ABSTRACT
A solution to the problem of high cost of roofing in low cost houses is explored
through the optimization of the span and mix proportions of palmnut fibre reinforced
mortar roofing tiles. Relevant physical and mechanical properties of palmnut fibre
mortar composites were tested in order to study the effect of mix proportions on their
structural and functional behaviour. Semi-empirical relationships between volume
fraction of fibre, sandlcement ratio and the properties of the materials were derived
from statistical analysis. Based on results of the investigation, cost and practical
considerations, the optimum span and mix proportion for the fibre-mortar tiles were
proposed for the optimum shape of the tiles which was established by theoretical
analysis. The economic viability and performance of the tile was assessed by comparing
it with asbestos-cement roofing sheet and Benimo roofing tile. It was found that the
structural efficiency (measured in terms of weight/strcngth ratio) of palmnut fibrcmortar
roofing tile with optimum span of 1.0 m is lower than the asbestos-cement
roofing sheet but superior to the Benimo roofing tile. The fibre-mortar roofing tiles
were also found to be about 41% and 14% cheaper than asbestos-cement and Benimo
roofing tiles respectively, while the Benimo roofing tiles were about 32% cheaper than
asbestos-cement roofing sheets. It is then expected that about 9% reduction in the
overall cost of roofing would be achieved by optimizing the span and mix proportions
of fibre reinforced mortar roofing tiles.
TABLE OF CONTENTS
Certification …………………………………………………………………………….
Dedi,c ati.o n …………………………………………………………………………………..
Acknowledgement ……………………… … ………………………………………
List of Tables …………………………………………………………………………….
List of Figures ………………………………………………………………………….
List of Plates …………………………………………………………………………..
List of Symbols …………………………………………………………………………
Abstract ………….. ……… . .. ………………………………………………………..
Page
iii
viii
X
xii
xiii
xiv
CHAPTER ONE: INTRODUCTION …………………………………………………….. 1
1.1 Background …………………………………………………………………….. 1
1.2 Objectives and Definition of the Project …….. …………………. 5
1.3 Scope of the Project ……………….. . …………………………………… 6
CHAPTER TWO: LITERATURE REVIEW ………………………………………… 7
2.1 General …………………………………………………………………………….. 7
2.2 Fibres ……………………………………………………………………………… 9
2.2.1 Inorganic Fibres …………………………………………………………. 10
2.2.2 Organic Fibres ……………………………………………………………. 11
2.3 Mechanics of Fibre Reinforcement of Cement Materials ………….. 15
2.3.1 .Fibre Geometry …………………………………………………………… 17
2.3.2 Fibre Spacing …………………………………………………………… 17
2.3.3 Fibre Volume Fraction and Aspect Ratio …………………… 18
2.3.4 Fibre Orientation ……………………………………………………… 20
2.3.5 Mix Proportions ……………………………………………………….. 21
2.4 Properties of Inorganic Fibre-Cement Composites ……… .. ……… 22
2.5 Properties of Organic Fibre-Cement Composites …………………… 25
2.6 Applications of Fibre-Cement Composites ……………….. . ……….. 30
2.6.1 Housing Applications ……………………………………………….. 31
2.7 Palmgut Fibre ………………….. … ………………………………………….. 33
CHAPTER THREE: PHYSICAL AND MECHANICAL PROPERTIES OF
PALMNUT FIBRE ………….. .. …………………………… 35
3.1 General Description …………………………………………………………. 35
3.2 Stress-Strain Characteristics ………………………………………………… 35
3.3 Specific Gravity …………………………………………………………………. 54
3.4 Bulk Density ……………………………………………………………………….. 55
3.5 Water Absorption ………….. – ………………… 56
. CHAPTER FOUR: RAW MATERIALS AND TEST PROCEDURE ………. 5 8
Procurement of Raw Materials ………………………………………………. 58
Mixing Technique ………………………………………………………….. 59
Curing Condition …. ………. .. …….. ………. …. . . ………………. .. . . 61
Flexural Strength …………………………. ……… …..,. . .. .. … ….. …… ….. 61
