The document is a seminar report on autoclaved aerated concrete (AAC) bricks, submitted by Vigyan Nidhi as part of a Bachelor of Technology degree in Civil Engineering. It discusses the various types, characteristics, manufacturing processes, and advantages of AAC bricks over traditional clay bricks, highlighting their eco-friendliness, cost-effectiveness, and superior construction quality. The report emphasizes the importance of adopting AAC bricks for future construction projects to benefit both the environment and the economy.

1. AUTOCLAVED AERATED CONCRETE BRICKS.
A Seminar Report Submitted
In Partial Fulfillment of the Requirement
For the Degree
BACHELOR OF TECHNOLOGY
IN
CIVIL ENGINEERING
BY
VIGYAN NIDHI
(1428400093)
Guided By:- MR. VIKRANT SINGH
UNITED INSTITUTE OF TECHNOLOGY
NAINI, ALLAHABAD.
TO THE
FACULTY OF CIVIL ENGINEERING.
A.P.J. ABDUL KALAM TECHNICAL UNIVERSITY, LUCKNOW.

2. CERTIFICATE
This is to certify that the report entitled
“AUTOCLAVED AERATED BRICKS”, Which is
submitted by “VIGYAN NIDHI”, Roll No.-
1428400093, in partial fulfillment of the
requirement for the award of degree Bachelor of
Technology in Department of Civil Engineering of
United Institute of Technology, Allahabad. It is a
record of the candidate’s own work carried out by
him under my supervision. The matter embodied
in this is original and has not been submitted for
the award of any other degree.
Signature:
MR. VIKRANT SINGH
Faculty of Civil Department,
United Institute of Technology,
Allahabad.
Date: 10/11/2017

3. ACKNOWLEDGEMENT
In gives me a great sense of pleasure to present the seminar
report undertaken during B. Tech, Final Year. I owe special debt
of gratitude to Mr. VIKRANT SINGH, Department of civil
engineering, United Institute of Technology, Allahabad, for her
constant support and guidance throughout the course of
inspiration for me. It is only his effort that my endeavors have
seen light of the day.
I also take the opportunity to acknowledge the contribution of
Mr. Santosh Kumar Singh, Head of Department of Civil
Engineering, United Institute of Technology, Allahabad, for his
full support and assistance during the development of the
project.
I also do not like to miss the opportunity to acknowledge the
contribution of all faculty member of the department for their
kind assistance and cooperation during the development of our
project. I like to acknowledge my friends for their contribution in
the completion of the project and last but not least I would to
thank my parent and almighty god.
(VIGYAN NIDHI)

4. CONTENTS
 INTRODUCTION.
 IMPORTANCE OF AAC BRICKS.
 TYPES OF AAC BRICKS.
 CHARACTERSTICS OF AAC
BRICKS.
 MANUFACTURING PROCESS.
 COMPARISON BETWEENAAC
BRICKS & CLAY BRICKS.
 COST ANALYSIS.
 AAC BRICKS IN INDIA.

5.  CONCLUSION.

6. INTRODUCTION
 AUTOCLAVED AERATED CONCRETE(AAC) Brick was first inventedinmid-
1923 in Swedenby a SwedenArchitect Dr. JohanErrikson. It is alsoknown
as AutoclavedCellular Concrete (ACC) bricks or AutoclavedLightweight
Concrete (ALC) bricks and, autoclavedaeratedconcrete bricks (AAC).
 These AAC bricks are made witha mixture of cement, fly ash, lime,
aerationagents and water involving an aerationprocess that gives it the
unique cellular structure.
Fig.1 AAC bricks.
 For a project developer it means faster andlower cost construction. For
environmentally conscious it means eco-friendly products andfor those
who occupy buildings built withAAC blocks it means better safety and
lower energy costs for cooling or heating.
 Primary raw material for AAC is fly ash.
 Thousands of tonnes of fly ash is generatedby thermal power plants
everyday and its disposal is a cause of concern. Moreover, using fly ash
does not harm the environment at all. In fact using fly ash takes care of
issues relatedtodisposal of fly ash.
 So using fly ash toproduce AAC products provides asustainable,
economic and environment friendly option.
 At the end it all translates toabetter worldfor future generations.

