1.1 Introduction
Grout is basically a liquid solution or suspension that is injected into the soil under pressure in order to fill up the voids present between the soil particles and to bind them together (Ali Abdul et al., 2008). The construction of structure on weak ground often requires the soil to be improved in order to ensure the safety and the stability of surrounding buildings. The ground improvement in granular soils can be achieved by different methods such as vibro-floatation, compaction piles, and compaction with explosives, excavation and replacement and grouting. The selective of the most suitable method depend on a variety of factors. Ground improvement refers to the improvement to the Engineering properties of soil which is not present in its natural state. Ground improvement refers to the increase in shear strength, decrease in permeability, and decrease in compressibility. A number of techniques have been developed so far to improve the ground conditions (Kumar, 2010).
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, Research questions, Limitation of the study and Definition of technical terms.
1.2 Background of Study
The development and history of compaction grouting over the last 30-40 years as been established by many distinguished researcher, design engineer and design contractor. Many technical papers are been published dealing physically with the issues surround compaction grouting design such as: “compaction grouting, 1973”, “planning and performing compaction grouting” 1974. These and other important reference are the main stream basis of knowledge for the highly specialize engineering and construction technique know as compaction grouting. The compaction grout method as some unique features which allow distinct advantages over other remedial method of geo-technical construction.
In many distances growth is the only viable solution. Some of the advantages include: Economic: Many time compaction grouting is the only feasible solution to foundation settlement problems, other than demolishing the structure and re-building with expensive deep foundation technique. Minimal disturbance: During the grouting operation, the structure may remain occupied and in service. Minimal risk: Compaction grouting offers minimal risk of catastrophic structural failure while re-leveling structure. Other are: Minimal geotechnical exploration, provide greater support for structures, cost factor e.t.c.
Soil compaction can offer effective solutions for many foundation problems and his especially useful for reducing total settlement in sand. Sandy soil means most of the soil particles are bigger than 2mm in diameter. It gives good water drainage and has a low capacity to hold nutrients. Sandy soil does not hold moisture very well. It is granular and consists of rock and mineral particle that are very small.
Therefore, the texture is gritty and is formed by the disintegration and weathering of rocks such as limestone, granite, quartz and shale. Is also easier to cultivate it if it is rich in organic materials but then it allows drainage more than needed. This results in over drainage and dehydration of the plant in summer. It warms very fast in the spring season. Grouting on the other hand is a process whereby stabilizes either in the form of suspension or solution is injected into sub surface soil. Sandy soil is the largest particle in the soil when you rub it, if feels rough. This is because it has sharp edges and it does not hold many nutrients.
Therefore, in Nigeria where the research was carried out, the activities that was conducted is to know the Improvement of Bearing Capacity of Sandy Soil by Grouting.
1.3 Statement of Problems
Investigation revealed that many of the foundation problems can be effectively solved by compaction, which will cause reduction in total settlement. But compaction of soil depends upon the vertical effective stress and gradation of soil etc. That is well graded soil compact more than poorly graded soil (Dayakar et al., 2012).
Dynamic compaction gives best results up to depth of 10 to 20m. The relative density of Sandy soil properties cannot be increased by compaction or by vibration, the best method is grouting. Grouting is mostly used in foundations of the structures. It is also used in seepage control in dams, rocks, cutoff walls and tunnels. The technique of grouting is to fill the voids between the medium by a grouting material in order, to improve the Engineering properties (Robert, 2009).
1.4 Aim and Objectives of Study
The aim of the study is to examine the Improvement of Bearing Capacity of Sandy Soil by Grouting. In achieving this aim, the following specific objectives were laid out as follows:
- To determine the degree of the sandy soil compatibility and nature of the sandy soil particles;
- To carry out the improvement of sandy soil through grouting; and
- To carry out some laboratory test on sandy soil such as compaction test California bearing ration (CBR) test, atterberg LIMIT test, liquid limit test, Plastic limit test, sieve analysis test in comparing the effectiveness of grouting system.
1.5 Research Questions
The study came up with research questions so as to be able to ascertain the above stated objectives. The specific research questions for the study are stated below as follows:
- What is the degree of the sandy soil compatibility?
- What is the nature of the sandy soil particles?
- What is the improvement of sandy soil through grouting?
1.6 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.
1.7 Scope of Study
The scope of the research is focused on the Improvement of Bearing Capacity of Sandy Soil by Grouting.
1.8 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.
- Area of Study: This project is limited the technical study of sandy soil properties.
- 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).
