Production of different types of unfired clay bricks · flexural strength of bricks is get for the...
Transcript of Production of different types of unfired clay bricks · flexural strength of bricks is get for the...
I
Production of different types of
unfired clay bricks
Student’s Name:
1- Hussain Ali Abd ul-sada
2- Mohammed Majid Yasser
Supervisor
Assist. Prof. Dr. Abbas Oda dawood
A project report submitted in partial fulfilment of the
Requirements for the award of the degree of
Bachelor of Civil Engineering
Civil Engineering Department
Engineering College
University of Maysan
Iraq
2018-2019
III
DECLARATION
I hereby declare that this project report is based on my original work except for citations and
quotations which have been duly acknowledged.
Signature : _________________________
1- Name : Hussain Ali Abd ul-sada
Date : _________________________
Signature : _________________________
2- Name : Mohammed Majid Yasser
Date : _________________________
IV
APPROVAL FOR SUBMISSION
I certify that this project report
“Production of different types of unfired clay bricks”
was prepared by Hussain Ali Abd ul-sada and Mohammed Majid Yasser has met
the required standard for submission in partial fulfilment of the requirements for the award
of Bachelor of Civil Engineering at University of Maysan.
Approved by,
Signature : _________________________
Supervisor : Assist. Prof. Dr. Abbas Oda dawood
Date : _________________________
V
Dedication
Dedicate this work, to my mother and father
To my family, to my teachers, to candles that burn to light up for others
To everyone who taught me characters I dedicate this humble project to the
Lord Almighty to find acceptance and success
And to all who stand by my side of my professors and colleagues
And in particular, Assist. Prof. Dr. Abbas Oda dawood
VI
ACKNOWLEDGEMENTS
I would like to thank everyone who had contributed to the successful
completion of this project. I would like to express my gratitude to my research
supervisor, Assist. Prof. Dr. Abbas Oda dawood for his
invaluable advice, guidance and his enormous patience throughout the
development of the research.
In addition, I would also like to express my gratitude to my loving parent
and friends who had helped and given me encouragement......
VII
ABSTRACT
The mud is considered one of the oldest construction material in Iraq and
still used in the country regions for farmers houses or animals shelters. In Iraq,
there are different types of mud constructions, included adobe, unfired bricks
and cob, the present study is focused on unfired clay brick masonry
construction. The main material of unfired clay brick used in the present study
is the clay, which obtained from south Amarah from depth of 2 m below natural
ground level to obtain pure and clean clay. The study mainly focused on
production different types of unfired clay bricks according to local procedure
used in the south of Iraq, by addition different materials to the clay to improve
its properties and especially large deformation due to shrinkage. The materials
added classified into three concept, the first additives included natural fibers to
improve tensile strength of brick and reduce the cracking due to shrinkage, the
natural fibers included straw, sawdust and rice husk. The second additives
included added the fine and coarse sand as stabilizer to reduce the volumetric
changes. The third additives is adding cement to increase adhesive and cohesion
of the mud matrix. The measurements included compressive strength of both
brick, mortar and masonry and also the flexural strength of bricks alone. Also
the behaviour of unfired masonry prisms are compared to the traditional fired
clay brick prisms. The results indicated that the higher compressive strength of
bricks is get for the mix that included clay, coarse sand straw and the maximum
flexural strength of bricks is get for the mix that include clay and sawdust, while
for unfired masonry prism the higher compressive strength is obtained with mix
that included clay, coarse sand straw. Finally a proposed formula to obtain the
compressive strength of unfired brick masonry from the compressive strength of
brick and mortar is presented.
VIII
TABLE OF CONTENTS
CHAPTER Page
1 1-1 INTRODUCTION 1
1 -2 -Brick-Making History 4
1-3-Traditional Unfired Clay Bricks 6
1-4- Strength of unfired clay brickwork 9
1-5- Mortars for unfired clay brickwork 9
1-6-Advantages of Unfired Clay-Brick 11
1-7-Disadvantages 11
1-8- Objectives of Project 12
1-9- Project Layout 12
2 2-1 Introduction 13
2-2 Literature Review 13
3 3-1-General 17
3-2-Materials 17
3-3-Method of Mixing 19
3-4- Raw materials proportions 26
3-5- Failed Mixes 30
4 4-1- General 31
4-2 Effect of Natural Fibres 31
4-2-1Comparison among Straw, Husk rice and Sawdust 37
4-3- Effect of Sand 38
4-3-1 Comparison among fine and coarse sands 41
4-4 Effect of Cement 43
4-4-1 Comparison among mixes incorporated cement 47
4-5-Masonry 48
4-5-1: Unfired bricks used for masonry prisms 49
4-5-2: Mud Mortar 50
4-5-3: Unfired Masonry 51
IX
CHAPTER Page
4 4-6-1 Traditional Fired Brick Masonry 57
5 5-1 Conclusions 60
5-2- Recommendations 61
List of Tables
Table (3-4-1): Mix proportions of clay only and different types of fibers 25
Table (3-4-2): Mix proportions of clay with sand 27
Table (3-4-3): Mix proportions of clay with cement 28
Table 4.2: Results of Effect of Natural Fibres 38
Table (4-3) : Result of effect of sand 43
Table (4-4 ): Result of effect of Cement 49
Table (4-5-1): Compressive Strength for Unfired bricks used for masonry prisms 50
Table (4-5-3): The compressive strength for Unfired Masonry 57
Chapter one Introduction
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CHAPTER ONE
Introduction
1.1 Introduction
Maysan province is located in the eastern south of Iraq. The top soil of Maysan
province is mainly clay soil, and considered one of main sources of clay bricks in
Iraq, therefore a Brick Factories are widely spread through areas of the province.
The spread of these factories leads to pollutants spread in wide areas and
negatively affected the surround villages. According to output gases and smoke
produced by traditional bricks factories the environmental problems could not be
skipped. The Diseases like asthma, lung diseases and other respiratory system
diseases caused by these factories has spread in a scary shape. This fact forces us
to look for another way to product a clay bricks for construction.
Clay bricks are commonly used in construction sector in Iraq. Mud bricks had been
used in the construction of shelters for thousands of years, and approximately 30%
of the world’s present population still live in earthen structures [1].Clay brick had
been used as the earliest building materials since ancient time and still be used yet.