7. 1
TYPES OF AEROCON BRICKS
AAC bricks are currently available in three sizes:
1. Infill blocks/ Bricks:
The size of the Infill AAC brick is 600X600 mm and the thickness
varies in the ranges of 75,100,125,150,200 mm.
The main advantage of Infill blocks is that they can easily replace
60% of the concrete in roof slabs and thus help in saving
significant amounts of concrete, steel, labor, water, plaster etc.
These blocks are especially suitable for building roofs in large
column-free constructions.
2. Jumbo blocks/ Bricks:
Jumbo blocks are typically in the size of 600X200 mm, and
thickness ranges from 75,100,125,150, to 200 mm.
Jumbo AAC bricks results in the usage of much fewer bricks and
hence less mortar is required. These bricks are more suitable for
non-load bearing walls, multi-storied buildings etc.
3. Thermal blocks/Bricks:
These blocks are also called as Aerocool thermal blocks whose size
and thickness is 300X200 mm and 50 mm respectively.
These blocks are ideal for roofing, since they delay the
transmissionofheat flowand also help interiors remainwarm
during winters and cool during summers.

8. 2
**CHARACTERSTICS OF AAC BRICKS**
Light-weight:
The typical structure of AAC bricks resulted in light-weight
blocks.
Their weight is only one third the density of clay bricks
which makes them easy to handle on-site.
 Reduced weight of the brick decreases the dead weight on
the structure; hence AAC bricks are ideal for low load
bearing soil and for seismic zones.
 Even for building additional floors in an existing building,
AAC blocks are perfect choice as their less weight will not
affect the stability of the structure.
Using AAC bricks from the foundation stage of the building
helps to save substantial amounts of concrete and steel.
Fire resistance:
 Walls build with AAC bricks, with a minimum thickness of
100mm can resist fire for up to four hours which make them
the safe choice in construction.
 Especially for industries and companies, which are vulnerable
to fire accidents, these blocks are of much help.

9. 3
Sound insulation:
 One more interesting characteristic of AAC bricks is their
sound insulation.
 A good quality AAC brick can minimize the sound transmission
up to 42 decibels.
 Reputed manufactures of AAC bricks do have a sound
transmission class rating for their blocks, which made them
ideal for wall construction in hotels, auditoriums, hospitals,
etc., where sound insulation is quite essential.
 Thermal insulation:
 Due to the closed cell structure of the AAC bricks, they provide
excellent thermal insulation.
 They help interiors to remain cooler during summer and
warmer during winter which further aid the user to save
electricity bills and thus help in conserving natural resources.
 Strength and durability:
 AAC bricks made with higher weight ratio help in building
stronger and economical structure.
 As they remain unaffected by the environmental conditions
they ensure longer life for the building.
4

10.  Perfect finish and dimensional stability:
 The autoclaving process used in the manufacturing of AAC
bricks gives perfect dimensions to the blocks along with low
tolerances.
 Dimensionally perfect blocks help in building uniform, thin
walls with perfect finish.
 Consistent quality control:
 As brick making is in India is an unorganized market, the
quality of regular bricks often vary based on the manufacturer.
 Hence consistent quality control is an issue with traditional
bricks which is not an issue with the AAC bricks.
Fig. 2.Cellular Structure of AAC blocks
5

11. MANUFACTURING PROCESS OF AAC BRICKS.
Step 1 – Raw Material Preparation:-
AAC blocks manufacturing process starts with raw material preparation.
List of raw materials and relevant details are mentioned below:
 Fly ash:-
 Key ingredient for manufacturing Autoclaved Aerated Concrete (AAC)
blocks is silica rich material like fly ash, pond ash or sand.
 Most of the AAC companies in India use fly ash to manufacture AAC
blocks.
 Fly ash is mixed with water to form fly ash slurry. Slurry thus formed
is mixed with other ingredients like lime powder, cement,gypsum and
aluminium powder in quantities consistent with the recipe.
 Alternately sand can also be used to manufacture AAC blocks. A
‘wet’ ball mill finely grinds sand with water converting it into sand
slurry. Sand slurry is mixed with other ingredients just like fly ash
slurry.
Fig. 3. A worker feeding pond ash into slurry tank for AAC blocks manufacturing process.
6

12.  Limestone powder:-
 Lime powder required for AAC production is obtained either by
crushing limestone to fine powder at AAC factory or by directly
purchasing it in powder form from a vendor.
 Although purchasing lime powder might be little costly, many
manufacturers opt for it rather than investing in lime crushing
equipment like ball mill, jaw crusher, bucket elevators, etc.
Fig. 4. Crusher for grinding lime stone..
 Cement:-
 53-grade Ordinary Portland Cement (OPC) from reputed
manufacturer is required for manufacturing AAC blocks. Cement
supplied by ‘mini plants’ is not recommended due to drastic variations
in quality over different batches.
7

