ABSTRACT

This work presents the design, fabrication and performance evaluation of a multiple sandcrete blocks moulding machine (MSBMM) for simultaneously moulding three of 6 inches sandcrete blocks of size 450 x 150 x 225mm. The machine was designed to operate at speed of 151.8 rad/s, and provided the vibration right through compactor drive shaft (CDS)-eccentric system that compressed the three sandcrete blocks with 1.26 X 10-6 N/mm2 with the aid of automatically controlled ram. Machine parts like frame, chassis, lever, vibration compaction chamber, ram, mould, handle as well as rack and pinion were designed while standard parts like electric motors and wheel were simply chosen after calculation during the fabrication of MSBMM. The performance of the machine was compared to that of a conventional sandcrete block moulding machine (CSBMM) by using them to mould blocks from same concrete mix sample. MSBMM was able to produce 90 sandcrete blocks per hour by two (2) workers while CSBMM can produce 125 blocks by minimum of five (5) workers. Average compressive strength produced by these machines were determined then blocks produced from these machines were subjected to water absorption test. Results obtained showed that the average compressive strength test for MSBMM was found to be 1.78 N/mm2 while blocks produced from it have average water absorption of 10.35%. However, CSBMM has average compressive strength of 0.62 N/mm2 while blocks produced from it has average water absorption of 9.29%. The cost of fabricating the machine was one hundred and five thousand, six hundred naira (N 105, 600:00) only, whereas, CSBMM in Nigeria cost about two hundred fifty thousand naira (N 250, 000.00) only based on current market price. This is about 57.76% reduction in price of commercial machine available in market. Thus, the machine is very affordable for small and medium enterprise (SME) based on the price difference.

 

 

TABLE OF CONTENTS

Contents Page
title Page……………………………………………………………………………………………………………………………… i
Declaration …………………………………………………………………………………………………………………………. ii
Certification……………………………………………………………………………………………………………………….. iii
Dedication. ………………………………………………………………………………………………………………………… iv
Abstract ……………………………………………………………………………………………………………………………….v
Acknowledgement ………………………………………………………………………………………………………………. vi
Table of Contents………………………………………………………………………………………………………………. viii
List of Figures ……………………………………………………………………………………………………………………. xi
List of Tables …………………………………………………………………………………………………………………….. xii
List of Plates …………………………………………………………………………………………………………………….. xiii
List of Appendices ………………………………………………………………………………………………………………xiv
Lists of Abbreviations ………………………………………………………………………………………………………….. xv
Chapter One: Introduction……………………………………………………………………………………………………….1
1.1 Background of the Study ………………………………………………………………………………………………..1
1.2 Statement of Research problem ……………………………………………………………………………………….3
1.3 Present Research Work ………………………………………………………………………………………………….4
1.4 Aim and Objectives ……………………………………………………………………………………………………….4
1.4 Significance of the Study ………………………………………………………………………………………………..5
1.5 Justification ………………………………………………………………………………………………………………….5
1.6 Scope of the study …………………………………………………………………………………………………………6
Chapter Two: Literature Review ………………………………………………………………………………………………7
2.1 Block Making Concepts …………………………………………………………………………………………………7
2.2 Blocks …………………………………………………………………………………………………………………………8
2.3Sandcrete Block Making Technologies ……………………………………………………………………………. 10
2.3.1 Batching and Mixing …………………………………………………………………………………………….. 10
2.3.2 Compaction …………………………………………………………………………………………………………. 11
2.3.3 Curing ………………………………………………………………………………………………………………… 12
2.3.4 Storage of cured blocks …………………………………………………………………………………………. 13
