1. CONTENTS
1.INTRODUCTION
2.LITERATUREREVIEW
3.HLL(Hindustan LatexLtd) LIFECARELTD.
3.1.Introduction
3.2.EffluentTreatment Plant
3.2.1. Collection Tank/Equalisation tank
3.2.2. Lime Mixing Channel
3.2.3 FeCl3 mixing Channel
3.2.4 Mixing Channel
3.2.5 Primary Settling Tank
3.2.6 Aeration Tank
3.2.7 Secondary Settling Tank
3.2.8 Sludge Recirculation Sump
3.2.9 Chemoxidation Tank
3.2.10 Pressure Sand Filter
3.2.11 Treated effluent water collection tank
3.2.12.Recycling of treated effluent water
3.2.13.Sludge Drying Beds
3.3.Characteristics of treated water
4.BRICKS
4.1.Composition of good brick earth

2. 4.2.Properties of good bricks
4.3.Standard Size and weight of bricks:
4.4.Manufactureof Bricks
4.4.1.Raw materials
4.4.2.Manufacturing Process
4.5.Tests on Burnt Clay Building Bricks
4.5.1.Test for Compressive Strength of Bricks [Ref: IS 3495 (Part 1):1992]
4.5.2.Water Absorption test of Building Bricks (Ref: IS 3495 (Part 2)-1992
4.6.Types of bricks
5.MATERIALS AND METHODS USED
5.1.Moisture Content
5.2.Specific Gravity
5.3.Preparation of bricks
5.3.1. Sieving
5.3.2.Mixing
5.3.3.Drying
5.3.4.Burning
5.3.5.Testing
6.RESULTS AND DISCUSSIONS
6.1.Proportioning

3. 1.INTRODUCTION
A large quantity of sludge is generated each year from various industries. Large amount
of waste water is produced from various processes within the industry like manufacturing
processes, cleaning processes, kitchen wastes etc. for discharging this wastewater into the
specified water bodies, certain standard specified by the Regulatory Authorities have to be met.
For this purpose. The wastewater has to be subjected to various treatment processes. As a
result of these treatment processes, sludge is produced. The quantity of the sludge produced
depends upon the amount of wastewater and the type of treatment adopted for treating the
wastewater. Common method adopted for disposing the sludge is land filling. Landfill disposal
of the sludge has drawbacks like high cost of transportation, difficulty in getting suitable sites
for land filling, heavy metal contamination of the land, emission of foul gases etc. so, disposal of
sludge has become a major issue. Efforts are being made to utilize the sludge for making useful
materials. This is a win-win strategy because it not only converts the wastes into useful
materials but it also alleviates the disposal problem. The use of sludge in construction industry
is considered to be the most economic and environmentally sound option.
This study focuses on the possibility of using sludge as a brick material. The sludge for
this study was collected from HLL Lifecare Limited; peroorkada. The main raw material used in
this industry is Latex. A latex is a colloidal suspension of very small polymer particles in water.
Natural latex is produced from the rubber tree (Hevea brasilienesis) and is the protective fluid
contained beneath the bark. It is a cloudy white liquid, similar in appearance to cow milk. It is
collected by cutting a thin strip of bark from the tree and allowing the latex to exude into a
collecting vessel over a period of few hours.
2.LITERATURE REVIEW
Different industries produce sludge of different quality and in different quantities. This
may be due to difference in the manufacturing processes and treatment given to the
wastewater. Disposal of sludge has become a major issue. Efforts are being made to utilise the
sludge for making useful materials. Major research is being conducted in the field of utilization
of sludge in brick manufacturing. The quality and type of brick made depends on various factors
like composition of sludge, additives used, temperature at which the brick is fired, water
content etc.

