conductivity of oil contaminated soils 58

2.2 Summary of Literature Review 59

CHAPTER 3 MATERIALS AND EXPERIMENTAL PROCEDURES 60

3.1 Materials 60

3.1.1 Properties of soils, mineralogical content of clays and oil characteristics 60

3.1.1.1 Particle size distribution of bentonite, kaolinite and sand 60

3.1.1.2 Mineralogical content of bentonite and kaolinite 61

3.1.1.3 Characteristics of Shell Tellus oil 68 62

3.1.1.4 Soil mixture ratio and oil content 62

3.2 Significance of tests 64

3.2.1 Grading modulus using aggregate size distribution 64

3.2.2 Atterberg limits 66

3.2.3 Compaction 67

3.2.4 Hydraulic conductivity 68

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3.3 Specimen preparation 68

3. 3.1 Specimen for the grading modulus tests 68

3.3.2 Specimen for the Atterberg limits tests 69

3.3.3 Specimen for the compaction test 70

3.3.4 Specimen for the hydraulic conductivity test 70

3.4 Equipment for experimental testing 70

3.5 Experimental procedures and typical test result 71

3.5.1 Procedure for the grading modulus test 71

3.5.2 Procedure for the Atterberg limits tests 72

3.5.3 Procedure for the compaction test 75

3.5.4 Procedure for the hydraulic conductivity test 80

3.6 Summary of Chapter 3 83

CHAPTER 4 RESULTS AND DISCUSSION 85

4.1 Aggregate size distribution of contaminated soils 85

4.2 Grading modulus of oil contaminated soils 88

4.3 Plasticity characteristics of oil contaminated soils 90

4.4 Compaction of oil contaminated soils 95

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4.4.1 Compaction curves using variation of dry density and water content 95

4.4.2 Compaction curves using variation of dry density and total fluid content 101

4.4.3 Compaction curves from variation of dry density and total fluid content

using data of some previous researchers 104

4.5 Plasticity characteristics and compaction of oil contaminated soil 109

4.6 Hydraulic conductivity of oil contaminated soil 111

4.7 Plasticity characteristics and hydraulic conductivity of oil contaminated soil 113

4.8 Compaction characteristics and hydraulic conductivity of oil contaminated soil 117

4.9 Summary of results and discussions 119

CHAPTER 5 CONCLUSIONS AND RECOMMENDATIONS FOR

FUTURE WORK 120

5.1 Grading modulus of oil contaminated soils 120

5.2 Plasticity characteristics of oil contaminated soils 120

5.3 Compaction of oil contaminated soils 121

5.4 Hydraulic conductivity of oil contaminated soils 121

5.5 Recommendations for future work 122

REFERENCES 123

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APPENDIX A AGGREGATE SIZE DISTRIBUTION AND

GRADING MODULUS TESTS RESULT 131

A1 Particle size analysis test result of sand 131

A2 Specific gravity of sand 132

A3 Specific gravity of bentonite and kaolinite 133

A3.1 Specific gravity of bentonite 133

A3.2 Specific gravity of kaolinite 134

A4 Hydrometer test 134

A4.1 Calibration parameters 134

A4.2 Hydrometer test formulae 135

A4.3 Calibration correction equations 135

A4.4 Hydrometer test (Bentonite) 137

A4.5 Hydrometer test ( Kaolinite ) 138

A5 Aggregate size distribution test results 139

A5.1 Soil 1 139

A5.2 Soil 2 141

A5.3 Soil 3 144

A5.4 Soil 4 146

A5.5 Soil 5 149

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A6 Grading modulus 152

A6.1 Soil 1 152

A6.2 Soil 2 152

A6.3 Soil 3 152

A6.4 Soil 4 152

A6.5 Soil 5 153

APPENDIX B ATTERBERG LIMITS TESTS RESULT 154

B1.1 Atterberg limits data for bentonite 154

B1.2 Atterberg limits data for kaolinite 155

B1.3 Atterberg limits data for soil 1 (0.0% oil content) 156









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B2 Oil loss test 181

APPENDIX C COMPACTION TEST RESULTS 185

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APPENDIX D PLASTICITY CHARACTERISTICS AND

COMPACTION OF CONTAMINATED SOIL 198

APPENDIX E HYDRAULIC CONDUCTIVITY 200

APPENDIX F PLASTICITY CHARACTERISTICS AND

HYDRAULIC CONDUCTIVITY OF CONTAMINATED

SOIL. 210

APPENDIX G COMPACTION CHARACTERISTICS AND

HYDRAULIC CONDUCTIVITY OF CONTAMINATED

SOIL 212

LIST OF TABLES

Table 2.1: Properties of clay, before and after contamination (Rehman et al, 2007) 41

Table 2.2: Summary on Atterberg limits 47

Table 2.3: Summary of Maximum dry density and optimum water content of soils 55

Table 3.1: Mineralogical content of Wyoming bentonite and China clay kaolinite

(MSDS, 2011; WMA, 2013) 61

Table 3.2: Characteristics of high viscosity Shell Tellus oil 68 (MSDS, 2006) 62

Table 3.3: Soil mixtures with different oil content chosen for the present study 63

Table 3.4: Plastic limit of uncontaminated soil 1 75

Table 3.5: Comparison of known water added to contaminated soil and measured

water content (Zheng et al, 2014) 79

Table 3.6: Quantity of flow, Q interval (ml) in 5 mins for uncontaminated soil 83

Table 4.1: Liquid limit and plastic limit of soil minerals and clay soils of study 91

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Table 4.2: Summary of study 119

Table A1: Particle size distribution data for sand 131

Table A2: Specific gravity of sand 133

Table A3.1: Data of specific gravity of bentonite 133

Table A3.2: Data of specific gravity of kaolinite 134

Table A4.1: Calibration data for hydrometer 136

Table A4.2: Data of hydrometer test for bentonite 137

Table A4.3: Data of hydrometer test for kaolinite 138

Table A5.1: Aggregate size distribution data for soil 1 (0.0% oil content) 139




Table A5.5: Aggregate size distribution data for soil 1 (7.1% oil content) 141`






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Table A5.22 Aggregate size distribution data for soil 5 (1.8% oil content) 149




Table A6.1: Percentage of mass of soil retained on sieves for soil 1 152



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Table A6.6: Grading modulus of oil contaminated soils 153

Table B1.1: Liquid limit data for bentonite 154

Table B1.2: Plastic limit data for bentonite 154

Table B1.3: Liquid limit data for kaolinite 155

Table B1.4: Plastic limit data for kaolinite 155

Table B1.5: Liquid limit data for soil 1(0.0% oil content) 156

Table B1.6: Plastic limit data for soil (0.0% oil content). 156


Table B1.8: Plastic limit data for soil (1.8% oil content) 157



Table B1.11: Liquid limit data for soil 1 (5.3% oil content) 159



Table B1.14: Plastic limit data for soil 1 (7.1% oil content) 160


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Table B1.27: Liquid limit data for soil 3 (1.8% oil content 167







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Table B1.45: Liquid limit data for soil 5 (0.0% oil content 176







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Table B2.1: Oil loss test for soil 1 181





Table B2.6 Oil loss (g) per mass of oil (g), in percentage 182

Table B3: Atterberg limits of soils 183

Table B4: Total fluid content at Atterberg limits and plasticity of soils 184

Table C1.1: Compaction data for soil 1 (0.0% oil content) 185







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Table C2: Variation of maximum dry density with optimum water content of soils 195

Table C3: Variation of maximum dry density with optimum total fluid content

of soils 195

Table C4: Variation of maximum dry density with optimum water content of soils

used by some previous researchers. 196

Table C5: Variation of maximum dry density with optimum total fluid content of soils

used by some previous researchers. 197

Table D1.1: Plasticity and compaction characteristics of soil 1 198





Table E1.1: Quantity of flow, Q (ml) in 5 mins for soil 1 (0.0% oil content) 200







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Table E2: Hydraulic conductivity of soils 209

Table F1.1: Plasticity characteristics and hydraulic conductivity of soil 1 210





Table G1.1: Compaction characteristics and hydraulic conductivity of soil 1 212





LIST OF FIGURES

Figure 2.1: Aggregate size distribution curves of uncontaminated and contaminated

soils (Ijimdiya, 2012) 40

Figure 2.2: Atterberg limits of low plasticity contaminated clay (Khosravi et al,

2013) 42

Figure 2.3: Atterberg limits for contaminated basaltic grade V soil (Rahman et al,

2010) 43

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Figure 2.4: Atterberg limits for contaminated basaltic grade VI soil (Rahman et al,

2010) 43

Figure 2.5: Atterberg limits for contaminated granitic sandy loam soils (Rahman et al,

2011) 45

Figure 2.6: Atterberg limits for contaminated metasedimentary soils (Rahman et

al, 2011) 45

Figure 2.7: Variation of plasticity index with oil content (Ijimdiya, 2012) 46

Figure 2.8: Dry density and water content for contaminated and uncontaminated high

plasticity clay (Rehman et al, 2007) 48

Figure 2.9: Oil lubricating high plasticity clay (Rehman et al, 2007) 48

Figure 2.10: Compaction curve for metasedimentary soils (Rahman et al, 2011) 49

Figure 2.11: Compaction curves for poorly graded sand (Al Sanad et al, 1995) 50

Figure 2.12: Compaction curves for poorly graded sand (Khamehchiyan et al ,

2007) 51

Figure 2.13: Compaction curves for sand with 5 to 15% silt (Khamehchiyan et al,

2007) 51

Figure 2.14: Compaction curves for low plasticity clay (Khamehchiyan et al, 2007) 51

Figure 2.15: Compaction curves for grade V basaltic soils (Rahman et al, 2010) 53

Figure 2.16: Compaction curves for grade VI basaltic soil (Rahman et al, 2010) 53

Figure 2.17: Compaction curve for granitic sandy loam soil (Rahman et al, 2011) 54

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Figure 2.18: Hydraulic conductivity of poorly graded sand (Shin and Das, 2000) 56

Figure 2.19: Variation of hydraulic conductivity with oil contents in sand with

5 to 15% silt, low plasticity silt and low plasticity clay (Rojas et al,

2003) 57

Figure 2.20: Variation of hydraulic conductivity with oil palm biodiesel content

(Chew and Lee, 2006) 58

Figure 3.1: Particle size distribution of bentonite, kaolinite and sand 61

Figure 3.2: Aggregate size distribution curve of uncontaminated soil mixtures

and sand 64

Figure 3.3: Aggregate size distribution curve of uncontaminated and contaminated

soil 1 72

Figure 3.4: Liquid limit of uncontaminated soil 1 74

Figure 3.5: Compaction curves of uncontaminated and contaminated soil 1 using

water content 78

Figure 3.6: Compaction curves of uncontaminated and contaminated soil 1 using

total fluid content 78

Figure 3.7: Hydraulic conductivity test set up – Rowe cell (vertical flow) 81

Figure 4.1: Aggregate size distribution of soils 86

Figure 4.2: Soil clods on (a ) 2mm sieve (b) 0.425mm sieve for soil 1 (7.1% oil

content) 88

Figure 4.3: Grading modulus of oil contaminated soils 89

Figure 4.4: Atterberg limits and plasticity index of soils 91

Figure 4.5: Total fluid content at Atterberg limits and plasticity index of soils 92

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Figure 4.6: Compaction of uncontaminated and contaminated soils 96

Figure 4.7: Variation of dry density with total fluid content for metasedimentary

soils (Rahman et al, 2011) 102

Figure 4.8: Variation of dry density with total fluid content for poorly graded sand

(Al Sanad et al, 1995) 105


(Khamehchiyan et al , 2007) 105

Figure 4.10: Variation of dry density with total fluid content for sand with 5 to 15%

silt (Khamehchiyan et al , 2007) 106

Figure 4.11: Variation of dry density with total fluid content for low plasticity clay

(Khamehchiyan et al , 2007) 106

Figure 4.12: Variation of dry density with total fluid content for basaltic grade V


Figure 4.13: Variation of dry density with total fluid content for basaltic grade VI


Figure 4.14: Variation of dry density with total fluid content for granitic sandy

loam (Rahman et al, 2011) 108

Figure 4.15: Variation of maximum dry density with optimum water content,

optimum total fluid content and plasticity characteristics of soils 108

Figure 4.16: Variation of hydraulic conductivity with oil content 110

Figure 4.17: Variation of hydraulic conductivity with plasticity characteristics of

soils 111

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Figure 4.18: Variation of hydraulic conductivity with plasticity characteristics of

soils 116

Figure 4.19: Compaction characteristics and hydraulic conductivity of soils 118

Figure A1: Coefficient of uniformity and coefficient of curvature for sand 132

Figure A4.1: Calibration of hydrometer 135

Figure A4.2: Calibration graph for hydrometer 136

Figure B1.1: Liquid limit of bentonite 154

Figure B1.2: Liquid limit of kaolinite 155

Figure B1.3: Liquid limit of soil 1 (0.0% oil content) 156

Figure: B1.4: Liquid limit of soil 1 (1.8% oil content) 157










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Figure B1.14: Liquid limit of soil 3 (1.8% oil content). 167














LIST OF ABBREVIATIONS

CH High Plasticity Clay

CL Low Plasticity Clay

GM Grading Modulus

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ML Low Plasticity Silt

MSDS Material and Safety Data Sheet

OMC Optimum Water Content (%)

RHA Rice Husk Ash

SM Silty Sand

SP Poorly Graded Sand

SW Well Graded Sand

XRD X Ray Diffraction

LIST OF SYMBOLS

Non Greek symbols

Cc Coefficient of Curvature

Cu Coefficient of Uniformity

D Sample Diameter (mm)

d Drain Outlet Diameter (mm)

Gs Specific Gravity

H Sample Height (mm)

M Mass of Content of Mould (g)

Md Mass of Dry Soil (g)

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MMB Mass of Mould and Base (g)

Mo Mass of Oil (g)

Moilr Mass of Oil Residue (g)

Mols Mass of Oil Loss (g)

Mor Mass of Oil Residue (g)

Mr Mass of Dried Contaminated Soil (g)

Ms Mass of Soil Solids (g)

MSMB Mass of Uncontaminated Soil, Mould and Base (g)

Msl Mass of Solids (g)

Msoil Mass of Uncontaminated Soil

Msolids Mass of Solids (g)

Mt Mass of Wet Contaminated Soil (g)

Mv Mass of Loss of Oil

Mw Mass of Loss of Water (g)

Mwt Mass of Water (g)

oc Oil Content (%)

OL Oil Loss (%)

P0.075 Percentage Retained on 0.075mm Sieve (%)

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P0.425 Percentage Retained on 0.425mm Sieve (%)

P2 Percentage Retained on 2mm Sieve (%)

Q Quantity of Flow (ml)

q Flow Rate (ml/min)

t time (mins)

V Volume of Mould

w Water Content (%)

wd Water Content at a Dry Unit Weight (%)

wo Water Content of Oil Contaminated Soil (%)

wu Water Content of Uncontaminated Soil (%)

Greek symbols

ɣav Unit Weight at Zero Air Voids (kN/m3)

ɣw Unit Weight of Water (kN/m3)

∆p Pressure Difference (kPa)

ρ Bulk Density (g/cm3)

ρd Dry Density (g/cm3)

Word count: 37536

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Name of the University: The University of Manchester Submitted by: Miebaka Ransome Daka Degree Title: Master of Philosophy Thesis Title: Geotechnical properties of oil contaminated soil Date: January 27, 2015

ABSTRACT

This research investigated the effect of oil contamination on grading modulus, Atterberg limits, compaction, and hydraulic conductivity of bentonite-kaolinite-sand mixtures. An area that lacked experimental data was chosen for the research. Data on oil contaminated soil containing montmorillionte were scarce; hence, bentonite-kaolinite-sand mixtures at oil contents of 0.0, 1.8, 3.5, 5.3 and 7.1% by dry mass of the soil were used for the study.

The first aspect of the study was the use of grading modulus to confirm reduction of fine aggregate in the contaminated soils. Atterberg limits tests were performed to determine the liquid and plastic limits of uncontaminated and contaminated soils. Proctor compaction tests were performed to determine the compaction characteristics of the oil contaminated soils. Hydraulic conductivity tests were performed using a Rowe cell. Aggregate size distribution analysis of the oil contaminated soil mixtures showed that the aggregate size distribution curves shifted from finer to coarser as the oil content increased, indicating that oil contamination caused reduction of fine aggregate in the soil while forming soil clods. The Atterberg limits tests showed that the liquid limit and plastic limit increased as oil contamination increased in the soil mixtures. The plasticity index of the soils also increased as oil contamination increased. It was deduced from the research that soils 1 and 2 had plasticity index below 65%, those of soils 3, 4 and 5 were above 65%. However, soil 3 had plasticity index close to 65. The results of the compaction tests with respect to maximum dry density and optimum water content showed that oil contamination resulted in decreased maximum dry density and optimum water content in the five soils. The hydraulic conductivity of soil mixtures decreased as oil contamination increased. Generally, soils 3, 4 and 5 had hydraulic conductivities that were close to 1 x 10-9m/s. Soil 3 had plasticity index close to 65% and hydraulic conductivity less than 1 x 10-9m/s, hence, it is suitable as soil liner for landfill. However, soils with plasticity index above 65% are difficult to handle.

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DEDICATION

This research work is dedicated to all those who spend hours carrying out research in

order to make the world a better place for living.

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DECLARATION

I hereby declare that this dissertation is an original research and was never submitted to

another university or this university. This dissertation was entirely carried out by me,

however, there is reference made to other research works.

---------------------------------- Miebaka Ransome Daka

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COPYRIGHT STATEMENT

i. The author of this thesis (including any appendices and/ or schedules to this thesis)

owns certain copyright or related rights in it (the “Copyright”) and he has given The

University of Manchester certain rights to use such Copyright, including for

administrative purposes.

ii. Copies of this thesis, either in full or in extracts and whether in hand or electronic

copy, may be made only in accordance with the Copyright, Designs and Patents Act

1988 (as amended) and regulations issued under it or, where appropriate, in

accordance with licensing agreements which the University has from time to time.

This page must form part of any such copies made.

iii. The ownership of certain Copyright, patents, designs, trade marks and other

intellectual property (the “Intellectual Property”) and any reproductions of copyright

works in the thesis, for example graphs and tables (“Reproductions”), which may be

described in this thesis, may not be owned by the author and may be owned by third

parties. Such Intellectual Property and Reproductions cannot and must not be made

available for use without the prior written permission of the owner(s) of the relevant

Intellectual Property and/or Reproductions.

iv. Further information on the conditions under which disclosure, publication and

commercialisation of this thesis, the Copyright and any Intellectual Property and/or

Reproductions described in it may take place is available in the University IP policy

(http://documents.manchester.ac.uk/DocuInfo.aspx?DocID=487), in any relevant

Thesis restriction declarations deposited in the University Library, The University

Library’s regulations (http://www.manchester.ac.uk/library/aboutus/regulations) and

in The University’s policy on Presentation of Theses.

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ACKNOWLEDGEMENT

I express my thanks to Dr. Syed Mohd Ahmad, Dr Rob Young, and Dr Hossam Abuel

Naga for their contributions that made this research work a success.

I am grateful to the Rivers State Sustainable Development Agency for sponsoring this

study.

I am also grateful to Prof. Ayotamuno Miebaka Josiah, Prof. Daka Erema, Associate

Prof. A. J. Akor, Engineer Daka Otonye and Mrs Gladys Miebaka Daka for their

support.

I am grateful to all staff in the School of Mechanical, Aerospace and Civil Engineering

for their encouragement and support.

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CHAPTER 1

INTRODUCTION

This section contains the background of the main problem the research work sought to

address, the aim, objectives, scope of research work and structure of thesis.

1.1 Background

Oil spillage occurs as a result of wars, accidents, drilling, storage, transportation of

product, and natural disasters. Singh et al (2008) stated that when oil is released, it

resides in the soil system, in the pore space of the soil, modifying the behaviour of the

soil. Crude oil was released into the soil when storage tanks and well heads were

destroyed in Kuwait during the gulf war of August 2, 1990 to February 28, 1991 (Al-

Sanad et al, 1995; Rehman et al, 2007). Despite the good oil tanker maintenance

culture, oil leaked from storage tanks and polluted the soil in the United States of

America (Patel, 2011). Ijimdiya (2012) stated that due to oil exploration, oil was

released to the environment in the Niger Delta of Nigeria, exposing the area to

environmental degradation.

Oil leakage into soil results in contamination and there is a need for bioremediation

(Khamehchiyan et al, 2007). A basic step for effective bioremediation is an

understanding on how the geotechnical properties of the soil are affected by the oil

contamination. Geotechnical testing of soil aids in finding an alternative usage for the

contaminated soil (Al-Duwaisan and Al-Naseem, 2011). A few studies have been

performed by experts to evaluate the effects of oil contamination (Khamehchiyan et al,

2007; Rehman et al, 2007; Rahman et al, 2010; Ijimdiya, 2012). Khamehchiyan et al

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(2007) stated that proposals made for the use of soil with oil content included that of

using it for road base material and topping layer in car parks after mixing with

aggregates. Treatment methods for the contaminated soil included bioremediation, soil

washing and incineration. Soil contamination is affected by the type of contaminant as

well as the soil’s properties (Fine et al, 1997). Hence, an adequate understanding of the

geotechnical characteristics of soils contaminated by oil is imperative.

