Description
CHAPTER ONE
1.0 INTRODUCTION
1.1 BACKGROUND OF THE STUDY
In most developing nations like Nigeria, housing for the poor remains a major
challenge, for where majority of the population still live in sub-standard
houses. According to Anthonio (2003), housing can be described as an
essential component of human settlement that ranks comparably with the
provision of food and clothing in the hierarchy of the basic primary elements
required for human existence. At its most elemental level, it addresses the
basic human needs by serving as shelter, offering protection against
excessive cold, heat, rain, high winds and any other form of inclement weather
as well as protection against unwanted aggression. As observed by Mustapha
(2004), homelessness and the incidence of people living in poor housing and
unhealthy neighborhoods are rapidly growing. The housing problem is acute
especially in the urban areas due to shortage of affordable housing for low-
income earners and the poor who constitute over 70% of the urban population.
Laterite is the commonly used building materials in rural Nigeria. Some lateritic
soils are suitable for use in their natural state, while others require additives in
order that they satisfy certain requirements to make them suitable for the
intended application (Kamang 1998, UNCHS 1986). According to Abalaka
(2006) the reason for the popularity of lateritic soil as a traditional building
construction material is its availability, low processing cost and ease of
handling with little or no equipment and skill requirements. However, lateritic
soils are generally weak in compression and tend to absorb moisture and
become soften. Any improvement in the compressive strength of the materials
will enhance its performance as building construction materials. He also stated
that the compressive strength of lateritic blocks could be greatly increased by
either mechanical compaction of laterite or the use of binder such as cement
with low compaction, or by employing both methods. A high percentage of the
bond is believed to be achieved by particle interlock in the damped soil
depending on the particle size distribution and clay content of the laterite. The
remaining strength is gained by pozzolanic reaction between hydrated ferric
oxide and silica. Compressive strength of lateritic blocks could equally be
improved by fixing the blocks in kilns designed for that purpose.
Traditionally, vegetable straws have been used for the stabilization of lateritic
soils for block making in rural Nigeria and elsewhere (Roach 1993, Adesanga
2000, Abalaka 2006). Straws were found to reduce shrinkage of lateritic blocks
and improve their quality and strength. However, the strength of such blocks
depends upon the quality and quantity of straws added. Other materials had
also been used in stabilizing laterite. Apart from cement which is the most
predominantly used material, others such as lime, bitumen, gypsum, meta-
kaoline, carbide, silica fume, burnt clay and ash from agricultural waste;
including palm kernel shell, coconut fibre/shell, rice husk, sugar cane leaf,
sugar cane bagasse etc. have been tested and found suitable for lateritic soil
stabilization (Adams and Agib 2001, Okoli 1998).
The high cost of building materials has been observed to be the major factor
besetting housing delivery in Nigeria (Okoli, 1998). This has been partly traced
to the rising cost of cement; which is commonly used in the production of
sandcrete blocks, concrete and as stabilizing admixture in soil blocks. In
addition, there are also issues arising from the production processes of
cement which ranges from huge energy consumption to large emission of
CO2; a major greenhouse gas. Hence, for a nation which is faced with what
can be described as an unprecedented energy crisis and with the global
campaign against the emission of greenhouse gasses to curb warming of the
environment, it is only appropriate to seek alternative means to the use of
cement in the effort to achieving the goal of housing delivery.
All over the world, Pozzolans have been discovered to be viable alternative
binder to cement, especially in the realm of partial replacement. Pozzolans are
fine silica and alumina rich materials which when mixed with hydrated lime
produce cementitious materials suitable for stabilization and construction
needs. Recently, it was reported that bamboo leaf ash is an equally good
pozzolanic material which reacts with calcium hydroxide to release additional
calcium silicate hydrate (C-S-H); the main cementitious component (Dwivedi et
al. 2006, Singh et al. 2007, Frias et al. 2012) . The chemical characterization
of the bamboo leaf ash (BLA) in comparison with those of the ordinary
portland cement (OPC) using X-ray fluorescense (XRF) and scanning electron
microscopy techniques (SEM) is as shown in Table 1. It should be noted that
the chemical characterization of BLA is generally dependent on the specie of
bamboo that produces the ash (Frais M. et al. 2012).
In this effort, the effect of bamboo leaf ash blended with cement on the
engineering properties of lateritic blocks has been investigated so as to
establish the optimum bamboo leaf ash content suitable for stabilizing lateritic
block for building construction. Since these materials are readily in abundance,
it is expected to impact positively on the building industry in Nigeria;
particularly in the area of cost of housing delivery and environmental
protection from harmful gases.
1.1 AIM / OBJECTIVE OF THE PROJECT
The main aim of this work is to investigate the effect of bamboo leaf ash
blended with cement on some engineering properties of lateritic blocks.
1.2 SCOPE OF THE STUDY
This study was carried out using bamboo leaf ash ( BLA), the leaves were sun-
dried, burnt in an open atmosphere and then heated in a muffle furnace at 600oC
for 2hours to obtain the bamboo leaf ash (BLA). Tests on the physical and
chemical properties of bamboo leaf ash blended with cement were conducted in
accordance with BS 4550: 1978 and BS 12: 1996. The chemical analysis of the
BLA showed that the combined Silica Oxide (SiO₂), Aluminum oxide (Al₂O₃) and
Ferrous oxide (Fe₂O₃) content was above the 70% minimum standard
requirement specified by ASTM (ASTM C 618, 2008) for pozzolanic materials.
Varying levels of percentage replacement of cement with bamboo leaf ash was
obtained at 0%, 5%, 10%, 15%, 20% and 25%. A total of 72 blocks comprising of
12 blocks for each percentage replacement of the lateritic block size of
225mm x 113mm x 75mm of mix ratio 1:20 and water-cement ratio of 0.8 were
cast, cured and crushed at 7, 14, 28, and 56 days curing respectively. Analysis of
the compressive strength, moisture absorption resistance and the abrasion
resistance of the lateritic blocks produced from cement blended with bamboo leaf
ash (BLA) showed that the 5% and 10% cement replacements is suitable for load
bearing outer walls whereas the 20% and 25% substitution was found more
suitable for non-load bearing indoor walls. The 15% substitution was however
found to be suitable for non-load bearing outer walls.
1.3 PROJECT ORGANISATION
The work is organized as follows: chapter one discuses the introductory part of the work,
chapter two presents the literature review of the study, chapter three describes the
methods applied, chapter four discusses the results of the work, chapter five summarizes
the research outcomes and the recommendations.