4. A study was conducted on the use of recycled paper processing residues in making
porous brick with reduced thermal conductivity by Mucahit Sutcu et.al. Mixtures containing
brick raw materials and the paper waste were prepared at different proportions (upto 30 wt%).
The granulated powder mixtures were compressed in a hydraulic press, and the green bodies
were dried before firing at 1100°C. Dilatometric behaviours, drying and firing shrinkages were
investigated as well as the loss on ignition, bulk density, apparent porosity, water absorption
and thermal conductivity values of the fired samples. Their mechanical and microstructural
properties were also investigated. The results obtained showed that the use of paper
processing residues decreased the fired density of bricks down to 1.25 g/cc. compressive
strengths of the brick samples produced in this study were higher than that required by the
standards. Thermal conductivity of the porous brick produced in this study (<0.4 W/m K)
showed more than 50% reduction compared to local brick of the same composition (0.8 W/m
K). Conversion of this product to a perforated brick may reduce its thermal conductivity to very
low values.
Another study conducted by Chih-Huang Weng et.al. investigated the influence of
sludge proportion and the firing temperature in determining the brick quality. Increasing the
sludge content results in a decrease of brick shrinkage, water absorption and compressive
strength. Results also showed that the brick weight loss in ignition was mainly attributed to the
organic matter content in the sludge being burnt out during the firing process. With upto 20%
sludge added to the bricks, the strength measured at temperatures 960 and 1000°C met the
requirements of the Chinese National Standards. Toxic characteristic leaching procedure (TCLP)
tests of bricks also showed that the metal leaching level is low. The conditions for
manufacturing good quality bricks is 10% sludge with 24% of moisture content prepared in the
moulded mixtures and fired at 880-960°C.
The study conducted by Chihpin et al. investigated yhe use of sludge as partial substitute
for clay in brick manufacturing. In this study, four different series of sludge and clay
proportioning ratios were studied, which exclusively involved the addition of sludge with ratios
50, 60, 70 and 80% of the total weight of sludge-clay mixture. Each series involved the firing of
bricks at 950, 1000, 1050 1nd 1100°C, giving 16 different brick types. The physical properties of
produced bricks were then determined and evaluated according to Egyptian Standard
Specifications and British standards. From the obtained results, it was concluded that by
operating at the temperature commonly practiced in the brick kiln, 50% was the optimum
sludge addition to produce brick from sludge-clay mixture. The produced brick properties were
superior to those available in the Egyptian market.

5. 3.HLL (Hindustan Latex Ltd.) LIFECARE LTD.
3.1.Intoduction
Hindustan Latex Limited or HLL Lifecare Limited is a Government of India undertaking,
Ministry of Health and Family Welfare, Government of India which started as a corporate entity
in March 1966. Their product ranges from contraceptive aids and healthcare aids to social
marketing products. HLL is one of the largest manufacturers of male contraceptives in the
country.
HLL commenced its operation and established a plant at Trivandrum, the capital city f
the natural rubber rich state of Kerala on 5th April 1969. HLL started working at Peroorkada,
Trivandrum with an annual production capacity of 144 million pieces in 1969, which was
doubled to 288 million pieces in 1976, by putting additional manufacturing lines to the existing
plants. In 1986, two additional plants with latest Japanese technology were commissioned one
at Trivandrum and other at Kangala near Belgaum, Karnataka making the total production
capacity to 608 million pieces. In Trivandrum, HLL has two factories; one at Peroorkada and
other at Akkulam. In the Akkulam factory the products are Copper T. IUDs, blood transfusion
bags, Surgical Sutures and Hydrocephalous Shunt. Peroorkada factory produces condoms. With
a vast array of innovative products and social programmes HLL is year after taking a step. HLL
has grown today into a multi-product, multi-unit organization addressing various public health
challenges facing humanity.
HLL has been declared a Mini Ratna Company by the Government of India and is
upgraded as a Schedule B PSU. HLL has set its sights to be Rs1000 crore company by the year
2010. HLL Lifecare Limited is the only company in the world manufacturing and marketing the
widest range of contraceptives. It is unique in providing a range of Condoms, including Female
Condoms, Intra Uterine Devices, Oral Contraceptive Pills- Steroidal, Non-steroidal and
Emergency Contraceptive Pills and Tubal Rings. HLL’s healthcare products range includes Blood
Collection Bags, Surgical Sutures, Auto Disable Syringes, Vaccines, In-Vitro Diagnostic Test Kits,
Pharma Products for Women, Natural Products, Hydrocephalous Shunt, Tissue Expanders,
Surgical and Examination Gloves, Blood Banking Equipment, Neonatal Equipment, Blood
Transfusion and Intravenous Sets, Vending Machines, Iron and Folic Acid Tablets, Sanitary
Napkins, Oral Rehydration Salts and Medicated Plasters.
HLL has introduced Closed System Blood Bags that are integrated with Leukocyte Filter
called LD Bags. These bags are intended for Leuko-depletion immediately upon collection of
blood from donors at blood banks. In collaboration with the Female Health Company (FHC) of
US, HLL is marketing FC female condom in India. The female condom is the only female

