Bituminous Stabilization of Clay Soils for Road Construction
CHAPTER ONE
OBJECTIVES OF RESEARCH
The objectives of this research work include the following.
- To obtain the particle size of the soil chosen to confirm its grading
- To determine the Atterberg’s limits of the soil. Its moisture-density relationship and CBR values.
- Identify a bitumen (stabilizer) that is readily available for the stabilization from the various classification of
- Determine maximum dry density, optimum moisture content and CBR values of stabilized soil.
CHAPTER TWO
- LITERATUREREVIEW
- RELATEDWORK
Although there is little or no previous work done in this field in Nigeria, enormous research work has been done elsewhere in the world, new approaches have been evolved due to the research efforts and better and more cost effective and environmentally friendly ways of the application of bitumen as a stabilizer.
On the fore front of this renaissance is South Africa. Extensive research and development of methods and specifications for foamed bitumen stabilization has been undertaken in South Africa. CSIR Transportek (1998) gives a detail of the methods used in South Africa until the release in 2002 of the Asphalt Academy Interim Guideline TG2 (Asphalt Academy 2002), and this formed the basis of many specifications for foamed bitumen pavements elsewhere in the world. The Asphalt Academy is a Southern African centre for the development of knowledge transfer programmes and skills development in bituminous products technology. It is a nonprofit organization funded by the South African bitumen association (Sabita). Road construction the world over would have been reduced in cost by at least 40% if there were no poor subgrade in existence.
Haris,P et al (1983) reported that bituminous stabilization for the construction of road bases has become increasingly used in developing countries in the last 30 years, particularly in areas characterized by cohesionless soils and which are poor in aggregate sources.
Onyelowe and Okafor (2012) worked on the Geochemistry of soil stabilization. Here bitumen is described as highly viscous, black and entirely soluble in carbon disulphide,CS2 and composed primarily of highly condensed polycyclic aromatic hydrocarbon. Bituminous soil stabilization refers to a process by which a controlled amount of bituminous material is thoroughly mixed with an existing soil material to form a stable or wearing course.
Bolarinwa (2009) conducted experiments on the geotechnical properties of Nigerian soils. The long term performance of any construction project, especially roads depends on the nature of the underlying soils A subgrade is considered unsuitable for construction purposes if after a geotechnical survey of the soil in question, certain properties of the soil such as its bearing capacity, moisture content, etc are not in tandem with the minimum required for structural purposes. Soils that cannot be used for engineering purposes without some form of stabilization are generally referred to as problem soils.
Jones et al. (2012) conducted an experimental study on bitumen soil stabilization. Here asphalt emulsion is a mix of asphalt binder, water, and emulsifying agent. In this case, a series of Indirect temperatures. It accelerates breaking of the emulsion and for additional early strength to accommodate traffic during curing of the layer.
Paul et al. (2011) suggested an introduction to soil stabilization in pavement taking a mixture of bitumen and well-graded gravel or crushed aggregate. After compaction it gave an exceedingly steady waterproof mass of subbase or base course quality. The fundamental system involved in asphalt stabilization of fine-grained soils is a waterproofing wonder. Soil particles or soil agglomerates were covered with asphalt that forestalls or abates the entrance of water which could regularly bring about abatement in soil quality. What’s more, asphalt stabilization can enhance durability qualities by making the soil impervious to the unfavourable impacts of water, for example, volume. In non-iron materials, for example, sands and gravel, pounded gravel, and smashed stone, two fundamental systems are dynamic: waterproofing and adhesion. The asphalt coating on the union less materials gives a film which anticipates or hinders the entrance of water; subsequently reducing the inclination of the material to lose quality in the vicinity of water. The second instrument had been distinguished as adhesion and characteristics of gravelly soils.
CHAPTER THREE
MATERIALS ANDMETHOD
SOIL(SUBGRADE)
The soil to be stabilized with bitumen is identified at a certain location in Nigeria. Trial pit was dug at a locations at a depth of 1.5 meters and soil samples collected for testing in the laboratory. Soil samples were collected along Umuahia- Enugu expressway, Umuahia section at Km 2+300- Km 6+100 ( Where Arab Contractor is currently rehabilitating).
Soil samples were collected at a locations at a depth of 1.5 meters, samples collected were then taken to the soil mechanics laboratory of the University of Nigeria Nsukka for analysis. The following analysis was performed.
CHAPTER FOUR
RESULTS ANDDISCUSSION
PARTICLE SIZEDISTRIBUTION
The result of the sieve analysis of the soil sample indicated that well over 50% of the sample passed through the standard sieve no 200 (0.075mm) and lie within the area designated on the Casagrande Chart as CL-/A-6.
CHAPTER FIVE
CONCLUSION ANDRECOMMENDATIONS
CONCLUSION
This research proved that bitumen emulsion can be used to stabilize clay soil and improve its engineering properties. Applying this technique to poor subgrades especially of the class of fine grained soil known as inorganic clay will provide more stable subgrade for road construction and will in turn reduce the thickness of pavement provided for most roads constructed in many parts of the world. Again rural communities will benefit immensely as most of their roads can now be constructed and opened to traffic without any further surfacing.
RECOMMENDATIONS
This researcher recommends thus:-
- The use of bitumen emulsion to stabilize poor subgrades especially of the inorganic clay
- Bitumen stabilized roads can be constructed in rural areas and traffic opened to use it without further
- Further research work in this area is recommended, most probably in the area of availability and production of the
REFERENCES
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- BS 1377, Methods of tests for soils for Civil Engineering purposes,British standard institution,London,1990.
- Council for Science and Industrial Research (CSIR) Transportek (1998): Methods and Specifications for Foamed Bitumen Stabilization.
- Ebels and Jenkins (2009), Interim guideline on the use of foamed bitumen TG1 F M 5410: Chapter 9- Soil stabilization for Roads and Airfields.
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