This is due to their simplicity, low cost, good thermal isolation, acoustic isolation
properties, simple manufacturability and long building's life. The clay material can
be easily reused or resumed to the ground without any negative impaction the
environment [2 - 4]
Chapter one Introduction
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Fig. (1.1): pollution due to Bricks factories in Maysan Province
The conventional method of bricks production has brought undeniable
shortcomings. The consumption of earth-based materials as clay, shale and sand in
brick production resulted in resource depletion, environmental degradation, and
energy consumption. Virgin resources mined from riverbeds and hillsides to
service brick industry leaving mines areas un-reclaimed. Environmental
degradation accompanies such mining activities with air pollution and remains
after the mines cease operations, leaves scars on the landscape. The brick was
anciently produced by mixing the virgin resources, forming the bricks, drying them
and then firing them [5 - 7]
Chapter one Introduction
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Most of the researches went through enhancing the clay brick quality and
properties by mixing the clay with various recycled wastes as foundry sand, granite
sawing waste, harbor sediments, perlite, fly ash, clay waste and fine waste of
boron, sewage sludge, waste glass from structural wall and other different wastes
[8]
What we really need is to find another way to product a clay brick which will be
friendlier with the Environment and which will lead to decrease the pollution, so in
our experiments we decided to focus on producing Unfired Clay Bricks (UCB).
Unfired clay materials provide a sustainable and healthy alternative as a
replacement to conventional masonry materials, such as fired clay and concrete
block, in both non-load bearing and low rise load-bearing applications .Unfired
clay materials offer potential health benefits to internal built environments,
primarily through passive regulation of relative humidity. Though traditional clay
masonry materials, such as adobe, clay lump and cob blocks, as well as more
recently developed compressed earth blocks have been used successfully in a
variety projects, more and more interest has been shown in using unfired clay
bricks produced by high volume industrial brick manufacturers. The tensile
strength of unfired clay materials is low and the bond between unfired clay units
and traditional clay mortars is poor, therefore walls have relied on their bulk mass
to ensure lateral load resistance and resilience [9]
Traditional forms of unfired clay bricks (cob blocks, adobe and mud bricks) are
generally made by hand and as a result, have variable dimensions and other
properties. Traditional earth masonry has thick walls (often over 300mm thick) as
the mortar provides low bond strength and the thick walls have sufficient mass to
keep themselves stable against lateral loads in dwellings Because of the
environmental and financial cost of using materials in construction, it is preferable
Chapter one Introduction
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to reduce the wall thickness to approximately 100mm for internal partitions (the
standard thickness for fired clay bricks and concrete block work). Thinner walls
also reduce the structural weight loading and increase available space inside
buildings.
Modern unfired clay brickwork uses units manufactured to accurate tolerances
using a commercial extrusion or pressing system to provide a consistent, high
quality product. This enables rapid, cost effective, 100mm thick walls with low
environmental impact to be constructed. In most cases, modern unfired clay bricks
are produced in commercial fired brick manufacturing plants using similar
materials to fired bricks, but without putting the bricks through the firing process.
This significantly reduces the energy used in manufacture and previous research
has indicated unfired bricks have 14% of the embodied energy of fired bricks and
25% of the embodied energy of concrete blocks. In Germany, some fired brick
plants have moved to making only modern earth masonry and associated products.
[10]
1-2 -Brick-Making History
One of the oldest building materials were mud bricks, which molded by hand and
dried in the sun for days. Later, bricks were made of clay and fired in kilns to
create a strong. The raw materials that were required to make bricks were widely
available, and brick-making quickly became a trade. Bricks are commonly made of
a combination of clay and sand. The mineral content of the brick determines what
color the brick will be. For instance, red bricks contain more iron, while whiter
bricks have little iron content. Throughout history, bricks have been used in every
culture, from the Ancient Chinese to the Romans. People viewed brick as a
stronger material than wood, in term of good resistance to fire, rot, and pests. Brick
has been used to build most structures from homes to barriers to tombs. In modern
Chapter one Introduction
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times, bricks have been used to create outdoor living spaces like patios and bars, as
well as for decorative uses, including flowerpots, mailboxes.
The Middle East has a rich history of brick-making structures. Bricks that date
back almost 10,000 years made from excess mud from flooded rivers have been
discovered throughout the Middle East, Fig(1-2). The oldest testament to the use of
brick was recorded in the Bible, which recounts the Israelite slaves building
pyramids for the Egyptians. Bricks were made by combining clay with straw,
which better allowed them to withstand the elements and the test of time. These
become known as adobe bricks, qualified by their composition of straw and clay,
and being dried only by the sun. While adobe construction is often linked to
Mexican peoples, adobe bricks can be found across the globe including in the
Middle East, West Asia, and Africa [10 - 12]
Figure (1-2) : Brick-Making History
Chapter one Introduction
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1-3-Traditional Unfired Clay Bricks
Unfired Clay Bricks still used in some villages in Iraq and there are many
buildings are still extant for a long years. Fig(1-3). The traditional way industry
Unfired Clay Bricks is by mixing soil with straws and water. The ratios of
materials are determined manually using expertise without any kind of
calculations. After the materials have set, they started mixing the soil with the
straw until it mix together perfectly they added the water to the mix. Then, they
mixed the materials together using their feet. After that, they left the mix for 1 day.
In the next day, they started casting the bricks using wooden mold.
The mold is open from its both upper sides. They started molding the mix in the
mold and compressing it using their hands bonding together perfectly, then the
uplifted the mold and the mix still in its place taking the mold shape. The repeated
this process until they have the enough number of bricks. The bricks have a perfect
shape with sharp corners without any kind of irregular shapes Fig (1 – 4 ).
After end the molding, they left the bricks to drying in the sun for several days (it
takes approximately 3 days in the summer in Iraq), Fig(1 – 5 ).
In some places they use a rice husk instead of a straw but in same industry way.
After the bricks dried, they use it for building houses. The mortar they used also
made from a clay mixed with straw. The houses are faced inappropriate weathers
like rains and winds but they still extant and it will still extant for lot of years.
Chapter one Introduction
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1-4- Strength of unfired clay brickwork
The compressive strength of unfired clay brickwork is much more complicated
than for block work or fired clay bricks and no single strength value can be
assigned. The strength of unfired brickwork is dependent on the material
properties, the dimensions of the wall and the water content. The material property
that influences the masonry strength more than any other is the clay content in the
masonry.
As the water content in the masonry units is increased, the strength decreases and it
is therefore important to keep the masonry dry once constructed through
appropriate detailing, such as provision of a fired masonry or block work plinth to
prevent accidental wetting from spills. The water content will normally be highest
during construction (from application of wet mortar and render), and will then
stabilize to a lower level (stronger masonry) during use.