2.4 Types of Block Moulding Machines ………………………………………………………………………………. 13
2.4.1 Hand-operated block moulding machines………………………………………………………………….. 13
2.4.2. “Egg-laying” mobile machines ……………………………………………………………………………….. 14
2.4.3 Fully mechanized, stationary machines …………………………………………………………………….. 15
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2.5 Methods of producing Sandcrete Block in Nigeria ……………………………………………………………. 16
2.5.1 Manual Compaction ……………………………………………………………………………………………… 16
2.5.2 Mechanized Compaction ……………………………………………………………………………………….. 17
2.6 Common Components of the sandcrete block moulding machine ………………………………………… 18
2.6.1 Wheel …………………………………………………………………………………………………………………. 18
2.6.2 Chassis ……………………………………………………………………………………………………………….. 19
2.6.3 Mould box …………………………………………………………………………………………………………… 19
2.6.4 Rammer ……………………………………………………………………………………………………………… 19
2.6.5 Handle (ejector) ……………………………………………………………………………………………………. 19
2.6.6 Rack and Pinion Mechanism …………………………………………………………………………………… 19
2.6.7 Electric motor ………………………………………………………………………………………………………. 20
2.7 Review of Past Works on Sandcrete Block Moulding Machine …………………………………………… 20
2.8Conclusion and Research Gap ……………………………………………………………………………………….. 25
Chapter Three: Materials And Methods …………………………………………………………………………………… 27
3.1Introduction ……………………………………………………………………………………………………………….. 27
3.2 The Description of the Multiple Sandcrete Blocks Moulding Machine …………………………………. 27
3.3 Design Considerations and Specifications……………………………………………………………………….. 29
3.4. Design Theory…………………………………………………………………………………………………………… 30
3.4.1 Design for Ram Weight …………………………………………………………………………………………. 30
3.4.2 Design for mould box ……………………………………………………………………………………………. 32
3.4.3 Design of vibrator-compactor chamber (mould compartments) …………………………………….. 33
3.4.4Design for shaft diameter for compactor drive shaft (CDS) and the eccentric system …………. 35
3.4.5 Torque (T) and shear stress (τ) generated in the rack and pinion shaft ……………………………. 37
3.4.6 Design for lever of the machine ………………………………………………………………………………. 38
3.4.7 Design for machine chassis …………………………………………………………………………………….. 40
3.5 Material Selection ………………………………………………………………………………………………………. 41
3.6 Working Principle of the Multiple Sandcrete Blocks Moulding Machine ……………………………… 41
3.7 Cost Evaluation of the Multiple Sandcrete Block Moulding Machine…………………………………… 42
3.8 Performance Evaluation of the Multiple Sandcrete Block Moulding Machine ……………………….. 42
3.8.1 Sample Preparations and Testing …………………………………………………………………………….. 42
3.8.2 Production Rate ……………………………………………………………………………………………………. 43
3.8.3Compressive Strength Test Procedure ……………………………………………………………………….. 44
3.8.4 Water Absorption Test Procedure ……………………………………………………………………………. 44
Chapter Four:Results and Discussion ……………………………………………………………………………………… 46
4.1 Introduction ………………………………………………………………………………………………………………. 46
4.2 Design Calculations ……………………………………………………………………………………………………. 46
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4.3 Material Selection ………………………………………………………………………………………………………. 50
4.4 Fabrication Processes ………………………………………………………………………………………………….. 50
4.5 Cost Evaluation of the Multiple Sandcrete Block Moulding Machine…………………………………… 54 4.6 Performance Evaluation Results ……………………………………………………………………………………. 56 4.6.1 Production rate …………………………………………………………………………………………………….. 56
4.6.2 Compressive Strength …………………………………………………………………………………………… 57
4.6.3 Water Absorption …………………………………………………………………………………………………. 59
Chapter Five:Conclusion And Recommendations ……………………………………………………………………… 61
5.1 Conclusion ………………………………………………………………………………………………………………… 61
5.2 Recommendations ………………………………………………………………………………………………………. 61
REFERENCES …………………………………………………………………………………………………………………… 62
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CHAPTER ONE

