The document compares autoclaved aerated concrete (AAC) blocks and red clay bricks. It discusses their history, constituents, uses, advantages, disadvantages, properties, efficiency, and on-site construction comparison. AAC blocks are lighter weight, more durable, provide better insulation, reduce construction costs and time, and have less environmental impact than red clay bricks. However, AAC blocks have a higher initial production cost per unit. The document concludes that both materials have important uses in wall construction based on their properties, availability, and cost for a given project.
2. AUTOCLAVED AERATED CONCRETE BLOCKS
Introduction
Autoclaved Aerated Concrete is a Lightweight, Load-bearing, High-insulating, Durable building
product, which is produced in a wide range of sizes and strengths. AAC Blocks is lightweight and
compare to the red bricks AAC blocks are three times lighter.
History
The Autoclaved Aerated Concrete (AAC) material was developed in 1924 in Sweden. It has become
one of the most used building materials in Europe and is rapidly growing in many other countries
around the world.
AAC is produced from the common materials lime, sand, cement and water, and a small amount of
rising agent. After mixing and molding, it is then autoclaved under heat and pressure to create its
unique properties. AAC has excellent thermal insulation and acoustic absorption properties. AAC
is fire and pest resistant, and is economically and environmentally superior to the more traditional
structural building materials such as concrete, wood, brick and stone.
Constituents
AAC offers incredible opportunities to increase building quality and at the same time reduce costs
at the construction site.
AAC is produced out of a mix of quartz sand and/or pulverized fly ash (PFA), lime, cement, gypsum,
water and aluminum and is hardened by steam-curing in autoclaves. As a result of its excellent
properties, AAC is used in many building constructions, for example in residential homes, commercial
and industrial buildings, schools, hospitals, hotels and many other applications. AAC contains 60%
to 85% air by volume.
3. RED CLAY BRICKS
Introduction
A brick is building material used to make walls, pavements and other elements in masonry
construction. Traditionally, the term brick referred to a unit composed of clay, but it is now used
to denote any rectangular units laid in mortar. A brick can be composed of clay-bearing soil,
sand, and lime, or concrete materials. Bricks are produced in numerous classes, types, materials,
and sizes which vary with region and time period, and are produced in bulk quantities. Two basic
categories of bricks are fired and non-fired bricks.
Block is a similar term referring to a rectangular building unit composed of similar materials, but
is usually larger than a brick. Lightweight bricks (also called lightweight blocks) are made from
expanded clay aggregate.
History
Fired bricks are one of the longest-lasting and strongest building materials, sometimes referred
to as artificial stone, and have been used since circa 4000 BC. Air-dried bricks, also known as
mudbricks, have a history older than fired bricks, and have an additional ingredient of a mechanical
binder such as straw.
Bricks are laid in courses and numerous patterns known as bonds, collectively known as brickwork,
and may be laid in various kinds of mortar to hold the bricks together to make a durable structure.
Constituents
Normally, bricks contain the following ingredients:
Silica (sand) – 50% to 60% by weight
Alumina (clay) – 20% to 30% by weight
Lime – 2 to 5% by weight
Iron oxide – ≤ 7% by weight
Magnesia – less than 1% by weight
4. AAC BLOCKS vs RED BRICKS
RED BRICKS AAC BLOCKS
GENERAL
A Red brick is a block, or a single
unit of a ceramic material used
in masonry construction, usually
stacked together or laid using
various kinds of mortar to hold
the bricks together and make a
permanent structure.
Bricks are typically produced in
common or standard sizes in bulk
quantities.
AAC Blocks are lightweight building
materials cut into masonry blocks or
formed larger planks and panels.
AAC Block is relatively uniform when
compared to other wall unit and
does not contain coarse aggregate
phase.
RAW MATERIAL
Itismadebymixtureofclay(alumina),
sand, Lime, iron oxide and Magnesia
Natural soil is used for Production of
Bricks. Hence ultimately it will vary
depending upon the quality of local
soil, i.e. Top soil of Earth Crust.
It is made from the mixture of fly
ash, cement, lime, gypsum and an
aeration agent.
The Fly ash used in AAC Blocks
production is eco-friendly & Cement
is used in very little Quantity.