Sand and clay mixtures are used as soil liners for landfill. When clay is scarce, a

mixture of sand and clay is used (Mohamedzein et al, 2003). Soil mixtures are

commonly those of sand, kaolinite and bentonite or sand and bentonite (Muntohar,

2003). When sand is mixed with natural clay and bentonite, the mixture can be used as a

water barrier in landfills (Mohamedzein et al, 2003). Bentonite-kaolinite-sand mixtures

are used as vertical cut-off walls for containment of movement of fluids (Evans, 1993).

Evaluation of the effect of oil on contaminated soil using crude oil or its oil product as

its representative was important as it could aid in decisions on using the material for

alternative purposes like construction of slabs and support of structures (Mohamedzein

et al, 2003).

Bioremediation of crude oil contaminated soils involves hydrocarbon utilising bacteria

degrading oil in the presence of water (Kogbara, 2008). When water moves to an

initially dry contaminated soil, the rate of oil degradation by the bacteria increases as it

feeds on nutrients that dissolve in water. It is therefore pertinent to determine the

hydraulic conductivity of water in the oil contaminated soil, in order to suggest area of

contaminated soil with increased bacterial degradation of oil. Incineration is an

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alternative to bioremediation (Khamehchiyan et al, 2007); in this case, the soil is

excavated and burnt in an incinerator.

It is pertinent to evaluate the effect of oil on bentonite-kaolinite-sand mixtures as

bentonite is used as buffer and backfill material in the containment of radioactive

wastes (Akgun, 2010), mine effluents (Gratchev et al, 2012), exploratory boreholes and

diversion tunnels (Pusch, 1992), waste leachates and water barrier (Chalermyanont and

Arrykul, 2005).

This research focused on investigating the geotechnical properties of soil, using low oil

content. According to Khamehchiyan et al (2007), when the oil content in soil is below

16%, oil does not drain out from soil; similarly, Erten et al (2011) stated that when oil

content in soil is low, oil would not be expelled from the soil during geotechnical tests.

Al-Sanad et al (1995) stated that field condition at a contaminated site in Kuwait

contained a maximum of 6% by dry weight of the soil. In the light of the

aforementioned, this study investigated the geotechnical properties of bentonite-

kaolinite-sand mixtures at low oil contents limited to 7.1%.

1.2 Problem statement

Oil contamination alters the geotechnical properties of soils. There were few research

works that assessed the effect of oil contamination on geotechnical properties of soils.

The research works were mainly on soils that did not contain montmorillonite.

This research work investigated the effect of oil on soils that contained montmorillonite

by using bentonite-kaolinite-sand mixtures. Bentonite contained montmorillonite with

swelling characteristic and this influenced the behaviour of the soil mixture distinctly

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from those without bentonite. The bentonite-kaolinite-sand mixture was used in the

study to fill the void created by lack of data on effects of oil on soils that contain

montmorillonite.

1.3 Aim and objectives

The aim of the study was to evaluate the geotechnical properties of oil contaminated

bentonite-kaolinte-sand mixture. The particular objectives were to investigate the effect

of oil contamination on grading modulus, Atterberg limits (liquid limit and plastic

limit), compaction, and hydraulic conductivity of bentonite-kaolinite-sand mixture.

1.4 Scope of the study

The research work was limited to the evaluation of the effect of oil contamination on

bentonite-kaolinite-sand mixtures. The geotechnical properties investigated for the oil

contaminated soils were grading modulus, Atterberg limits, compaction and hydraulic

conductivity.

This study evaluated both variation of maximum dry density with optimum water

content and variation of maximum dry density with optimum total fluid content1 for the

compaction test. Previous studies did not include variation of maximum dry density

with total fluid content.

1 Total fluid content - sum of water content and oil content in the soil.

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1.5 Limitations of the study

The oil was mixed into dry soil for all tests before addition of water. Hence, effect of oil

contamination on soils that initially contained water was not investigated.

The liquid limit test was not carried out by adding appropriate amount of oil, rather,

appropriate amount of water was added to a soil containing a specific amount of oil.

The oil loss was considered as insignificant for the Atterberg limit tests.

Known water contents were added to the oil contaminated soil used for the compaction

test. There was no further determination of water contents by oven drying method. The

transfer of soil from the container to the mould with its extension and vice versa was

done with great care to avoid soil loss. The test was not performed by adding oil to soils

that already contained water.

Chemical reactions in the soil were not investigated.

Specific gravity tests were not done for the uncontaminated and oil contaminated soils;

hence, zero air void and saturation lines were not drawn for the compaction curves in

this study. Variation of dry density with water content in g/cm3 was used for the

compaction curves for consistency and comparison with those of other researchers. The

equation for zero air void line is ɣav = [ɣw Gs/(1 + 0.01wdGs)], with ɣav = unit weight at

zero air voids, ɣw = unit weight of water, Gs = specific gravity of a soil and wd = water

content at a dry unit weight. This involves unit weight and results are in kN/m3. This

study and previous research works used density (g/cm3) and not dry unit weight

(kN/m3). When the acceleration due to gravity is used to multiply the density, the result

is a different value, expressed as that for force (kN) per m3 (Fratta et al, 2007).

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Scanning Electron Microscope imaging was not performed for the uncontaminated and

oil contaminated soils.

Numerical analysis was not performed in this study.

1.6 Structure of the thesis

The thesis introduces the topic in chapter 1 and in chapter 2 evaluates literature on

geotechnical properties of oil contaminated soil. Chapter 3 includes the materials and

experimental procedures, clearly mentioning the materials and explaining the

procedures used for the experiment. Chapter 4 presents the experimental results and

discussion while chapter 5 contains the conclusion and recommendation. The

Appendices contain experimental results that were not included in Chapter 4.

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CHAPTER 2

LITERATURE REVIEW

This literature review evaluated all aspects of literature related to this research work. It

reviewed literature on geotechnical properties of soil after contamination with crude oil

or its derivatives, an approach that enables a thorough understanding of this important

area of research.

2.1 Geotechnical properties of oil contaminated soils

This section reviewed literature on how geotechnical properties of soils are affected

when the soils are contaminated. The manner in which oil affects a soil would

determine the approach of handling the contaminated soil with the aim of putting it into

alternative use. Oil contamination has become a major problem, and there is clamour for

remediation of contaminated soil. Patel (2011) stated that in spite of the different

approaches to prevent oil leakage, 25% of oil petroleum associated products leak in the

United States of America alone, contaminating the soil. An understanding on how oil

affects the properties of soil is a basic step in designing an effective remediation system.

The variations in findings on effect of oil on the geotechnical properties of soil are due

to variation in oil composition and soil mineralogy (Khosravi et al, 2013). The research

on geotechnical properties of oil contaminated soils is an important area of research.

Few studies are available in this area and this section reviews previous studies.

40

2.1.1 Aggregate size distribution2 of oil contaminated soils

Ijimdiya (2012) investigated the effect of oil contamination on aggregate size

distribution. The soil used was reddish brown and obtained from a borrow pit at Shika,

Zaria, Nigeria. The soil had a large amount of kaolinite clay mineral and 87% silt.

Various concentrations of the oil (1, 2, 3, 4, 5 and 6% oil content) were mixed with the

dry soil sample. The oil contaminated soil was passed through 2.4 to 0.075mm sieve

sizes and percentage of soil that passed through each sieve was determined to get the

aggregate size distribution. Figure 2.1 shows the aggregate size distribution curves of

the contaminated and uncontaminated soils. The aggregate size distribution curve

shifted from finer to coarser as oil contamination increased from 0 to 6% by dry weight

of the soil.

Figure 2.1: Aggregate size distribution curves of uncontaminated and contaminated

soils (Ijimdiya, 2012).

2 Aggregate size distribution curve is obtained using percentage of soil that passed through various sieves in sieve analysis. Oil contamination resulted in flocculation of soil composition into different aggregate sizes, hence, oil contaminated soils have varying aggregate size distribution curves.

41

2.1.1.1 Summary on aggregate size distribution of oil contaminated soils

The study of Ijimdiya (2012) showed that an increase in oil content shifted the

aggregate size distribution curve from finer to coarser.

There is a need to carry out further investigations on how oil affects the aggregate size

distribution curve using different soils as a contribution to knowledge.

2.1.2 Atterberg limits of oil contaminated soils

The Atterberg limits tests are used for the plasticity characterization of soils. Atterberg

limits of soils are used to identify, describe and classify soils.

2.1.2.1 Oil contamination increases the Atterberg limits

Rehman et al (2007) investigated the geotechnical behaviour of oil contaminated high

plasticity clay. The soil was air dried, pulverized, sieved through 0.420mm sieve, mixed

with crude oil, and then air dried. Atterberg limits test was carried out for the soil.

Table 2.1 shows that when crude oil was added, Atterberg limits and plasticity index

increased because oil gave additional cohesion to the clay particles.

Property Uncontaminated clay Contaminated clay (oil content was not stated)

Liquid limit ( % ) 172 185

Plastic limit ( % ) 48 50

Plasticity index 124 135

Table 2.1: Properties of clay, before and after contamination (Rehman et al, 2007).

42

Khosravi et al (2013) studied the effect of oil contamination on Atterberg limits by

contaminating a low plasticity clay containing kaolinite with oil contents of 2, 4, 6, 12

and 16% by dry weight of the soil. The liquid limit and the plasticity index of the soil

increased as the oil content increased in the soil from 0 to 12% as shown in Figure 2.2.

However, there was a reduction in the aforementioned parameters from 12 to 16% oil

content because the oil reduced the cohesion of the soil.

Figure 2.2: Atterberg limits of low plasticity contaminated clay (Khosravi et al, 2013).

2.1.2.2 Oil contamination decreases Atterberg limits

Rahman et al (2010) studied the effect of oil contamination on the geotechnical

properties of basaltic grade V3 and VI4 residual soils. The soils were of loam and silty

3 Basaltic grade V soil - residual soil from igneous or volcanic rock that still possesses

the original soil texture. 4 Basaltic grade VI soil - residual soil from igneous or volcanic rock that no longer has

its original rock texture.

43

textures. XRD analysis indicated that the soil had feldspar, quartz and clay minerals of

kaolinite and contained little amount of gibbsite and goethite (Gibbsite is an aluminium

ore while goethite is a product of iron rich minerals). Atterberg limits were determined

for various levels of oil contamination in accordance with BS 1377 (1990). The results

for Atterberg limits were shown in Figures 2.3 and 2.4 for the basaltic grade V and

grade VI soils respectively. It shows that liquid limit and the plastic limit are reduced

when the oil content is increased. This was because oil occupied more space without

adding more cohesion to the soil.

Figure 2.3: Atterberg limits for contaminated basaltic grade V soil (Rahman et al,

2010).

Figure 2.4: Atterberg limits for contaminated basaltic grade VI soil (Rahman et al,

2010).

44

Rahman et al (2011) investigated the effect of oil on the Atterberg limits of granitic5

sandy loam and metasedimentary6 soils. The soil samples in the study were taken from

in situ weathered granitic and sedimentary rocks. The granitic soil had 64% sand, 34%

silt and 2% clay while the metasedimentary soil consisted of gravel, sand, silt and clay

of 34%, 37%, 27% and 2% respectively. The minerals in the granitic soil were quartz,

kaolinite and gibbsite while the metasedimentary soil consisted of quartz and kaolinite.

They used a component of crude oil at different percentages of 0 to 16 percent by dry

weight of soil. Disturbed soil specimens were used and tests were done in accordance

with BS 1377 (1990).

The Atterberg limits reduced in the granitic sandy loam and metasedimentary soils as

shown in Figures 2.5 and 2.6. Khamehchiyan et al (2007) stated that oil caused a

reduction in the amount of water that surrounded the clay and sand particles. The first

contact of the oil was with the soil and not the water. Oil contaminated soil deform as

liquid or plastic in the presence of water. This was less when oil content increased,

hence, liquid limit and plastic limits generally reduced.

5 Granitic soil - soil formed from granite, an igneous rock. 6 Metasedimentary soil - soil formed from sedimentary rock that have undergone

metarmophism.

45

Figure 2.5 Atterberg limits for contaminated granitic sandy loam soils (Rahman et al,

2011).

Figure 2.6 Atterberg limits for contaminated metasedimentary soils (Rahman et al,

2011).

Ijimdiya (2012) studied the effect of oil contamination on plasticity characteristics of

lateritic soil. The material used for determination of the plasticity characteristic was soil

that passed through a sieve of 0.425mm. Liquid and plastic limits were determined

using BS 1377 (1990). It was found that 2 percent oil content reduced the plasticity

46

index from 16.0 percent to 15.5 percent as shown in Figure 2.7. When the soil was

mixed with oil content of 1, 2, 3, 4, 5 and 6 percent, it was confirmed that clods were

formed, hence, crude oil could glue soil particles together, thereby reducing the

influence of water on the soil particles.

Figure 2.7: Variation of plasticity index with oil content (Ijimdiya, 2012).

2.1.2.3 Summary on Atterberg limits of oil contaminated soils

Oil contamination affected the Atterberg limits of soils. There is a lack of consensus on

how oil contamination affects the Atterberg limits of the soil, however, it is seen in the

literature that oil can either increase or decrease the Atterberg limits of the soil. There is

need to use different soils to investigate the effect of oil on the Atterberg limits of soils.

This will contribute to existing knowledge.

A summary on increase or decrease of Atterberg limits as oil content increased in soil

from the literature review is shown in Table 2.2.

47

Reference Soils Atterberg limits Rehman et al (2007) High plasticity clay Atterberg limits increased Khosravi et al (2013) Low plasticity clay

Rahman et al (2010) Basaltic grade V

Atterberg limits decreased

Basaltic grade VI

Rahman et al (2011) Granitic sandy loam Metasedimentary

Ijimdiya (2012) Lateritic

Table 2.2: Summary on Atterberg limits

2.1.3 Compaction of oil contaminated soils

Compaction is the expulsion of air from voids of soils by compressing the soil particles

through the application of mechanical energy. When a soil is compacted, a relationship

between dry density and both water content and total fluid content can be derived.

2.1.3.1 Oil contamination, increase in maximum dry density and decrease in

optimum water content

Rehman et al (2007) investigated the compaction characteristics of oil contaminated

high plasticity clay. They used the standard Proctor compaction test and the variation of

maximum dry density with optimum water content of the soil is shown in Figure 2.8.

The contaminated soil (oil content was not stated) had a higher maximum dry density at

lower optimum water content; this was because the oil lubricated the soil aggregates.

Figure 2.9 shows the oil lubricating the soil.

48

Figure 2.8: Dry density and water content for contaminated and uncontaminated high

plasticity clay (Rehman et al, 2007).

Figure 2.9: Oil lubricating high plasticity clay (Rehman et al, 2007).

Rahman et al (2011) studied the compaction characteristics of oil contaminated

metasedimentary soils (silty clay loam), by using the standard Proctor compaction test.

Generally, oil contamination resulted in an increase in the maximum dry density of the

soil, accompanied by a reduction in the optimum water content as shown in Figure 2.10;

49

The oil glued more of the soil aggregates together as the oil content increased from 0 to

12%. However, the maximum dry density reduced at 16% oil content because the oil

content was in excess and caused separation of soil voids.

Figure 2.10: Compaction curve for metasedimentary soils (Rahman et al, 2011).

2.1.3.2 Oil contamination, decrease in maximum dry density and decrease in

optimum water content

Al-Sanad et al (1995) investigated the effect of oil contamination on poorly graded

sand. The soil was mixed with 2, 4, and 6% oil content by dry weight of the soil and

compacted with 4.5kg rammer. Compaction performed using 4.5kg rammer results in

higher soil densification than that of 2.5kg for the standard Proctor test rammer. The

compaction curves are shown in Figure 2.11.

50

Figure 2.11: Compaction curves for poorly graded sand (Al Sanad et al, 1995).

Generally, there was a decrease in the maximum dry density as the oil content increased

from 2 to 6% due to excessive lubrication of the soil. However, maximum dry density

increased as the oil content increased from 0 to 2% because the oil gave cohesion to the

soil at 2%. When oil content was above 2%, the oil gave less cohesion to the soil,

resulting in reduced maximum dry density.

Khamehchiyan et al (2007) investigated the effect of crude oil contamination on the

compaction characteristics of Bushehr coastal soils in Iran. The soils were poorly

graded sand, sand with 5 to 15% silt and low plasticity clay. These soils were mixed

with 0, 4, 8, 12 and 16% oil by dry weight of the soils. Compaction was done by the

standard Proctor compaction tests on the contaminated soils. They confirmed that

maximum dry density decreased when the oil content of the soil was increased. Out of

the three soil types, the decrease was more for sand with 5 to 15% silt and low plasticity

clay.

51

The poorly graded sand had a decrease in maximum dry density as oil content increased

in the soil as shown in Figure 2.12, because the sand has large pore spaces and oil

moves easily through these pores with ease. Furthermore, due to the ease of movement

of the oil within the soil pores, the decrease in the maximum dry density is small.

Figure 2.12: Compaction curves for poorly graded sand (Khamehchiyan et al , 2007).

The sand with 5 to 15% oil content had less pore spaces than the poorly graded sand,

consequently, there was no ease of movement of oil as that of sand. However, the oil

content sufficiently lubricated the soil and the maximum dry density decreased with

increase in the oil content as shown in Figure 2.13.

Figure 2.13: Compaction curves for sand with 5 to 15% silt (Khamehchiyan et al ,

2007).

52

The low plasticity clay had smaller particles than the poorly graded sand and the sand

with 5 to 15% silt. However, as oil content increased in the soil, the oil separated the

voids in the soil and this caused a reduction in the maximum dry density of the soil. The

optimum water content in the soil also decreased. The compaction curve of the low

plasticity clay is shown in Figure 2.14.

Figure 2.14: Compaction curves for low plasticity clay (Khamehchiyan et al, 2007).

Rahman et al (2010) investigated the influence of oil on compaction characteristics of

basaltic residual soil. The soils were sticky when wet. Figures 2.15 and 2.16 show the

compaction characteristics of grade V and grade VI basaltic soils respectively, using 2.5

kg rammer, with 300 mm height of drop (BS 1377, 1990).

53

Figure 2.15 Compaction curves for grade V basaltic soils (Rahman et al, 2010).

Figure 2.16 Compaction curves for grade VI basaltic soil (Rahman et al, 2010).

The initial maximum dry densities for the uncontaminated soils were 1.67g/cm3 for

grade V and 1.60g/cm3 for grade VI basaltic soil. The initial optimum water content in

percentage were 24 for grade V and 23 for grade VI basaltic soil. When 4 percent of oil

was added to the soil, the maximum dry density of contaminated grade V soil reduced

54

from 1.67 to 1.50g/cm3 and the reduction continued linearly with increase in oil content

of 8 to 16 percent (Fig 2.15). There was also a decrease in the maximum dry density of

contaminated grade VI soil as oil content was increased (Figure 2.16), but the decrease

was less than that of grade V.

Rahman et al (2011) investigated the effect of oil on compaction characteristics of

granitic sandy loam soil. The maximum dry density reduced as oil contamination

increased in the soil as shown in Figure 2.17 because oil occupied the soil pores rapidly.

Figure 2.17: Compaction curve for granitic sandy loam soil (Rahman et al, 2011).

2.1.3.3 Summary on compaction of oil contaminated soils

The literature review showed that when oil contaminated soils were compacted, the

compaction characteristics of the soils differed because the soil composition differed. It

showed that the maximum dry density increased with increase in oil content, when

Rehman et al (2007) and Rahman et al (2011) compacted an high plasticity clay and

55

metasedimentary soils respectively. On the other hand, the maximum dry density

decreased with an increase in oil content, when Al-Sanad et al (1995), Khamehchiyan et

al (2007), Rahman et al (2010) and Rahman et al (2011) compacted a variety of soils

such as poorly graded sand, sand with 5 to 15% silt, low plasticity clay and basaltic

soils. The lack of consensus on the effect of oil on compaction characteristics warrants a

further study wherein different soil compositions contaminated by oil are compacted to

investigate their compaction characteristics. This will add to existing knowledge in this

area of study.

The summary of increase or decrease in maximum dry density and optimum water

content as oil content increased in soil is shown in Table 2.3.

Reference Soils Maximum dry density(g/cm3)

Optimum water content (%)

Rehman et al (2007) High plasticity clay Increased

Decreased

Rahman et al (2011) Metasedimentary Al-Sanad et al (1995) Poorly graded sand

Decreased

Khamehchiyan et al (2007)

Poorly graded sand Sand with 5 to 15% silt Low plasticity clay

Rahman et al (2010) Grade V (basaltic) Rahman et al (2011)

Grade VI (basaltic) Granitic sandy loam

Table 2.3: Summary of Maximum dry density and optimum water content of soils

2.1.4 Hydraulic conductivity of oil contaminated soils

Hydraulic conductivity is a measure of the movement of water in a soil. Oil

contamination of soil affects the flow rate of water in the soil.

56

2.1.4.1 Oil contamination decreases hydraulic conductivity

Shin and Das (2000) investigated the effect of oil content on the hydraulic conductivity

of oil contaminated poorly graded sand. The soils were mixed with oil contents of 1, 2,

4 and 6% by dry weight of the soils. The kinematic viscosities of engine oil, Oman

crude oil, and lamp oil were 300, 50 and 4 mPas respectively.

Specimens of 100mm diameter and 150mm height were used for constant head

permeability tests. The results of these hydraulic conductivity tests are shown in Figure

2.18.

Figure 2.18 Hydraulic conductivity of poorly graded sand (Shin and Das, 2000).