The strength of unfired brickwork is normally lower than fired clay bricks or
concrete block work, and 100mm thick unfired clay brick walls are currently not
recommended for high load structural applications. Increasing the wall thickness
will open the possibility for structural use of unfired brickwork.
1-5- Mortars for unfired clay brickwork
As the wall thickness decreases, the mortar must bond more to the masonry units to
provide sufficient structural strength against lateral loads (pushing horizontally
against the wall). The effect of wall thickness on required bond strength can be
determined by a structural engineer, but it can be calculated that a 300mm thick
wall with almost no bond strength (traditional earth masonry) can support the same
load as a 100mm thick wall with a bond strength of approximately 0.2N/mm2. The
Chapter one Introduction
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bond strength of different mortars with modern earth masonry is shown in the
figure below. This figure includes clay/sand and lime mortars used for traditional
earth masonry and a cement/sand mortar used with fired bricks.
As shown, the mortars used for traditional earth masonry do not provide the bond
strength required to construct 100mm thin walls using modern earth masonry. The
use of a preformulated sodium silicate/clay/sand mix does, however, provide the
required strength and provides a bond strength similar to cement mortars with fired
bricks. The preformulated sodium silicate mortar has less than 10% of the
embodied CO2 than typical cement based mortars but does not perform as well at
high water contents. These high water contents can be avoided through appropriate
detailing. An alternative to a sodium silicate based mortars is to tie 100mm thick
modern earth masonry to a timber or other frame to provide the required lateral
load capacity. This will provide the environmental benefits of earth masonry
(thermal mass and humidity buffering) to a timber framed building.[10]
Chapter one Introduction
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1-6-Advantages of Unfired Clay-Brick
1- Minimizing the environmental pollution caused by the gases emitted from
the brick production factories.
2- There is no need for fuel as that required in burning fried bricks, which
reduces the cost of production.
3- The availability of raw materials and low of the prices of the materials to be
added to the mix.
4- The community accepts this type of material as well as its historical
importance.
5- The possibility of using it to strengthen and restore historic sites such as
shrines and pyramids.
6- Low-cost and great thermal behavior.
1-7-Disadvantages
1- The tensile strength of unfired clay bricks is low and the bond between
unfired clay units and traditional clay mortars is poor, and therefore walls
have relied on their self’s weight to ensure lateral load resistance.
2- The compressive strength of unfired clay bricks is weak compared with fired
clay bricks that make it unsuitable for loaded walls.
3- It has a high absorption ratio compared with fired clay bricks so it would be
unsuitable to use in exposed places.
Chapter one Introduction
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4- To produce unfired clay bricks we need use the Sun heat to make it dry so
we will be able to produce it in the summer only which the temperature will
be suitable, but even in summer it will need a lot of days to make it usable.
1-8- Objectives of Project :
Although mud brick is considered one of the oldest construction materials,
engineers and builders do not have enough information about its mechanical
properties. Also there is no accurate design code to follow before construction.
The research aims to produce building blocks that can be used as an alternative to
burnt mud bricks in which their manufacturing process accompanied toxic gases as
side effect, that have a significant impact on the health side.
Different materials are added to clay to produce the unfired clays. The comparison
among different types of produced unfired clays is restricted to compressive
strength of bricks as main structural characteristics in additional to volumetric
change.
1-9- Project Layout
The present project consisted of five chapters:
1- Chapter One: General Introduction and Historical abstract about Producing
Unfired Clay Bricks.
2- Chapter Two: Literature Review.
3- Chapter Three: Experimental Work.
4- Chapter Fourth: Result and Discussion
5- Chapter Five: Conclusions and recommendations
Chapter two Literature Review
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CHAPTER TWO
Literature Review
2.1 Introduction
The present chapter presented the available studies related to unfired clay
bricks. In general there are limited researches available in the literature related
to production of unfired clay bricks.
2.2 Literature Review
Oti and kinuthia [14], 2009, used Lower Oxford Clay (LOC), two different
types of lime (L1 and L2), GGBS and Portland cement (PC) in production
unfired clay bricks. They found that the performance of using lime-activated
GGBS for both laboratory and industrial-scale unfired clay masonry brick
production is better than that of the PC-activated GGBS bricks.
Maheri, [15] et al , 2011, studied the improving of the durability of straw-
reinforced clay plaster cladding for earthen buildings. Four different tests were
conducted to investigate the effects of crusher dust and clay contents on the
strength and durability. The material used was clay soil, crusher dust, lime and
straw. When 5% lime is added to the mix, the compressive strength increases by
more than 5, which indicates the effectiveness of lime in increasing the strength
of the dried plaster. By comparing the results of samples of mix types it appears
that addition of 10% crusher dust, corresponding to a reduction of
approximately 5% in clay content, improves the compressive strength by 26%.
The increase in strength due to addition of crusher dust seems to be as a result
Chapter two Literature Review
14
of improved consistency of the mix. However, as the crusher dust content
increases to 20% and higher, resulting in a reduction in clay content beyond
40%, a marked reduction in the strength of the plaster.
Miqueleiz et al [16], 2013, investigated the using of alumina filler wastes and
coal ash waste for unfired brick production. Mechanical test and durability
assessment were carried out on unfired brick test specimens made using marl
clay soil and alumina filler waste as a target material, and 70% mix of coal ash
waste were used as commercials additive (Portland cement and Lime)
replacement. They concluded that the compressive strength resistance of the
unfired bricks reduced as the clay replacement level increased .Also, the unfired
brick test specimens made with the blended mixtures containing coal ash waste
and lime tended to achieve higher strength values when compared with the coal
ash waste and Portland cement blends. The unfired brick test specimens were
able to withstand the repeated 48-hour freezing/thawing cycles.
Smeu et al.[17],2014, studied the unfired clay bricks as building materials made
from clay mixed with cement (C), lime (L), sand (S) and sawdust (SD). They
tried to stabilize the mixtures with clay using cement and lime as binder. The
cement (C) was 10% and 5%, lime (L) was 15% and 5%, sand (S) was 10% and
sawdust (SD) was 2.5% and 5%. Bending tensile strengths and the compressive
strengths are increasing from 7 days age to 28 days age. Also see that using lime
as a binder instead of cement; the compressive strengths will increase
significantly at 28 days age compared when using only cement.Used only lime
as a binder had a significantly and visible shrinkage of the dimensions of the
batches. Added sand, the compressive strength and also the bending tensile
strength are lower at 28 days age.