6. controlled prevention technology approved by the US FDA and the WHO. FC is distributed in
over 100 countries around the world.
HLL has launched several initiatives in the services sector for medical infrastructure
development, diagnostic centres and procurement consultancy. These have been conceived to
bring about a whole new realm of accessible, affordable healthcare delivery to every citizen.
Over the years each of the initiatives taken up by HLL has been targeted towards making
quality healthcare available at the doorstep of every family. Associate Institutions of HLL
namely HLFPPT and Lifespring Hospitals have ensured that healthcare delivery.
HLL gives emphasis on effective quality control at every manufacturing stage right from
the raw material to the final product, during its various production stages. I n recognition of its
quality and manufacturing process, the company got ISO 9002 certificate from NQA Quality
System Register Limited in1996 and ISO 14001 in 2000. Also HLL got approval from the Federal
Drugs Administration (FDA) and South African Bureau of Standards (SABS).
3.2.Effluent Treatment Plant
The Effluent Treatment Plant (ETP) is installed for clear water discharge from production line
since 1969. Present ETP can handle up to 1000Kl/day of wastewater.
3.2.1. Collection Tank/Equalisation tank
The function of the equalisation tank is to collect effluent from the different streams and to
keep uniform characteristics for the effluent stream. Effluents from various sections of the
plant, which includes latex, filtrate from Nutsche filter, wash water and canteen effluent are
collected in this tank. Four such collection tanks are installed to collect wastewaters from the
three plants A, B and C.
3.2.2. Lime Mixing Channel
PH of the raw effluent ranges from 9-10. Hydrated lime, i.e., 1% solution of lime (10Kg of lime
mixed with 1000litres of water, agitated for 1min and allowed to settle for another 1min) is
therefore added to the effluent in order to make the pH 12. This enhances floc formation. Lime
is allowed to flow into the channel under gravity.

7. 3.2.3 FeCl3 mixing Channel
Next FeCl3 reagent stored in Sintex tank is transferred under gravity and is added to the effluent
at the rate of 150-1000ml/min. This neutralizes the pH and brings the pH level to 6-8.
Provision is given to add chemicals at overflow mixing tank also. If incoming effluent is acidic,
lime addition is increased to bring down acidity. If pH is less than 7, after lime and FeCl3
addition; FeCl3 dosage is reduced and if pH is more, dosage is increased.
3.2.4 Mixing Channel
The combined effluent from the equalisation tank is pumped to the mixing box of mixing
channel where chemicals are added at adequate dosages. General flow rate of raw effluent is 7
to 20 litres per second. The mixing channel is a baffled type mixing channel. Here flocs are
formed, precipitation and coagulation takes place and flocs grow denser.
3.2.5 Primary Settling Tank
Water from mixing tank is send to primary settling tank by gravity flow through a 6 inch pipe.
Here the flocs get settled at the inclined base.
3.2.6 Aeration Tank
The water from the primary settling tank overflows in to the aeration tank. Aeration is done in
this tank by making use of twin blowers and slotted PVC/MS pipes for bubbling air through the
water collected in the tank. This prevents foul smell.
3.2.7 Secondary Settling Tank
The finer suspended particles present in the clear overflow from the aeration tank is allowed to
settle in the secondary settling tank. It is cleaned once in a month.
3.2.8 Sludge Recirculation Sump

8. Sludge from secondary settling tank is to be fed to sludge recirculation sump by gravity. Sludge
will be partially recycled back to the aeration tank. Balance portion will be send to sludge drying
bed. It is cleaned once in a month.
3.2.9 Chemoxidation Tank
Overflow from secondary settling tank is fed to Chemoxidation tank. Diluted sodium
hypochlorite solution is dosed for 24 hours (20 litre NaHOCl in 180 litre of water). General flow
rate is maintained as 1400-200ml/min. Addition of NaHOCl oxidizes residual biodegradable
organics. pH after dosing is maintained at 7-8.
3.2.10 Pressure Sand Filter
The clear overflow from the chemoxidation tank is pumped through two Pressure Sand Filters
operated in parallel for removing any precipitated solids during Chemoxidation. Filter feed
pumps are used for feeding the effluent to the pressure sand filter. The filter is backwashed
every 20 minutes.
3.2.11 Treated effluent water collection tank
Overflow from sand filter fed to final effluent water collection tank through a cascade. The
overflow from the final treated water is discharged through the final outlet. pH of treated water
is maintained at the range of 6-8 and recycled on hourly basis. The flow rate through final
outlet is noted using V notch. Calculation using V notch
Q=H5/2 X 1.4 X 60 X 60 X 24
Height of water flow through V notch is maintained in the range of 6.5-12.5 cm.
3.2.12 Recycling of treated effluent water
40% of treated water is used for gardening, toilet flushing, floor cleaning, ETP cleaning works
etc. In addition to the above, treated water is supplied in tankers for gardening at Golf Club,
Trivandrum.