The hydraulic conductivity of the soil decreased with an increase in the oil content as oil

occupied the pore spaces of the soil.

Soils with higher kinematic viscosities and higher relative densities were found to have

a lower hydraulic conductivity.

Rojas et al (2003) investigated the effect of kinematic viscosity and hydraulic

conductivity of different oil contaminated soils (sand with 5 to 15% silt, low plasticity

57

silt and low plasticity clay).The soils were contaminated with oil content of 2, 4, and

6% by dry weight of the soil. The kinematic viscosities of the oils for gear oil, engine

oil and crude oil were 300, 80 and 3 mPas respectively.

The hydraulic conductivity test was done for the three soils using falling head

permeability test with one back pressure system and deaired water. Standard

geotechnical hydraulic conductivity equation was used as oil does not mix with water

(Silverstein, 1998). The soils were compacted at the maximum dry unit weight, using

4.5kg rammer.

The study confirmed that hydraulic conductivity reduced as the amount of oil increased.

For contaminated soils with oils of higher kinematic viscosities, a larger decrease of the

hydraulic conductivity was observed as shown in Figure 2.19 because there was more

limitation to the flow of water in the pores of soils.

Figure 2.19: Variation of hydraulic conductivity with oil contents in sand with 5 to

15% silt, low plasticity silt and low plasticity clay (Rojas et al, 2003).

58

Chew and Lee (2006) investigated the effect of palm biodiesel on hydraulic

conductivity of poorly graded sand. The palm biodiesel was a blend of 20% palm oil

with 80% petroleum diesel and having a kinematic viscosity of 4 mPas.

The poorly graded sand used for each test was compacted to a relative density of 60%.

Constant head permeability tests were carried out and the hydraulic conductivity of the

contaminated soils are shown in Figure 2.20.

Figure 2.20 Variation of hydraulic conductivity with palm biodiesel content (Chew

and Lee, 2006).

The hydraulic conductivity of the soil decreased as the oil content increased because the

palm biodiesel in the soil pores filled the pores of soil, limiting the flow of water.

2.1.4.2 Summary on hydraulic conductivity of oil contaminated soils

The hydraulic conductivity of the soils decreased as oil contamination increased. It is

necessary to use different soils from those soils used by Shin and Das (2000), Rojas et

al (2003) and Chew and Lee (2006) to investigate the effect of oil on the hydraulic

conductivity because soil behaviour differs.

59

The study of Shin and Das (2000), Rojas et al (2003) and Chew and Lee (2006) showed

that an increase in oil contamination resulted in a decrease of hydraulic conductivity in a

variety of soils such as poorly graded sand, sand with 5 to 15% silt, low plasticity silt

and low plasticity clay.

2.2 Summary of Literature Review

The literature review showed that oil contamination caused reduction of fine aggregate

as evident in the shifting of the aggregate size distribution curve from finer to coarser.

The Atterberg limits, maximum dry density and optimum water content increased or

decreased depending on the kind of soil that was contaminated with oil. The hydraulic

conductivity of oil contaminated soils decreased.

The tests performed by the researchers scarcely contained montmorillionite, hence, a

study on soils that contained montmorillonite was necessary, because montmorillonite

has a different behaviour from those minerals contained in soils of previous research

works because of its swelling characteristic. This research work aimed to fill the gap in

that area by using bentonite- kaolinite-sand mixture as an important study area to

investigate the geotechnical properties of oil contaminated soils by using grading

modulus, compaction and hydraulic conductivity. The standards and equipment used by

the researchers varied, as there were many standards and equipment that could generate

data that were acceptable within the geoenvironmental practice. The main criteria for

choosing the equipment for this important area of research were their ability to generate

data and the British standard was adopted to achieve that purpose. The equipment

chosen to generate data for the study and the experimental procedures are included in

Chapter 3 of this research.

60

CHAPTER 3

MATERIALS AND EXPERIMENTAL PROCEDURES

This chapter presents a description of the materials used for the experiments and the

procedures followed in performing these experiments. Uncontaminated and

contaminated bentonite-kaolinite-sand mixtures were used for the experiments. Oil was

mixed into the soil mixtures for contamination. This study is important as it investigates

the geotechnical properties of oil contaminated sand-clay mixtures with varying

amounts of bentonite and kaolinite.

3.1 Materials

The type of soil and contaminant used for the experimental work are described in this

section.

3.1.1 Properties of soils, mineralogical content of clays and oil characteristics

The soil mixtures used for the experiments contained Wyoming bentonite, China clay

kaolinite and sand while the oil was Shell Tellus oil 68.

3.1.1.1 Particle size distribution of bentonite, kaolinite and sand

The particle size distributions of bentonite, kaolinite (done using a hydrometer analysis)

and sand (done using a dry sieving method) as per BS 1377:1990 are shown in Figure

3.1. The sand was poorly graded with coefficient of uniformity, Cu of 1.7 and gap

graded with coefficient of curvature, Cc of less than 1 (Fig A1). The specific gravity

(Gs) of the sand was 2.64 (Appendix A2), while those for bentonite and kaolinite were

61

2.65 and 2.60 respectively, as shown in Appendix A3. Specific gravity tests were done

in accordance with BS 1377:1990.

Figure 3.1: Particle size distribution of bentonite, kaolinite and sand.

3.1.1.2 Mineralogical content of bentonite and kaolinite

Bentonite and kaolinite are clay soils that contain mostly montmorillonite and kaolin

respectively. The exact locations of the origin of the soils were not included in the

material safety and data sheets of the products, however, the stated mineralogical

content of Wyoming bentonite and China clay kaolinite are shown in Table 3.1.

Mineral Bentonite Kaolinite Sodium montmorillonite (%) 92 0 Kaolin (%) 0 96 Quartz (%) 4 1.6 Feldspar (Albite) (%) 3 0.4 Biotite (%) 1 2

Table 3.1: Mineralogical content of Wyoming bentonite and China clay kaolinite

(MSDS, 2011; WMA, 2013).

62

3.1.1.3 Characteristics of Shell Tellus oil 68

Shell Tellus oil 68 was used for contamination. The oil has a high viscosity index. The

viscosity index is a scale that states the resistance of the oil to flow, ranging from 0 to

100, with 0 as the most likely to change viscosity with variation in temperature. The

properties of the oil as included in its manufacturer's specification sheet are shown in

Table 3.2.

Oil characteristics Values

Kinematic viscosity at 40 degrees (mPas) 60248

Viscosity index 97

Density of oil (g/cm3) 0.886

Table 3.2: Characteristics of high viscosity Shell Tellus oil 68 (MSDS, 2006)

3.1.1.4 Soil mixture ratio and oil content

Bentonite-kaolinite-sand soil mixtures were prepared with varying amounts of bentonite

and kaolinte and the soils were named soils 1, 2, 3, 4 and 5 as shown in Table 3.3.

Generally, oil content was the ratio of mass of oil (g) to mass of uncontaminated soil

(g). Oil volumes of 0, 2, 4, 6 and 8% of 5000cm3 were measured via graduated cylinder

(cm3), it was assumed that, 1g = 1cm3 for water. The oil had a density of 0.886g/cm3,

hence, for example, the oil content when 2% volume of oil was mixed into 5000g for

soil prepared for compaction test was obtained as:

2/100 x 5000 = 100cm3

but, 0.886g = 1cm3 for oil

100cm3 = 100 x 0.886 = 88.6g of oil

63

Oil content (%) = 88.6/5000 x 100 = 1.8%

The same procedure was followed for 4, 6, and 8% volumes of oil. Consequently, the

oil contents were generally represented by 0.0, 1.8, 3.5, 5.3, and 7.1%. However, as a

result of contaminated soil sticking to equipment and containers used for experiment, oil

contents may be slightly higher. The aforementioned sticking of contaminated soil may

be more as the oil content increase in soil. Zheng et al (2014) stated that such technical

challenges exist when performing experiments with oil contaminated soils.

The oil was manually mixed with the dry mass of the soil mixtures before water was

added for carrying out different tests. This is to replicate periods of dry season in some

oil producing countries, for example, in Iran, 85% of the country is arid (Badripoor,

2004). Hence, oil contamination affects the dry soil before rainfall. Researchers often

mix oil into soil by the dry weight of the soil in order to carry out tests with

predetermined oil content in the soil. However, there are cases in which water might

have already been present in the soil before contamination with oil, but such a scenario

has not been investigated in this study. Nevertheless, whether oil was added to the soil

first before addition of water or water was added to the soil first before addition of oil,

the soil will contain the same oil and water contents. Section 4.4.2 is a further

discussion on the aforementioned issue.

Soil Bentonite content (%)

Kaolinite content (%)

Sand content (%)

Oil content (%)

Soil 1 10 30 60

0.0, 1.8, 3.5, 5.3,7.1 Soil 2 15 25 60 Soil 3 20 20 60 Soil 4 25 15 60 Soil 5 30 10 60

Table 3.3: Soil mixtures with different oil content chosen for the present study

64

Typical aggregate size distribution curves of the uncontaminated soil mixtures and sand

are shown in Figure 3.2. The curves were obtained by dry sieving of oven dried soils.

Figure 3.2: Aggregate size distribution curve of uncontaminated soil mixtures and sand

The aggregate size distribution of contaminated soil mixtures are shown in Chapter 4

and Appendix A5.

3.2 Significance of tests

The tests presented in this chapter include the grading modulus using particle size

analysis test (dry sieving method), Atterberg limit tests (liquid limit and plastic limit),

compaction and hydraulic conductivity.

3.2.1 Grading modulus using aggregate size distribution

SAPEM (2011) defined aggregate as a composition of soils that can be separated by

mechanical means and stated that the aggregate is passed through a set of sieves and the

65

ratio of the sum of percentage of mass of soil retained on 2, 0.425 and 0.075mm sieves

to 100 is the grading modulus.

Grading modulus is an assessment of the reduction of fine aggregates in a soil. It is

calculated as shown in equation 3.1.

GM = (P2 + P0.425 + P0.075)/100 (3.1)

where GM = grading modulus; P2 = percentage of the soil retained on 2mm sieve; P0.425

= percentage of the soil retained on 0.425mm sieve; P0.075 = percentage of the soil

retained on 0.075mm sieve.

The more the percentage of soil aggregates retained on the 2, 0.425 and 0.075mm

sieves, the higher the grading modulus of the soils. Generally, soils with higher

proportion of larger grain sizes have higher grading modulus (SAPEM, 2011).

However, due to clay and sand adhering to each other, and soil aggregates clogging

sieve aperture, grading modulus is not a satisfactory assessment for design (Somayajulu

and Anderson, 1971). Hence, it is not definitive that soils with higher proportion of

larger grain sized particles would have higher grading modulus.

The procedure of carrying out the test is described in section 3.5.1. The test confirms

reduction of fine aggregates in a soil. Although the grading modulus is not a true

representation of gradation of soil, it is an important test to confirm if oil contamination

reduced the fine aggregate in the experimental soils. The test is important as it shows

the effect of oil on contaminated soils without water. Grading modulus test results are

shown in Appendix A6.

66

3.2.2 Atterberg limits

The liquid limit is the minimum water content at which the soil behaves like a liquid

while the plastic limit is the minimum water content at which the soil exhibits a plastic

state, as the soil changes from plastic to semi-solid state. The plasticity index is the

difference between the liquid limit and the plastic limit. The Atterberg limits are

relevant because they are used for plasticity characterization of the soil. They show if

the plasticity of the soil increase or decrease as that affects the behaviour of the soil.

Appropriate amount of water was added to the contaminated soils to carry out the liquid

limit tests as stated in section 3.3.2.

When oven drying soil to determine water content for liquid limit and plastic limit, there

may be oil loss due to evaporation. According to Khosravi et al (2013), oil loss in

percentage for their study was less than 3% of the mass of oil in the soil. Hence, the oil

loss was considered insignificant. Appendix B1 showed the Atterberg limts results for

this study. There was insignificant oil loss in this study (Appendix B2).

The oil content was the ratio of mass of oil (g) to that of mass of uncontaminated soil

(g). However, oil contents may be higher because of contaminated soil sticking to

container used in mixing the soil with oil.

oc = Mo/Msoil x 100 (3.2)

where oc = oil content (%); Mo = Mass of oil (g); Msoil = mass of uncontaminated soil

(g).

67

The oil loss (%) was the ratio of mass oil loss (g) to the mass of dry contaminated soil

(g). The dry contaminated soil contained soil solids and oil residue (Tong, 2008; Zheng

et al, 2014). They stated that it was necessary to add the mass of oil residue to the mass

of soil solids because when oil evaporated, there was residue left in the dry soil. This

was considered as part of the technical issues when performing experiments with soils

that contained oil.

OL = Mols/(Msolids + Moilr) x 100 (3.3)

where OL = oil loss (%); Mols = mass of oil loss (g); Msolids = mass of soil solids (g);

Moilr = mass of oil residue (g).

The oil loss (g) per mass of oil (g) was expressed in percentage (Table B2.6), this was

less than 5% in majority of the soils.

Table B2.1 showed, for example, that in the case of 1.8% oil content, oil loss (g) and

mass of dry soil were 0.01g and 12.66g respectively. The oil loss (%) = 0.01/12.66 x

100 = 0.08%. The oil loss in (g) per mass of oil (g), expressed in percentage for the

same soil was 0.01/0.23 x 100 = 4.3% (Table B2.6). The same procedure was followed

for other soils and the values are shown in Table B2.1 to B2.6.

3.2.3 Compaction

The purpose of compaction was to investigate the dry density and water content/total

fluid content relationships for oil contaminated soils.

68

3.2.4 Hydraulic conductivity

The purpose of the test was to evaluate differences in hydraulic conductivity of the

uncontaminated and contaminated soils. The soil was compacted in order to produce a

specimen with low hydraulic conductivity, because it was required for a soil to be used

as liner for landfill to have low hydraulic conductivity of less than 1 x 10-9m/s (Nwaiwu

et al, 2009).

3.3 Specimen preparation

The oil contaminated soils for different tests were sealed in containers and kept for one

week to reach equilibrium.

3. 3.1 Specimen for the grading modulus test

200g of soil mixture was used for the uncontaminated soil. The ratio of bentonite,

kaolinite, sand and oil content in each soil mixture was shown in Table 3.3. In the case

of the contaminated soil, mass of contaminated soil used was calculated; for example,

1.8% oil content as:

Mass of uncontaminated soil = 200g.

1g = 1cm3, for oil measured using graduated cylinder (cm3).

2/100 x 200 = 4g

But, density of oil = 0.886

Mass of oil = 0.886 x 4 = 3.5g

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Mass of contaminated soil placed in top sieve for test = 200 + 3.5 = 203.5g.

The same procedure was followed in the calculation of mass of contaminated soil

placed in the sieve for grading modulus test, with oil contents of 3.5, 5.3, and 7.1%;

mass obtained were 207.1g, 210.6g and 214.2g respectively. There was loss of soils due

to contaminated soils sticking to containers, in which the soils were mixed with oil.

When uncontaminated soils are sieved, the mass retained may be lower than the initial

mass of soil used, due to soil loss (Fratta et al, 2007). Hence, the mass of soil retained in

this study were lower than the initial mass used for the tests (Appendix A5).

The test was carried out as stated in section 3.5.1 by the dry sieving method. However,

the contaminated soils contained oil before sieving, hence, oil contaminated soil

aggregates were sieved.

3.3.2 Specimen for the Atterberg limit test

Sand was sieved through 0.425mm sieve, then, an appropriate mass of sand was

manually mixed with the appropriate mass of bentonite and kaolinite. 250g of soil

mixture was contaminated with the appropriate oil content. Appropriate amount of

water was added to the contaminated soil and mixed thoroughly to form a thick

homogenous paste. The paste was kept for 24 hours in a sealed container before

carrying out the Atterberg limits test. 20g was separated and used for the plastic limit

test. The ratio of the soils and oil in the mixtures was stated in Table 3.3 and the same

procedure was used for all soils. The Casagrande's apparatus was used for the liquid

limit test while while plastic limit test was done by the hand rolling of soil.

Generally, liquid limit tests are done using cone penetrometer or Casagrande cup. Both

apparatus are reliable for the testing of soils, however, the cone penetrometer gives

70

slightly lower values when liquid limits are higher than 100% (Head and Epps, 1980).

Hence, this study used the Casagrande cup as it was an acceptable method for testing.

3.3.3 Specimen for the compaction test

5000g of oven dried soil mixture was contaminated with oil and separated for each test.

A known amount of water was added and manually mixed into the contaminated soil.

The soil mixture that contained oil and water was kept in a container for 24 hours. The

compaction test for each soil mixture was carried out as stated in section 3.5.3. Known

water contents were measured incrementally and added into the soil.

3.3.4 Specimen for the hydraulic conductivity test

The optimum water content for a particular soil was added to its soil mixture, then

mixed thoroughly and compacted in three layers. The optimum water content is the

water content at which the maximum dry density of a soil is attained (Fratta et al, 2007).

Section 3.5.3 explains procedures for compaction of soil and shows typical compaction

curves. The hydraulic conductivity test was done on uncontaminated and contaminated

soils for the five soil mixtures as shown in Table 3.3. Section 3.5.4 explains procedures

for carrying out the test.

3.4 Equipment for experimental testing

The grading modulus tests were done using sieves of different sizes. Liquid limit test

was done using the Casagrande apparatus while plastic limit test was done by the hand

rolling of soil. Compaction test was done with a compaction machine and mould while

hydraulic conductivity test was done with a Rowe cell. The compaction equipment used

71

was manufactured by Newman Industries Limited, Bristol, England while the Rowe cell

was manufactured by Armfield Engineering Limited, Hampshire, England.

A pressure system for confining pressure and two combined digital back pressure input

and quantity of flow reading equipment manufactured by GDS, United Kingdom, was

used along with the Rowe cell (see section 3.5.4).

3.5 Experimental procedures and typical test result

3.5.1 Procedure for the grading modulus test

SAPEM (2011) stated that soil aggregates are sieved in order to obtain the grading

modulus. The soil was prepared as stated in section 3.3.1. The soils used for this study

were oven dried and contaminated with oil, based on the fact that contaminated soils

formed aggregate. The soil aggregates were sieved through 2, 0.425, 0.3, 0.25, 0.212,

0.18, 0.15, 0.125, 0.18, 0.15, 0.125, 0.106, 0.09, 0.075 and 0.063mm sieves. The 0.25,

0.18, 0.15, 0.125, 0.106 and 0.09mm sieves are not BS 1377: 1990 sieves. The grading

modulus was calculated using equation 3.1 as shown in section 3.2.1.

Typical aggregate size distribution curves are shown in Figure 3.3. The oil contents in

the soil were 0.0, 1.8, 3.5, 5.3 and 7.1% and aggregate size distribution curves shifted

from finer to coarser as the oil content increased as shown in Figure 3.3. This showed

that the fine aggregate in soil decreased as the oil content increased.

72

Figure 3.3: Aggregate size distribution curve of uncontaminated and contaminated

soil 1.

The shifting of the aggregate size distribution curve from finer to coarser as oil

contamination increased indicated that larger soil clods were formed in the soil as the oil

contamination increased. Hence, generally, higher percentages of mass of soil clods

were retained on the 2, 0.425 and 0.075mm sieves used for the grading modulus test

(Appendix A6).

3.5.2 Procedure for the Atterberg limits test

Liquid limit test was done using Casagrande method while plastic limit test was done by

hand rolling of soil (BS 1377:1990). In order to perform the liquid limit test for a

particular soil, appropriate amounts of water were added to the contaminated soils and

thoroughly mixed. Appropriate amount of soil was placed in a Casagrande cup, a

groove cut through the soil; then, the crank handle of equipment turned at two

revolutions per second. The cup lifts and drops, and groove closed along a distance of

13mm, with two parts of soil in contact at the bottom of the groove. The number of

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bumps was recorded. The number of bumps at which the groove closed varied as the

soil was mixed with more water. This was performed for number of bumps within 10

and 50, by remixing the soil taken out from the Casagrande cup with wet soil on glass

plate and remixing with more water. Two bump counts were on each side of 25 bumps.

Wet soil was taken from the zone where the two portions of soil divided by cutting of

the groove had flowed together, via a spatula. The wet soil was placed in a container

and water contents were measured by oven drying of soils. The water content for the

plastic limit test was determined by oven drying soil that crumbled at 3mm diameter,

via the hand rolling method.

The fall cone test is the preferred test for liquid limit tests; however, it is unreliable for

use with clays that possess expansive properties. This study was done using soils with

expansive characteristics as a result of the bentonite content; hence, the Casagrande cup

was used as recommended by Gronbech et al (2011).

The water contents of the contaminated and uncontaminated soils defined the Atterberg

limits of the soils. The formulae used for calculating the water contents in the

uncontaminated and contaminated soils agreed with Tong (2008) and Zheng et al

(2014). It is shown below:

Uncontaminated soil

wu = Mw/ Md x 100 (3.4)

where wu = water content of uncontaminated soil (%); Mw = mass of loss of water (g);

Md = Mass of dry soil (g).

74

Oil contaminated soil

Wo = [(Mt - Mr) - Mv] )/(Ms + Mor) x 100 (3.5)

= [(Mt - Mr) - Mv] / Mr x 100 (3.6)

where wo = water content of oil contaminated soil (%); Mt = mass of wet contaminated

soil (g); Mr = Ms + Mor = mass of dried contaminated soil (g); Mv = mass of loss of oil

(g); Ms = mass of dried soil without oil and water (g); Mor = mass of oil residue (g).