INTRODUCTION
1.1Background of the Study
Housing is recognized world-wide as one of the basic necessities of life and a pre-requisite to survival of man (Onibokun, 1983; Salau, 1990; United Nations, 1992). In the traditional African setting, in particular, housing is, in fact, one of the greatly cherished materials need. Thus, the importance of providing adequate housing in any country cannot be overemphasized. However, in spite of the fundamental role of housing in the life of every individual and the nation, and in spite of the United Nations’ realization of the need to globally attain adequate shelter for all, the housing crisis remains one of the global problems posing great challenge to both urban and rural residents, particularly in most developing countries (Samuel, 2014). The Nigerian Government as part of its effort of overcoming housing problem has initiated the building of low cost houses for workers, especially low income earners since 1979 by Shehu Shagari Administration(Ademiluyi, 2010). Even with more recent initiatives by the government up till 2014, the problem of affordable housing has been a source of concern to all and sundry especially in Nigeria. In fact there is an estimated deficit of between 17 and 18 million housing units in Nigeria in 2012 (Chuku, 2014). However, the cost of housing can be reduced through reduction in the cost of the building materials by developing our indigenous technology. The need for locally manufacturing of building materials has been emphasized in many countries of the world. There is imbalance between the expensive conventional building materials coupled with depletion of traditional building materials. To address this situation, attention has to be focused on the production of low cost alternative building material such as sandcrete blocks (Aguwa, 2009).
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Sandcrete blocks are the most common type of blocks used in forming walls units and over 90% of houses in Nigeria today are being constructed using sandcrete blocks (Baiden and Tuuli, 2004). The importance of the sandcrete blocks as part of the local building materials cannot be over emphasized in the building and construction industry. Sandcrete blocks are usually produced using a semi-mechanised stationary type machine. The other production systems are manual moulds that require hand tamping, a mobile semi-mechanised egg-laying machine and fully mechanised system that combines compression and vibration. These requirements are of fundamental importance since the homogeneity of the product, its surface finished and its mechanical strength depend directly upon these parameters (Segun, et al. 2009). Although there are sophisticated and cheap block moulding machines available at international markets, the challenge is the requirement for high level operation skills which are scarce among many labour force used in block industries. Examples of such machines are the CINVA RAM, the Montgomery’s dynamic CEB making machine and so on. They cost between N120.000 and N180.000 (Yakubu and Umar, 2015). To indigenize the technology and make the operation simplerand reducing cost of imported products such as Hydrafoam which is sold at about six million Naira (N6,000,000:00), considerable efforts have been made at designing and construction of sandcrete block making machine by local industries in recent years. Some of the locally fabricated mechanical block moulding machine costs between N 250, 000 and N 300, 000 depending on the quality of the fabrication (Field Survey, 2016), however, they possesssome constrains such as high level of physical labour (fatigue stress) and increase in operation cost due to the use of pallet. This has led to increased interest in quest for developing alternatives to traditional moulding practices.
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1.2Statement of Research problem
In many developing Countries, including Nigeria, housing crisis is escalating unabated despite a number ofpolicies, programs and strategies being engaged in by public and private sectors in addressing this problem. Some of the major stumbling blocks in achieving the goal providing affordable home to the populace of Nigeria can be summarized as follows:
i. The current commercial block moulding technology is found to be labour intensive especially in transferring green bodied block from moulding machine to curing place.
ii. An average of 6-8 semi-skilled labourers is requiring for an average production of 800 – 1000 blocks per day.
iii. The current production process is very slow and time wasting as it involves lot of processes done manually. These processes includepicking off the ejected block on the supporting wooden pallet as ejected from themould, taking them to curing place and placing a fresh wooden pallet each time into the mould box from a pallet-stack.
iv. Also, there is no locally made block moulding machine that can produced more than two blocks at a time thereby working at low efficiency.
v. On the other hand, the imported block making machine which could serve as alternative required high capital and operational costs. This machines require specialists for maintenance and repairs; spare parts are usually difficult to get and are usually expensive.
vi. Finally, the general production conditions make the price of average soundcrete to be between N120.00 to N250.00 (6 inch hollow block) which makes building construction more expensive.
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From the afore-mentioned factors, making block moulding machine locally and more efficient will go a long in solving some of the problems as it is considered to be the major equipment of sandcrete block production. This serves as the main reason for undergoing this research work.
1.3Present Research Work
In order to solve the problem of low efficiency of moulding operation as well as that of labour intensiveness and the use of foreign technology, this research work tends to produce sandcrete moulding machine that can mould multiple blocks simultaneously and use less number of labour making the operation more efficient and less labour intensive.
1.4Aim and Objectives
The aim of this research work is to design and fabricate a multiple sandcrete block moulding machine that can simultaneously mould three (3) blocks suitable for use by small and medium scale enterprises (SMEs). The specific objectives of this dissertation are:
i. To carry out design analysis of the multiple blocks moulding machine.
ii. To fabricate and assemble the block moulding machine that will produce three (6 inch hollow) standard blocks in a single operation locally.
iii. To carry out performance evaluation of the machine.
iv. To carry out the comparative cost analysis of the design machine with the conventional block mould machine.
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1.4Significance of the Study
The design and development of a multiple sandcrete block moulding machine is significant in the following ways.
i. It will reduce the cost of producing sandcrete block by reduction in the overhead cost of sandcrete block as results of reduction in labours and elimination of pallet for curing the blocks.
ii. It will also contribute significantly to theeffort in the development of indigenous technology especially in the block production industries.
iii. It will improve working conditions and encourage our youths to venture into block moulding business.
1.5Justification
Shelter is one of the basic human needs and is usually ranked third after food and clothing. Building materials form one of the main constraints that restrict the supply of housing and between 60-70 percent accounts for the cost of building (Ogunsemi, 2010). Recently, in the many developed countries, it has been verified that the traditional and conventional technologies used for construction and maintenance of buildings are inefficient and resource wasteful due to enormous amount of resources consumed (Ghosh, 2002). The colossal waste associated with traditional and conventional technologies facilitated the search for more appropriate sandcrete block moulding technology that can accommodate three 6 inch blocks (450 x 150 x 225 mm). This research work is borne out of the desire to solve housing problem in Nigeria through reduction in the cost of the building materials like the sandcrete block.
Efforts made in proper design and fabricated will be justified owing to the increasing need for more alternative methods for producing sandcrete block as reported by Lawal (2010). This will eliminates or at least minimizes the challenges that are encountered during the production of sandcrete block.
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1.6Scope of the study
The scope of the research work is limited to:
1. Designing of a sandcrete block moulding machine for simultaneous production of three (3) 6 inches blocks.
2. Construction of the essential components such as chassis, moulds, ram and handle (ejector mechanism).
3. Carrying out performance evaluation on the machine.

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