9. 3.2.13 Sludge Drying Beds
Solid cake from the filter press will be transferred to sludge drying beds. Sludge from the other
tanks during cleaning operation will also be transferred to sludge drying beds. There are 6 cells
in sludge drying beds. After filling each cell, sludge will be taken to the next cells. This process is
separated till the sludge covers the entire cells in drying cells. Filtrate from the bed is allowed to
enter aeration tank for further treatment.
3.3.Characteristics of treatedwater
Test Item Unit Amount Limit
pH ... 7 6 to 8
COD mg/l 54 250 max
Oil & Grease mg/l 5 10 max
Suspended Solids mg/l 34 100 max
Kjeldahl’s Nitrogen mg/l 34 100 max
Sulphide mg/l Nil 2 max
BOD mg/l 18 30 max
Total dissolved solids mg/l 111 2100 max
Ammoniacal
Nitrogen
mg/l 8 50 max

10. 4.BRICKS
Brick is one of the oldest building materials and it is extensively used even at present
because of its durability, strength, reliability, low cost, easy availability etc. Bricks are obtained
by moulding clay in rectangular blocks of uniform size then by drying and burning these blocks
in brick kilns.
4.1.Composition of good brick earth
A good brick should contain clay and sand in such a way that when water is added, it can be
easily moulded and dried without cracking or warping. Following are the main constituents of
good brick earth:
1. Silica-50% to 60% by weight. Presence of this constituent prevents cracking, shrinking
and warping of raw bricks. It imparts uniform shape to bricks. If silica is in excess, it
makes the brick brittle.
2. Alumina-20% to 30% by weight. It imparts plasticity to earth so that it can be moulded
easily. If alumina is present in excess, raw bricks shrink and warp during drying and
burning.
3. Lime-2% to 5% by weight. Lime causes the grains of sand to melt and bind the particles
of clay together. It prevents shrinkage of raw bricks. If lime is excess, it will cause the
brick to melt and hence shape is lost.
4. Iron oxide-5% to 6% by weight. Iron oxide act as a flux to cause the grains of sand to
melt and this helps to bind the particles together. It imparts red colour to brick on
burning. Excess amount of iron oxide makes the brick dark blue.
5. Magnesia-less than 1% by weight. It imparts yellow colour to brick and it decreases
shrinkage. Excess magnesia leads to decay of bricks.

11. 4.2.Properties of good bricks
A good brick should have the following properties:
 Bricks should have perfect edges, well burnt in kilns, copper coloured, free from
cracks with sharp and square edges.
 It should be uniform in shape and of standard size.
 Colour should be uniform and bright.
 The brick when broken should show a bright homogeneous and uniform compact
structure free from voids.
 It should produce clear ringing sound when struck with each other.
 Water absorption should not be greater than 20% for first class bricks and 22% for
second class bricks when soaked in water for 24 hours.
 Bricks should be sufficiently hard, i.e. no nail impression must be present when
scratched.
 It should not break when dropped from a height of one metre.
 It should have low thermal conductivity and should be sound proof.
 Good brick should not show any white or grey deposits of salts when immersed in
water and dried. i.e. it should not have any efflorescence.
 Good brick should have crushing strength above 5.5N/mm2.
4.3.Standard Size and weight of bricks:
Size of standard bricks is 19 X 9 X 9cm. Such brick is known as Modular Bricks. The size of bricks
including mortar thickness is 20 X 10 X 10cm. Average weight of brick is about 3 to 3.5kg.
4.4.Manufacture of Bricks
4.4.1.Raw materials