The loss of oil (Mv) was considered insignificant for this study, hence, water content

(%) of oil contaminated soil will be:

= (Mt - Mr) / Mr x 100 (3.7)

Typical variation of water content with the number of bumps is shown in Figure 3.4.

The liquid limit is the water content corresponding to 25 number of bumps. The liquid

limit of the soil in Figure 3.4 is 48%.

Figure 3.4: Liquid limit of uncontaminated soil 1.

A typical plastic limit test result is shown in Table 3.4.

75

Test number 1 2

Mass of wet soil (g) 7.90 14.38

Mass of dry soil (g) 7.00 12.74

Water loss (g) 0.90 1.64

Water content (%) 12.85 12.87 Plastic limit (average) 12.86

Plastic limit 13

Table 3.4: Plastic limit of uncontaminated soil 1

The plastic limit of the soil in Table 3.4 is 13.

The results of the test are explained in Chapter 4, and the liquid limit and plastic limit of

the soils are shown in Appendix B.

When the soil was contaminated with oil, the sum of the oil content and liquid limit or

plastic limit was the total fluid content at Atterberg limits while the sum of oil content

and plasticity index was the total fluid content at plasticity index as shown in Figure 4.5

in Chapter 4 and Table B3 to B4 of Appendix B.

3.5.3 Procedure for the compaction test

Compaction was done following the British Standard light compaction test as outlined

in BS 1377:1990, using 2500g rammer with 50mm diameter of face at a drop of

300mm. The compaction mould had a diameter of 105mm and length of 115.5mm, with

volume of 1000cm3 . Appropriate amount of soil was taken from the soil mixture

prepared for the test as stated in section 3.3.3 and compacted in three layers in a mould

with extension collar for one compaction test; each layer received 27 blows. The soil

was compacted in three layers for thorough densification, however, soils compacted in

more than three layers have more densification. Great care was taken to transfer the soil

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from its container into the mould fitted with an extension collar for each compaction

and vice versa, so that soil loss was avoided. The extension collar was removed at the

end of the compaction procedure and the soil was trimmed to the top level of the mould.

The soil, mould and base were weighed. Bulk density (ρ) from each compaction test

was calculated as:

ρ = (MSMB – MMB)/V (3.8)

Where, MSMB = mass of the soil, mould and base; MMB = mass of the mould and base;

V= volume of the mould.

The soil was removed from the mould using an extruder, then broken and remixed

manually with the remainder of the prepared sample. Known increment of water was

added manually to the remixed soil and the above mentioned compaction procedure was

repeated. The procedure was repeated until five compactions were carried out. The ratio

of the sum of mass of water increment added and the mass of water in the soil to the

mass of soil was the water content for a compaction.

The formulae used in calculating the dry density for the uncontaminated and

contaminated soils are shown below:

Uncontaminated soil

M = Msl + Mwt (3.9)

ρ = M/V = (Msl + Mwt)/V (3.10)

Mwt = wMsl (3.11)

where M = total mass of compaction mould content; Msl = Mass of solids;

Mwt = mass of water; ρ = bulk density; w = water content.

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Substituting Mwt = wMsl into equation 3.10.

ρ = (Msl + wMsl)/V (3.12)

ρ = Msl (1+ w)/V (3.13)

However, Msl/V = ρd = dry density

ρ = ρd (1+ w) (3.14)

ρd = ρ/ (1+ w) (3.15)

Oil contaminated soil

M = Msl + Mwt + Mo (3.16)

M = Msl + wMsl + ocMsl

(3.17)

M = Msl (1 + w + oc) (3.18)

Msl = M/(1 + w + oc) (3.19)

where Mo = mass of oil; oc = oil content.

But, ρd = Msl/V (3.20)

ρd = M/[V(1 + w + oc)] (3.21)

ρd = ρ/(1 + w + oc) (3.22)

Typical variation of dry density and water content of soils are shown in Figure 3.5 with

the dry density and water content corresponding to the peak of each compaction curve

as the maximum dry density and optimum water content respectively. The compaction

curves are shown in Chapter 4 and results in Appendix C. Furthermore, variation of dry

density with total fluid content and results are also shown in Chapter 4 and Appendix C

respectively. The total fluid content corresponding to the peak of each compaction curve

is the optimum total fluid content. Typical compaction curves using variations of dry

density and total fluid content are shown in Figure 3.6.

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Figure 3.5: Compaction curves of uncontaminated and contaminated soil 1 using water

content.

Figure 3.6: Compaction curves of uncontaminated and contaminated soil 1 using total

fluid content.

Zheng et al (2014) measured the water content of oil contaminated soils. They used

diesel contaminated sand, gasoline contaminated clay and engine oil contaminated sand

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for analysis. Known mass of oil and water were initially mixed into known mass of soil.

Hence, the initial water and oil contents were known. The results are shown in Table

3.5.

Known oil and water contents were used in this study, the same quantities were used for

calculations. However, soil loss could occur as a result of contaminated soil sticking to

experimental equipment and containers. This could result in higher oil contents and

water contents. Higher oil contents and water contents could result in lower dry

densities (Equation 3.22). Minute higher water contents were observed in the measured

water contents of Zheng et al (2014) in Table 3.5.

Soil Oil

content (%)

Known water content added to

soil (%)

Measured water content (%)

Gasoline contaminated clay

4 2 2.00 4 2 2.01 12 2 2.00 12 10 10.00

Diesel contaminated sand 4 2 2.00 4 10 10.01 12 2 2.02

Engine oil contaminated sand 4 2 2.01 4 10 10.01 12 10 10.02

Table 3.5: Comparison of known water content added to oil contaminated soil and

measured water content (Zheng et al, 2014).

The study of Zheng et al (2014) showed that both known water content and measured

water content could be used for experimental computations. However, in a scenario in

which there is a reduction in measured oil and water contents, the effect would be

higher dry densities (See Equation 3.22).

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Gardner and Hillel (1962) stated that heated uncontaminated loam soil column with

water content of 45%, which was left uncovered, had water evaporation of 1.6% in 24

hrs. Evaporation rate was achieved by adjusting air circulation and radiant heat energy

via a heat pump. The soil column (7cm diameter and 22cm long) had measured

temperatures of 26.5, 25.8, 25.4 and 25 ⁰C at depths of 2, 5, 10, 15, and 20cm

respectively in the soil. The temperature of the laboratory in which the experiment was

performed was within 24 to 26 ⁰C, with an uncontrolled humidity of 30 to 40%. The

rate of evaporation decreases as the temperature and water content decreases (Terzaghi

et al, 1996).

The wet soils in containers, used in this study were always covered by the lids, and this

minimized water evaporation as suggested by Head and Epps (1980). The soils used

were not heated; Gardner and Hillel (1962) heated the soil for their study. The heating

system of the laboratory was switched off during the period of experimental work, for

minimal water evaporation. Zheng et al (2014) observed that measured water contents

in oil contaminated soil could be lower than known water contents in soils obtained by

adding a known mass of water (g) to a known mass of soil (g). This could be because

prepared specimens in containers were not covered with lids or water was lost by

keeping wet soils close to very hot sources of heat.

3.5.4 Procedure for the hydraulic conductivity test

The hydraulic conductivity test was done in accordance with the procedures by Rowe

and Barden (1966). The set up for hydraulic conductivity test is shown in Figure 3.7.

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Figure 3.7: Hydraulic conductivity test set up – Rowe cell (vertical flow).

The sample used for each test was taken from soil compacted at its optimum water

content in a 1000cm3 mould (section 3.4.3) via sample ring of 76mm diameter and

30mm height. The sample ring was pushed into the compacted soil from the top of the

soil. Soil around the sample ring was trimmed off. The sample diameter was measured

as D and its height as H by pushing the soil out of sample ring and taking the

measurements using a Vernier caliper. The outlet drain diameter, d was also measured

as 3.8mm.

Filter paper (characteristics was not stated) was placed at the base of the cell, the soil

specimen was placed in the Rowe cell and another filter paper was placed on top of the

specimen. A confining pressure of 50kPa was applied, a pressure difference using back

pressure of 40kPa at inflow and back pressure of 20kPa at outflow was used to

introduce water flow till equilibrium was observed as recommended for tests that

contain swelling soils (Meegoda and Rajapakse, 1993; Chalermyanont and Arrykul,

2005). The pressure difference maintained the flow in the soil (Shapiro et al, 1998). The

water flow was measured by taking the outflow reading when it became constant using

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a timer. Hence, the flow rate was the measured quantity of flow (interval) per time (see

Appendix E). The input flow was not recorded; it was assumed that hydraulic

conductivity values based on steady outflow were reliable for small soil specimens, as

recommended by Green et al (1998). They used soil specimen of 76mm diameter for

their study. The height of sample was stated as within 60 to 75mm. The study was on

the laboratory outflow measurement for hydraulic conductivity of small soil specimen,

without the recording of input flow.

The readings used for this study were constant; there was no archiving of non-constant

outflow.

The confining pressure 50kPa was applied through a pressure control system via the

confining pressure port of the Rowe cell, by choosing 50kPa as the pressure. The back

pressures of 40kPa and 20kPa that introduced the flow were applied through combined

digital back pressure input and quantity of flow reading equipment. One was connected

to the inflow port of the Rowe cell while the other was connected to the outflow port of

the Rowe cell. The back pressure was introduced by typing the value of back pressure

on the key pad of the equipment. The back pressure was shown on the back pressure

display screen after its input. The volume of water was shown on the volume reading

screen of the equipment (see Fig 3.7).

According to Meegoda and Rajapakse (1993), hydraulic conductivity tests conducted

on clays gave steady state reading within one week. It was observed in this study that

hydraulic conductivity readings were constant within one week.

The hydraulic conductivity was determined using the standard equation for the

experiment:

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kv = Q/60Ait m/s (3.23)

where Q = volume of water (ml) in time, t (mins); A = Area of sample (mm2), i =

hydraulic gradient (102Δp/H), Δp = pressure difference (kPa) between back pressure at

inflow and back pressure at outflow, H = height of sample (mm), kv = hydraulic

conductivity for vertical flow (m/s).

A typical reading is shown in Table 3.6.

Time (mins) Q (mm3) Q interval (mm3) Q interval (ml ) 0 45154 310 0.31 5 45464 10 45774 15 46084 20 46394 25 46704 30 47014 35 47324 40 47634 45 47944

Table 3.6: Quantity of flow, Q interval (ml) in 5 mins for uncontaminated soil.

* Q interval (mm3) was divided by 1000 to obtain Q interval (ml).

Table 3.5 showed that the quantity of flow (interval) was 0.31 ml in 5 minutes.

The hydraulic conductivity of soils is discussed in Chapter 4 and the results are shown

in Appendix E.

3.6 Summary of Chapter 3

Chapter 3 presented the materials and experimental methods used for this study.

Bentonite-kaolinite-sand mixtures with oil contents of 0.0, 1.8, 3.5, 5.3, and 7.1% were

used for the experiments.

84

The appropriate mass of bentonite, kaolinite and sand were separately oven dried, then,

manually mixed together. Known amounts of oil were mixed into the soil mixtures and

kept in a sealed container for one week to reach equilibrium.

Grading modulus was used for determination of effect of oil on the aggregate size

distribution of the soil mixtures. Liquid limit test was conducted using the Casagrande

cup and plastic limit was done through the hand rolling of soil. Compaction tests were

done using Proctor compaction method and hydraulic conductivity tests were performed

using the Rowe cell.

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CHAPTER 4

RESULTS AND DISCUSSION

The results of the experimental work are presented and discussed in this Chapter.

4.1 Aggregate size distribution of contaminated soils

The particle size distribution of the bentonite and kaolinite obtained using a hydrometer

and that of sand obtained using a set of sieves was shown in Figure 3.1. Hydrometer test

was not done for oil contaminated sand-clay mixtures because the test cannot be carried

out for soils with organic matter content (Head and Epps, 1980). Oil used in this study

originated from organic matter and contains hydrocarbons.

The aggregate size distribution curves of uncontaminated soil mixtures in Figure 3.2

were different from those of bentonite, kaolinite and sand in Figure 3.1, because soil

aggregates were mixtures of soils, while the particle size distribution curves were for

specific soils (clays and sand).

The aggregate size distribution curve of oven dried uncontaminated soils obtained by

dry sieving in this study generally shifted from coarser to finer as shown in Figure 3.2

because the bentonite content increased in the soil. The bentonite filled pores of

kaolinite and sand and clogged aperture of the sieves as it increased from

uncontaminated soil 1 to soil 5, and when the soils were contaminated by oil, the

aggregate size distribution curve generally shifted from finer to coarser in each soil as

shown in Figure 4.1. This was a result of both bentonite filling the soil pores and oil

contamination forming soil clods.

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Figure 4.1: Aggregate size distribution of soils

a. Soil 1 b. Soil 2

c. Soil 3 d. Soil 4

e. Soil 5

87

For oil contaminated soils flocculation occurs when oil is added to soils while there is

dispersion of soil aggregates when water is present. Flocculation is the process of

particles adhering to each other and forming clods, in this case as a result of oil

contamination while dispersion is the detaching from each other of solid particles in the

presence of water (Lambe, 1958). Because of oil contamination, the aggregate size

distribution curve shifted from finer to coarser (Figure 4.1), thereby implying that the

oil contamination caused the soil to flocculate. The shifting of the aggregate size

distribution curve further to the coarser in each of the five soils (Figure 4.1) as oil

contamination increased from 0.0% to 7.1% indicated that as oil content increased in

each soil, soil aggregation also increased; hence, the oil glued together more of the fine

aggregate as the oil content increased in the soil. The shifting of the aggregate size

distribution curve of soil from finer to coarser as oil content increased in the soil was

also observed by Ijimdiya (2012), when lateritic soil was contaminated with oil.

The behaviour of the soil as shown on the aggregate size distribution curves laid an

important foundation for other tests such as Atterberg limits, compaction and hydraulic

conductivity. It showed that when oil comes in contact with dry soil, the first effect it

had on it was flocculation. Ijimdiya (2012) stated that when oil was mixed into dry soil,

there was formation of soil clods. This study did not investigate the effect of oil

contamination on the aggregate size distribution of soil that contains water. However,

the presence of water results in dispersion of soil aggregates, consequently, it is

suggestive that the aggregate size distribution curve would shift from coarser to finer.

The contaminated soil aggregates could be deflocculated when water is introduced and

when that happens, the soil is dispersing. The flocculation and dispersion affect the

88

behaviour of the contaminated soil. The effect is explained in sections 4.3, 4.4 and 4.7

on Atterberg limits, compaction and hydraulic conductivity. .

4.2 Grading modulus of oil contaminated soils

Oil contaminated soil clods are different sized soil aggregates formed by the presence of

oil in the soil. The soil clods retained on soil 1 with 7.1% oil content is shown in Figure

4.2. Generally, larger sized clods were formed as the oil content increased in each soil

(Appendix A6). Consequently, in general, there was an increase in the grading modulus

of each soil (Figure 4.2). The amount of larger clods formed by oil contamination was

mainly retained on the 2mm and 0.425mm sieves (Appendix A6).

Figure 4.2: Soil clods on (a ) 2mm sieve (b) 0.425mm sieve for soil 1 (7.1% oil

content).

Assessing the grading modulus by using the formulae [(P2 + P0.425 + P0.075)/100, soils

that contain a high proportion of fine aggregate have a grading modulus below 2.0. In

the context of grading modulus, fine aggregate are soil aggregates with sizes less than

4.75mm while coarse aggregate are soil aggregates with sizes above 4.75mm

(a) (b)

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(Wieffering and Fourie, 2009). Figure 4.3 and Table A6.6 show the grading modulus of

the soils used for this research.

Figure 4.3: Grading modulus of oil contaminated soils.

The grading modulus of soil 1 ranged from 0.05 to 0.42, soil 2 ranged from 0.14 to 0.36,

soil 3 ranged from 0.08 to 0.47 and soil 4 ranged from 0.02 to 0.67, hence, even with oil

contamination that reduced the fine aggregate, the grading modulus of soils 1, 2, 3 and 4

were below 2.0. This was consistent with the nature of the soils used for the test, a

mixture of sand, kaolinite and bentonite that constituted the fine aggregate. It was also

deduced from Figure 4.3 that soil 4 had the least grading modulus at some points,

followed by soil 3, 2 and 1. However, for soil 5 there was more formation of soil clods

on the 2mm and 0.425mm sieves due to more reduction of fine aggregate, hence its

grading modulus values became high but still below 2.0 (SAPEM, 2011) .

The soils in this research had grading modulus below 2.0, hence, the soils are likely to

be good materials for use as soil liners for landfills, although grading modulus is not a

reliable parameter for design and does not give satisfactory results with regard to the

90

properties of the soil as it is not a true representation of the gradation of the soil

(Somayajulu and Anderson, 1971), and properties of soils influence their behaviour.

Soils with grading modulus below 2.0 are considered as soils of poor quality for road

construction because they possess low strength (SAPEM, 2011). It was deduced that the

soils used for this study are not good for road construction as they had grading modulus

below 2.0.

This study agreed with the findings of Somayajulu and Anderson (1971) that soils with

more fine grained sized particles do not always have lesser grading modulus. They

reported that sand-cement mixtures with 0, 6, 8 and 10% cement content had the same

grading modulus. However, Paige-Green (1999) reported that soils with 63% gravel,

22% sand, 8% silt and clay; 47% gravel, 39% sand, 8% silt and clay; and 32% gravel,

54% sand, and 8% silt and clay had grading modulus of 2.50 , 2.13, and 2.07

respectively. The aforementioned studies used dry soils while the present study was

done with oil contaminated soils, however, the soil aggregates were fine aggregates

(less than 4.75mm aggregate sizes) in all studies. Grading modulus data are interpreted

cautiously to avoid erroneous conclusions (Somayajulu and Anderson, 1971). This is

recommended for interpretation of grading modulus data of this study.

4.3 Plasticity characteristics of oil contaminated soils

The liquid limit and the plastic limit tests were done for the present study. Liquid limit

and plastic limit were defined in section 3.2.2. The range of the liquid limit and plastic

limits of uncontaminated montmorillonites and kaolintes, as stated by Fratta et al (2007)

are shown in Table 4.1. The liquid limit and plastic limit of Wyoming sodium bentonite

and China clay used for this study are shown in Table 4.1 and Appendix B.

91

Soil minerals and clay soils Liquid limit (%)

Plastic limit (%)

Montmorillonites 100 - 800 50 - 100 Kaolinites 35 - 100 25 -35 Wyoming sodium bentonite 540 66 China clay 61 32

Table 4.1 Liquid limit and plastic limit of soil minerals and clay soils of study.

The Atterberg limits and plasticity index of the soils of this study are shown in Figure

4.4 while the total fluid content at the Atterberg limits and plasticity index are shown in

Figure 4.5.

Figure 4.4: Atterberg limits and plasticity index of soils

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Figure 4.5: Total fluid content at Atterberg limits and plasticity index of soils

Das (2010) stated that water molecule has a negative charge at one end and a positive

charge at the other end, an arrangement referred to as dipole while plate shaped clay

particles possess a negatively charged surface. The cations (positive charges) of water

are attracted to the negatively charged clay surface, hence, by force of attraction, water

is held to clay particle, known as double layer water, and the innermost layer of the

double layer water is adsorbed by the clay. Generally, bentonites are described as clays

with negatively charged surfaces, which are attracted to the positive charges of water. In

the case of kaolinites with zero net charge, water is adsorbed by individual particles of

the soil (Al-Rawas and Goosen, 2006).

There was soil aggregation when the soils were contaminated by oil, as proved by the

aggregate size distribution tests of the contaminated soils, but, when water was added

during the liquid limit test, the soil dispersed and more of the soil surface was in contact

with water. The increase of water content for the contaminated soil to flow caused an

increase in the liquid limit of the soil, and this was precisely what was observed for soils

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1, 2, 3, 4 and 5. The soils with higher bentonite content generally required more water

for their dispersion and flow; hence, they had higher liquid limits.

Wilbourn et al (2007) carried out Atterberg limits tests on uncontaminated sand-

bentonite-kaolinite mixtures, they added sand and kaolinite to bentonite and there was a

reduction in Atterberg limits. The bentonite-kaolinite-sand ratios they used were

bentonite 10%, kaolinite 40%, sand 50% (soil A); bentonite 15%, kaolinite 35%, sand

50% (soil B); bentonite 20%, kaolinite 30% and sand 50% (soil C). This study had

lower Atterberg limits for uncontaminated soils 1, 2 and 3 in comparison with that of

Wilbourn et al (2007) due to the higher percentage of sand in the soil ratios, however,

they were close to that of Spagnoli and Sridharan (2012) as their uncontaminated sand-

clay mixtures contained quartz powder that increased the liquid limits of the soils.

The plasticity of the soils in this study ranged from high to very high. Burmister (1949)

classified soils using the plasticity index as non plastic (0%), slightly plastic (0 - 5%),

low plasticity (5- 10%), medium plasticity (10 - 20%), high plasticity (20 - 40%) and

very high plasticity (> 40%). Soil 5 contained the highest amount of bentonite,

consequently, its liquid limits and plastic limits were the highest, next was soil 4, then

soils 3, 2 and 1. The Atterberg limits of the soils were increased because bentonite and

oil contents in the soils influenced the characteristics of the soils. Rehman et al (2011)

stated that when oil gives extra cohesion to a soil, the liquid limit increases. The soils

also had increased plastic limits that resulted in increased plasticity index for the soils.