Tensile Strength ……………………………………………………………… 62
Compressive Strength ………. …… ….. …………… . . . . . ……… . 64
Density …… .. .. .. .. . … .. .. .. .. …. .. .. .. .. .. . . .. .. .. .. . . . . .. ,. .. .. .. .. .. . . . . . . . . . . . . . . . . 64
Water Absorption …… ……….. ………… …. ,, …………… . . . ….. , . ,. . 65
CHAPTER FIVE: TEST RESULTS, ANALYSIS AND DISCUSSION ….. 66
Test Results . .. .. . . .. .. .. .. .. .. .. .. .. … .. .. .. .. , , , . . . .. . . .. .. .. . . . . .. . . ,. . … …. …… 66
Statistical Analysis ………………………………………. ……. 66
– –
Graphical Representation ………………………………………… . ………….. 86
Mathematical Model ……………………………………. . ……….. . ……. 133
Test for Extremum ……………………………….. , ,.,.. . …. ………………… 145
Discussion of Test Results ………………………………………………… 148
CHAPTER SIX: PRODUCTION AND PERFORMANCE CHARACTERISTICS
OF PALMNUT FIBRE-MORTAR ROOFING TILES 156
6.1.2 Folded Plates ……………………………………………………….. 160
6.1.3 Choice of Section …………………………. . ………………. 163
Production Sequence ………………………………………………………. 168
Optimum Mix Proportion ………………………………………………….. 175
6.4 Performance Characteristics ……………….. .. ………………………. 180
6.4.1 Rain Shielding …………………………………………………… 180
6.4.2 Load Bearing Capacity ………………………………………….1.8. 3
6.5 Comparison of Load Bearing Capacity …………………………….. 189
6.6 Optimum Span …………………….. … ……………………………….. 194
6. 7 Cost Analysis ………………………………………………………. . . . . 197
6.7.1 Design of Roof Rafters . . . . . . . . . . . . . . . . . . . . . . 197
* . , * – 6.7.2 Cost Comparison . . .204
CHAPTER SEVEN: CONCLUSIONS ……………………………………………….. 2 i i
REFERENCES …………………………………………………………………………………….2. 15
CHAPTER ONE
INTRODUCTION
1.1 BACKGROUND
Apart from food, the most basic problem facing man is shelter. The
problem of shelter is as old as man and it is unfortunate that no ideal solution
to this problem has evolved over the many centuries of mans existence. This
problem is acute in Nigeria and other developing countries due mainly to the
high growth rate of the population, inflation, unemployment and poor economic
resources. Today in Nigeria both middle and low income earners can hardly
afford their own houses. This has led both the State and Federal Governments
to intensify their efforts in the provision of “shelter for all” by constructing lowcost
houses.
Nevertheless, the costs of these low-cost houses are so high and well out
of the reach of the middle income earners as a result of the high cost of building
materials used in their construction. This is due mainly to the tremendous impact
of the Structural Adjustment Programme (SAP) introduced by the present
1
Federal Military Government. The resultant inflation and depreciation of the
naira by over 2,000 percent, causing the costs of imported goods to be very high
has been the major effect. The conventional roofing materials like galvanized iron
and asbestos-cement have high proporiion of imported compoileil:s which
presently make their cost too high for low-cost houses [1,2]. There is also a health
hazard associated with the use of asbestos materials.
Based on their properties, source of raw materials and cost, the advantages and
disadvantages of different types of roofing materials in Nigeria may be
summarized in Table 1.
Table 1: Types sf Woofing Materials in NPgecia [I-31.
Advantages Disadvantages
Thatch
Burnt clay tiles Moderate cost, good sound
and heat insulation.
Very low initial cost, good
sound and heat insulator.
High energy input in production, require
very closely spaced purlins and high
labour input for installation.
Galvanized iron
Very poor durability and prone to fire.
Moderate weight, good
handleability and good
durability. Good sound and
~ i g hwt e ig!!t and very good
hnndleability.
