TABLE OF CONTENTS
Front page i
Acknowledgement iv-v
Table of contents vii-ix
CHAPTER ONE INTRODUCTION
- General statement……………………………………………………………………………………….. 1
- Scope of study……………………………………………………………………………………………… 3
- Location and accessibility……………………………………………………………………………… 3
- Regional Geology of Nigeria…………………………………………………………………………. 8
- Geology of study area……………………………………………………………………………….. 23
- Literature review on Weathering and Laterite soil………………………………………… 25
- Origin and Formation of Lateritic soil………………………………………………………… 27
CHAPTER THREE METHODOLOGY
- Field study……………………………………………………………………………………………… 32
- Laboratory analysis………………………………………………………………………………… 34
- Specific gravity…………………………………………………………………………………….. 34
- Laboratory analysis………………………………………………………………………………… 34
- Consistency Limit determination…………………………………………………………….. 36
- Linear Shrinkage…………………………………………………………………………………….. 37
- California Bearing Ratio…………………………………………………………………………… 38
Results and Interpretation………………………………………………………………………….. 41
CONCLUSION AND RECOMMENDATION
Conclusion………………………………………………………………………………………………….. 52
Recommendation……………………………………………………………………………………….. 53
REFRENCES APPENDIX
LIST OF FIGURES
Figures Pages
1: Topography map of Ibadan showing the study area…………………………………… 4
- : Map of Nigeria showing the Geology of Nigeria…………………………………………. 9
- : Basement Geology of Nigeria…………………………………………………………………. 11
- : Geologic Map of the study area……………………………………………………………… 24
3: Sample collection on the Field…………………………………………………………………… 33
4: Diagram showing a typical CBR equipment……………………………………………….. 40
5: Graph of particle size analysis JA………………………………………………………………. 43
6: Graph of Particle size analysis JB………………………………………………………………. 45
7: Graph of Particle size analysis JC……………………………………………………………….. 47
LIST OF TABLES
Tables Pages
4.1 Summary of the Specific gravity of the sampled soil…………………………….. 41
- Summary of the of the particle size analysis carried out on JA…………….. 42
- Summary of the particle size analysis for JB……………………………………… 44
- Summary of particle size analysis carried out on sample JC………………… 46
- Result of Consistency Limits (Plastic limit, Liquid limit and Plasticity Index) 49
- Result of Consistency limits on the soil studied…………………………………….. 49
- Average moisture density Relation using West African Standard………………. 50
- Showing the summary of CBR results from the sampled soil………………………. 51
- Showing the parameter of % Finer against the sieve opening/diameter for JA 57
- Showing the parameter of % Finer against the sieve opening/ diameter for JB 59
- Showing the parameter of %Finer against sieve opening/diameter for JC…….. 62
- Showing the CBR values for JA…………………………………………………………………… 63
- Showing the CBR values for JB……………………………………………………………… 64
- Showing CBR values for JC………………………………………………………………….. 65
- Showing the moisture density relation of soil JA………………………………………. 66
- Showing the moisture density relation of soil JB……………………………………… 67
- Showing the moisture density relation of soil JC………………………………………. 68
- Showing the determination of liquid and plastic limit JA…………………………. 69
- Showing the determination of liquid and plastic limit JB…………………………… 70
- Showing the determination of liquid and plastic limit JC……………………………. 71
CHAPTER ONE
- Introduction
The understanding of soil behavior in solving engineering and environmental issues such as swelling of the soil, especially expansive lateritic soils that can cause significant damage to road construction and other engineering application, is the sole aim of geotechnical engineering (Abubakar, 2006; Oke and Amadi, 2008).One of the major causes of road accident is bad road which is usually caused by wrong application of constructional materials especially laterite as subgrade or sub-base material by construction companies (Oke et al., 2009). For a material to be used as either subgrade or sub-base course, depends on its strength in transmitting the axle-load to the sub-soil and or sub-grade (the mechanical interlock). The characteristics and durability of any constructional material is a function of its efficiency in response to the load applied on it (Oke et al., 2009b; Nwankwoala and Amadi, 2013). The mineralogical composition of the lateritic soil has an influence on the geotechnical parameters such as specific gravity, shear strength, swelling/expansion, CBR( California bearing ratio), Atterberg limits, compatiblity and petrographic properties (Amadi et al., 2012). However, it has been observed for a long time that classification systems fail to accurately predict the engineering behavior of laterites and lateritic soils of which the reason for this failure is the variation in plasticity and gradation characteristics of these soils resulting from sample preparation and handling which disrupt the natural structure of the soils. Therefore, engineering properties of laterites and lateritic soils are not reproducible. In order to avoid such difficulties, many authors have advocated a classification of laterites and lateritic soils for engineering purposes, based on parent material and degree of weathering. The degree to which the parent rocks may weather to laterite depends on other factors such as the weathering ability of the parent rocks, degree of permeability of the soil, climate, local topography, drainage condition, vegetation, time and the pH value of the environment. Since these factors vary from place to place, it is obvious that the distribution of soils will be determined in a complex manner by the distribution of the influence of the soil forming factors. Laterization process consists of the breaking down of the bases (either in the solution or suspension) and the redeposition of the remaining OH+ of Al²+, Fe²+ and Ti²+ (Fagoyingbo, 2016).
ENGINEERING CHARACTERISTICS OF GNEISS-DERIVED LATERITIC SOIL AT KM 4 ALONG OLOGUNERU-ELEYELE, IBADAN RD, SOUTHWESTERN NIGERIA