Chapter two Literature Review
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Al-Ajmi et al [18] , 2016, studied the using of earth construction as energy
efficient housing. They used mud bricks consist of clay, water, and binding
material such as rice husks or straw. They found that although mud brick is
considered one of the oldest construction materials, engineers and builders do
not have enough information about its mechanical properties, also there is no
accurate design code to follow before construction. Their study is devoted to
enhance the low compressive strength of mud brick without sacrificing its low
thermal conductivity properties. The experimental program in this research
includes the use of different admixtures to increase the compressive strength of
the basic mud mix. The experimental results show that the increase of cement
ratio, as ingredient to a certain limits, can lead to an optimum compressive
strength of the brick.
Saravanakumar et al. [19] 2018, investigated experimentally the replacement of
clay by metal powder and sawdust in unfired bricks. The specimens were made
using 10% cement,8% sand, 2% sawdust and different percentage of steel slag.
Mechanical test were carried out on unfired brick. there is potential in using
steel slag as a strengthening material for unfired brick production. the ideal ratio
for steel slag was 32% where it gave the highest compression strength. When
increasing or decreasing the ratio, the compression resistance decreases with it.
Water absorption percentages are in the range of high class bricks. The strength
resistance and water absorption values were within the acceptable limits for
masonry unit.
El-Mahllawy et al [20] 2018, evaluated the feasibility of stabilizing clay bricks
with marble cutting waste (MCW). This waste currently discarded in huge
quantities as a sludge resulted from sawing the marble blocks to slabs, grinding
and polishing of marble processes to the landfills located around the marble
Chapter two Literature Review
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processing factories located in the Shaq El-Thoban industrial zone, Cairo
governorate, Egypt causing negative impacts on the environment, health and
sustainable development. Experimental investigations were carried out to
explore the effect of addition of the MCW in different clay-base mixes at
different percentages up to 25% at the expense of the hydrated lime. Cement,
hydrated lime and MCW are the three types of solidification agents used, clay
and sand were also added in the formulations of the unfired clay brick
specimens. Laboratory cylindrical stabilized and compressed specimens were
made, and then they were cured in a humidity chamber for 2 and 4 weeks, then
after were air dried, tested and evaluated according to the Egyptian code for the
building by the stabilized and compressed earth soil (ECBS, 2016). To enhance
the durability of the cured specimens, transparent silicon – based paint was used
for this purpose. The laboratory results demonstrate high potential usage of
MCW based additives up to 15% incorporating HL. In addition, the used paint
could be an effective treatment way for the use of stabilized bricks in a wet
environment. The use of eco-friendly building materials will be a great
contribution for the environmental advantages and suggest a remarkable
economical alternative to the fired building units.
Chapter Three Experimental Work
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CHAPTER three
Experimental Work
3-1-General
The experimental program was accomplished in the laboratories of the college
of Engineering, University of Maysan. The objective of this project was to
produce different types Unfired Clay Bricks (UCB) with regular size using
different materials like soil, straw, sawdust, rice husk, cement etc…
3-2-Materials
The materials used in this investigation were commercially available materials,
which include soil, straw, sawdust, rice husk, cement, sand.
1- Soil: In our experiments, we used south Amarah soil from depth of 2 m
below natural ground level, which is used by most local factories in the
production of bricks, the liquid limit of this soil was 37%, and plastic
limit was 21%.
2- Cement: Ordinary Portland cement was used throughout this
investigation. The full quantity required was brought to the laboratory
and stored in a dry place.
3- Coarse Sand: The retained sand on sieve No. 4 was added to the mix to
increase the compressive strength of the unfired bricks.
Chapter Three Experimental Work
18
4- Fine Sand: Also fine sand that pass through sieve No. 4 and retained on
sieve No. 19 was used to increase the compressive strength and
homogeneity of the mixture as well.
5- Straw: Straw is main part of adobe or unfired bricks traditionally used in
the south of Iraq .The length of straw ranges between (2 – 6) cm,
therefore it is considered as main part in the present study, Fig(3-1).
Sawdust used in this investigation was collected from local farms in
Maysan province .The major contribution of the sawdust admixture is
the reduction in the dry density and increasing the bonding strength.
6- Sawdust: The coarse sawdust is used in the present experimental study
passing from sieve No. 12 mm , sawdust was collected from the carpentry
shops scattered throughout the region . Fig(3-2)
Figure (3-1) : Straw Figure(3-2): Sawdust
Chapter Three Experimental Work
19
7- Rice husk: The rice husk, also called rice hull, is the coating on a seed or
grain of rice. It consists of hard materials, including silica and lignin .In
the present study sawdust are used it as an alternative to straw in the mix.
Passing from sieve No. 4.75 mm, Fig (3-3).
Figure (3-3) : Rise husk
3-3-Method of Mixing
1- The mixing procedures for clay to make unfired bricks are different for
country to other. In the present work two mixing procedures are used:
First Method- Traditional Method: In this method or procedure, the
traditional work method used by local Iraqi builders for adobe contraction is
used with the following steps:
2- Preparation of the soil fermentation area by enclosing a floor area (1 )
with concrete and Wrapping of floors and ends with thin nylonlayer.Fig
(3-4)
Chapter Three Experimental Work
20
Figure (3-4): Soil fermentation
3- Weighing a quantity of the soil and placing it in the fermentation place
And Spray it with water ratio of 25% from dry weight of soil and leave
for 24 hours.
4- After 24 hours, we mix the clay mixture with one of the materials
according to the ratios in table (3-1) until the homogenization matrix is
obtained.
5- A sample of the mixture is then taken and placed in the oven to verify the
water content used in the mixture. Fig.(3-5)
Chapter Three Experimental Work
21
Figure (3-5): mix mud with one of materials
6- Preparing the brick mold with dimensions (240 mm x 110 mm x 75 mm)
by cleaning it and grease from the inside. Fig (3-6)
Figure (3-6): Molds
Chapter Three Experimental Work
22
7- Fill the mold on three layers with compaction. After that we settle and lift
the mold and then clean it and paint it and return the process again.Fig(3-
7)
Figure (3-7): Fill the mold
8- After 24 of casting the bricks, samples are taken and placed in the oven at
65 ° C for drying purposes due to poor natural temperature in the winter
season and also leaving samples to dry naturally. Fig(3-8)
Figure (3-8): Bricks after casting
Chapter Three Experimental Work
23
Second Method: Due to the fact that the cement granules are very soft and
difficult to mix with the clay, and also the hardening speed of the cement, we
had to use another method to mix it.
