INVESTIGATING MECHANICAL PROPERTIES OF RICE HUSK ASH (RHA) CEMENT STABILIZED BRICKS

INVESTIGATING MECHANICAL PROPERTIES OF RICE HUSK ASH (RHA) CEMENT STABILIZED BRICKS

ABSTRACT

The project, reports on investigating mechanical properties of rice husk ash (RHA) stabilized cement bricks. About forty eight unit of rice husk ash (RHA) stabilized bricks were produced with mix proportion of 1:10 (weight batching) of cement/literite.19 unit each for 3 different replacement of cement with rice husk ash (0%, 10%, 20%) were produced by mixing each mix with appropriate quantity of water in a mould of size 290mmX140mmX170mm.the quantity of literite was kept constant while the quantity of cement and rice husk ash varies depending on the percentage replacement for cement. The average compressive strength and percentage water absorption were determine for each mix proportion .Result of the study indicate that rice husk ash increase the compressive strength of rice husk ash cement-stabilized bricks from 0.499N/mm2 for zero % rice husk ash up to a maximum of 1.11N/mm²,1.150N/mm² and 1.30N/mm² for 7, 14 and 28, days hydration period respectively. At 20% replacement with (RHA), compressive strength increase by 29%, then decreases by 12% and 20% for hydration period of 7, 14 and 28 days respectively. The result of water absorption meet up with (NIS)7:1976 25% maximum  for common building bricks.15.38%,13.93% and 18.16% for 0%,10% and 20% respectively.

CHAPTER ONE

1.0                                                          INTRODUCTION

1.1 BACKGROUND OF THE STUDY

Soil is readily and richly available, making it possible the most accessible and economic natural material for producing building material, such as brick. Development in material engineering has yet to render earth obsolete as a building material, particularly in financially and resources challenged places (Olutuah, 2008). This clearly calls for the search for low-priced possible materials which can be used to solve the resulting difficulty of severe housing shortage for the overgrowing population (Acheunu, 1999).

The accepted performance standard of materials and construction element are established by building codes and regulations, unfortunately in most of the developing countries, building standard have not been fully developed or applied in the field of earth construction (Ikoyi, 1997). This has made it extremely demanding to investigate into the properties of late rite soils and develop possible way of improving their performance.

The use of earth-base technologies has been greatly limited by concerns of their physio-mechanical properties. Consequently, there are restrictions on their use. For example, in the New Mexico building code section that governs the use of compressed earth block construction, a general clause – A forbid their use in any building more than 2 stories in height. Compressed bricks are also less durable than conventional building materials (maini, et al 2005).

(Achuenu, et al 2005) evaluate the performance of bitumen stabilized compressed earth brick in terms of strength at different water content and stabilization durability in terms of wear, water erosion and resistance to heat. The result of the compressive strength of 1.11/Nmm² was attained at 2% bitumen stabilization and 10 % water content at 14 days of age. It was summarily deduced that there was a low compressive strength with increase in bitumen content especially beyond 2 % stabilization. The stabilized bricks have high water exclusion properties as well as high resistance to water erosion and hence fair durability. However, the bricks were highly affected by the fire as shown by combustibility test.

(Mbiminah, 1992) on the effect of rice-husk on the compressive strength and durability of burnt clay bricks. Test results show that rice husk has a decreasing effect on the compressive strength of the brick and increasing effect on the water absorption of the bricks.

(Michael, 1994) on rice husk as a stabilizing agent in clay bricks. Clay bricks were produce with 0%, 1%, 2%, 3%, 4%, and % rice husk. It was conclude that the addition of husk reduces the compressive strength of the bricks and the husk clay brick becomes light as the percentage of husk clay increase.

(Uche and Joseph) research was aimed at experimental investigation of the compressive strength of cement cow dung stabilized bricks. The test on the bricks Mets minimum strength requirement of 2.5N/mm² at 28 days by the British institute of masonry unit specification for the cement and blend bricks. The Cow dung brick values are not consistent with the specification for load bearing walls except for partition walls.

(Daramola, 2005) summarize the limitation of compressed stabilized late rite bricks (cslbs) as follows

1. Reduced durability – if not regularly maintained and properly protected, particularly in areas affected by medium to high rainfall.
2. Low tensile strength- poor resistance to bending moments, to be used only in compressive e.g. bearing walls, domes, and vaults.
3. Low resistance to abrasion and impact-if not sufficiently reinforced or protected.

1.2 STATEMENT OF THE PROBLEM

Method of Disposing Agro-waste post a lot of implication to the environment, and also the recycling of this waste require investigation in to their inherent properties which determines the efficiency of their performance.

The global interest about the environment has increased the use of earth as a building material. The direct use of earth without modification for wall construction in any form has the disadvantage of low performance. The shortcomings principally are low mechanical characteristics, unsatisfactory resistance to weathering and liability to volume change especially in the case of clay. These disadvantages can be improved to make the material compatible with desired application in construction by combined chemical and mechanical action technically known as stabilization.

1.3 AIM OF THE STUDY

The main aim of this study is to investigate the mechanical properties of rice husk ash (RHA) cement stabilized bricks

1.4 OBJECTIVES

The following objectives will be adopted to achieve the aim of the research:

1- To produce Rice husk ash cement stabilized bricks with RHA replacing cement at 10%-20% cured in membrane.

2- Evaluate the stabilized bricks for two mechanical properties:

.   Compressive strength

.    Absorption.

3-To evaluate the effectiveness percentage of RHA replacing cement in RHA cement stabilized brick

1.5   METHODOLOGY

To address the aim of this research extensive literature in journals, books, research reports, and seminar papers were reviewed. Based on the available literature an experimental program was drawn and carried out in the Laboratory.

For the purpose of this research a mortar mix of 1:10 (cement/late rite) was used to produced stabilized brick of dimension 290×140×170mm among which include control measures (100% cement), while the subsequent bricks were at 10%, and 20% replacement of cement with rice husk ash (RHA).

A total of forty eight (48) bricks were produced at the same time and cured with water for 7, 14, and 28 days. At the end of each curing days 9 bricks were taken to the Laboratory for crushing using a cube crushing machine to determine the compressive strength of each brick.

Also some physical property tests were carried out on fine aggregate (late rite soil), and rice husk ash (RHA). The tests include sieve analysis test, specific gravity test, and bulk density test.

1.6 SCOPE / LIMITATION OF STUDY

This study will concentrate on investigating the properties of brick of composite materials: cement as stabilizing agent, rice husk ash as replacement for cement and late rite in terms of compressive strength, absorption,

A sample of Rice Husk ash will be prepared in the laboratory to determine the optimum mix and mechanical behavior of the stabilized brick. Series of the brick mix design with rice husk ash will be mold. The amount of percentage of rice husk ash that will be added comprises of 10%, and 20% from the total weight of the cement to be used in stabilizing the brick. The hardened bricks will be taken out from mould for test to be conducted after 17, 14, 28, of curing period.

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