The Problem of fly ash utilisation is
solved by the use of fly-ash in AAC
Block. This was a major problem till
day.
USES
As a Structural Unit:
Buildings, Bridges, Foundations,
Arches and cornices, Pavements.
As an Aesthetic and Finish Surface:
As Facing Bricks, Architectural
Purposes, Exposed practice work
AAC Block can be used to build
internal and external walls.
It can also be used as load bearing
and non load bearing walls.
ADVANTAGES
Raw material is easily and cheaply
available. So it is economical.
Red Bricks are low maintenance,
permanent, hard and durable
building material.
Compressive strength is good
enough for ordinary construction.
Different orientations and sizes give
different surface textures
Demolishing of brick structures is
very easy and less time consuming.
It is reusable and recyclable.
Highly fire resistant.
AAC blocks are very easy to handle
and ordinary tools are used for cut-
ting.
AAC blocks are available in large siz-
es and hence less no of joints. This
ultimately results in faster construc-
tion on site and less consumption of
cement.
AAC blocks are made from an inor-
ganic material which helps to avoid
termites, damages or losses.
Saves steel and concrete due to the
reduction in dead weight.
Increase in floor area due to a reduc-
tion in the size of columns and thick-
ness of the wall.
Easy to transport on upper floors.
Time-saving in construction.
Minimal wastage of AAC blocks.
It is environment-friendly and also
saves water. Hence it is popularly
used as a green product.
5. AAC BLOCKS vs RED BRICKS
RED BRICKS AAC BLOCKS
DISADVANTAGES
Time consuming construction
Red Bricks cannot be used in high
seismic zones for load bearing
structures.
A red brick absorbs water easily
so Efflorescence occurs due to the
presence of salt in water.
Rough surfaces of bricks may cause
moulds growth if it is not properly
cleaned.
Continuous use of Red bricks in
construction will lead to extensive
loss of fertile top soil and hence
potential agricultural land.
Red bricks are heavy in weight
so that the structure needs to
withstand greater weight, and
hence construction cost increases.
Big damage to environmental and
loss of fertile land due to use of clay
soil excavation for making of bricks.
The production cost per unit for AAC
Block is higher.
Plaster sometimes does not stick
properly because of its smooth
surface. Needs care during
production itself, so that surface is
not very smooth.
IDENTIFICATION
ON SITE
Its colour is Red. Colour of AAC Block is Grey.
COST
1 cum brick work cost around
3100/- in india.
1 cum block work cost around
2800/- in india.
ENVIRONMENT
IMPACT
Soil Consumption:
One clay brick consumes 3.2 kgs of
top fertile soil.
Green Product:
Red Brick is not a green product.
On the country, it is the enemy of
green.i.e.environment.
Red Bricks are made from the clay
which is naturally available material
but it reduces the top fertile soil
cover.
Earthquake Resistance:
Red Bricks have resisted average
earthquake forces because the
density of brick is more than AAC
Block.
Soil Consumption:
Zero soil Consumption. The basic Raw
material of AAC Block is fly ash. Which
otherwise has a disposal problem.
Green Product:
AAC Blocks are made from a non-
toxic material which does not harm
the environment. Using it reduces the
industrial waste, and it also decreases
greenhouse gas emissions.
During the manufacturing process,
Waste of the AAC Block is recycled
and used again. This waste is made
from the cutting process.
Hence AAC Blocks are a Green
product.
Earthquake Resistance:
Earthquake forces are proportional
to the weight of the building. AAC
Blocks reduce the weight of building
so it increases the safety against
earthquake.
6. PROPERTIES
AAC BLOCKS vs RED BRICKS
PROPERTIES RED BRICKS AAC BLOCKS
Size Available in
Market
230 x 110 x 70
230 x 110 x 30
400-600×100-200×100-300mm
Variation in Size
5mm(+/-)
Red Bricks are not accurate in size,
a largely from area to area.
1.5mm(+/-)
The AAC Blocks are accurate in size
because it is produced by wire cut
technology and is a factory product.