1- Take dry soil and grind it with a grinding machine to get soft soil. Fig(3-
9)
Figure (3-9) : Soil grinding
2- Weighing a quantity of grinding soil and place it in the mixing vessel.
3- Weighting the amount of cement or sand according to the mixing
percentages in Table (3-4-1) and put them in the mixing vessel.
4- A 25% water content of dry soil weight and 50% of the weight of the
cement shall be taken and gradually added to the mixture
5- Mix the mixture well to get a homogeneous mix. Fig (3-10)
Chapter Three Experimental Work
24
Figure (3-10) : mixing of materials
6- Preparing the brick mold with dimensions (240 mm x 110 mm x 75 mm)
by cleaning it and grease from the inside.
7- Fill the mold on three layers with compaction and settle the surface.
8- Leave the bricks in the mold for 24 hours after that, lift the mold and
leave the block under the sun to dry. Fig(3-11)
Chapter Three Experimental Work
25
Figure (3-11) :Mud with mold
3-4- Raw materials proportions
The mix proportions of deferent mixtures are listed in Tables (3-4-1) to (3-4-3).
Tables (3-4-1) showed the mix proportions for clay unfired clays with different
binders fibers namely straw, sawdust and husk rice. Tables (3-4-2) showed the
traditional mix proportions of abode in the south of Iraq which consisted of clay
and straw by modified with different percentages of sand. Tables (3-4-3)
showed mixes included cement and sand.
Table (3-4-1): Mix proportions of clay only and different types of fibers
Group Clay
(%)
Straw
(%)
Sawdust
(%)
Rise
husk
(%)
Water
(%)
G1 100 - - - 27
G2 95 5 - - 28
G3 95 - 5 - 28
G4 95 - - 5 27
Chapter Three Experimental Work
27
Table (3-4-2): Mix proportions of clay with sand
Figure (3-13): Some images while working
Group Soil
(%) Fine
sand (%) Coarse
sand (%)
Straw
(%) Water
(%)
G5 87.5 10 - 2.5 28
G6 82.5 15 - 2.5 28
G7 87.5 - 10 2.5 29
G8 82.5 - 15 2.5 27
Chapter Three Experimental Work
28
Table (3-4-3): Mix proportions of clay with cement
Group Soil
(%) Cement
(%)
Sand
(%) Straw
(%)
W.C % for
Cement
%
Water
(%)
G9 90 10 - - 50 26
G10 80 10 10 - 50 26
G11 77.5 10 10 2.5 50 26
Chapter Three Experimental Work
30
3-5- Failed Mixes
In additional to above materials, its tried to used plastic wastes fibers instead of
straw but the process is failed. Fig (3-15)
Figure(3-15) : plastic wastes fibers
CHAPTER FOUR RESULTS and DISCUSSION
31
CHAPTER FOUR
RESULTS and DISCUSSION
4-1- General
In the present chapter the results are listed and discussed. The results included
compressive strength, flexural strength and description of volumetric changes
during pressing of unfired bricks. Then the behavior of unfired brick masonry
prisms are presented and compared with that of fired clay brick masonry
prisms. A proposed formula are presented for evaluation the compressive
strength of unfired masonry from the compressive strength of unfired brick and
mortar based on Euro Code procedure.
4-2 - Effect of Natural Fibers
In the present study three types of natural fibers are used into mud matrix to
produce unfired clay bricks, namely straw, rice husk and sawdust, in which
straw are the traditional fibers in the south of Iraq in mud matrix for structural
applications like adobe construction. In additional to these natural fibers its
tried to use the recycled plastic fibers PET fibers but its failed may be due to
smooth surface of PET fibers which is failed in bonding stresses before develop
the required tensile strength. The effect of the three natural fiber types is listed
below.
1- Clay only: When the soil is only used to produce mud bricks, we notice
that during the drying period, cracking on the surface and sides of the bricks
occurs due to the shrinkage tensile stresses. The weak tensile strength of
CHAPTER FOUR RESULTS and DISCUSSION
32
mud as weak brittle material and also the absence of an additive that helps to
increase the cohesion of the matrix, led to early failure of these samples. The
maximum cracked compressive strength is 1.1 MPa. While the flexural
strength is 0.55 MPa. The proposed formula for the flexural strength of
unfired clay bricks consisted on clay only is:
√ ́
ft = flexural tensile strength of unfired brick
fb = compressive strength of unfired brick
2- Soil with Straw: Using straw as an admixture for the mud mix increased
the performance of clay bricks compared with samples included clay only.
The straw worked as links or natural fibers which led to increase the tensile
resistance of the samples for shrinkage and prevent the cracks due to tensile
stresses, which was clear during the drying period where no cracks appeared
in the resulting bricks which happened in the first mix (Clay only). The
addition of straw also increased the compressive strength of the bricks as
well as its compressibility. In spite of the Deformations, the cracks did not
appear even after the brick depth pressed to about half of the centimeter,
after increasing the strength of compression, the sides of the block were
crushed and there was no longitudinal or transverse cracks, Fig. (4-1). The
maximum cracked compressive strength is 2.4 MPa . While the flexural
strength is 0.5 MPa. . The proposed formula for the flexural strength of
unfired clay bricks consisted on clay only is:
√ ́
CHAPTER FOUR RESULTS and DISCUSSION
33
ft = flexural tensile strength of unfired brick
fb = compressive strength of unfired brick
a- Brick before test
b- Brick after test
Figure (4-1) : compressive for brick
CHAPTER FOUR RESULTS and DISCUSSION
34
3- Soil with Rice Husk: As a result of the small size of rice husk, the
bonding strength has been lower than in straw, which was longer. The rice
husk added an extra compressive force in the bricks, preventing severe
deformation of the brick (the thickness of the brick and the lack of
significant descent) which obtained in the straw mix with the clay. However
,rice husk is increased the stability of the brick and reduced its
compressibility and led to the appearance of cracks along the surface of the
brick, Fig. (4-2). The maximum cracked compressive strength is 2.4 MPa
and the compressive strength at failure is obtained for clay only bricks is
2.64 MPa. While the flexural strength is 0.6 MPa.
√ ́
ft = flexural tensile strength of unfired brick
fb = compressive strength of unfired brick
a- Brick before test
CHAPTER FOUR RESULTS and DISCUSSION
35
b- Brick after test
Figure (4-2) : compressive for brick
4- Soil with Sawdust: The sawdust was the best additive for the bricks as
the sawdust was not as hollow as in the straw and it were longer than the rice
husk. It was also more flexible than straw and lighter as well. These
differences were evident during its use in the mixture. The mixing process
was easier and the shrinkage was less than in the rest of the mixtures. The
test showed that the compressive strength was higher than the previous
mixtures and also the deformations were significantly lower. When the
compressive strength increased, the failure appeared in the form of capillary
cracks on the surface of the block as well as a collapse on its sides.Fig. (4-3).