13.  Some AAC factories might plan their captive cementprocessing units
as such an unit can produce cement as well as process lime.
 Such factories can opt for ‘major plant’ clinker and manufacture their
own cement for AAC production. Cement is usually stored in silos.
 Gypsum:-
 Gypsum is easily available in the market and is used in powder form.
 Aluminium powder/paste:-
 Aluminium powder/paste is easily available from various
manufacturers.
 As very small quantity of Aluminium powder/paste is required to be
added to the mixture, it is usually weighed manually and added to the
mixing unit.
8

14. Step 2 – Dosing and Mixing:-
Fig. 5. Slurry, water, lime powder, cement and gypsum being poured as per set dosage
during AAC blocks manufacturing.
 A dosing and mixing unit is used to form the correct mix to produce
Autoclaved Aerated Concrete (AAC) blocks.
 Fly ash/sand slurry is pumped into a separate container. Once the
desired weight is poured in, pumping is stopped.
 Similarly lime powder, cementand gypsum are poured into individual
containers using screw conveyors.
 Once required amount of each ingredient is filled into their individual
containers control system releases all ingredients into mixing drum.
 Mixing drum is like a giant bowl with a stirrer rotating inside to ensure
propermixing of ingredients.
 Steam might also be fed to the unit to maintain temperature in range
of 40-42oC.
9

15. Fig. 6. Cement, lime powder and gypsum is sent from silo to mixing tank using screw conveyor
during AAC blocks manufacturing.
 A smaller bowl type structure used for feeding Aluminium powder is
also attached as a part of mixing unit.
 For AAC blocks manufacturing, entire dosing and mixing operation is
completelyautomated and requires minimum human intervention.
 Dosing and mixing processis carried out continuously because if
there is a long gap between charging and discharging of ingredients,
residual mixture might start hardening and choke up the entire unit.
10

16. Fig. 7. Cement, lime powder and gypsum is sent from silo to mixing tank using screwconveyor
during AAC blocks manufacturing.
 For AAC blocks manufacturing, entire dosing and mixing operation is
completely automated and requires minimum human intervention.
 This entire operation is monitored using control systems integrated
with computer and CCTV cameras.
 As with any industrial operation, there is provision for human
intervention and emergency actions integrated inside the control
system.
Fig. 8. Control panel and CCTV cameras help monitor and control AAC
blocks manufacturing process.
11

17. Step 3 – Casting, Rising and Pre-curing:-
 AAC blocks manufacturing process involves casting, rising and pre-
curing. Once desired mix of raw materials is ready, it poured is in
moulds. This process has differentnames. It is called casting, pouring
or moulding. For current discussion, we’ll call it casting.
 After thorough mixing, slurry containing fly ash (or sand), lime
powder, cement,gypsum and Aluminium is poured in moulds. Moulds
can be of various sizes depending upon installed capacity.
 Before casting, moulds are coated with a thin layer of oil. This is done
in order to ensure that green-cake does not stick to moulds.
 While slurry is mixed and poured into greased moulds, Aluminium
reacts with Calcium Hydroxide and water to form Hydrogen. Millions
of tiny Hydrogen bubbles are released due to this reaction. This leads
to formation of tiny unconnected cells causing slurry mix to expand.
Such expansion may be twice its original volume. This process is
very similar to rising of idli or dhokla dough.
 The cells are the reason behind light weight and insulating properties
of AAC blocks. Once rising process is over, green-cake is allowed to
settle and cure for some time. This ensures cutting strength required
for wire cutting.
 Usually rising and pre-curing process takes around 60-240 minutes.
Rising is dependent on raw material mix and weather conditions. It
should be noted that weather is a major factor affecting
rising process.
12

18.  It should be ensured that green-cake is not subjected to
vibrations during pre-curing or else it might develop cracks.
Fig. 9. Casting during AAC blocks manufacturing process.
Step 4 – Demoulding and Cutting:-
 In earlier posts we have seen how slurry is cast in moulds and
allowed to rise and gain strength during pre-curing.
 Once green cake has achieved cutting strength, it is ready to be
demoulded and cut as per requirements.
 Demoulding and cutting are very critical processes in AAC
blocks manufacturing. These two processes play a major role in
defining amount of rejection as well as dimensional accuracy of
the final product.
 Once a mould is out of pre-curing room, it is lifted by a crane or
rolled on tracks for demoulding operation. Lifting or rolling
green cake is determined by technology deployed.
13

