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.
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