Abstract
The purpose of this study is to investigate the different types of bricks as a construction
material. In this study, monitoring different technical specification or characteristics of the
bricks. At the end of study, Brick Quality Index (BQI) evaluated. According to BQI, bricks
were classified poor to excellent quality. [Keywords: Bricks, Bricks Types, Technical
Specification of Bricks, Building Materials, Brick Quality Index]
BRICK MASONRY WORK
CHAPTER-1
Introduction
Bricks is one of the most important construction materials. Bricks may be manufactured from
clay, shale or combination of these materials [1]. Other materials such as Silica, Alumina,
Lime, Iron oxide, Magnesia may be used for manufacturing good quality brick [2].
Depending on manufacturing process, uses, shape bricks can be classified as different types
[4]. In this study some general types of bricks will be investigated with their technical
specification including dimension, visual appearance, compressive strength, average water
absorption (%), efflorescence characteristics and unit weight. On the basis of manufacturing
& preparation burnt clay bricks can be classified as 1st class, 2nd class, 3rd class bricks.
Based on constituent materials bricks can be classified as Common Burnt Clay Bricks, Sand
Lime Bricks (Calcium Silicate Bricks), Engineering Bricks, Concrete Bricks, Fly ash Clay
Bricks etc. [2]. To know the quality of bricks different tests are performed such as
Compressive strength test, Water Absorption test, Efflorescence test, Visual appearance test
etc. [2,5,9]. Water absorption results represents in percentages and for good quality value is
less than 20% [4,11]. Larger compressive strength indicates higher stability, efflorescence
test finds out the presence of alkalis which is very essential for building structures [2]. In this
study all of these test results for several bricks collected and analyzed for final outcomes.
Hope this study will be helpful for knowing some general types of bricks with their technical
specification and create a new dimension for further brick quality investigation.
CHAPTER-2
Materials and methods
This study includes data collection, data rearrangement, analysis and final outcomes. The
data were collected from several existing study [1, 3-14]. After collection, data were analyzed
by MS Excel 2016 software. First general technical specification was identified, after that
some plots were generated for comparative study among different bricks type. At the end of
the study Bricks Quality Index (BQI) was evaluated to know the quality of several types of
bricks.
For brick quality evaluation the steps were followed as bellow:
1. Rating the specification/ characteristics of bricks from 1 to 5. Where 1 for poor quality, 2
for slightly poor, 3 for moderate, 4 for good and 5 stands for excellent quality of bricks.
2. The rating is provided based on some general class. For example, first considering the
value of compressive strength (kg/cm2 ). According to this, bricks are classified as poor
(which has 0-30 kg/cm2 compressive strength), slightly poor (which has 31-75 kg/cm2
compressive strength), moderate (which has 76-100 kg/cm2 compressive strength), good
(which has 101-140 kg/cm2 compressive strength), excellent (which has >141 kg/cm2
compressive strength). When bricks are classified as poor then rated it 1, rated 2 for slightly
poor, rated 3 for moderate, 4 for good and 5 for excellent class of bricks.
3. Similarly, for water absorption (%), unit weight (kg/m3 ) and efflorescence the bricks
were classified as Table-1.
Table-1: Classification of bricks based on different characteristics.
4. After that, all of rating value averaged to obtain the Brick Quality Index (BQI).
5. Based on BQI the bricks were identified as poor to excellent quality. Bricks were identified
as poor when (0< BQI<BQI<BQI< BQI<=4.5), better BQI (4.5< BQI=5
CHAPTER-3
Brick’s Frog
An indent called frog, 1 – 2 cm deep is provided for 9 cm height bricks only. Frog is not
provided in 4 cm high bricks.
Purpose of providing frog :-
1) To form a key for holding the mortar and therefore, the bricks are laid with frogs on top.
2) Manufacturer of bricks also put their logo in frog.
Good Brick Earth
INGREDIENTS to make good brick making earth :- ( remember by MALISH)
1. Alumina
2. Silica
3. Lime
4. Magnesia
5. Iron
Oxide
1) Alumina This is one of the main Constituents of clay. It can readily absorb water and
provide plasticity to the clay. It should be present within 20 to 30 % . If content is
more than the limit, then raw bricks are liable to warp and shrink in the process of
drying and burning
2) . 2) Silica Silica may exist in clay as free sand or it may exist as silicate of alumina.
Silica content in brick earth shall be 50 % to 60 % Excess of silica causes brick to
become brittle.
3) 3) Lime Small quantity of lime (less than 5%) is useful. Shrinkage of raw bricks is
prevented by lime. Presence of lime helps in fusion of sand at high temperature in the
kiln. The brick particles can bind well by fused sand. Lime should be added in finely
divided form and not in lumps.
4) Magnesia It is present in very small extent. Magnesia reduces shrinkage of bricks.
Excess of Magnesia results in decay of bricks.
5) Iron Oxide 5% to 6% of Iron Oxide is desirable in brick earth. It helps to bind the
brick particles making the brick hard and strong. Red colour of brick shows iron oxide
is present at the above limit.