The maximum cracked compressive strength is 2.85 MPa and the
compressive strength at failure is obtained for clay only bricks is 3.9 MPa.
While the flexural strength is 0.85 MPa.
√ ́
ft = flexural tensile strength of unfired brick
fb = compressive strength of unfired brick
CHAPTER FOUR RESULTS and DISCUSSION
36
a- Brick before test
b- Brick after test
Figure (4-3): compressive for brick
CHAPTER FOUR RESULTS and DISCUSSION
37
4.2.1 Comparison among Straw, Husk rice and Sawdust
As mentioned above the straw, rice husk and sawdust play the same role in mud
matrix, namely as natural fibers that increased the tensile stresses and general
cohesion of brick body.
Figure( 4-1) : (4-3) and Table (4-2) showed the comparison among these three
fibers on the compressive strength of unfired clay brick in which straw fibers are
considered as reference brick due to straw is the traditional fibers in unfired clay
brick in the south of Iraq. The sawdust fibers yielded the higher compressive
strength with about 118.75% larger than straw fibers, also rice husk presented
higher compressive strength than straw fiber by about 110%. For flexural strength,
the sawdust presented a higher tensile strength than the straw by about 170%, also
rice husk presented higher compressive strength than straw fiber by about 120%.
Table 4.2: Results of Effect of Natural Fibers
Group
Description Specimens Compressive strength (MPa)
Flexural
strength
(MPa)
Flexural
strength
% straw Cracked
strength
Failure
strength
Comparison
per straw
(%)
G1
Clay only A1
1.1 -
45
0.4
80
B1 0.95 -
G2
Clay + straw
A2 2.4 -
1
0.5
1 B2 2.1 -
G3
Clay +
Sawdust
A3 2.4 2.8
118.75
0.85
170 B3 2.85 3.9
G4
Clay + Rice
Husk
A4 2.2 2.6
110
0.6
120 B4 2.4 2.64
CHAPTER FOUR RESULTS and DISCUSSION
38
Figure(4-4) : The compressive strength of Natural Fibers
4-3- Effect of Sand
In this phase, the traditional mud matrix that consisted of straw and clay is
modified by adding sand. The addition of sand to mud matrix play the role of
stabilizer to reduce the volumetric change of unfired bricks. Both fine and
coarse sands are used in the mud matrix that consisted of both clay and straw.
1- Soil, Fine sand and Straw: When the straw was used with the Fine sand,
the Fine sand increased the compressive strength of the brick and the
straw added the elasticity to it as well as the bond strength and reduced
the cracks during the drying period. The increased compression strength
of the brick is due to sand resistance to compressibility,In addition, the
addition of sand and reduce the proportion of straw in the mixture, which
led to the reduction of deformation of the brick during the test while
maintaining flexibility. We noticed that increasing the proportion of sand
0
0.5
1
1.5
2
2.5
3
1G 2G 3G 4G
Compressive strength
Compressive strength
CHAPTER FOUR RESULTS and DISCUSSION
39
in the mixture to some extent improves the properties of the resulting
bricks, such as its resistance to pressure, as well as its elasticity. Fig(4-5).
The maximum cracked compressive strength is 2.75 MPa and the
compressive strength at failure is obtained for clay only bricks is 5.2
MPa. While the flexural strength is 0.64 MPa.
√ ́
ft = flexural tensile strength of unfired brick
fb = compressive strength of unfired brick
a- Brick before test
CHAPTER FOUR RESULTS and DISCUSSION
40
b- Brick after test
Figure (4-5) : compressive for brick
2- Soil, Coarse Sand and Straw: The addition of coarse sand instead of
fine sand was not a significant change in the resistance of the brick to
compression, where the values were close to different mixing ratios of
the mixtures.fig(4-6). The maximum cracked compressive strength is
2.87 MPa and the compressive strength at failure is obtained for clay
only bricks is 4.1MPa. While the flexural strength is 0.52 MPa.
√ ́
ft = flexural tensile strength of unfired brick
fb = compressive strength of unfired brick
CHAPTER FOUR RESULTS and DISCUSSION
41
a- Brick before test
b- Brick after test
Figure (4-6) : compressive for brick
4.3.1 Comparison among fine and coarse sands
As mentioned above the straw, Fine sand and Coarse sand play the same role in
mud matrix, namely as natural fibers that increased the tensile stresses and general
cohesion of brick body.
CHAPTER FOUR RESULTS and DISCUSSION
42
Figure (4-5) : (4-6) and Table (4-3) showed the comparison among these two fibers
on the compressive strength of unfired clay brick in which straw fibers are
considered as reference brick due to straw is the traditional fibers in unfired clay
brick in the south of Iraq. The Fine sand yielded the higher compressive strength
with about 112.5% larger than straw fibers, also Coarse sand presented higher
compressive strength than straw fiber by about 120%. For flexural strength, the
sawdust presented a higher tensile strength than the straw by about 110%, also rice
husk presented higher compressive strength than straw fiber by about 150%.
Table (4-3) : Result of effect of sand
Grou
p
Descripti
on
Specim
ens
Compressive strength (MPa)
Flexur
al
strengt
h
(MPa)
Flexur
al
strengt
h %
straw
Cracked
strength(MPa)
Failur
e
strengt
h
(MPa)
Comparis
on per
straw (%)
G5
Clay +
10% Fine
Sand +
Straw
A5 2.7 3.74
112.5
0.55
110 B5 2.33 3.81
G6
Clay +
15% Fine
Sand +
Straw
A6 2.64 5.5
114.6
0.64
128 B6 2.75 5.2
G7
Clay +
10%
Coarse
Sand +
Straw
A7 2.7 3.8
120
0.52
104 B7 2.87 4.1
G8
Clay +
15%
Coarse
Sand +
Straw
A8 2.4 4.1
100
0.75
150 B8 2.42 4.22
CHAPTER FOUR RESULTS and DISCUSSION
43
Figure(4-7) : The compressive strength of effect of sand
4-4 Effect of Cement
The effect of cement on unfired clay brick is investigated. Firstly the cement is
added to the clay only, secondly cement is added for clay and sand mix and
finally cement is added for the mix that included clay, straw and sand mix.