The five soils had liquid limits that were more than 20% and their plasticity index were

more than 7%. Ige (2010) specified those limits for soils to be used as soil liners.

Atterberg limits are determined and qualitative interpretations are done, however, it is

94

difficult to establish and interprete a quantitative relationship between Atterberg limits

and composition of the soils, as soils could possess the same liquid limit or plastic

limit and exhibit varying behaviours.

The plasticity of the oil contaminated soils increased as confirmed by addition of more

water to soils that contain more oil for the soils to flow. Rehman et al (2007) stated that

when more water was added to high plasticity clay that was contaminated by oil, there

was a change in the Atterberg limits of the soil. The soils of this study could flow when

dispersed by water, and the liquid limits increased, hence, in spite of the formation of

clods as oil comes in contact with soils, the permeation of water through soils in the

presence of oil could result in elevated liquid limits as the oil imparts cohesion to the

soils. The presence of bentonite and kaolinite had imparted a plastic behaviour to the

soil; when contaminated with oil and water added, the result was an oily soil with

increased liquid limit. Oil contamination lubricated the soil, and its interaction with

water resulted in increased liquid limit as more water was required to change the state of

the soil to a flowing mass.

There was an increase in the plasticity index of the soils as the bentonite content

increased because the liquid limit and plastic limit increased. The plasticity index of soil

1 ranged from 35% to 42%. Soil 2 had a plasticity index that ranged from 56% to 60%

while soil 3 had a plasticity index between 67% to 71%. Wilbourn et al (2007) also

reported very high plasticity index because of the presence of bentonite in the soil. Soils

with plasticity index of less than 65% are generally considered suitable as soil liners for

landfills (Ige, 2010). Soils 1 and 2 possessed plasticity index that was less than 65%,

that of soil 3 was close to 65% while those for soils 4 and 5 were beyond the

aforementioned limit.

95

4.4 Compaction of oil contaminated soils

4.4.1 Compaction curves using variation of dry density and water content

The compaction tests were done for soils 1, 2, 3, 4 and 5, the results are shown in

Appendix C while the compaction curves are shown in Figure 4.6. The aim was to

determine how an increase in the oil content affected the maximum dry density and

optimum water content of the soil.

96

Figure 4.6: Compaction of uncontaminated and contaminated soils.

a. Soil 1 b. Soil 2

c. Soil 3 d. Soil 4

e. Soil 5

97

The aggregate size distribution of the soils established that oil caused flocculation. The

soils had different proportion of bentonite and kaolinite and when the flocculated

contaminated soils were compacted, they exhibited different behaviours because at

various levels of oil contamination, the flocculation of the soils differed. Addition of

water to the flocculated soils resulted in dispersion of the clay content in the

contaminated soils, thereby causing a variation in the behaviour of the various oil

contaminated soils from the uncontaminated soil.

Water content affected the oil contaminated soil during compaction; the oil

contaminated soil was more flocculated when water content was low in the soil.

Dispersion increased when more water was added to soils, and at the optimum water

content, the soils had a combination of dispersed and flocculated soil fabric.

The dispersion of the soil from a flocculated soil fabric in each of the soils was

responsible for the varying maximum dry density of the soils, as each soil had a

combination of less flocculated and water dispersed soil content at its optimum water

content. This behaviour of the soil mix actually agreed with Lambe (1958) who also

found that both dispersion and flocculation could occur during compaction.

The contaminated soils with more oil content had lower optimum water content because

soil pores already contained more oil. The higher the oil contents in the soil, the lower

the water content that would be deflocculating the contaminated soil to attain the

maximum dry density. The soil was a combination of a flocculated and dispersed soil at

the optimum water content, hence, it was deduced that as the oil content increased in

each soil, the water content that produced a combination of dispersed and flocculated

soil at which the optimum water content was attained was lower.

98

Generally, as the bentonite content increased from soil 1 to soil 5, the maximum dry

density reduced. The uncontaminated soils with a lower content of bentonite were

dispersed faster than the soils with more bentonite content. Furthermore, generally, the

uncontaminated soils with higher bentonite content had higher optimum water content

and lower maximum dry density. This showed that as the bentonite content increased in

the soils from uncontaminated soil 1 to soil 5, there was an increase in the absorption of

water by the bentonite, also as kaolinite content decreased in the soil, there was a

decreasing hydrous nature of the kaolinite. This resulted in a decreased maximum dry

density in soils of higher bentonite content.

Chalermyanont and Arrykul (2005) reported that as bentonite content increased in

uncontaminated sand-bentonite mixtures, maximum dry density reduced; however

Jawad (2014) reported an increase in the maximum dry density as the bentonite content

increased in uncontaminated sand-bentonite mixtures. Wilbourn et al (2007) used

uncontaminated soil A (bentonite 10%, kaolinite 40%, sand 50%); soil B (bentonite

15%, kaolinite 35%, sand 50%) and soil C (bentonite 20%, kaolinite 30%, sand 50%),

soil B had highest maximum dry density, while in this research uncontaminated soil 2

had highest maximum dry density. Soil A had the lowest maximum dry density in their

study while in this study uncontaminated soils 3, 4 and soil 5 had the lowest maximum

dry density because the high bentonite content resulted in reduction of the maximum

dry density of the uncontaminated soil. Kenney et al (1992) stated that bentonite content

of about 20% in uncontaminated sand-bentonite mixtures resulted in a reduction of

maximum dry density. Soils 3, 4 and 5 with bentonite content of 20%, 25% and 30%

had lower maximum dry density than soils 1 and 2.

99

Soil 1 (Figure 4.6) with lowest bentonite content (10%) had maximum dry density that

generally reduced because of increasing oil content. Soil 1 had more porosity than other

soils because it contained the smallest amount of bentonite; addition of oil filled these

pores, consequently, the maximum dry density reduced. Bentonite and kaolinite filled

the pore spaces of the sand in this study, that resulted in reduced maximum dry density

and optimum water content as the soil was compacted at increased levels of oil

contamination.

Al-Rawas et al (2005) stated that a soil had reduced dry density because oil filled the

voids of the soil. Soils 2, 3, 4 and 5 in this research had a decrease in dry density as oil

content increased because oil lubricated the soil by filling voids. It could be suggested

that although bentonite and kaolinite filled the pores of sand, oil also infiltrated into the

pores, thereby lubricating the soil and consequently reducing the maximum dry density

accompanied by a reduction of the water content. Al-Sanad et al (1995) stated that oil

content decreased maximum dry density of well graded sand. Khamehchiyan et al

(2007) stated that oil lubrication decreased maximum dry density, as oil content

increased in low plasticity clay and sand with 5 to 15% silt, accompanied by a reduction

in the water content. They stated that when oil reduces the contact of soil particles and

water, the capillary tension force reduces as oil content increases and this result in a

decrease of the maximum dry density of the soil.

The reduction of optimum water content as oil content increased in soils means that oil

does not have a water absorbing nature. The nature of oil in terms of water absorption is

in contrast to that of cement. Al-Rawas et al (2005) stated that increase in cement

content decreased maximum dry density as optimum water content increased because of

its water absorbing nature. Okafor and Okonkwo (2009) discovered that rice husk ash

100

reduced maximum dry density of lateritic soil as optimum water content increased, as it

reduced fine aggregate of the soil.

Oil and water do not mix, oil is hydrophobic, restricting the contact between particles in

soil and water, this action results in decreased density of the soil. The oil in the

lubricated soil, a soft soil paste, resulted in a decreased maximum dry density as oil

content increased in the soil, accompanied by decreased optimum water content.

Soils 3, 4 and 5 had a decrease in maximum dry density as the oil content was increased

as shown on the compaction curves in Figure 4.6.

Oil contamination of soils resulted in formation of soft oil contaminated clods. When

the contaminated soils were compacted, there was a decrease in the maximum dry

density and optimum water content in the soils. The clods also contained oil in their

voids and compaction of the lubricated soil resulted in decreased maximum dry density.

This agreed with the findings of Al-Rawas et al (2005) that oil in soil voids resulted in a

decrease in maximum dry density.

Addition of water to soils resulted in the clay content in the sand-clay mixture absorbing

water; the oil contaminated soil was a swelled contaminated soil mostly due to bentonite

content and the swelled contaminated soil occupied more space in the compaction

mould. The outcome was a reduction of the maximum dry density of the soil. This

agreed with the findings on the effect of oil contamination on soils by Rahman et al

(2010). It also agrees with the findings of Chalermyanont and Arrykul (2005), that

bentonite in soils could result in a reduction of maximum dry density.

101

The compaction of soils at increasing oil contents resulted in less water used for

compaction to attain the maximum dry density as the oil and water filled the soil pores.

Oil contamination and the presence of water caused separation of soil voids, resulting in

reduced maximum dry density (Al-Rawas et al, 2005).

4.4.2 Compaction curves using variation of dry density and total fluid content

The compaction curves of the soils using variation of dry density with total fluid content

are shown in Figure 4.7. The results are shown in Appendix C. Previous studies used

variation of dry density and water content only.

102

Figure 4.7: Variation of dry density with total fluid content of soils.

a. Soil 1 b. Soil 2

c. Soil 3

d. Soil 4

e. Soil 5

103

Figure 4.7 showed that as optimum total fluid content increased in each soil, the

maximum dry density of the soil decreased. Generally, the compaction curves shifted to

higher optimum total fluid contents because the oil content increased in the soil.

However, it was observed that the compaction curves of soils with 7.1% oil contents in

soil 1 to 4 did not have optimum total fluid contents greater than that of 5.3% because

the soils had very low optimum water contents.

In a scenario in which the soil contained water before oil was added to the soil, the

amount of water in the soil was the water content. Furthermore, the total fluid content

would be the sum of water content and the oil content of the soil. Addition of more

water to the contaminated soil would result in increased water content. Generally, the

uncontaminated soils in each of the five soils of this study had higher optimum water

content and higher maximum dry density. It is suggestive that if soils contained water

before oil was added for the tests, the soils with more water content would have higher

maximum dry density.

According to Daniel (1991), when a clay soil is wet with water, it becomes sticky,

forming soil clods that disperse as the water content increases. This behaviour applied

to the soils of this study, if water was added firstly, before addition of oil. Hence, oil

added to soil containing water will flocculate the soil. Also, oil contamination of a soil

that did not contain water, resulted in flocculation of the soil (Ijimdiya, 2012), and

addition of water to the oil contaminated soil would result in dispersion of the soil. Oil

lubricates a soil that contains water, hence, there is flocculation of soil, but, when the

soil comes firstly in contact with oil, the soil becomes lubricated; hence, addition of

water results in dispersion of the soil.

104

Soils used for compaction test were flocculated when oil was mixed into the soils.

When water content increased in the soil as the compaction test was carried out, the soil

dispersed. There was a combination of flocculated and dispersed soil at the maximum

dry density. Generally, in this study, soils with higher optimum total fluid contents had

lower maximum dry densities. It is suggestive that the combination of flocculated and

dispersed soil at which the maximum dry density is attained is reached faster when the

oil content is higher in the soil. This is in agreement with Lambe (1958) who stated that

dispersion of flocculated clay soil increases as the water content increase when

compaction test is performed. However, this study did not carry out scanning electron

imaging of the soil to observe dispersion and flocculation.

4.4.3 Compaction curves from variation of dry density and total fluid content

using data of some previous researchers.

Data of some previous researchers were used for compaction curves. The compaction

curves of variation of dry density with total fluid content are shown in Figure 4.8 to

4.15. The curves were derived from Figures 2.10 to 2.17. Generally there was an

increase in the maximum dry density as the optimum total fluid content increased in Fig

4.8 while the maximum dry density decreased as the optimum total fluid content

increased in Figure 4.9 to 4.15. Generally, the compaction curves shifted to higher

optimum total fluid contents as a result of increase in oil contents (Appendix C4 and

C5).

105

Figure 4.8: Variation of dry density with total fluid content for metasedimentary soils

(Rahman et al, 2011), from Figure 2.10.


(Al Sanad et al, 1995), from Figure 2.11.

106


(Khamehchiyan et al , 2007), from Figure 2.12.

Figure 4.11: Variation of dry density with total fluid content for sand with 5 to 15% silt


107

Figure 4.12: Variation of dry density with total fluid content for low plasticity clay


Figure 4.13: Variation of dry density with total fluid content for basaltic grade V soils


108

Figure 4.14: Variation of dry density with total fluid content for basaltic grade VI soils


Figure 4.15: Variation of dry density with total fluid content for granitic sandy loam


109

4.5 Plasticity characteristics and compaction of oil contaminated soil

The liquid limits of soils increased as oil contamination increased because more water

was added to disperse the soils, so that the soils could flow (Figure 4.16). The

compaction of the oil contaminated soil 1 to 5 showed that generally as the oil content

increased in the soil, the optimum water content decreased, accompanied by a reduction

in the maximum dry density. The reduction of the optimum water content of the soil

was because a low content of water was required to produce a dispersed flocculated soil

mixture that gave the maximum dry density. Oil content filled soil pores, hence, a lower

water content than that of the uncontaminated soil was required to fill more of the soil

pores at reduced maximum dry density. Generally, the more the oil content, the less the

water content required to reach the maximum dry density of a soil. However, for the

liquid limit, the soil was dispersed before it could flow and the presence of more oil

required more amount of water for the oil contaminated soil to be dispersed and flow.

The liquid limits and plastic limits increased as oil content increased in the bentonite-

kaolinite-sand mixtures of study as a result of dispersion. Figure 4.16 and Appendix D

show that generally as plasticity characteristics and optimum total fluid content

increased in the soils, the maximum dry density and optimum water content of the soils

decreased.

110

Figure 4.16: Variation of maximum dry density with optimum water content, optimum

total fluid content and plasticity characteristics of soil 1.

a. Soil 1 b. Soil 2

c. Soil 3 d. Soil 4.

e. Soil 5

111

4.6 Hydraulic conductivity of oil contaminated soil

The hydraulic conductivity test was done for soils 1, 2, 3, 4 and 5 and the test was

carried out as described in section 3.5.4.

Hydraulic conductivity of contaminated soil does not involve complex equations

because oil does not mix with water (Silverstein, 1998). The premise that water and oil

were immiscible was used in this study and flow rate was taken as that for water, hence,

in carrying out the test for this study, standard hydraulic conductivity equation was

used.

The variation of hydraulic conductivity with oil content is shown in Figure 4.25 and

results are shown in Appendix E.

Figure 4.17: Variation of hydraulic conductivity with oil content.

112

Generally, the hydraulic conductivities of the soils decreased as the bentonite content

increased from soil 1 to 5. The decrease of the hydraulic conductivity was as a result of

the clay content in the soils. The bentonite content filled soil pores which resulted in

decreased hydraulic conductivity.

The hydraulic conductivity of uncontaminated soil 1 was less than that of

uncontaminated soils used by Ameta and Wayal (2008) and Gueddouda et al (2008) that

reported hydraulic conductivities of sand-bentonite mixture with 10% bentonite as 6.38

x 10-8m/s and dune7 sand-bentonite mixture with 10% bentonite as 1 x 10-7m/s

respectively. The hydraulic conductivities of this study were low in comparison with

that of Rojas et al (2003).

The increase of oil content in the soils of this study resulted in a decrease in hydraulic

conductivity. The oil content filled the pores of the soils and limited the flow of water

through the soils. Each soil had further reduction in hydraulic conductivity as the oil

content increased because the oil content filled the pores of the soils along with the clay.

This study agreed with findings of Shin and Das (2000), Rojas et al (2003) and Chew

and Lee (2006). They stated that the presence of oil in soil results in reduced hydraulic

conductivity because oil filled the pores of the soils.

The type of bentonite used for this study resulted in decrease of hydraulic conductivity.

Wyoming bentonite is a sodium bentonite that has high expansive property, Gueddouda

et al (2008) used calcium bentonite reported a higher hydraulic conductivity as stated

earlier.

7 Dune sand - deposited hill of sand as a result of the movement of wind or water.

113

A criterion for evaluating the performance of soil liner for landfill is its hydraulic

conductivity. Nwaiwu et al (2009) stated that the hydraulic conductivity of soil liners

for landfills should be low (below 1 x 10-9 m/s). Generally, hydraulic conductivity tests

conducted on the samples showed that soils 3, 4 and 5 had hydraulic conductivities that

were close to 1 x 10-9 m/s (see Figure 4.17). The soils met the requirement for use as

soil liners, using hydraulic conductivity as the basis for assessment.

4.7 Plasticity characteristics and hydraulic conductivity of oil contaminated soil

Liquid limit increased in each of the five soils as oil content increased. The hydraulic

conductivity decreased as the liquid limits increased because there was increased

dispersion of the oil contaminated clay content of the soil in the presence of water

(Lambe, 1958). Dispersion of oil contaminated clay soil also resulted in a decrease in

hydraulic conductivity.

Liquid limit and plastic limits generally increased in the soils of this study because of

dispersion of soil in the presence of water. Soil dispersion is mainly caused by the

presence of sodium ions in the soil structure, not in the pore water. The use of sodium

bentonite that contained sodium ions contributed to the high liquid limits and low

hydraulic conductivity of the soils via soil dispersion. In contrast, the presence of

sodium ions in pore water caused an increase in the hydraulic conductivity of soil-

bentonite mixtures (Shariatmadari et al, 2011). Bhuvaneshwari et al (2007) stated that

when clays come in contact with water, dispersion occurs as the force of attraction of

particles within the clay soils is reduced by the presence of water. The effect of

dispersion due to the bentonite and kaolinite in the soils of this study increased liquid

114

limits and reduced hydraulic conductivity, as the bentonite content increased from

uncontaminated soil 1 to 5 and oil content increased in each soil.

Mineralogical content of the soil is a major factor that causes an increase in the

plasticity of a soil, hence, sodium adhering to montmorillonite causes expansion of the

bentonite in soil. The effect of the expansion is increased dispersion of the clay soil;

consequently, the presence of bentonite in the soils caused an increase in the liquid limit

and decrease in the hydraulic conductivity of the soils.

The presence of sodium in the mineralogy of bentonite caused its dispersion (Das,

2010), hence, the dispersed clay content of the soil resulted in increased liquid limits as

bentonite content increased in the soils from soil 1 to soil 5 and decreased hydraulic

conductivity in the soils as the dispersed clay plugged the soil pores.

The dispersed soil plugged the soil pores while the swelling of clay reduced soil pores

in the presence of water and this caused an increase in the liquid limits of the soils as

bentonite content increased from soil 1 to 5 and as oil content increased in each of the

soils.

The characteristics of the soils used in this study were influenced by the presence of

bentonite and kaolinite. Bentonite has a higher specific surface area than kaolinite. The

specific surface area of a soil is the total surface area of a soil per unit mass of the soil.

Liquid limits of the soils increased because there was much absorption of water, as a

large surface area of the clay soil was in contact with water. Furthermore, as more water

was added to the soil, the clay absorbed water, resulting in an increased liquid limit of

the soil.

115

The study showed that soils with higher plasticity characteristics had reduced hydraulic

conductivity. Figure 4.18 and Appendix F show that liquid limits of the soils increased

while the hydraulic conductivity decreased as the oil content increased.

116

Figure 4.18: Variation of hydraulic conductivity with plasticity characteristics of soils.

a. Soil 1 b. Soil 2

d. Soil 4 c. Soil 3

e. Soil 5

117

4.8 Compaction characteristics and hydraulic conductivity of oil contaminated soil

Generally, when bentonite content increased in bentonite-sand mixture, the maximum

dry density and hydraulic conductivity reduced, while the optimum water content

increased (Chalermyanont and Arrykul, 2005). Generally, in the present study, the soils

had reduced maximum dry density, accompanied by increased optimum water content

as the bentonite content increased from uncontaminated soil 1 to 5. Furthermore, each

of the soils had reduced maximum dry density as the oil contamination increased,

accompanied by a reduction in the optimum water content.

A result of compaction was reduction of hydraulic conductivity. The addition of water

to the soil dispersed the oil flocculated soil during compaction, however, at the optimum

water content; there was a combination of dispersed and flocculated soil. The optimum

water content was attained at lower water content with increase of oil content in each

soil, because oil also filled the pores of the soil. This influenced the hydraulic

conductivity of the soils, as generally, the soils with lower maximum dry density

containing higher oil contents had lower hydraulic conductivity; hence, hydraulic

conductivity reduced with reduction of maximum dry density as a result of oil content.

This agreed with the observation of Chalermyanont and Arrykul (2005) that soils with

lower maximum dry density had lower hydraulic conductivity.

Hydraulic conductivity reduced because soft soil clods were present in the contaminated

soil. The soft soil clods were soft and easily compressible when the soils were

compacted, resulting in reduced hydraulic conductivity (Benson and Daniel, 1990).

Figure 4.19 and Appendix G show that generally as maximum dry density and optimum

water content decreased in the soils, the hydraulic conductivity decreased.

118

Figure 4.19: Compaction characteristics and hydraulic conductivity of soils.

a. Soil 1 b. Soil 2

c. Soil 3 d. Soil 4

e. Soil 5

119

4.9 Summary of results and discussions

The experimental results shows that the aggregate size distribution curve of oil

contaminated soils 1, 2, 3 4 and 5 shifted from finer to coarser as oil content increased

indicating that oil reduced the fine aggregate of the soil while forming soft oily soil

clods. The low values of grading modulus of soils indicated that they could be used as

soil liners for landfill. The Atterberg limits tests showed that soil 1 and 2 had plasticity

index below 65%, that of soil 3 was close to 65%, while those of soil 4 and 5 were

above the aforementioned limit. Maximum dry density and optimum water content

reduced in the soils as oil content increased while the optimum total fluid content

increased. The hydraulic conductivity of soils reduced as the amount of bentonite

increased from uncontaminated soil 1 to 5. Oil contamination also reduced the hydraulic

conductivity of the soils.