12. Bricks for building may be made from clay, shale, soft slate, calcium silicate, concrete etc. True
bricks are ceramic and are created by the action of heat followed by cooling. Clay is the most
commonly used material for the manufacture of bricks. Natural clay minerals,
including kaolin and shale, make up the main body of brick. Many additives have been used in
brick, including byproducts from papermaking, ammonium compounds, wetting
agents, flocculents (which cause particles to form loose clusters)
and deflocculents (which disperse such clusters). Some clays require the addition of sand. A wide
variety of coating materials and methods are used to produce brick of a certain color or surface
texture. To create a typical coating, sand is mechanically mixed with some type of colorant.
Sometimes a flux or frit (a glass containing colorants) is added to produce surface textures. The
flux lowers the melting temperature of the sand so it can bond to the brick surface.
4.4.2.Manufacturing Process
1. Grinding, sizing & combining raw materials
First, each of the ingredients is conveyed to a separator that removes oversized materials. A
jaw crusher then crushes the particles in order to render finer particles. After the raw materials
for each batch of bricks have been selected, a scalping screen is often used to separate the
different sizes of material. Material of the correct size is sent to storage silos, and over-sized
material goes to a hammermill, which pulverizes it with rapidly moving steel hammers. The
hammermill uses another screen to control the maximum size of particle leaving the mill, and
discharge goes to a number of vibrating screens that separate out material of improper size
before it is sent on to the next phase of production.
2. Extrusion
Pulverized material and water are fed into one end of a pug mill, which uses knives on a
rotating shaft to cut through and fold together material in a shallow chamber. The blend is then
fed into an extruder at the far end of the mill. The extruder usually consists of two chambers.
The first removes air from the ground clay with a vacuum, thereby preventing cracking and
other defects. The second chamber, a high-pressure cylinder, compacts the material so the
auger can extrude it through the die. After it is compressed, the plastic material is forced out of

13. the chamber though a specially shaped die orifice. The cross-section of the extruded column,
called the "pug," is formed into the shape of the die.
In moulding, soft, wet clay is shaped in a mould, usually a wooden box. The interior of the box is
often coated with sand, which provides the desired texture and facilitates removing the formed
brick from the mold. Water can also be used to assist release.
3. Chamfering the brick
Chamfering machines were developed to produce a furrow in brick for such applications as
paving. These machines use rollers to indent the brick as it is being extruded. They are
sometimes equipped with wire cutters to do the chamfering and cutting in one step. Such
machines can produce as many as 20,000 units per hour.
4. Coating
The choice of sand coating, also applied as the brick is extruded, depends on how soft or hard
the extruded material is. A continuous, vibrating feeder is used to coat soft material, whereas
for textured material the coating may have to be brushed or rolled on. For harder materials a
pressure roller or compressed air is used, and, for extremely hard materials, sand blasting is
required.
5. Drying
Before the brick is fired, it must be dried to remove excess moisture. If this moisture is not
removed, the water will burn off too quickly during firing, causing cracking.
6. Firing
After drying, the bricks are fired to high temperatures in furnaces called kilns at 900-1000 °C

14. 4.5.Tests on Burnt Clay Building Bricks
4.5.1.Test for Compressive Strength of Bricks [Ref: IS 3495 (Part 1):1992]
Apparatus
A compression testing machine, the compression plate of which shall have a ball seating in the
form of apportion of a sphere the center of which coincides with the center of the plate shall be
used.
Specimens
Six numbers of bricks from the sample to be tested are to be taken. The dimensions shall be
measured to the nearest 1mm.
Preconditioning
Remove the unevenness observed in the bed faces of the bricks to provide two smooth and
parallel faces by grinding. Immerse in water at room temperature for 24 hours. Remove the
specimen from water and drain out any surplus moisture at room temperature. Fill the frog(if
provided) and all voids in the bed and flush with cement mortar (1 cement, clean coarse sand of
grade 3mm and down).Store under damp jute bags for 24 hours followed by immersion in
clean.
Procedure
Place the specimen with flat faces horizontal, and mortar filled face facing upwards between
two 3-ply plywood sheets each of thickness 3mm and carefully centered between the plates of
the testing machine. Apply load axially at a uniform rate of 14N/mm2 (140 kgf/cm2) per minute
till failure occurs and note the maximum load at failure. The load at failure shall be the

15. maximum load at which the specimen fails to produce any further increase in the indicator
reading of the testing machine.
Compressive strength in N/mm2= Maximum load at failure in N
Average area of bed faces in mm2
The average of results shall be reported as the compressive strength of bricks in N/mm2.
Observations & Calculations
Specimen No
Dimensions
(mm)
Failure load
(N)
Compressive Strength
(N/mm2)
Result
Average Compressive Strength of the given building brick sample=................. N/mm2
IS Specification