1- Soil and Cement: When cement is added to the soil alone, it makes the
bricks fragile, brittle and weak. The maximum cracked compressive
strength is 0.9. While the flexural strength is 0.7 MPa.
√ ́
ft = flexural tensile strength of unfired brick
fb = compressive strength of unfired brick
0
0.5
1
1.5
2
2.5
3
3.5
G5 G6 G7 G8
Compressive strength
Compressive strength
CHAPTER FOUR RESULTS and DISCUSSION
44
2- Soil, Sand and Cement: When sand was used with cement as a clay
additive, we did not notice a change in the properties of the brick, where
it remained fragile and weak.fig(4-8).The maximum cracked compressive
strength is 1.1. While the flexural strength is 0.63 MPa.
√ ́
ft = flexural tensile strength of unfired brick
fb = compressive strength of unfired brick
a- Brick before test
CHAPTER FOUR RESULTS and DISCUSSION
45
b- Brick after test
Figure (4-8) : compressive for brick
3- Soil, Sand, Straw and Cement: The addition of straw, along with the
presence of sand and cement to the clay mix, increased the strength of the
bonding between the mixing elements, and also increased the bearing of
the bricks for compressing, even if it less than the cement-free mixtures,
where the cement makes the mix brittle.The presence of straw has
increased the elasticity of the brick and the lack of cracks.fig(4-8). The
maximum cracked compressive strength is 2.4 MPa and the compressive
CHAPTER FOUR RESULTS and DISCUSSION
46
strength at failure is obtained for clay only bricks is 2.9 MPa. While the
flexural strength is 0.85 MPa.
√ ́
ft = flexural tensile strength of unfired brick
fb = compressive strength of unfired brick
a- Brick before test
CHAPTER FOUR RESULTS and DISCUSSION
47
b- Brick after test
Figure (4-9) : compressive for brick
4.4.1 Comparison among mixes incorporated cement
As mentioned above the straw, (Cement+ Sand)and (Cement + Sand + Straw) play
the same role in mud matrix, namely as natural fibers that increased the tensile
stresses and general cohesion of brick body.
Figure( 4-8) : (4-9) and Table (4-4) showed the comparison among these two
Materials on the compressive strength of unfired clay brick in which straw fibers
are considered as reference brick due to straw is the traditional fibers in unfired
clay brick in the south of Iraq. The Cement & Sand yielded the lower compressive
strength with about 46 % larger than straw fibers, also Cement, Sand & Straw
presented equal compressive strength for straw fiber by about 100%. For flexural
strength, The Cement & Sand presented a higher tensile strength than the straw by
about 140%, also Cement; Sand & Straw presented higher compressive strength
than straw fiber by about 170%.
CHAPTER FOUR RESULTS and DISCUSSION
48
Table (4-4 ): Result of effect of Cement
Figure(4-10): The compressive strength effect of Cement
4-5-Masonry:
Generally, the masonry units represent the units that consisted of bricks and
mortars. The behavior of masonry units are different from the behavior of
bricks or mortar alone. Generally the compressive strength of masonry is
0
0.5
1
1.5
2
2.5
3
G9 G10 G11
Compressive strength
Compressive strength
Grou
p
Descripti
on
Specimen
s
Compressive strength (MPa)
Flexural
strength
(MPa)
Flexura
l
strengt
h %
straw
Cracked
strength
Failure
strengt
h
Compariso
n per straw
(%)
G9
Soil +
Cement
A9 0.9 -
37.5
0.7
140 B9 0.8 -
G10
Soil +
Cement
+ Sand
A10 1.1 -
46
0.63
126 B10 0.92 -
G11
Soil +
Cement
+ Sand
+Straw
A11 2.2 2.6
100
0.85
170 B11 2.4 2.9
CHAPTER FOUR RESULTS and DISCUSSION
49
less than the compressive strength of bricks and mortar due to weak bonding
between them which failed before reaching the strength of bricks or mortars.
In the present study the prisms of masonry are investigated which consisted
of three unfired bricks and mortars from similar materials of that used to
manufactured the unfired bricks. Also the present study incorporated the
testing of traditionally fired clay bricks masonry in order to compared the
behavior of fired bricks with unfired bricks masonry.
4-5-1: Unfired bricks used for masonry prisms
Six types of unfired bricks are considered for masonry assemblage as
following:
1- Clay and Straw
2- Clay and Sawdust
3- Clay with 10% Fine Sand and Straw
4- Clay with 10% Coarse Sand and Straw
5- Clay with cement and sand
6- Clay with cement and sand in additional to straw
The compressive strength of each type of unfired bricks is listed in Table
(4-5-1).
CHAPTER FOUR RESULTS and DISCUSSION
50
Table (4-5-1): Compressive Strength for Unfired bricks used for masonry
prisms
Group Description Compressive Strength
(MPa)
G2 Clay + Straw 2.4
G3 Clay + Sawdust 2.85
G5 Clay + 10% Fine Sand + Straw 2.7
G7 Clay + 10% Coarse Sand + Straw 2.87
G10 Clay + Cement + Sand 1.1
G11 Clay + Cement + Sand + Straw 2.4
4-5-2: Mud Mortar
The mortar used for unfired masonry brick was produced by mixing clay and 5%
straw with water content was equal to 40% from the dry weight of clay. The mortar
compressive strength was 1.5 MPa which was used by testing a cube with
dimensions of (10x10x10) cm. fig (4-10)
a- cube during test
CHAPTER FOUR RESULTS and DISCUSSION
51
b- Cube after test
Figure (4-11) : Cube Mud Mortar
4-5-3: Unfired Masonry
The unfired masonry behavior is studied by using prisms consisted of three
bricks and mortar. Six mixes are considered
1. Clay and Straw
2. Clay and Sawdust
3. Clay with 10% Fine Sand and Straw
4. Clay with 10% Coarse Sand and Straw
5. Clay with cement and sand
6. Clay with cement and sand in additional to straw
The compressive strength of each mix is listed in Table (4-5-2).
