ABSTRACT
This study examined the mechanical properties of earth-based materials that are relevant to the future development of affordable housing. Earthcrete structures were produced by mixing various proportions of laterites, clay and cement, while natural fibre-reinforced composites were produced by mixing earth-based matrices with natural fibre (Straw). Mechanical testing showed that optimum performance of the various samples was obtained at a fibre content of 20% by volume, with compressive strength values of about 2.91 MPa, flexural strength values of about 34.4 MPa and fracture toughness in the range of 1.40 – 1.50 MPa . The results indicate that the mechanical performance of the composites being studied is in line with those in prior studies on natural fiber-reinforced cementious matrix composites.
CHAPTER ONE
1.0 INTRODUCTION
1.1 BACKGROUND
In our society today, the choice of materials for building is greatly influenced by the cost, properties (mechanical and chemical) and availability. Industrialized societies have developed various materials which are applied in all works of construction (including buildings). Unfortunately, developing countries such as Nigeria where alternative materials exist have failed to explore such opportunities even when there is the possibility of producing such, locally. There is therefore, a need to explore new ways of producing robust building materials from locally available materials.
Such needs have stimulated recent efforts to develop affordable building materials that are strengthened and toughened by locally available natural fibers (Savastano et al., 2003) and matrix materials that are available in developing countries. However, in most cases, the matrix materials utilize cement, which is a relatively expensive synthetic material that emits ~ 14% of the CO2 emissions that are thought to contribute to global warming.
In contrast, earth-based materials are readily available materials that could be used as matrix material in building composites. They can also be stabilized by the use of binders, such as dung or cement, to produce materials that are strong and tough enough for applications in buildings. They can also be reinforced with natural fibers (such as sisal and straw) or industrial wastes (saw dust), while the matrices can be optimized by the use of industrial wastes, such as blast furnace slag and crushed charcoal from the burning of wood.
1.2 PROBLEM STATEMENT
There has been great progress in both the production and application of reinforced materials (except little for earth-based materials). In most cases where high strength and toughness of earth-based materials are required, the materials are stabilized with cement or dung (John, 2001). Some local people have also used straw and other natural fibers to strengthen earth-based materials that are used in local construction of earthen homes.
However, the scientific and engineering bases for such application are very limited. There is, therefore, a need to develop the scientific understanding that can provide the necessary basis for the design of novel earth-based materials that can be used in rural and urban construction.
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