High cost a7d high proportion of
imported components. There is health
hazard caused by asbestos. 1
Long span aluminium
High cost and high proportion of
imported wmpnents. Susceptible to rust,
poor sound and heat insulator.
heat insulator.
Improved rain shielding Very high cost and high proportion of
because of the relatively few
Fibrearnent mortar
tiles (50 cm and 60
end laps. Good durability.
Low cost and locally available
raw materials. Good sound
Require closely spaced purlins and high
labour input for installation.
3
The government has realized that local sourcing of raw materials is one
of the ways out of the nation’s present economic predicament and hence the
establishment of the Directorate of Food, Road and Rural Infrastructure
(DFRRI). A part of DFRRI’s programme for encouraging rural devA :pment
is by edtcating and assisting the rural dvrellers on how to build loiv-cost houses
using locaily available materials.
In a bid to finding acceptable solution to the problem of housing, there
appears to be a general consensus among researchers [35-491 of the potentials
of natural vegetable fibres for reinforcing cement composites to produce low
cost building components like roofing and ceiling materials. Some of the
research findings in this field of materials and construction engineering have
been put into commercial use. For instance, thc Roof Tile Factory at the
Leprosy Settlement, Uzuakoii, Abia State established by the Methcdist Church
of Nigeria and Benimo Nigeria Ltd., Enugu produce 50 cm and 60 cm long
cement mortar roof tiles respectively, using palmnut fibre reinforcement.
However, these tiles have short span and therefore require closer purlin spacing
a d high labour input for installation thereby increasing the cost.
4
There are great potentials for availability of palm fruits for producing
palmnut fibre building components in Nigeria. Palm fruit is cultivated and
grows mainly in the southern States of the country with high concentration in
the coastal areas along the coastal plains of the West African sub-region. The
recent governments efforts to encourage cultivation of palm fruits by providing
improved palm h i t seedlings at subsidized rates to the public in addition to
the public enlightenment campaign – “Palm For Palm” have tremendously
increased the production of palm fruit in the country. This obviously will
guarantee the availability of palmnut fibre in commercial quantities for a long
time to come.
It is hoped that the research into the optimization of span and mix
proportions for palmnut fibre-cement mortar roofing tiles will greatly
complement the efforts by governments and private organizations in solving the
problem of housing in Nigeria and other developing countries.
OBJECTIVES AND DEFINITION OF THE PROJECT
Palmnut fibre is relatively abundant in Nigeria and is also in use for
commercial production of roofing tiles but with very little basic studies and
documentation. Some of the production factories include the Roof Tile Factory at the
leprosy Settlement, Uzuakoli, Abia State and Benimo Nigeria Ltd., Enugu. Hence, this
work focuses on palmnut fibre reinforced mortar and sets out to carry out studies on
fundamental properties of the composite as mix parameters change to corroborate
available data.
The main thrust of the project however is to further reduce cost of palmnut
fibre-mortar roofing tiles by determining optimum length in view of production
practice which uses short lengths (600 mm). In order to achieve this objective, a
theoretical analysis was carried out to justify the general preference of the parabolic
shape in roof tile as the best shape. In addition the optimum mix of this composite
material had to be established in order to determine how the roofing tiles compare
with asbestos-cement roofing materials and Benimo tiles vis-a-vis cost and
performance.
1.3 SCOPE OF THE PROJECT
The scope of the project is as follows:
(i) Determination of relevant properties of palmnut fibre-mortar
composite.
(ii) Investigation of the effect of mix variables (SIC, wlc and V,) on the
following engineering properties of the composite:
(a) compressive strength
(b) tensile strength
(c) flexural strength
(d) density
(e) water absorption
(iii) Mathematical/statistical analysis of the relationship between the
engineering properties of the composite and mix variables.
(iv) Theoretical analysis of roof tile shapes to justify the general
preference of the parabolic shape in roof tiles as the best shape.
(v) comparative cost study and performance characteristics tests on
palmnut fibre reinforced mortar roofing tiles, Benimo tiles and asbestoscement
roofing sheet
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