Dry Density
1600-1720 kg/m3
1721-1820 kg/m3
1821-1920 kg/m3
451-550 Kg/m3
551-650 Kg/m3
651-750 Kg/m3
751-850 Kg/m3
851-1000 Kg/m3
Weight
2.5 – 3.5 Kg
It will depend on density & size of
brick.
3 – 4 kg
It will depend on Density & size of
Block.
Compressive
Strength
30-35 N/mm2
Strength is defined as a capacity to
resist force or pressure.
30-35 Kg/cm2
WaterAbsorption
Water absorption of brick should
not be more than 20% of its weight.
Water Absorption of this block should
not be 10% its weight.
Fire Resistance
100 mm thick wall can resist fire for
up to 2 hours.
100 mm thick wall can resist fire for up
to 4 hours.
Thermal
Conductivity
0.6- 1.0 W/mk
The thermal conductivity of brick is
high, and hence heat transfer from
brick is more than AAC block.
0.21 – 0.42 W/mk
Thermal conductivity of block is lower
and less heat transfer from the block.
Moisture
Resistance
Moisture Resistance of Red Brick is
Average.
Moisture resistance will depend
on water absorption of brick and
proportion of cement mortar.
100/115 mm wall will not have
adequate moisture resistance. If
poor, it will make walls damp & wet.
Moisture resistance of AAC block is
better than the Red Brick.
AAC block consists of unconnected
micropores which prevent the
capillary transport of moisture over a
long distance.
Sound
Insulation/Noise
Transmission
The brick wall has good sound
insulation property due to its dense
structure.
45 db sound is reduced by 150 mm
and 50 db sound is reduced by 230
mm walls.
The AAC block has good sound
transmission property due to the
presence of air voids.
40-45 db sound is reduced for 200
mm thick.
Termite
Resistance
Red bricks are not termite resistant
as they are made from clay which is
an organic material.
AAC blocks are insect resistant,
inorganic and solid wall construction
material.
AAC block does not allow the spread
of termites and pests and hence
increase the life of wall.
7. EFFICIENCY
AAC BLOCKS vs RED BRICKS
EFFECIENCY RED BRICKS AAC BLOCKS
Labour Output
The speed of red Brick work will be
slow as compared to Block work.
The Speed of work will be double
than that of clay brick work.
Carpet Area
Less carpet area available
compared to block work.
More carpet area available due to
less thickness of block.
Applicability
Red bricks are used for both load
bearing and Non-Load Bearing
walls.
AAC Blocks are recommended
for high-rise buildings because it
substantially reduces total dead
load of building.
Mortar
Consumption
Requires more mortar due to
irregular surface & more number of
joints.
Requires less mortar due to flat and
even surface & less number of joints.
Speed of
Construction
The speed of construction of the
brick wall is slower than the block
construction.
Speedy construction of wall due to
the bigger block size, light in weight
and less number of joint.
Water usage
during
Manufacturing
Requires more water for curing and
hence high amount of electricity bill
and labour cost.
Block is cured by steam and block
masonry also requires less curing
hence less water is used and there is
saving in electricity bill.
Breakage
& Utilisation
Average 10 to 12 % breakage
happens on construction site, So
100% utilisation is not possible. Even
at some place, due to the poor
quality of bricks, wastage goes up
to 33%.
Negligible breakage almost 100 %
utilisation is possible.
Storage
In monsoon, Stock at the site is
compulsory which blocks large
working area on the site otherwise
work will get stopped.
Readily available at any time & in
any season at a short notice, so no
storage required.
Efflorescence
Generally present.
Efflorescence occurs due to
presence of salt in water and sand.
Efflorescence occurs through mortar
and water.
8. ON SITE CONSTRUCTION COMPARISON
AAC BLOCKS vs RED BRICKS
Conecc Concrete Solutions Private Limited,
Bellary, Karnataka, hosted a on-site
demonstration of the advantages of Modern
AAC Blocks over the Traditional Red Clay Bricks.
CONCLUSION
AAC Blocks and Red Bricks both are important building materials for constructing walls. Red
bricks & AAC blocks are used in walls as per their properties, availability and cost.
DIMENSIONS
NO. OF BRICKS CONSTRUCTION TIME
MORTAR COST OF LABOUR
COST OF MORTAR PLASTER THICKNESS
