STABILIZATION OF SILTY CLAY SOIL USING CEMENT AND SAW DUST ASH samson et al

ABSTRACT

Soils containing large quantities of clay and silt are the most burdensome to the engineer. These soils exhibit marked changes in volume with changes in water content and consequently affect the function of any layer lain upon it due to its shrink and up heave behavior when used as a subgrade or a layer built of it. The test assesses the geotechnical characteristics of silty clay soil in order to increase the shear strength and decrease the compressibility of the soil, so that the bearing capacity of the soil is increased and the settlement of the structures built on it are reduced by stabilization using saw dust ash SDA and cement. And to find out the optimum mix for percentage addition of saw dust ash to achieve most beneficial improvement of soil and reduce the cost of cement in soil cement stabilization. Preliminary test were carried out on the native soil sample for identification and classification. SDA was added on varying percentages of 2, 4, 6 and 8% with a constant percentage of cement by total weight of soil. Addition of SDA decreased the unit weight from 390g/cm3 to 370g/Cm3and increased the C and Φ at 8% SDA addition from 8kN/m2and 60 to 16kN/m2 and 130. The values of MDD increased from 1.77kg/m3 to 1.83kg/m3 and OMC increased from 19% to 29% at 6 and 8% SDA addition. The values of LL and PI reduced from 52% and 11.3% to 26.5 and 4.45 % at 8% SDA addition. The consolidation characteristics are also observed to reduce from 17.10m2/year to 9.71m2/year, while the CBR increased from 2.1% to 12.57%. It is therefore concluded that 8% SDA addition is the optimum mix and can be accepted that saw dust ash can be used as a cheap stabilizing agent for silty clay.

Title Page……………………………………………………………………………….i

Declaration Page……………………………………………………………………….ii

Approval Page…………………………………………………………………………iii

Dedication Page……………………………………………………………………….iv

Acknowledgement Page……………………………………………………………….v

Table of Content………………………………………………………………………vi

List of figures………………………………………………………………………….x

List of tables...................................................................................................................xi

List of Symbols and Abbreviations…………………………………………………..xii

Abstract………………………………………………………………………………xiii

Contents

CHAPTER ONE.. 14

1.0 Introduction. 14

1.2 Problem Statement15

1.1      Aims and Objectives. 16

1.2.1 Aim.. 16

1.2.2 Objectives. 16

1.3 Methodology. 16

1.4      Significance of Study. 17

1.5 Scope of Project18

1.6 Limitation. 18

CHAPTER TWO.. 19

2.0 Literature Review.. 19

2.1 Soil Stabilization. 21

2.2 Classification of Soil23

2.2.1 Field Identification and Classification. 23

2.2.1 AASHTO Soil Classification System.. 24

2.2.2 Unified Soil Classification System.. 26

2.2.3   Highway Soil Classification System.. 29

2.2.2      Laboratory Classification. 30

2.3 Components of Soil-Cement Stabilization. 34

2.3.1      Soil34

2.3.2      Stabilizing Agents. 35

2.3.2.1 Cement35

2.3.2.2 Lime. 37

2.3.2.3   Fly–Ash. 39

2.3.2.4 Blast Furnace Slags. 40

2.3.2.5 Pozzolanas. 41

2.3.2.6 Saw Dust Ash. 42

2.4 Suitability of Materials for Soil-Cement Stabilization. 44

2.5 Sampling of Material to Be Stabilized. 45

2.6 Factors Affecting the Strength of Stabilized Soil45

2.6.1 Organic Matter45

2.6.2 Sulphates. 45

2.6.3      Sulphides. 46

2.6.4 Compaction. 46

2.6.5 Moisture Content47

2.6.6 Temperature. 48

2.6.7      Freeze-Thaw and Dry-Wet Effect48

2.5 Stabilization Methods. 48

2.5.1 In–Situ Stabilization. 48

2.5.2      Deep Mixing Method. 49

2.5.3      Wet Mixing. 50

2.5.4      Dry Mixing. 51

2.5.5      Mass Stabilization. 52

2.5.6      Ex-Situ Stabilization. 54

2.6 Quality Control and Quality Assurance. 54

2.7 Applications. 55

CHAPTER THREE. 56

3.0      Materials and Methodology. 56

3.1      Tests for Selection Of Materials To Be Stabilised. 57

3.2      Laboratory And Field Test Were Conducted In Accordance With:58

3.3 Preliminary Investigation Tests. 58

3.3.1      Laboratory Tests Conducted On Obtained Soil Samples. 58

3.3.2      Laboratory Test Conducted On Cement59

3.3.3 Laboratory Test Conducted On Water Sample. 60

3.3.4 Preparation of Sawdust60

3.4 Laboratory Control Test to Determine the Most Efficient Percentage Addition. 60

3.4.1 Procedure for Estimation of Cement Content60

3.5 Procedures for the Laboratory Test Conducted On the Natural Soil Sample. 62

3.5.1      Natural Moisture Content Test62

3.5.2      Atterberg’s Limits Test64

3.5.2.1   Liquid Limit Test (Casagrande Method)64

3.5.2.2 Plastic Limit and Plasticity Index. 67

3.5.2.3     Linear Shrinkage. 68

3.5.3      B.S Compaction Test (Standard Proctor Test)70

3.5.4      California Bearing Ratio. 75

3.5.5      Sieve Analysis Test (Grain Size Analysis)78

3.5.6      Specific Gravity Test80

3.5.7 Triaxial Test - Undrained Shear Strength (Total Stress)82

3.6 Laboratory Test on Water Sample. 88

3.6.1 Ph and Temperature Test88

CHAPTER FOUR.. 91

4.0 Analysis of Test Results. 91

4.0.1      Cement Test Result91

4.0.2      Water Test Results. 92

4.0.3      Test Result on Soil95

4.0.3.1 Atterberg’s Limit Test95

4.0.3.1.1 Liquid Limit Test95

4.0.3.1.2 Plastic Limit96

4.0.3.1.3 Plasticity Index. 96

4.0.3.1.4 Linear Shrinkage (Ls)97

4.0.3.2 Moisture Content Test97

4.0.3.3 Triaxial Test Result98

4.0.3.4 Particle Size Distribution (Sieve Analysis) Test Result100

4.0.3.5 Specific Gravity Test Result101

4.0.3.6 Compaction Test102

4.0.3.7   California Bearing Ratio (CBR) Test Result104

4.0.3.8      Consolidation Test Calculation for Settlement Parameters. 104

4.0.3.9 Bearing Capacity Computation. 106

4.1 Discussion of Result110

4.1.1 Discussion of Cement Test Result110

4.1.2 Discussion of Soil Test Result110

4.1.3      Discussion of Water Analysis Results. 111

Table 4.12:  Summary for Result of Analysis of Water112

CHAPTER FIVE. 113

5.1 Conclusion. 113

5.2 Recommendation. 113

REFERENCES. 115

APPENDIX.. 118

PLATES. 119