CHAPTER FOUR RESULTS and DISCUSSION
52
1- Clay with Straw
Figure (4-12) : masonry brick( Clay + Straw )
CHAPTER FOUR RESULTS and DISCUSSION
53
2- Clay with Sawdust:
Figure (4-13) : masonry brick( Clay + Sawdust )
CHAPTER FOUR RESULTS and DISCUSSION
54
3- Clay, 10% Fine sand and Straw:
Figure (4-14) : masonry brick( Clay +Fine sand + Straw )
CHAPTER FOUR RESULTS and DISCUSSION
55
4- Clay,10% Coarse Sand and Straw:
Figure (4-15) : masonry brick( Clay +Coarse sand + Straw )
CHAPTER FOUR RESULTS and DISCUSSION
56
5- Clay, Sand, Straw and Cement
Figure (4-16) : masonry brick( Clay + Cement +Sand + Straw )
CHAPTER FOUR RESULTS and DISCUSSION
57
Table (4-5-2): The compressive strength for Unfired Masonry
4-6-1- Traditional Fired Brick Masonry
The compressive strength of fired clay brick was 10 MPa and the compressive
strength of mortar with mixing ratio of 1:3 was 20 MPa. The masonry compressive
strength was 4.5 MPa. The compressive strength of masonry fired brick was more
lower than the compressive strength of fired and mortar. The decreasing ratio was
equal to 45% of compression strength of fired clay brick and equal to 22.5% of
compression strength of the mortar. The cause of decreasing of compressive
strength of masonry was because of the deference in thermal expansion coefficient
between the fired clay brick and the mortar.
Group Description Compressive
strength (MPa)
G2 Clay + Straw 1.65
G3 Clay + Sawdust 1.6
G5 Clay + 10% Fine Sand + Straw 1.3
G7 Clay + 10% Coarse Sand + Straw 1.9
G10 Clay + Cement + Sand 1.5
G11 Clay + Cement + Sand + Straw 1.2
CHAPTER FOUR RESULTS and DISCUSSION
58
4-6-2- Unfired Brick Masonry
The highest decrease in the resistance of masonry bricks was equal to 52%
comparing it with the compressive strength of unfired clay brick and mortar, while
The highest decrease was 30%. This decreasing of the compression strength is low
comparing it with decreasing of the compression strength in masonry fired brick.
The reason that compressive strength of unfired masonry brick was close to unfired
bricks were because the bricks and mortar were made of the same material and
have the same Poisson ratio.
Proposed Formula for Compressive Strength of Unfired Clay Bricks
Due to difficulty and time consuming to measure the compressive strength of
masonry units which is needed for numerical analysis or design calculations the
codes of practice presented different formula to obtain the compressive strength of
masonry units from the compressive strength of mortar and bricks which could be
obtained easily.
The three compressive strengths of mortar, bricks, and masonry can be
conveniently related as done in Euro code6 as (Kaushik et al, 2007):
)(ffKf mbM 2
where fb : compressive strength of bricks, MPa; fm: compressive strength
of mortar, MPa;f'M : compressive prism strength of masonry, MPa; K:
constant depending upon brick properties and brick-mortar joint
configuration; α, β: constants representing contribution of bricks and mortar
compressive strengths on f'M
CHAPTER FOUR RESULTS and DISCUSSION
59
According to above results of bricks compressive strength, masonry
compressive strength, and masonry compressive strength, the following
equations are proposed to estimate the masonry prism compressive strength
from the compressive strengths of unfired bricks and mortar obtained
experimentally.
1- soil with straw
)3(685.0 55.075.0
mbM fff
2- soil with sawdust
)4(66.0 5.065.0
mbM fff
3- Soil, Fine sand & Straw
)5(69.0 35.05.0
mbM fff
4- Soil, Coarse sand & Straw
)6(761.0 49.068.0
mbM fff
5- Clay ,Cement & Sand
)7(96.0 74.087.0
mbM fff
6- Clay , Cement , Sand & Straw
)8(57.0 42.066.0
mbM fff
CHAPTER FIVE Conclusions and Recommendations
60
CHAPTER Five
Conclusions and recommendations
5-1 Conclusions
1- Use of clay alone is not appropriate as masonry unit where it considered a
brittle and fast-cracking material. Additional materials should be added to
the mix to increase its strength and flexibility of the brick. The maximum
compressive strength for this mixture was 1.1 MPa and the flexural
strength was 0.4 MPa.
2- Adding straw increased the strength and plasticity of the brick. Increased
plasticity of the bricks by adding straw is important thing. Despite the
great deformations that have happen to it, the cracks were not shown on
its surface as well as not get collapse. We can benefit from this property
in areas where earthquakes get. The maximum compressive strength for
this mixture was 2.4 MPa and the flexural strength was 0.5 MPa.
3- Adding rice husk somewhat increased the strength of the bricks but its
small size did not give a high bonding strength to the bricks. The
maximum compressive strength for this mixture was 2.4 MPa and the
flexural strength was 0.6 MPa.
4- The Sawdust considered as one of the best additive materials that we used
in this research as being thick, long and not hollow as in straw increased
brick compressive and bonding strength when adding it to the mix. Also
it decrease the cracks occurred during drying period. The maximum
compressive strength for this mixture was 2.85 MPa and the flexural
strength was 0.85 MPa.
5- Using the sand in production of bricks is considered as a good addition,
whether the sand is fine or coarse, it increased its strength and decreased
CHAPTER FIVE Conclusions and Recommendations
61
the deformation that occurred to it during test. The maximum
compressive strength for this mixture was 2.87 MPa and the flexural
strength was 0.75 MPa.
6- Using the cement in production of bricks is considered as a bad addition
because the cement made the mixture brittle, weak and fast-cracking
material. The maximum compressive strength for this mixture was 0.9
MPa and the flexural strength was 0.7 MPa.
7- The maximum compressive strength o masonry unfired brick was 1.9
MPa which was made of clay, coarse sand and straw. The compressive
strength of masonry bricks was close to compressive strength of unfired
bricks and mortar. This was because the bricks and mortar were made of
the same material and have the same Poisson ratio.
5-2- Recommendations
1- Use of high compressive materials such as steel slag as an additive to
increase the compressive strength.
2- Use of plasticized materials and reduce water content in the mix which
will facilitate the production industry, increase its strength and will
reduce the pores in it. Also reduce water content will reduce the salts that
cause efflorescence in the bricks.
3- Increase the brick dimensions which will increase its bonding and
compressive strength.
4- Use a high-mechanical pressure for the bricks during the production
process to increase its bonding strength and reduce the pores in it which
will increase its density.
CHAPTER FIVE Conclusions and Recommendations
62
5- Use additional materials as an addition to the bricks and check the
possibility of increasing its strength.
6- Study another type of mud construction like adobe and cob.
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CHAPTER FIVE Conclusions and Recommendations
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