16. As per IS 1077:1992, the bricks when tested in accordance with the procedure laid down in IS
3495 (Part 1): 1992 shall have a minimum average compressive strength for various classes as
given in the following table.
Class Designation
Average Compressive Strength not less than
N/mm2 Kgf/cm2
35 35.0 350
30 30.0 300
25 25.0 250
20 20.0 200
17.5 17.5 175
15 15.0 150
12.5 12.5 125
10 10.0 100
7.5 7.5 75
5 5.0 50
3.5 3.5 35
The compressive strength of any individual brick tested shall not fall below the minimum
compressive strength specified for the corresponding class of brick. The lot shall then be
checked for the next lower class of brick.
4.5.2.Water Absorption test of Building Bricks (Ref: IS 3495 (Part 2)-1992
Apparatus
A sensitive balance capable of weighing within 0.1 percent of the mass of the specimen and a
ventilated oven.

17. Test Specimen
Five numbers of bricks from the sample to be tested are to be taken. The dimensions shall be
measured to the nearest 1mm.
Preconditioning
Dry specimen in a ventilated oven at a temperature of 105 to 115°C till it attains substantially
constant mass. Cool the specimen to room temperature and obtain its weight(W1). Specimen
warm to touch shall not be used for the purpose.
Procedure
Immerse completely the dried specimen in clean water at a temperature of 27±2°C for 24
hours. Remove the specimen from water and wipe out any traces of water with a damp cloth
and weigh the specimen. Complete the weighing within 3 minutes after the specimen has been
removed from the water (W2). Water absorption, percentage by weight, after 24 hour
immersion in cold water is given by the following formula:
Percentage water absorption = (W2-W1) X 100
W1
Observations & Calculations
Specimen N0.
Weight of dry brick
(W1)
Weight of wet brick
(W2)
Percentage Water
absorption
Result
Water absorption of the given burnt clay building brick sample, percentage by weight, after 24
hour immersion in cold water=...........%

18. Is Specification
As per IS 1077:1992, the bricks when tested in accordance with the procedure laid down in IS
3495 (Part 2):1992 after immersion in cold water for 24 hours, water absorption shall not be
more than 20% by weight upto class 12.5 and 15% by weight for higher classes.
4.6.Types of bricks
1. Common Burnt Clay Bricks: Clay bricks are fired bricks. These are formed by pressing in
moulds or by an extrusion and wire cutting process. Then these bricks are dried and
fired in a kiln.
2. Sand Lime Bricks (Calcium Silicate Bricks): These bricks are mixtures of sand and
hydrated lime pressed in moulds and cured in a high-pressure steam autoclave.
3. Concrete Bricks: Concrete bricks are mixtures of cement, sand and aggregates vibrated
in moulds and steam cured.
4. Fly ash Clay Bricks: Fly ash is used along with clay in these bricks. Fly ash is obtained
from boilers of thermal power stations.
5. Fire Clay Bricks: Fire clay exists at much depth below the surface and is usually mined.
Generally, Fire clays contain metallic oxides less than surface clays and have more
uniform chemical and physical properties.
Special types of bricks
1. Face bricks: Special bricks having uniform colour, texture, size, etc are used for face
works, sometimes it may contain some face design. It is used for garden walls, steps,
side walls, and other exposed works where good appearance is desired.
2. Fire bricks: They are made up of special fire clay. And it is used for lining furnaces, fire-
places, etc, where high temperature are prevalent and where ordinary bricks get
decomposed.