19.  Manufacturing process can be broadly classified as flat-cake
and tilt-cake based on how green cake is demoulded and sent
to cutting line.
 Horizontal cutting machine does not have any moving parts.
Cutting operation is achieved by moving green cake through
horizontal cutting machine.
 It has a profile plate that scrapes sides of green cake to give it
an even finish. Once profiling is done, horizontal cuts are made
through green cake using stationary steel wires. These wires
can be adjusted offline to get desired height of AAC blocks or
panels. Depending on client preference,some horizontal cutting
machines may sport a top crust removal device shaped like an
arrow.
Fig. 10. Horizontal cutting machine using stationary wires.
14

20. *The Comparison Between AAC Bricks and Clay Bricks*
S.No. Parameters AAC Bricks Clay Bricks
1. Soil Consumption. Zero soil consumption. 1 square ft. of area
with clay brick
walling will consume
25.5 kg of top soil.
2. Labour. Organized sector with proper HR
practices.
Unorganized sector
with rampant use of
child Labour.
3.
Production Facility.
State-of-the-art factory facility. Unhealthy working
conditions due to
toxic gases.
4.
Compressive
Strength.
3-4 N/m2. 2.5-3 N/m2
5.
Fire Resistance
(8″ wall).
Up to 7 hours. Around 2 hours.
6.
CostBenefit.
Reduction in dead weight leading
to savings in steel and concrete.
None
7.
Thermal Resistance.
Approximately 30% for heating
and cooling.
None
8.
Speedof
manufacturing.
HIGH LOW
15

21. **COST ANALYSIS**
Cost of building materials vary from
region to region.
In Mumbai, bricks cost between Rs.6-7/-
per unit.
In Uttar Pradesh it is approxRs. 5/- per
unit.
For Instance, one cubic meter comprises of
600 bricks, which costs around Rs.3000-
4000/- cubic meter.
However, AAC blocks are available at the
range of Rs.2800-4000/- per m3.
Builders prefer AAC considering
numerous advantages of the materials as
seen above.
16

22. **AAC Manufacturing in India**
o The first AAC blocks plant in India was set up in early 1970s by Siporex at
Pune.
S.No. Brand Name Company Location
1. Aerocon Aerocon India. Rajkot
2. Aerocon HIL Golan.
3. Ascolite Aswani Construction
Pvt. Ltd.
Surat.
4. Xtralite Ultratech. Hyderabad
5. Renacon RenaatusProconPvt.Ltd. Chennai
6. Reliconz Reliconz Brix Pvt. Ltd. Hyderabad
7. JK Smart Blox JK LakshmiCement. Jhajjar
8. Magicrete MegicreteBuilding. Surat
9. Prime AAC Ecocare Building
Products Pvt. Ltd.
Vijayvada
10. Siorex BG Shirke Group. Pune
11. Efcon PhenixProcon Pvt.Ltd. Bawla
12. Ecogreen EcogreenPvt. Ltd. Gandhinagar
13. Ecolite JVS Comastco Sinaar
14. BBEL Avantha Palwal
17

23. CONCLUSION
o However it is difficult to replace the old materials
with new one. Comparative Analysis indicates
that in almost all the parameters, the AAC blocks
have a superior edge over burnt clay bricks.
o The use of AAC blocks leads to savings in overall
project cost; enables to speed up the
construction process reduced environmental and
social impact.
o Therefore we can conclude that use of ACC
blocks over burnt clay bricks is recommended.
o It is advisable to developers, contractors, and
individuals to encourage this product as its use is
in national interest.
18

24. *REFERENCES*
o www.aacindia.com
o www.indiamart.com
o www.constructionworld.in
o www.grihaindia.org,Report by AtulKapur, “HIL
Upgrading India‟s life spaces”, 26th February
2013.
o www.iosrjournals.org , An Investigation of Using
Aerocon Block and M-Sand in Constructing Low
Cost HousingK.Jaiganesh 1, S.Dinesh.
o International Journal of Engineering Research &
Technology (IJERT), Burnt Clay Bricks Versus
Autoclaved Aerated Concrete Blocks. A
Comparative Analysis , By RadhikaShukla,
Architecture dept. MIET Nagpur University,
Mumbai, India.
o www.google.com/images/aeroconbricks.
19

25. CONTENTS
 INTRODUCTION.
 IMPORTANCE OF AAC BRICKS.
 TYPES OF AAC BRICKS.
 CHARACTERSTICS OF AAC
BRICKS.
 MANUFACTURING PROCESS.
 COMPARISON BETWEENAAC
BRICKS & CLAY BRICKS.
 COST ANALYSIS.
 AAC BRICKS IN INDIA.

26.  CONCLUSION.