Appendix A to G show the results of this study. However, Table 4.2 is summary of this

study.

Geotechnical properties Soil 1 to 5 Atterberg limits Increased as oil content increased Maximum dry density Decreased as oil content increased Optimum water content Optimum total fluid content Increased as oil content increased Hydraulic conductivity Decreased as oil content increased

Table 4.2 Summary of study.

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CHAPTER 5

CONCLUSIONS AND RECOMMENDATIONS FOR FUTURE WORK

This research investigated the geotechnical properties of oil contaminated bentonite-

kaolinite-sand mixtures. The study generated data on grading modulus, Atterberg limits,

compaction and hydraulic conductivity. Section 5.1, 5.2, 5.3 and 5.4 are conclusions on

the effect of varied oil content on the geotechnical properties of bentonite-kaolinite-sand

mixtures.

5.1 Grading modulus of oil contaminated soils

The research showed that oil contamination shifted the aggregate size distribution curve

from finer to coarser in all the five soils (Figure 4.1). This implied that oil

contamination decreased the fine aggregate in the soil mixtures by forming soft oily soil

clods. The grading moduli of the five soils were below 2.0, hence, the soils could be

used as soil liners for landfills. However, grading modulus is not a sole criterion, as the

hydraulic conductivity of soil is also considered (Ige, 2010).

5.2 Plasticity characteristics of oil contaminated soils

The Atterberg limits tests showed that oil contamination generally increased the

Atterberg limits of the five soils (Figure 4.4). The increase in bentonite content from

uncontaminated soil 1 to 5 caused an increase in the Atterberg limits of the soils, and

when each soil was contaminated by oil, the Atterberg limits generally increased

because more water was added for the soil to flow as oil content increased. The

plasticity index of the five soils generally increased as oil content increased in each soil.

121

Soils 1 and 2 had plasticity index below 65%, while soil 3 had plasticity index close to

65. Soil 3 is suitable as soil liner for landfill, as Ige (2010) specified that soils with

plasticity index of 65% are suitable as soil liners. There is difficulty in handling soils

with plasticity index above 65 (Ige, 2010).

5.3 Compaction of oil contaminated soils

The compaction tests showed that increase in oil content in each of the soil mixtures

resulted in a reduction of both maximum dry density and optimum water content. The

maximum dry density reduced in the soils due to the swelling nature of bentonite.

Furthermore, oil lubrication reduced the maximum dry density as oil filled the soil

pores. The oil in soil pores reduced the contact of water and soil, resulting in the

reduction of maximum dry density.

5.4 Hydraulic conductivity of oil contaminated soils

The hydraulic conductivity test for the five soils showed that increase in bentonite

content from uncontaminated soil 1 to 5 caused a decrease in the hydraulic conductivity

of the soils. Oil contamination decreased the hydraulic conductivity in each of the five

soils because oil occupied soil pores. The oil used for this research had a very high

viscosity index that contributed to decrease of hydraulic conductivity.

Soil mixtures that have hydraulic conductivity of less than 1 x 10-9 m/s are suitable for

soil liners. Generally, the hydraulic conductivity of soils 3, 4 and 5 were below 1 x 10-9

m/s.

122

5.5 Recommendations for future work

A proper view of the findings of this research showed that there are some areas that will

need further research.

It is recommended that sand and bentonite mixtures be used for further research.

Kaolinite was included because kaolinite reduced the liquid limit of bentonite along

with sand, however, sand-bentonite mixtures are still used as soil liners for landfills,

putting into consideration the cost of clays.

It is recommended that future study use oil of varied viscosities. The oil used for this

research had a viscosity index of 97, which was highly viscous. Oil content of lower

viscosity could be used because crude oil products are of varied viscosity.

123

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131

APPENDIX A

AGGREGATE SIZE DISTRIBUTION AND GRADING MODULUS TESTS RESULTS

A1 Particle size analysis test result of sand

Mass of soil used for sieve analysis = 200g Sieves (mm)

Mass of empty sieve (g)

Mass of sieve and

sand (g)

Mass retained on

sieve (g)

Cumulative passed

(g)

Total percent passed

(%) 2.000 461.2 461.2 0.0 199.9 100

0.425 389.3 393.0 3.7 196.2 98.1 0.300 307.5 370.7 63.2 133.0 66.5 0.250 366.3 431.8 65.5 67.5 33.8 0.212 361.3 378.9 17.6 49.9 25.0 0.180 354.5 389.4 34.9 15.0 7.5 0.150 349.5 354.8 5.3 9.7 4.9 0.125 348.8 351.7 2.9 6.8 3.4 0.106 355.4 358.6 3.2 3.6 1.8 0.090 338.8 340.7 1.9 1.7 0.9 0.075 297.0 297.8 0.8 0.9 0.5 0.063 350.7 351.0 0.3 0.6 0.3 Pan 325.5 326.1 0.6 0 0

Total mass retained on sieve = 199.9

Table: A1 Particle size distribution data for sand.

132

Figure: A1.Coefficient of uniformity and coefficient of curvature for sand.

Cu = D60/D10 = 0.3/0.18 = 1.7

Cu < 3, the sand is uniform sand.

Cc = (D30 )2/D10. D60 = (0.23 x 0.23)/(0.18 x 0.3) = 0.0529/0.054 = 0.98

Cc < 1, the sand is gap graded

A2 Specific gravity of sand

(50ml bottle; 10g of soil used for test)

Specific gravity = D2 - D1/[(D4 - D1) - (D3-D2)]

where D1 = mass of density bottle and stopper; D2 = mass of density bottle, soil and

stopper; D3 = mass of density bottle, soil, water and stopper; D4 = mass of density

bottle, water and stopper.

133

Measurements Density bottle 1 Density bottle 2 Density bottle + Stopper (D1)g 32.008 32.006 Density bottle + soil + Stopper (D2)g 42.008 42.006

Density bottle + soil + water + Stopper (D3)g

88.045 88.043

Density bottle + water + Stopper (D4)g 81.833 81.831

Specific gravity 2.640 2.640 2.64

Table A2 Specific gravity of sand.

A3 Specific gravity of bentonite and kaolinite

A3.1 Specific gravity of bentonite

Measurements Density bottle 1 Density bottle 2

Density bottle + stopper (D1)g 32.008 32.006 Density bottle + soil + stopper (D2)g 42.008 42.006 Density bottle + soil + water + stopper(D3)g

88.063 88.061

Density bottle + water + stopper (D4)g 81.833 81.831 Specific gravity 2.652 2.652

2.65

Table A3.1: Data of specific gravity of bentonite

134

A3.2 Specific gravity of kaolinite

Measurements Density bottle 1 Density bottle 2

Density bottle + stopper (D1)g 32.008 32.006 Density bottle + soil + stopper (D2)g 42.008 42.006

Density bottle + soil + water + Stopper(M3)g

87.988 87.986

Density bottle + water + stopper (D4)g 81.833 81.831 Specific gravity 2.601 2.601

2.60

Table A3.2: Data of specific gravity of kaolinite.

A4 Hydrometer test

A4.1 Calibration parameters Mass of hydrometer = 59.8g

Volume of hydrometer , Vh= 59.8ml

Length between 100 and 900ml on sedimentation cylinder = 276mm

Cross sectional area of hydrometer, A = 2898.6mm2

Test temperature = 25 degrees centigrade

Meniscus correction, Cm = + 0.5

Temperature correction, Mt = +1.0 degrees centigrade

Dispersant correction (evaporating 50ml stock solution), x = 2md= 2 x 1.75 = 3.5

Water density correction (British Standard), Cw = 1.8

Hydrometer reading in dispersant = 0.5mm

Rh = Rh’ + Cm = Rh’ + 0.5

HR = 176 – 2.8 Rh

R = Rh + Mt – x + 1.8 = Rh – 0.7

135

A4.2 Hydrometer test formulae

Cross sectional area of cylinder, A = 800/L x 1000 mm2

Where L = Distance from 100 to 900ml on the sedimentation cylinder

Particle diameter D = 0.005531 √µH/(Gs – 1 )t

Where, D = particle diameter ( mm ); µ= viscosity of water at the temperature used for

test; Gs = the specific gravity of the specimen; t = time at which reading was taken

(min).

Percentage passing , k = Gs/[m(Gs – 1)] x R x 100%

Where Gs = specific gravity of specimen; m = mass of soil after it’s pretreatment;

R = Hydrometer reading that was totally corrected.

A4.3 Calibration correction equations

Figure A4.1: Calibration of hydrometer.

136

Scale mark (g/cm2)

Reading ( Rhr) (mm)

Distance from lowest mark Rh or D (mm)

H = Rh + N (mm)

HR (mm)

1.030 30 14 24 94 1.025 25 28 38 108 1.020 20 40 50 120 1.015 15 54 64 134 1.010 10 68 78 148 1.005 5 81 91 161 1.000 0 96 106 176 0.995 -5 111 121 191

Table 4.1 Calibration data for hydrometer.

N = 10mm, h = 140mm, HR = H + ½ (h - Vh/A)

Where N = distance from the neck of hydrometer to lowest calibration mark; h = length of hydrometer bulb (excluding the stem); HR = effective depth

Figure A4.2: Calibration graph for hydrometer.

Calibration equation: HR = 176 – 2.8Rh

137

A4.4 Hydrometer test (Bentonite)

Specific gravity of specimen = 2.65

Viscosity of water at test temperature (BS 1377:1990) = 0.8909mPaS

Initial dry mass of soil used = 59.38g

Soil dry mass after it was pretreated = 58.88g

Loss due to pretreatment = 0.50g

Pretreatment loss = 0.5/59.38 x 100 = 0.84%

D = 0.005531 √µH/( Gs – 1 )t = 0.005531√0.8909HR/1.65t = 4.064 √HR/t

k = Gs/[m(Gs – 1)] x R x 100% = 2.65/(58.88 x 1.65) x R x 100 = 2.726 x R%

Time elapsed (min)

Hydrometer reading (Rhr)

True reading (Rh)

Effective depth ( HR )

Fully Corrected reading ( R )

Particle diameter (D ) (µm )

Particle diameter (D ) (mm )

Percentage finer than D (% )

0.5 31.5 32 64 31.3 45.92 0.04592 85.3

1 31 31.5 87.8 30.8 38.08 0.03808 84

2 30.5 31 89.2 30.3 27.15 0.02715 82.6

4 30 30.5 90.6 29.8 19.34 0.01934 81.2

8 29.5 30 92 29.3 13.78 0.01378 79.9

15 29 29.5 93.4 28.8 10.16 0.01016 78.6

30 28.5 29 94.8 28.3 7.22 0.00722 77.2

60 27.5 28 97.6 27.3 5.18 0.00518 74.5

120 27 27.5 99 26.8 3.69 0.00369 73.1

240 26.5 27 100.4 26.3 2.63 0.00263 71.7

450 26 26.5 101.8 25.8 1.93 0.00193 70.4

1420 26 26.5 101.8 25.8 1.93 0.00193 70.4

Table A4.2: Data of hydrometer test for bentonite.

138

A4.5 Hydrometer test ( Kaolinite )

Specific gravity of specimen = 2.60

Viscosity of water at test temperature = 0.8909mPaS

Initial dry mass of soil used = 55.00g

Soil dry mass after it was pretreated = 54.50g

Loss due to pretreatment = 0.50g

Pretreatment loss = 0.5/50 x 100 = 1%

D = 0.005531√µH/( Gs – 1 )t = 0.005531√0.8909HR/1.6t = 4.126 √HR/t

k = Gs/[m(Gs – 1)] x R x 100% = 2.6/( 54.5 x 1.6) x R x 100 = 2.981 x R%

Time elapsed (min)

Hydrometer reading (Rhr)

True reading (Rh)

Effective depth ( HR )

Fully Corrected reading ( R )

Particle diameter (D ) (µm )

Particle diameter (D ) (mm )

Percentage finer than D (% )

0.50 31.0 31.5 87.8 30.8 54.23 0.05423 91.8 1.0 31.0 31.5 87.8 30.8 38.33 0.03833 91.8

2.00 30.5 31 89.2 30.3 27.55 0.02755 90.3 4.00 30.0 30.5 90.6 29.8 19.63 0.01963 88.8 8.00 29.5 30.0 92.0 29.3 13.99 0.01399 87.3

15.00 29.0 29.5 93.4 28.8 10.29 0.01029 85.8 30.00 28.5 29.0 94.8 28.3 7.33 0.00733 84.3 60.00 26.5 27.0 100.4 26.3 5.33 0.00533 78.4

120.00 24.5 25.0 99.0 24.3 3.73 0.00373 72.4 240.00 21.5 22.0 106.0 21.3 2.74 0.00274 63.5 420.00 18.5 19.0 114.4 18.3 2.15 0.00215 54.6

1420.00 8.5 9.0 150.8 8.3 1.34 0.00134 24.7

Table A4.3: Data of hydrometer test for kaolinite.

139

A5 Aggregate size distribution test results

A5.1 Soil 1

Mass of soil used for sieve analysis = 200.0g

Sieves (mm)

Mass of empty sieve

(g)

Mass of sieve and

sand (g)

Mass retained on

sieve (g)

Cumulative passed (g)


(%)

2.000 498.6 498.6 0.0 198.0 100.000 0.425 390.3 399.3 9.0 189.0 95.500 0.300 307.4 407.9 100.5 88.5 44.700 0.250 366.2 424.1 57.9 30.6 15.500 0.212 361.6 365.2 3.6 27.0 13.600 0.180 354.4 372.5 18.1 8.9 4.500 0.150 349.7 351.7 2.0 6.9 3.500 0.125 349.1 350.9 1.8 5.1 2.600 0.106 355.6 357.3 1.7 3.4 1.700 0.090 338.9 340.6 1.7 1.7 0.009 0.075 297.3 297.7 0.4 1.3 0.007 0.063 352.1 352.7 0.6 0.7 0.004 Pan 360.9 361.0 0.7 0.0 0.000

Total mass retained on sieve = 198.0g

Table A5.1: Aggregate size distribution data for soil 1 (0.0% oil content).

Mass of soil used for sieve analysis = 203.5g Sieves (mm)

Mass of empty sieve

(g)

Mass of sieve and

sand (g)

Mass retained on sieve

(g)



(%)

2.000 498.6 506.1 7.5 193.1 96.300 0.425 390.2 414.8 24.6 168.5 84.000 0.300 307.4 371.0 63.6 104.9 52.300 0.250 366.0 434.8 68.6 36.3 18.100 0.212 361.4 367.7 6.3 30.0 15.000 0.180 354.5 374.9 20.4 9.6 4.900 0.150 349.6 351.9 2.3 7.3 3.600 0.125 349.0 350.6 1.6 5.7 2.800 0.106 355.5 357.5 2.0 3.7 1.800 0.090 338.9 340.8 1.9 1.8 0.009 0.075 297.2 297.6 0.4 1.4 0.007 0.063 351.3 351.6 0.3 1.1 0.005 Pan 360.9 362.0 1.1 0.0 0.000



140


Mass of empty sieve

(g)

Mass of sieve and

sand (g)


(g)



(%)

2.000 498.6 506.4 7.8 196.6 96.200 0.425 390.2 435.3 45.1 151.5 74.100 0.300 307.3 391.8 84.5 67.0 32.800 0.250 366.0 408.2 42.2 24.8 12.100 0.212 361.4 364.5 3.1 21.7 10.600 0.180 354.5 369.4 14.9 6.8 3.300 0.150 349.6 351.0 1.4 5.4 2.600 0.125 349.0 350.3 1.3 4.1 2.000 0.106 355.5 356.6 1.1 3.0 1.500 0.090 338.9 340.4 1.5 1.5 0.007 0.075 297.1 297.4 0.3 1.2 0.006 0.063 351.3 351.7 0.4 0.8 0.004 Pan 360.9 361.7 0.8 0.0 0.000




Mass of empty sieve

(g)

Mass of sieve and

sand (g)


(g)



(%)

2.000 498.5 505.3 6.8 201.0 96.700 0.425 390.2 446.9 56.6 144.4 69.500 0.300 307.3 405.4 98.1 46.3 22.300 0.250 366.0 391.1 25.1 21.2 10.200 0.212 361.4 362.8 1.4 19.8 9.500 0.180 354.5 364.0 9.4 10.4 5.000 0.150 349.6 351.4 1.8 8.6 4.100 0.125 349.0 350.5 1.5 7.1 3.400 0.106 355.5 357.4 1.9 5.2 2.500 0.090 338.9 341.2 2.3 2.9 1.300 0.075 297.1 297.8 0.6 2.3 1.100 0.063 351.3 352.1 0.8 1.5 0.007 Pan 360.9 362.4 1.5 0.0 0.000



141


Mass of empty sieve

(g)

Mass of sieve and

sand (g)


(g)



(%)

2.00 498.5 513.7 15.2 196.9 92.800 0.425 390.2 465.2 75.0 121.9 57.500 0.300 307.3 386.2 78.8 43.1 20.300 0.250 366.0 388.1 21.9 21.2 10.000 0.212 361.4 363.8 2.4 18.8 8.900 0.180 354.6 365.4 10.8 8.0 3.800 0.150 349.6 351.6 2.0 6.0 2.800 0.125 349.0 350.5 1.5 4.5 2.100 0.106 355.5 356.7 1.2 3.3 1.600 0.090 338.9 341.0 2.1 1.2 0.006 0.075 297.1 297.5 0.3 0.9 0.004 0.063 351.4 351.7 0.3 0.6 0.003 Pan 360.9 361.5 0.6 0.0 0.000



A5.2 Soil 2


Mass of empty sieve

(g)

Mass of sieve and

sand (g)


(g)



(%)

2.000 498.3 499.0 0.7 198.2 99.600 0.425 390.2 416.2 26.0 172.2 86.600 0.300 307.4 400.3 92.9 79.3 39.900 0.250 366.2 430.2 64 15.3 7.700 0.212 361.4 366.5 5.1 10.2 5.100 0.180 354.6 361.3 6.7 3.5 1.700 0.150 349.6 350.3 0.7 2.8 1.400 0.125 349.0 349.8 0.8 2 1.000 0.106 355.5 356.1 0.6 1.4 0.007 0.090 339.0 339.8 0.8 0.6 0.003 0.075 297.2 297.3 0.1 0.5 0.003 0.063 351.4 351.5 0.1 0.4 0.002 Pan 360.9 361.3 0.4 0.0 0.000



142


Mass of empty sieve

(g)

Mass of sieve and

sand (g)


(g)



(%)

2.000 498.3 500.5 2.2 198.9 98.900 0.425 390.1 417.8 27.7 171.2 85.100 0.300 307.4 377.0 69.6 101.6 50.500 0.25 366.2 438.3 72.1 29.5 14.700

0.212 361.4 373.0 11.6 17.9 8.900 0.180 354.6 365.0 10.3 7.6 3.800 0.150 349.6 352.6 3.0 4.6 2.300 0.125 349.0 349.9 0.9 3.7 1.800 0.106 355.5 357.0 1.5 2.2 1.100 0.090 339.0 340.5 1.5 0.7 0.003 0.075 297.2 297.3 0.1 0.6 0.003 0.063 351.4 361.6 0.2 0.4 0.002 Pan 360.9 361.3 0.4 0.0 0.000




Mass of empty sieve

(g)

Mass of sieve and

sand (g)


(g)



(%)

2.000 498.3 499.3 1.0 203.7 99.500 0.425 390.1 419.9 29.8 173.9 85.000 0.300 307.2 413.5 106.3 67.6 33.000 0.250 366.1 407.1 41.0 26.6 13.000 0.212 361.4 363.6 2.2 24.4 11.900 0.180 354.6 367.4 12.8 11.6 5.700 0.150 349.6 352.5 2.9 8.7 4.300 0.125 349.0 350.8 1.8 6.9 3.400 0.106 355.5 357.4 1.9 5.0 2.400 0.090 338.9 341.3 2.4 2.6 1.300 0.075 297.2 297.7 0.5 2.1 1.000 0.063 351.4 352.0 0.6 1.5 0.007 Pan 360.9 362.4 1.5 0.0 0.000



143


Mass of empty sieve

(g)

Mass of sieve and

sand (g)


(g)



(%)

2.000 498.3 500.7 2.4 205.3 98.900 0.425 390.2 447.4 57.2 148.1 71.300 0.300 307.3 420.2 112.9 35.2 16.900 0.250 366.1 380.2 14.1 21.1 10.200 0.212 361.4 364.2 2.8 18.3 8.800 0.180 354.6 362.0 7.4 10.9 5.200 0.150 349.6 354.4 4.8 6.1 2.900 0.125 349.0 350.6 1.6 4.5 2.200 0.106 355.5 356.9 1.4 3.1 1.500 0.090 338.9 341.1 2.2 0.9 0.004 0.075 297.2 297.5 0.3 0.6 0.002 0.063 351.3 351.6 0.3 0.3 0.001 Pan 360.9 361.2 0.3 0.0 0.000




Mass of empty sieve

(g)

Mass of sieve and

sand (g)


(g)

Cumulative passed (g) Total percent passed

(%)

