1.1 Introduction
Pavement is a structure consisting of superimposed layers of selected and processed materials whose primary function is to distribute the applied vehicle loads to the sub-grade. The ultimate aim is to ensure that the transmitted stresses are sufficiently reduced that they will not exceed the supporting capacity of the sub-grade. One of the basic requirements for a pavement is that it should be of sufficient thickness to spread the surface loading to a pressure intensity that the underlying sub-grade is able to withstand, with the pavement itself sufficiently robust to deal with the stresses incident on it. Where required, the pavement should be sufficiently thick to prevent damage to a frost-susceptible sub-grade.
Flexible Pavement consists of many layers (asphalt concrete, base and sub-base) in addition to roadbed soil (sub-grade). In direct contrast to rigid pavements, the strength of the sub-grade is the main factor controlling the design of flexible pavements. When the sub-grade deflects, the overlying flexible pavement is expected to deform to a similar shape and extent. Thus the basic design criterion is the depth of pavement required to distribute the applied surface load to the sub-grade; the sub-grade must not be overstressed and caused to deform without damaging its own structural integrity.
As a prelude to other parts of this study, this chapter will discuss the background upon which this study was initiated, the statement of problems that led to this study, the Aim and Objectives of the study. Others are Significance of the study, Scope of work, Limitations of the Study and Definition of technical terms.
1.2 Statement of Problem
Basic engineering properties of Sub grade materials are required for design and Coarse grained soils serves as good for supporting pavements whereas fine grained soils, particularly clayey soils pose problem to pavement. Rufus Giwa Polytechnic is a big trade center and coffee production areas of in Nigeria but, the current existing condition most parts of the road are deteriorated.
1.3 Aim and Objectives of Study
The aim of the study is to determine the Basic Soil Test on Sub-grade Soil Material and Flexible Pavement Design using Rufus Giwa Polytechnic, Owo, Ondo State as a case study. In achieving this aim, the following specific objectives were set out as follows:
- To obtain a general information regarding the nature of the soil and their variation with depth throughout the length of the road under consideration.
- To obtain information regarding the strength characteristics of the soil.
- To obtain information which will enable engineers to group soils according to their appearances of the purposes of complying different soils.
- To ensure that the transmitted stresses are sufficiently reduced that they will not exceed the supporting capacity of the sub-grade.
- To investigate effects of subgrade and sub-base materials quality on flexible pavement.
1.4 Significance of Study
This study will be of immense benefit to other researchers who intend to know more on this study and can also be used by non-researchers to build more on their research work. This study contributes to knowledge and could serve as a guide for other study.
1.5 Scope of Study
The study focuses on the Basic Soil Test on Sub-grade Soil Material and Flexible Pavement Design using Rufus Giwa Polytechnic, Owo, Ondo State as a case study.
1.6 Limitations of the Study
During the course of this study, many things militated against its completion, some of which are:
- Time Constraint: The time frame given to accomplish this project was very short due to school academic calendar and it was carried out under pressure which made the researcher not to implement some necessary features.
- Research material: availability of research material is a major setback to the scope of the study.
- Frequent power failure: This made the researcher append more money on fuel to ensure sustainable power.
- Financial Constraint: Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection (internet).
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