Microstructural Investigation Cement Treated Laterite Stablized With Bamboo Leaf Ash

ABSTRACT

Laterite is the commonly used building materials in rural Nigeria. It has been observed that it became the traditional building construction material due to its availability, low processing cost and ease of handling with little or no equipment and skill requirements. However, studies have shown that lateritic soils are generally weak in compression and tend to absorb moisture and become soften. Consequently, walling materials such as lateritic blocks has been the subject of investigation for decades; partly, to serve as an alternative to the conventional sand Crete blocks. Such effort is especially desirable as it is well known that the production processes of cement; which is the main binder employed in the production of sand Crete blocks is associated with huge energy consumption and emission of harmful gases such as CO₂. This study investigated the effect of bamboo leaf ash blended with cement on some engineering properties of lateritic blocks. The bamboo leaves used for this study were collected in the campus of the University of Uyo and the laterite was obtained from a borrow pit in Itu L.G.A. of Akwa Ibom State, Nigeria.

TABLE OF CONTENTS

COVER PAGE

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWELDGEMENT

ABSTRACT

CHAPTER ONE

INTRODUCTION

1.1      BACKGROUND OF THE PROJECT

• AIM/OBJECTIVE OF THE PROJECT
• SCOPE OF THE PROJECT
• PROJECT ORGANISATION

CHAPTER TWO

LITERATURE REVIEW

• DEFINITION OF LATERITE
• FORMATION OF LATERITES
• MINERALS IN LATERITE
• USES OF LATERITE SOILS
• SOIL STABILIZATION
• TYPE OF SOIL STABILIZATION
• AGRO-WASTE AS STABILIZER
• REVIEW OF THE USE OF BAMBOO LEAF AS A SOIL STABILIZER

CHAPTER THREE

METHODOLOGY

• MATERIALS AND METHODS
• EXPERIMENTAL PROCEDURE

CHAPTER FOUR

RESULT ANALYSIS

• RESULTS
• DISCUSSION

CHAPTER FIVE

• CONCLUSION
• REFERENCES

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.