2.000 498.3 503.1 4.8 207.5 97.700 0.425 390.2 461.7 71.5 136.0 64.100 0.300 307.3 411.7 104.4 31.6 14.900 0.250 366.1 378.4 12.3 19.3 9.100 0.212 361.3 363.6 2.3 17.0 8.000 0.180 354.6 361.2 6.6 10.4 4.900 0.150 349.6 356.7 7.1 3.3 1.600 0.125 349.0 350.2 1.2 2.1 0.010 0.106 355.5 356.7 1.2 0.9 0.004 0.090 338.9 339.7 0.8 0.1 0.0005 0.075 297.1 297.2 0.1 0.0 0.000 0.063 351.3 351.3 0.0 0.0 0.000 Pan 360.9 360.9 0.0 0.0 0.000



144

A5.3 Soil 3


Mass of empty sieve

(g)

Mass of sieve and

sand (g)

Mass retained on

sieve (g)



(%)

2.000 498.2 498.9 0.7 198.3 99.600 0.425 390.3 405.1 14.8 183.5 92.200 0.300 307.4 392.5 85.1 98.4 49.400 0.250 366.2 423.4 57.2 41.2 20.700 0.212 361.4 381.6 20.2 21.0 10.600 0.180 354.5 370.2 15.7 5.3 2.700 0.150 349.6 352.2 2.6 2.7 1.400 0.125 349.0 349.4 0.4 2.3 1.200 0.106 355.5 356.2 0.7 1.6 0.008 0.090 339.0 339.9 0.9 0.7 0.004 0.075 297.2 297.4 0.2 0.5 0.003 0.063 351.3 351.5 0.2 0.3 0.002 Pan 360.9 361.2 0.3 0.0 0.000




Mass of empty sieve

(g)

Mass of sieve and

sand (g)


(g)


(%)

2.000 498.1 499.4 1.3 200.9 99.400 0.425 390.3 416.6 26.3 174.9 86.500 0.300 307.3 381.7 74.4 100.2 49.600 0.250 366.2 428.3 62.1 38.1 18.800 0.212 361.4 374.1 12.7 25.4 12.600 0.180 354.6 373.0 18.4 7.0 3.500 0.150 349.6 354.0 4.4 2.6 1.300 0.125 349.0 349.4 0.4 2.2 1.100 0.106 355.5 356.1 0.6 1.6 0.008 0.090 338.9 339.9 1.0 0.6 0.003 0.075 297.2 297.3 0.1 0.5 0.002 0.063 351.3 351.4 0.1 0.4 0.002 Pan 360.8 361.2 0.4 0.0 0.000



145


Mass of empty sieve

(g)

Mass of sieve and

sand (g)


(g)


(%)

2.00 498.2 499.6 1.4 203.8 99.300 0.425 390.1 416.6 26.5 177.3 86.400 0.300 307.3 401.9 94.6 82.7 40.300 0.250 366.2 414.6 48.4 34.3 16.700 0.212 361.4 365.9 4.5 29.8 14.500 0.180 354.7 371.5 16.8 13 6.300 0.150 349.7 357.3 7.6 5.4 2.600 0.125 349.1 350.3 1.2 4.2 2.000 0.106 355.5 356.8 1.3 2.9 1.400 0.090 339.0 341.1 2.1 0.8 0.004 0.075 297.2 297.3 0.1 0.7 0.003 0.063 351.2 351.6 0.4 0.3 0.002 Pan 360.9 361.2 0.3 0.0 0.000




Mass of empty sieve

(g)

Mass of sieve and

sand (g)


(g)


(%)

2.000 498.1 501.6 3.5 205.3 98.300 0.425 390.1 440.1 50.1 155.2 74.300 0.300 307.4 418.1 110.7 44.5 21.300 0.250 366.2 384.5 18.3 26.2 12.500 0.212 361.4 364.5 3.1 23.1 11.100 0.180 354.7 366.6 11.9 11.2 5.400 0.150 349.6 354.6 5.0 6.2 3.000 0.125 349.1 350.7 1.6 4.6 2.200 0.106 355.5 357.0 1.5 3.1 1.500 0.090 339.0 341.2 2.2 0.9 0.004 0.075 297.2 297.6 0.4 0.5 0.002 0.063 351.3 351.5 0.2 0.3 0.001 Pan 360.9 361.2 0.3 0.0 0.000



146


Mass of empty sieve

(g)

Mass of sieve and

sand (g)


(g)


(%)

2.000 498.1 505.8 7.7 204.7 96.400 0.425 390.1 481.5 91.3 113.4 53.400 0.300 307.5 412.1 104.6 8.8 4.100 0.250 366.2 367.7 1.5 7.3 3.400 0.212 361.4 363.0 1.6 5.7 2.700 0.180 354.7 357.1 2.4 3.3 1.600 0.150 349.6 351.7 2.1 1.2 0.005 0.125 349.1 349.8 0.7 0.5 0.002 0.106 355.5 355.9 0.4 0.1 0.0005 0.090 339.0 339.1 0.1 0.0 0.000 0.075 297.2 297.2 0.0 0.0 0.000 0.063 351.3 351.3 0.0 0.0 0.000 Pan 360.9 360.9 0.0 0.0 0.000



A5.4 Soil 4

Mass of soil used for sieve analysis = 200.0g

Sieves (mm)

Mass of empty sieve

(g)

Mass of sieve and

sand (g)


(g)


(%)

2.000 496.6 497.1 0.5 198.5 99.700 0.425 420.9 424.9 4.0 194.5 97.700 0.300 307.6 365.0 57.4 137.1 68.900 0.250 366.1 416.2 50.1 87.0 43.700 0.212 361.4 392.1 30.7 56.3 28.300 0.180 354.6 395.0 40.4 15.9 8.000 0.150 349.6 360.8 11.2 4.7 2.400 0.125 349.1 350.2 1.1 3.6 1.800 0.106 355.8 356.5 0.7 2.9 1.500 0.090 338.8 340.1 1.3 1.6 0.008 0.075 297.1 297.5 0.4 1.2 0.006 0.063 351.1 351.4 0.3 0.9 0.005 Pan 325.6 326.5 0.9 0.0 0.000



147


Mass of empty sieve

(g)

Mass of sieve and sand

(g)

Mass retained on

sieve (g)



(%)

2.000 496.6 497.5 0.9 199.8 99.600 0.425 420.9 430.2 9.3 190.5 94.900 0.300 307.5 387.1 79.6 110.9 55.300 0.250 365.9 426.2 60.3 50.6 25.200 0.212 361.4 371.6 10.2 40.4 20.100 0.180 354.5 372.2 17.7 22.7 11.300 0.150 349.6 358.2 8.6 14.1 7.000 0.125 349.0 350.1 1.1 13.0 6.500 0.106 355.5 357.5 2.0 11.0 5.500 0.090 338.8 342.5 3.7 7.3 3.600 0.075 297.1 298.0 0.9 6.4 3.200 0.063 351.1 352.4 1.3 5.1 2.500 Pan 325.6 330.7 5.1 0.0 0.000




Mass of empty sieve

(g)

Mass of sieve and

sand (g)


(g)



(%)

2.000 496.9 498.9 2.0 202.6 99.000 0.425 420.7 440.4 19.7 182.9 89.400 0.300 307.2 376.7 69.5 113.4 55.400 0.250 366.0 425.2 59.2 54.2 20.600 0.212 361.1 373.2 12.1 42.1 10.400 0.180 354.5 375.3 20.8 21.3 6.400 0.150 349.5 357.7 8.2 13.1 5.600 0.125 348.7 350.4 1.7 11.4 3.900 0.106 355.6 359.1 3.5 7.9 5.500 0.090 338.8 342.6 3.8 4.1 2.000 0.075 297.1 297.6 0.5 3.6 1.700 0.063 350.9 352.0 1.1 2.5 1.200 Pan 325.5 328.0 2.5 0.0 0.000



148


Mass of empty sieve

(g)

Mass of sieve and

sand (g)


(g)


(%)

2.000 496.9 498.6 1.7 205.2 99.20000 0.425 420.7 496.2 75.5 129.7 62.70000 0.300 307.1 404.0 96.9 32.8 15.90000 0.250 366.0 383.8 17.8 15.0 7.20000 0.212 361.3 365.5 4.2 10.8 5.20000 0.180 354.4 360.3 5.9 4.9 2.40000 0.150 349.5 352.1 2.6 2.3 1.10000 0.125 349.0 349.7 0.7 1.6 0.00800 0.106 355.5 356.2 0.7 0.9 0.00400 0.090 338.9 339.6 0.7 0.2 0.00097 0.075 297.1 297.2 0.1 0.1 0.00048 0.063 350.9 351.0 0.1 0.0 0.00000 Pan 325.5 325.5 0.0 0.0 0.00000




Mass of empty sieve

(g)

Mass of sieve and

sand (g)


(g)


(%)

2.000 496.8 503.2 6.4 204.2 97.00000 0.425 420.6 556.3 135.7 68.5 32.50000 0.300 307.2 370.9 63.7 4.8 2.30000 0.250 366.0 368.4 2.4 2.4 1.10000 0.212 361.3 362.2 0.9 1.5 0.00700 0.180 354.5 355.4 0.9 0.6 0.00300 0.150 349.5 349.9 0.4 0.2 0.00095 0.125 349.0 349.2 0.2 0.0 0.00000 0.106 355.5 355.5 0.0 0.0 0.00000 0.090 338.9 338.9 0.0 0.0 0.00000 0.075 297.1 297.1 0.0 0.0 0.00000 0.063 350.9 350.9 0.0 0.0 0.00000 Pan 325.6 325.6 0.0 0.0 0.00000



149

A5.5 Soil 5


Mass of empty sieve

(g)

Mass of sieve and

sand (g)


(g)


(%)

2.000 496.8 497.3 0.5 197.9 99.7 0.425 420.7 426.9 6.2 191.7 96.6 0.300 307.2 349.4 42.2 149.5 75.4 0.250 366.0 414.7 48.7 100.8 50.8 0.212 361.3 376.2 14.9 85.9 43.3 0.180 354.5 386.2 31.7 54.2 27.3 0.150 349.5 380.7 31.2 23.0 11.6 0.125 348.9 355.0 6.1 16.9 8.5 0.106 355.5 360.9 5.4 11.5 5.8 0.090 338.8 343.3 4.5 7.0 3.5 0.075 297.1 297.9 0.8 6.2 3.1 0.063 350.9 352.6 1.7 4.5 2.3 Pan 325.5 330.0 4.5 0.0 0.0




Mass of empty sieve

(g)

Mass of sieve and

sand (g)


(g)


(%)

2.000 496.8 498.8 2.0 197.9 99.0 0.425 420.5 437.5 17.0 180.9 90.5 0.300 307.2 354.1 46.9 134.0 67.0 0.25 366.0 414.0 48.0 86.0 43.0

0.212 361.2 372.7 11.5 74.5 37.3 0.180 354.4 380.2 25.8 48.7 24.4 0.150 349.4 371.2 21.8 26.9 13.5 0.125 348.9 353.1 4.2 22.7 11.4 0.106 355.5 359.3 3.8 18.9 9.5 0.090 338.9 345.6 6.7 12.2 6.1 0.075 297.2 298.8 1.6 10.6 5.3 0.063 350.9 353.2 2.3 8.3 4.2 Pan 325.5 333.8 8.3 0.0 0.0



150


Mass of empty sieve

(g)

Mass of sieve and

sand (g)


(g)


(%)

2.000 496.7 498.3 1.6 203.1 99.2 0.425 420.5 455.3 34.8 168.3 82.2 0.300 307.2 388.4 81.2 87.1 42.6 0.250 366.0 364.6 55.0 32.1 15.7 0.212 361.2 370.9 3.4 28.7 14.0 0.180 354.4 380.2 16.5 12.2 6.0 0.150 349.5 351.0 1.5 10.7 5.2 0.125 348.9 350.6 1.7 9.0 4.4 0.106 355.4 357.5 2.1 6.9 3.4 0.090 338.8 342.3 3.5 3.4 1.7 0.075 297.1 297.7 0.6 2.8 1.4 0.063 350.9 351.5 0.6 2.2 1.1 Pan 325.5 327.7 2.2 0.0 0.0




Mass of empty sieve

(g)

Mass of sieve and

sand (g)


(g)


(%)

2.000 496.7 499.4 2.7 205.5 98.7000 0.425 420.6 500.4 79.8 125.7 60.4000 0.300 307.2 408.0 100.8 24.9 12.0000 0.250 365.8 379.9 14.1 10.8 5.2000 0.212 361.2 363.0 1.8 9.0 4.3000 0.180 354.5 358.8 4.3 4.7 2.3000 0.150 349.5 351.6 2.1 2.6 1.2000 0.125 348.8 350.0 1.2 1.4 0.0070 0.106 355.4 356.4 1.0 0.4 0.0020 0.090 338.8 339.1 0.3 0.1 0.0005 0.075 297.0 297.1 0.1 0.0 0.0000 0.063 350.9 350.9 0.0 0.0 0.0000 Pan 325.5 325.5 0.0 0.0 0.0000



151


Mass of empty sieve

(g)

Mass of sieve and

sand (g)


(g)



(%)

2.000 496.6 512.0 15.4 196.4 92.7000 0.425 420.6 562.0 141.4 55.0 26.0000 0.300 307.3 358.8 51.5 3.5 1.7000 0.250 365.9 367.8 1.9 1.6 0.0080 0.212 361.1 362.5 1.4 0.2 0.0009 0.180 354.7 354.9 0.2 0.0 0.0000 0.150 349.5 349.5 0.0 0.0 0.0000 0.125 349.1 349.1 0.0 0.0 0.0000 0.106 355.3 355.3 0.0 0.0 0.0000 0.090 339.0 339.0 0.0 0.0 0.0000 0.075 297.1 297.1 0.0 0.0 0.0000 0.063 350.7 350.7 0.0 0.0 0.0000 Pan 325.5 325.5 0.0 0.0 0.0000



152

A6 Grading modulus

A6.1 Soil 1

Sieve Percentage retained

0.0% 1.8% 3.5% 5.3% 7.1% 2mm 0 3.74 3.82 3.27 7.1 0.425mm 4.5 12.26 22.06 27.24 35.36 0.075mm 0.2 0.2 0.1 0.3 0.001

Table A6.1: Percentage of mass of soil retained on sieves for soil 1.

A6.2 Soil 2

Sieve Percentage retained 0.0% 1.8% 3.5% 5.3% 7.1%

2mm 0.4 1.1 0.4 1.2 2.3 0.425mm 13.07 13.43 14.56 27.54 33.68 0.075mm 0.05 0.04 0.2 0.14 0.05


A6.3 Soil 3

Sieve Percentage retained 0.0% 1.8% 3.5% 5.3% 7.1%

2mm 0.4 0.6 0.7 1.7 3.63 0.425mm 7.44 13.01 12.91 23.99 42.98 0.075mm 0.1 0.05 0.05 0.2 0


A6.4 Soil 4


0.0% 1.8% 3.5% 5.3% 7.1%

2mm 0.25 0.45 0.98 0.83 3.04

0.425mm 2.01 4.63 9.63 36.49 64.43

0.075mm 0.2 0.45 0.24 0.5 0


153

A6.5 Soil 5


0.0% 1.8% 3.5% 5.3% 7.1% 2mm 0.25 1 0.78 1.29 7.27 0.425mm 3.13 8.5 17 38.32 66.76 0.075mm 0.4 0.8 0.29 0.05 0


Soils Grading modulus for oil contaminated soils

0.0% 1.8% 3.5% 5.3% 7.1% Soil 1 0.05 0.16 0.26 0.38 0.42 Soil 2 0.14 0.15 0.15 0.29 0.36 Soil 3 0.08 0.14 0.14 0.26 0.47 Soil 4 0.03 0.06 0.11 0.40 0.67 Soil 5 0.04 0.10 0.18 0.40 0.74

Table A6.6: Grading modulus of oil contaminated soils.

154

APPENDIX B

ATTERBERG LIMITS TESTS RESULTS B1 Atterberg limits data for soils

B1.1 Atterberg limits data for bentonite

Test number 1 2 3 4 Number of bumps 17 23 35 45 Mass of wet soil (g) 6.33 3.79 7.17 6.70

Mass of dry soil (g) 0.90 0.57 1.21 1.20 Water loss (g) 5.43 3.22 5.96 5.50 Water content (%) 603 565 493 458

Table B1.1: Liquid limit data for bentonite.

Liquid limit = 540%

Figure B1.1: Liquid limit of bentonite.

Test number 1 2 Mass of wet soil (g) 8.97 8.96 Mass of dry soil (g) 5.40 5.40 Water loss (g) 3.56 3.56 Water content (%) 65.93 65.93 Plastic limit (average) 65.93 Plastic limit 66

Table B1.2: Plastic limit data for bentonite.

155

B1.2 Atterberg limits data for kaolinite

Container number 1 2 3 4 Number of bumps 14 20 27 37 Mass of wet soil (g) 6.49 8.33 8.67 5.98

Mass of dry soil (g) 3.87 5.04 5.37 3.79 Water loss (g) 2.62 3.29 3.30 2.19

Water content (%) 67.70 65.27 61.45 57.78

Table B1.3: Liquid limit data for kaolinite.

Liquid limit = 61%

Figure B1.2: Liquid limit of kaolinite.

Test number 1 2 Mass of wet soil (g) 8.23 9.30 Mass of dry soil (g) 6.22 7.04

Water loss (g) 2.01 2.26 Water content (%) 32.31 32.10 Plastic limit (average) 32.21 Plastic limit 32

Table B1.4: Plastic limit data for kaolinite.

156

B1.3 Atterberg limits data for soil 1 (0.0% oil content)

Test number 1 2 3 4

Number of bumps 11 19 30 40 Mass of wet soil (g) 7.21 5.81 5.86 6.47

Mass of dry soil (g) 4.65 3.85 3.95 4.43

Water loss (g) 2.56 1.96 1.91 2.03 Water content (%) 55.05 50.91 48.35 45.82

Table B1.5: Liquid limit data for soil 1(0% oil content).

`

Liquid limit = 48%

Figure B1.3: Liquid limit of soil 1 (0.0% oil content).



Table B1.6: Plastic limit data for soil (0.0% oil content).

157


Test number 1 2 3 4

Number of bumps 14 23 35 47

Mass of wet soil (g) 4.94 7.99 5.03 6.69 Mass of dry soil (g) 3.25 5.35 3.39 4.59

Water loss (g) 1.69 2.64 1.64 2.10

Water content (%) 52.00 49.34 48.38 45.75

Table B1.7: Liquid limit data for soil 1(1.8% oil content).

Liquid limit = 50%





158


Test number 1 2 3 4

Number of bumps 11 22 35 49 Mass of wet soil (g) 5.68 6.17 5.33 7.84 Mass of dry soil (g) 3.57 4.02 3.55 5.39 Water loss (g) 2.11 2.15 1.78 2.45 Water content (%) 59.10 53.48 50.14 45.45

Table B1.9: Liquid limit data for soil 1(3.5% oil content).

Liquid limit = 52%





159


Test number 1 2 3 4


Table B1.11: Liquid limit data for soil 1 (5.3% oil content).

Liquid limit = 54%




Table B1.12: Plastic limit data for soil (6% oil content).

160


Test number 1 2 3 4 Number of bumps 12 20 30 42 Mass of wet soil (g) 4.45 5.85 4.91 3.86 Mass of dry soil (g) 2.78 3.69 3.12 2.51 Water loss (g) 1.67 2.16 1.79 1.35 Water content (%) 60.07 58.53 57.37 53.78


Liquid limit = 58%




Table B1.14: Plastic limit data for soil 1 (7.1% oil content).