19. 3. Glazed and coloured bricks: Glazed and coloured bricks have one surface glazed in
colour. They are used for exterior surfaces of walls in hospitals, dairies, etc where
cleanliness is important.
4. Imitation bricks: Bricks made of Portland cement and sand are known as imitation
bricks. They are used for the construction of compound wall, partition wall, etc. these
bricks have same qualities as good mortar.
5. Channel bricks: These bricks are moulded to the shape of a gutter or a channel and they
are glazed to prevent sediment deposition. These bricks are used to function as drains.
6. Coping bricks: These bricks are made to suit the thickness of walls on which coping is to
be provided. It take various forms such as chamfered, half-round or saddle-back.
7. Hollow bricks: These bricks are also known as cellular or cavity bricks. Such bricks have
wall thickness of about 20 to 25mm. they are light in weight hence transportation cost is
less. These bricks reduce the transmission of heat, sound and damp. They are used in
the construction of brick positioning.
8. Paving bricks: These bricks are prepared from clay containing a higher percentage of
iron. Excess iron vitrifies the bricks at a low temperature; such bricks resist the abrasive
action of traffic effectively. Thus they can be used for the construction of foot paths,
garden walks, stable floor, etc
9. Perforated bricks: These bricks contain cylindrical holes through out their thickness.
These bricks are light in weight and they require less quantity of clay for their
preparation. Bricks with perforations of about 30-40% of the total area of the
corresponding face of the brick would offer adequate thermal insulation property. The
distance between the side of brick and edge of perforation should not be less than
15mm. Water absorption should not exceed 20% by weight. The compressive strength
of perforated bricks should not be less than 7N/mm². These bricks are used for brick
wall where thermal insulation is important.
5.MATERIALS AND METHODS USED

20. The sludge used in this study was collected from the HLL Lifecare Limited, Peroorkada.
Before collection the sludge had been subjected to drying in the sludge drying bed for a period
of two weeks. The objective of this study is to identify the possibilities of using sludge obtained
from effluent treatment plant (HLL) as a brick material. The different engineering properties
studied are as follows:
5.1.Moisture Content
Moisture content is the ratio of weight of water present in the sludge to the weight of
dry sludge.
Procedure for determining moisture content:
 Weigh a dry container & note down its weight(w1)
 Place some amount of wet sludge in the container and weigh it(w2)
 Keep the container in the oven & allow it to dry for 24 hours at105-110°C
 Remove the container from the oven & weigh it(w3)
 Moisture Content=(w2-w3)/(w3-w1)
Obtained value of moisture content=162.31%. This indicates that more than 50% of the
total mass of the sludge is that of water.
5.2.Specific Gravity
Specific gravity of sludge is the ratio of weight in air of the given volume of dried sludge
to the weight of equal volume of water at 4°C.
Procedure for determining moisture content:
 Dry & weigh a pycnometer(w1)
 Oven dried sludge is filled in the pycnometer up to one-third of its volume &
weighed(w2)
 Add sufficient water to cover the sludge and shake it well. Note down its weight(w3)
 Fill the pycnometer completely with water & weigh(w4)
 Specific Gravity of sludge=(w2-w1)/((w4-w1)-(w3-w2))

21. Obtained value of specific gravity= 1.53. The value obtained corresponds to the specific
gravity of organic soil, which generally falls below 2.00
5.3.Preparation of bricks
Sludge and clay were first dried and powdered. Clay having very high plasticity when
subjected to sun drying became rock hard.
5.3.1. Sieving
Clay was used after sieving through IS Sieve 1.18mm . Sand used was also sieved
through IS Sieve 600micron.
5.3.2.Mixing
Sludge and additives were mixed together in different proportions. Different quantity of
water was added for different proportions till a workable mix is obtained. Hand mixing was
done to mix the sludge and additives uniformly. Brick moulds were properly oiled using furnace
oil. The mixed sludge was then filled in brick moulds in 3 layers. Each layer was compacted with
the compaction rod and the surface was finished with a trowel.
5.3.3.Drying
The bricks were removed from the mould immediately and were kept aside at room
temperature for drying.
5.3.4.Burning
After 1 day the bricks were subjected to burning in a muffle furnace. The bricks were
burned at a temperature of 1000°C for 2 days.
5.3.5.Testing
Standard tests as per IS Specification were conducted on bricks. The tests were
conducted in the strength of materials lab in the college. The following tests were conducted:

22. 1. Compression test
2. Water absorption test
3. Efflorescence test
6.Results and discussions
6.1.Proportioning
Sand:Sludge:clay 1:1:3 1:2:2
Total volume(cm³) 1.2x19x9x9x4 = 7387.2 1.2x19x9x9x4 = 7387.2
Yield 1/2.6 + 1/5.3 + 3/1.6 = 2.913 1/2.6 + 2/1.53 + 2/1.6 = 2.94
Weight of sand required(kg) 7387.2/2.913 = 2.54 7387.2/2.94 = 2.51
Weight of sludge required(kg) 2.54 5.03
Weight of clay required(kg) 7.6 5.03