CHAPTER-4
Manufacturing of bricks
Making the Bricks:- (remember by process of making Chapati/roti)
1. Material Procurement:
The clay is mined and stored in the open.
This makes the clay soft and removes unwanted oxides.
2. Tempering:
This clay is then mixed with water to get the right consistency for moulding. Mixing
is done manually with hands and feet. Sometimes and in certain areas, animal driven
pug mills are used
3. Moulding:
A lump of clay mix is taken, rolled in sand and slapped into the mould. The clay can
be moulded in two ways :-
1) Hand moulding.
2) Machine Moulding.
Hand Moulding
Moulding the clay is done by using wooden or steel moulds. Wooden mould consists
of rectangular wooden box opened at top and bottom. Internal dimensions of mould
are made 6 mm greater than required dimensions. This is because the raw bricks
shrink in the process of drying and burning
Bricks made by Hand moulding may be :-
1) Ground moulding bricks
2)Table moulded bricks
Ground moulded Bricks
In case of ground moulded bricks, ground should be leveled and a thin sand is spread
over the ground.
The mould is wetted in water and placed on ground firmly.
The tempered clay is now dropped into the mould.
Any surplus clay is removed using steel plate.
Now the mould is lifted up leaving the raw brick on the ground.
In this way, whole prepared ground is covered by raw bricks.
Table moulded Bricks
Same procedure is followed as in case of ground moulded bricks. In this case,
moulding is done over a table 2m x 1m The brick obtained on the table are moved to a
convenient place for drying.
Machine moulding
In case of machine molding, the clay is fed to the moulding machine. As clay moves
through it, it is compressed and cut into strips by wires and brick blocks are formed.
4. Drying:
The mould is emptied onto the drying area, where the bricks are arranged in a herring
bone pattern to dry in the sun.
Every two days they are turned over to facilitate uniform drying and prevent warping.
After two weeks they are ready to be burnt
5. Firing:
The raw bricks are arranged in a kiln and insulation is provided with a mud pack. Fire
holes left to ignite the kiln are later sealed to keep the heat inside. This is maintained for a
week.
6. Sorting:
After the kiln is disassembled, the bricks are sorted according to colour. Colour is an
indication of the level of burning. Over burnt bricks are used for paving or covering the
kiln while slightly under burnt bricks are used for building inner walls or burnt once again
in the next kiln.
CHAPTER-5
Results & Discussion:
General characteristics:
The general characteristics of several types of bricks displayed in Table-2. The table
includes the visual appearance of bricks, dimension of bricks (Length, weight and height),
water absorption rate (%), compressive strength (kg/cm2 ), Efflorescence and unit weight
(kg/m3 ).
Table-2: General Characteristics of Bricks.
CHAPTER-6
Comparison of different properties of Bricks
Average compressive strength of bricks type
Figure-1 represents the average compressive strength of several bricks. The outcomes
clarify that engineering bricks have larger compressive strength than others. Clinker
bricks have also larger compressive strength. In case of different blocks such as porothem
blocks, AAC or CLC blocks compressive strength is lesser. The lower value indicates
lower crushing strength that means lower pressure required to break the bricks. It also
indicates lower stability of bricks.
Average water absorption rate of different bricks type
The water absorption test performed by weighting the bricks at dry condition and
weighting these after 24 hours immerged in fresh water. The lower value of water
absorption represents good quality. In reverse the higher value of water absorption
represents poor quality. It can be noticed that the water absorption rate for 1st class
bricks, engineering bricks and 1st class machine made bricks are low which clarify these
are good quality bricks. In case of AAC blocks,2nd class or 3 rd class bricks the water
absorption rate is comparatively high which indicates the lesser quality. Figure-2
displayed the results.
Average unit weight of different bricks:
Unit weight represents the weight of any materials per unit volume. This weight help to
evaluate the structure’s weight, to specify the load which the structure of such materials can
carry, to quantify amount of material required for specific space, to determine whether the
materials will sink or float on water [10]. So, the unit weight of material is more important
for any construction purpose. The figure-3 showed the unit weight of different types of
bricks. The result clarifies that the unit weight of 1 st class machine made bricks and
perforated bricks are high on the other hand for chamber clay bricks this value is low.
CHAPTER-7
Conclusions
• For compressive strength, it can be seen that engineering bricks and clinker bricks have
high compressive strength. On the other hand, different types of blocks such as porothem
blocks, AAC, CLC, and 3rd class bricks also have lower compressive strength.
• The good quality bricks have lower water absorption rate but poor-quality bricks have
higher water absorption rate.
• For excellent or good quality bricks efflorescence is nil, compressive strength high, water
absorption low and unit weight is also high.
• According to BQI 1st class machine made bricks & engineering bricks classified as
excellent quality bricks, Picked Jama bricks, clinker bricks, common burnt 1st class bricks
classified as better quality, concrete bricks, calcium silicate/ sand lime bricks classified as
good quality bricks, 2 nd class blocks, porothem blocks etc. classified as slightly poor and
common clay burnt 3rd class bricks classified as poor-quality bricks.
CHAPTER-8
References
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