161


Test number 1 2 3 4 Number of bumps 11 23 30 40 Mass of wet soil (g) 4.43 4.17 5.20 7.14

Mass of dry soil (g) 2.44 2.35 3.09 4.28 Water loss (g) 1.99 1.82 2.11 2.86 Water content (%) 81.55 77.40 68.28 66.82


Liquid limit = 73%





162


Test number 1 2 3 4



Liquid limit = 74%





163


Test number 1 2 3 4



Liquid limit = 76%




164


Test number 1 2 3 4


Mass of wet soil (g) 4.07 5.14 3.09 5.94

Mass of dry soil (g) 2.26 2.86 1.74 3.51 Water loss (g) 1.81 2.28 1.35 2.43 Water content (%) 80.09 79.72 77.58 69.23


Liquid limit = 77%




165


Test number 1 2 3 4



Liquid limit = 78%




166

B1.13 Atterberg limits data for soil 3 (0% oil content)



Liquid limit = 85%




167


Test number 1 2 3 4 Number of bumps 11 20 37 47

Mass of wet soil (g) 5.42 4.76 4.59 4.89 Mass of dry soil (g) 2.82 2.53 2.47 2.65 Water loss (g) 2.60 2.23 2.12 2.24 Water content (%) 92.20 88.14 85.83 84.53


Liquid limit = 87%




168




Liquid limit = 90%




169


Test number 1 2 3 4 Number of bumps 13 24 35 49

Mass of wet soil (g) 6.26 4.51 5.50 4.99 Mass of dry soil (g) 3.13 2.34 3.02 2.76 Water loss (g) 3.13 2.17 2.48 2.23 Water content (%) 100 92.73 82.11 80.80


Liquid limit = 92%




170


Test number 1 2 3 4



Liquid limit = 94%




171


Test number 1 2 3 4



Liquid limit = 98%




172


Test number 1 2 3 4



Liquid limit = 98%




173


Container number 1 2 3 4


Mass of wet soil (g) 5.75 7.99 6.81 5.81 Mass of dry soil (g) 2.72 3.89 3.42 3.04 Water loss (g) 3.03 4.10 3.39 2.77 Water content (%) 111.39 105.40 99.12 91.12


Liquid limit = 100%




174




Liquid limit = 110%




175


Test number 1 2 3 4



Liquid limit = 125%




176


Test number 1 2 3 4



Liquid limit = 123%




177


Test number 1 2 3 4



Liquid limit = 128%




178


Test number 1 2 3 4



Liquid limit = 130%




179


Test number 1 2 3 4



Liquid limit = 134%




180


Test number 1 2 3 4



Liquid limit = 135%




181

B2 Oil loss test

Oil mixed into 250g of soil, some amount of the contaminated soil was put into a container and oven dried at 105 degree celsius for 24 hours

Oil loss test Oil content (%) 1.8% 3.5% 5.3% 7.1%

Mass of wet soil (g) 12.67 16.35 22.60 19.07 Mass of oil (g) 0.23 0.57 1.20 1.35 Mass of dry soil (g)

12.66 16.34 22.58 19.05

Oil loss (g) 0.01 0.01 0.02 0.02 Oil loss (%) of soil 0.08 0.06 0.09 0.10

Table B2.1: Oil loss test for soil 1


Mass of wet soil (g) 20.85 18.42 20.04 24.69 Mass of oil (g) 0.38 0.64 1.06 1.75 Mass of dry soil (g) 20.83 18.40 20.01 24.66







182


Mass of wet soil (g) 23.59 25.17 25.03 21.94

Mass of oil (g) 0.43 0.88 1.33 1.56 Mass of dry soil (g) 23.55 25.13 24.99 21.90







Soil Oil content (%) 1.8% 3.5% 5.3% 7.1%

Soil 1 4.3 1.8 1.7 1.5 Soil 2 5.3 3.1 2.8 1.7 Soil 3 6.1 3.3 2.6 2.2

Soil 4 9.3 4.5 3.0 2.6 Soil 5 11.9 6.0 4.8 4.1

Table B2.6: Oil loss (g) per mass of oil (g) in soil, in percentage

183

Soil Oil content

(%) Liquid

Limit (%) Plastic

Limit (%) Plasticity Index

(%)

Soil 1

0.0 48 13 35 1.8 50 15 35 3.5 52 15 37 5.3 54 16 38 7.1 58 16 42

Soil 2

0.0 73 17 56 1.8 74 17 57 3.5 76 18 58 5.3 77 18 59 7.1 78 18 60

Soil 3

0.0 85 18 67 1.8 87 19 68 3.5 90 21 69 5.3 92 22 70 7.1 94 23 71

Soil 4

0.0 98 20 78 1.8 98 20 78 3.5 100 22 78 5.3 110 22 88 7.1 125 23 102

Soil 5

0.0 123 22 101 1.8 128 23 105 3.5 130 24 106 5.3 135 24 111 7.1 135 24 111

Table B3: Atterberg limits and plasticity index of soils

184

Table B4: Total fluid content at Atterberg limits and plasticity index of soils

Soil Oil content(%)

Total fluid content at

Liquid Limit (%)

Total fluid content at

Plastic Limit (%)

Plasticity Index

(%)

Soil 1

0.0 48 13 35 1.8 52 17 37 3.5 56 19 41 5.3 59 21 43 7.1 65 23 49

Soil 2

0.0 73 17 56 1.8 76 19 59 3.5 80 22 62 5.3 82 23 64 7.1 85 25 67

Soil 3

0.0 85 18 67 1.8 89 21 70 3.5 94 25 73 5.3 97 27 75 7.1 101 30 78

Soil 4

0.0 98 20 78 1.8 100 22 80 3.5 104 26 82 5.3 115 27 93 7.1 132 30 109

Soil 5

0.0 123 22 101 1.8 130 25 107 3.5 134 28 110 5.3 140 29 116 7.1 142 31 118

185

APPENDIX C

COMPACTION TEST RESULTS

Data 1 2 3 4 5 Soil + mould + base plate (g) 6345 6397 6472 6489 6460

Mould + base plate (g) 4390 4390 4390 4390 4390 Mass of soil (g) 1955 2007 2082 2099 2070 Bulk density (g/cm3) 1.955 2.007 2.082 2.099 2.070 Water content (%) 9 10 11 12 13 Total fluid content (%) 9 10 11 12 13

Table C1.1: Compaction data for soil 1 (0.0% oil content).

Data 1 2 3 4 5

Soil + mould + base plate (g) 6231 6298 6443 6459 6441 Mould + base plate (g) 4390 4390 4390 4390 4390

Mass of soil (g) 1841 1908 2053 2069 2051 Bulk density (g/cm3) 1.841 1.908 2.053 2.069 2.051 Water content (%) 5 7 10 11 12 Total fluid content (%) 6.8 8.8 11.8 12.8 13.8


Data 1 2 3 4 5 Soil + mould + base plate (g) 6283 6329 6427 6462 6434 Mould + base plate (g) 4390 4390 4390 4390 4390 Mass of soil (g) 1894 1939 2037 2072 2044 Bulk density (g/cm3) 1.894 1.939 2.037 2.072 2.044 Water content (%) 5 7 8 10 11 Total fluid content (%) 8.5 10.5 11.5 13.5 14.5


186

Data 1 2 3 4 5 Soil + mould + base plate (g) 6344 6419 6442 6452 6419 Mould + base plate (g) 4390 4390 4390 4390 4390




Mould + base plate (g) 4390 4390 4390 4390 4390 Mass of soil (g) 1909 1931 1970 1998 2001 Bulk density (g/cm3) 1.909 1.931 1.970 1.998 2.001 Water content (%) 2 3 4 6 7 Total fluid content (%) 9.1 10.1 11.1 13.1 14.1


187


Mould + base plate (g) 4390 4390 4390 4390 4390

Mass of soil (g) 1865 1984 2101 2118 2030

Bulk density (g/cm3) 1.865 1.984 2.101 2.118 2.03 Water content (%) 7 8 11 12 13 Total fluid content (%) 7 8 11 12 13







188

Data 1 2 3 4 5

Soil + mould + base plate (g) 6366 6387 6436 6438 6392 Mould + base plate (g) 4390 4390 4390 4390 4390 Mass of soil (g) 1976 1997 2046 2048 2002 Bulk density (g/cm3) 1.976 1.997 2.046 2.048 2.002 Water content (%) 7 8 10 11 12 Total fluid content (%) 12.3 13.3 15.3 16.3 17.3





189

Data 1 2 3 4 5 Soil + mould + base plate (g) 6262 6315 6385 6417 6395 Mould + base plate (g) 4390 4390 4390 4390 4390 Mass of soil (g) 1872 1925 1995 2027 2005





Mass of soil (g) 1916 1979 2016 2014 2011

Bulk density (g/cm3) 1.916 1.979 2.016 2.014 2.011 Water content (%) 8 9 10 11 12

Total fluid content (%) 9.8 10.8 11.8 12.8 13.8



Bulk density (g/cm3) 1.848 1.893 2.005 2.024 2.010 Water content (%) 6 7 9 10 12 Total fluid content (%) 9.5 10.5 12.5 13.5 15.5


190





191



Mass of soil (g) 1807 1855 1968 1930 1910



Data 1 2 3 4 5

Soil + mould + base plate (g) 6236 628 6340 6334 6308


Mass of soil (g) 1846 1897 1950 1944 1918






192

Data 1 2 3 4 5






Mould + base plate (g) 4390 4390 4390 4390 4390 Mass of soil ( g ) 1815 1880 1939 1974 1976



193

Data 1 2 3 4 5



Mass of soil (g) 1814 1892 1959 1982 1971









194

Data 1 2 3 4 5

Soil + mould + base plate (g) 6290 6317 6345 6339 6322 Mould + base plate (g) 4390 4390 4390 4390 4390

Mass of soil (g) 1990 1927 1955 1949 1932






195

Oil

cont

ent (

%)

Soil 1 Soil 2 Soil 3 Soil 4 Soil 5

Max

imum

dry

de

nsity

(g/c

m3 )

Opt

imum

wat

er

cont

ent (

%)

Max

imum

dry

de

nsity

(g/c

m3 )

Opt

imum

wat

er

cont

ent (

%)

Max

imum

dry

de

nsity

(g/c

m3 )

Opt

imum

wat

er

cont

ent (

%)

Max

imum

dry

de

nsity

(g/c

m3 )

Opt

imum

wat

er

cont

ent (

%)

Max

imum

dry

de

nsity

(g/c

m3 )

Opt

imum

wat

er

cont

ent (

%)

0.0 1.880 11.4 1.896 11.7 1.828 11.0 1.757 12.0 1.734 13.0

1.8 1.840 10.1 1.839 11.0 1.804 10.4 1.729 11.0 1.712 11.4

3.5 1.838 9.1 1.830 9.8 1.786 9.6 1.722 10.9 1.688 11.8

5.3 1.798 8.9 1.775 10.0 1.756 9.0 1.714 9.2 1.680 11.4

7.1 1.774 4.4 1.748 7.0 1.740 7.0 1.712 6.4 1.660 10.0

Table C2: Variation of maximum dry density with optimum water content of soils.

Oil

cont

ent (

%)


Max

imum

dry

de

nsity

(g/c

m3 )

Opt

imum

tota

l flu

id c

onte

nt (%

)

Max

imum

dry

de

nsity

(g/c

m3 )

Opt

imum

tota

l flu

id c

onte

nt (%

)

Max

imum

dry

de

nsity

(g/c

m3 )

Opt

imum

tot

al

fluid

con

tent

(%)

Max

imum

dry

de

nsity

(g/c

m3 )

Opt

imum

tota

l flu

id c

onte

nt (%

)

Max

imum

dry

de

nsity

(g/c

m3 )

Opt

imum

tota

l flu

id c

onte

nt (%

)

0.0 1.880 11.4 1.896 11.7 1.828 11.0 1.757 12.0 1.734 13.0

1.8 1.840 11.9 1.839 12.8 1.804 12.2 1.729 12.8 1.712 13.2

3.5 1.838 12.6 1.830 13.3 1.786 13.1 1.722 14.4 1.688 15.3

5.3 1.798 14.2 1.775 15.3 1.756 14.3 1.714 14.5 1.680 16.7

7.1 1.774 11.5 1.748 14.1 1.740 14.1 1.712 13.5 1.660 17.1

Table C3: Variation of maximum dry density with optimum total fluid content of soils.

196

Table C4: Variation of maximum dry density with optimum water content of soils used

by some previous researchers.

Reference Soils Oil

content (%)

Maximum dry density

(g/cm3)

Optimum water content

(%)

Rahman et al (2011) Metasedimentary

0 1.56 22.0 4 1.70 22.0 8 1.68 21.0 12 1.90 16.0 16 1.78 8.0

Al-Sanad et al (1995) Poorly graded sand

0 1.89 13.0 2 1.95 8.0 4 1.93 7.0 6 1.83 2.0


Poorly graded sand

0 1.83 14.0 4 1.83 11.0 8 1.82 8.0 12 1.82 5.0 16 1.81 3.0

Sand with 5 to 15% silt

0 1.91 13.0 4 1.87 9.0 8 1.84 9.0 12 1.85 4.5 16 1.82 2.0

Low plasticity clay

0 1.86 16.0 4 1.84 14.0 8 1.83 9.0 12 1.80 7.0 16 1.81 3.0

Rahman et al (2010)

Grade V (basaltic)

0 1.67 24.0 4 1.57 22.0 8 1.55 20.0 12 1.53 18.0 16 1.50 18.0

Grade VI (basaltic)

0 1.60 23.0 4 1.57 23.0 8 1.56 22.0 12 1.55 20.0 16 1.55 17.0

Rahman et al (2011) Granitic Sandy loam

0 1.50 18.0 4 1.46 19.0 8 1.50 23.0 12 1.37 17.0 16 1.40 18.0

197

Table C5: Variation of maximum dry density with optimum total fluid content of soils

used by some previous researchers.

Reference Soils Oil

content (%)

Maximum dry density

(g/cm3)

Optimum total fluid content

(%)

Rahman et al (2011) Metasedimentary

0 1.56 22.0 4 1.70 26.0 8 1.68 29.0

12 1.90 28.0 16 1.78 24.0

Al-Sanad et al (1995) Poorly graded sand

0 1.89 13.0 2 1.95 10.0 4 1.93 11.0 6 1.83 8.0


Poorly graded sand

0 1.83 14.0 4 1.83 15.0 8 1.82 16.0

12 1.82 17.0 16 1.81 19.0

Sand with 5 to 15% silt

0 1.91 13.0 4 1.87 13.0 8 1.84 17.0

12 1.85 16.5 16 1.82 18.0

Low plasticity clay

0 1.86 16.0 4 1.84 18.0 8 1.83 17.0

12 1.80 19.0 16 1.81 19.0

Rahman et al (2010)

Grade V (basaltic)

0 1.67 24.0 4 1.57 26.0 8 1.55 28.0

12 1.53 30.0 16 1.50 34.0

Grade VI (basaltic)

0 1.60 23.0 4 1.57 27.0 8 1.56 30.0

12 1.55 32.0 16 1.55 33.0

Rahman et al (2011) Granitic sandy loam

0 1.50 18.0 4 1.46 23.0 8 1.50 31.0

12 1.37 29.0 16 1.40 34.0

198

APPENDIX D

PLASTICITY CHARACTERISTICS AND COMPACTION OF CONTAMINATED SOIL

Oil content

(%)

Maximum dry density

(%)

Optimum water

content (%)

Optimum fluid

Content (%)

Liquid limit (%)

Plastic Limit (%)

Plasticity index (%)

0.0 1.880 11.4 11.4 48 13 35

1.8 1.840 10.1 11.9 50 15 35

3.5 1.838 9.1 12.6 52 15 37 5.3 1.798 8.9 14.2 54 16 38 7.1 1.774 4.4 11.5 58 16 42

Table D1.1: Plasticity and compaction characteristics of soil 1.

Oil content

(%)

Maximum dry density

(g/cm3)

Optimum water

content (%)

Optimum fluid

content (%)

Liquid limit (%)

Plastic Limit (%)


0.0 1.896 11.7 11.7 73 17 56 1.8 1.839 11.0 12.8 74 17 57 3.5 1.830 9.8 13.3 76 18 58

5.3 1.775 10.0 15.3 77 18 59 7.1 1.748 7.0 14.1 78 18 60


Oil content

(%)

Maximum dry

density (g/cm3)

Optimum water

content (%)

Optimum fluid

content (%)

Liquid limit (%)

Plastic Limit (%)


0.0 1.828 11.0 11.0 85 18 67 1.8 1.804 10.4 12.2 87 19 68 3.5 1.786 9.6 13.1 90 21 69 5.3 1.756 9.0 14.3 92 22 70 7.1 1.740 7.0 14.1 94 23 71


199

Oil content

(%)

Maximum dry

density (g/cm3)

Optimum water

content (%)

Optimum fluid

content (%)

Liquid limit (%)

Plastic Limit (%)


0.0 1.757 12.0 12.0 98 20 78 1.8 1.729 11.0 12.8 98 20 78 3.5 1.722 10.9 14.4 100 22 78 5.3 1.714 9.2 14.5 110 22 88 7.1 1.712 6.4 13.5 125 23 102


Oil content

(%)

Maximum dry

density (g/cm3)

Optimum water

content (%)

Optimum fluid

content (%)

Liquid limit (%)

Plastic Limit (%)


0.0 1.734 13.0 13.0 123 22 101 1.8 1.712 11.4 13.2 128 23 105 3.5 1.688 11.8 15.3 130 24 106 5.3 1.680 11.4 16.7 135 24 111 7.1 1.660 10.0 17.1 135 24 111


200

APPENDIX E

HYDRAULIC CONDUCTIVITY


Table E1.1: Quantity of flow, Q (ml) in 5 mins for soil 1 (0.0% oil content).

* Q interval (mm3) was divided by 1000 to obtain Q interval (ml).

Time (mins) Q (mm3) Q interval (mm3) Q interval (ml ) 0 44375 230 0.23 5 44605 10 44835 15 45065 20 45295 25 45525 30 45755 35 45985 40 46215 45 46445 50 46675


201







202







203





204







205





206







207





208







209





Oil content

(%)

Hydraulic conductivity (m/s)


0.0 3.35 x 10-9 2.24 x 10-9 1.08 x 10-9 7.02 x 10-10 4.32 x 10-10

1.8 2.49 x 10-9 1.64 x 10-9 8.21 x 10-10 5.94 x 10-10 3.78 x 10-10

3.5 1.25 x 10-9 8.21 x 10-10 3.46 x 10-10 2.16 x 10-10 1.24 x 10-10

5.3 1.51 x 10-10 8.64 x 10-11 4.32 x 10-11 1.62 x 10-11 1.08 x 10-11

7.1 1.62 x 10-11 1.08 x 10-11 5.40 x 10-12 3.60 x 10-12 2.70 x 10-12

Table E2: Hydraulic conductivity of soils.

210

APPENDIX F

PLASTICITY CHARACTERISTICS AND HYDRAULIC CONDUCTIVITY OF CONTAMINATED SOIL.

Oil content (%)

Hydraulic conductivity

(m/s)

Liquid limit (%)

Plastic Limit (%)


0.0 3.35 x 10-9 48 13 35 1.8 2.49 x 10-9 50 15 35 3.5 1.25 x 10-9 52 15 37 5.3 1.51 x 10-10 54 16 38 7.1 1.62 x 10-11 58 16 42

Table F1.1: Plasticity characteristics and hydraulic conductivity of soil 1.

Hydraulic

conductivity (m/s)

Liquid limit (%)

Plastic Limit (%)

Plasticity index (%) Oil content

(%) 0.0 2.24 x 10-9 73 17 56 1.8 1.64 x 10-9 74 17 57 3.5 8.21 x 10-10 76 18 58 5.3 8.64 x 10-11 77 18 59 7.1 1.08 x 10-11 78 18 60



(m/s) Liquid limit

(%)

Plastic Limit (%)


Oil content (%)

0.0 1.08 x 10-9 85 18 67 1.8 8.21 x 10-10 87 19 68 3.5 3.46 x 10-10 90 21 69 5.3 4.32 x 10-11 92 22 70 7.1 5.40 x 10-12 94 23 71


211

Oil content Hydraulic conductivity Liquid limit Plastic Limit

(%)


(m/s) ( % )

( % ) 0.0 7.02 x 10-10 98 20 78

1.8 5.94 x 10-10 98 20 78 3.5 2.16 x 10-10 100 22 78

5.3 1.62 x 10-11 110 22 88 7.1 3.60 x 10-12 125 23 102


Oil content (%)


(m/s) Liquid limit

(%) Plastic Limit

(%) Plasticity index

(%) 0.0 4.32 x 10-10 123 22 101

1.8 3.78 x 10-10 128 23 105

3.5 1.24 x 10-10 130 24 106 5.3 1.08 x 10-11 135 24 111

7.1 2.70 x 10-12 135 24 111


212

APPENDIX G

COMPACTION CHARACTERISTICS AND HYDRAULIC CONDUCTIVITY OF CONTAMINATED SOIL

Oil content Hydraulic

conductivity (m/s)

Maximum dry density (g/cm3)


(%)


(%) 0.0 3.35 x 10-9 1.880 11.4 11.4 1.8 2.49 x 10-9 1.840 10.1 11.9 3.5 1.25 x 10-9 1.838 9.1 12.6 5.3 1.51 x 10-10 1.798 8.9 14.2 7.1 1.62 x 10-11 1.774 4.4 11.5

Table G1.1: Compaction characteristics and hydraulic conductivity of soil 1.

Oil content (%)


(m/s)



(%)


(%) 0.0 2.24 x 10-9 1.896 11.7 11.7 1.8 1.64 x 10-9 1.839 11.0 12.8 3.5 8.21 x 10-10 1.830 9.8 13.3 5.3 8.64 x 10-11 1.775 10.0 15.3 7.1 1.08 x 10-11 1.748 7.0 14.1

Table G1.2: Compaction characteristics and hydraulic conductivity of soil 2

Oil content (%)


(m/s) Maximum dry density (g/cm3)


(%)


(%) 0.0 1.08 x 10-9 1.828 11.0 11.0 1.8 8.21 x 10-10 1.804 10.4 12.2 3.5 3.46 x 10-10 1.786 9.6 13.1 5.3 4.32 x 10-11 1.756 9.0 14.3 7.1 5.40 x 10-12 1.740 7.0 14.1


213

Oil content (%)


(m/s)



(%)


(%) 0.0 7.02 x 10-10 1.757 12.0 12.0 1.8 5.94 x 10-10 1.729 11.0 12.8 3.5 2.16 x 10-10 1.722 10.9 14.4 5.3 1.62 x 10-11 1.714 9.2 14.5 7.1 3.60 x 10-12 1.712 6.4 13.5


Oil content (%)


(%)



(%)


(%) 0.0 4.32 x 10-10 1.734 13.0 13.0 1.8 3.78 x 10-10 1.712 11.4 13.2 3.5 1.24 x 10-10 1.688 11.8 15.3 5.3 1.08 x 10-11 1.680 11.4 16.7 7.1 2.70 x 10-12 1.660 10.0 17.1


geotechnical properties of oil contaminated soil

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