Fly Ash Bricks
Manufacturing Process
Fly ash Bricks ( FAL-G) manufacturing Process(STEP 1)
•Process of Manufacture:
• Fly ash, Hydrated lime, Quarry dust and gypsum are manually fed into a
pan mixer where water is added in the required proportion for intimate
mixing.
• The proportion of the raw material is generally in the ratio
62%
8%
5%
25%
• depending upon the quality of raw materials.
After mixing, the mixture is shifted to the hydraulic Brick Making machines.
•The bricks are carried on wooden pellets to the open area where they are
dried and water cured for 14 days.
• The bricks are tested and sorted before dispatch.
Procurement of Raw Material
FAL-G PROCESS
Storage of Raw Material
(STEP 2)
Batch Mixing of Raw Material
Wet mixing in Roller Mixer
Raw materials are kneaded under rollers
for achieving homogenous mortar
Mechanized Transfer from Pan Mixer
to Automatic Brick Making Machine
Drying & Curing – Fly ash Bricks
Fly ash Bricks Vs Normal Clay Bricks
Comparison
NORMAL CLAY BRICK
FLYASHBRICK
Varying colour as per soil
Uneven shape as hand made
Lightly bonded
Plastering required
Heavier in weight
Compressive strength is around
35 Kg/cm2
More porous
Thermal conductivity
1.25 – 1.35 W/m2 ºC
Water absorption 20-25%
Uniform pleasing colour like cement
Uniform in shape and smooth in finish
Dense composition
No plastering required
Lighter in weight
Compressive strength is around
100 Kg/cm2
Less porous
Thermal conductivity
0.90-1.05 W/m2 ºC
Water absorption 6-12%
Fly Ash Bricks
. Here we have compared both the bricks on the basis of their characteristics which will certainly
help you to choose the better one.
Fly ash bricks
Clay bricks
The colour of fly ash brick is same as the
manufacturing is carried out using machinery
in controlled condition.
Not in uniform colour as the colour of brick
depends upon type of soil and quality control
during production.
Uniform in shape and smooth in finish as the
manufacturing is carried out using machinery.
As the surface is even and joints are thinner,
no plastering required in normal cases.
Fly ash bricks are lighter as the main
composition is fly ash.
Fly ash bricks are less porous.
The cost of fly ash brick is approximate 30%
lower than clay brick.
Clay bricks are uneven in shape as mostly clay
bricks are made manually.
As the surface finish is not even, plastering is
necessary.
Clay bricks are heavier as compared to fly ash
bricks.
Clay bricks are more porous.
The cost of clay brick is higher than fly ash
brick.
Continuing use of clay bricks in construction
industry will lead to extensive loss of fertile
top soil. This could be a devastating
environmental hazard.
This is made by using by-product of Thermal
Power Plant, which save environment from
being polluted.
From the above comparison it is very much clear that fly ash
bricks are superior to clay bricks and one can use fly ash
bricks for construction of house without any hesitation.
Advantages of Fly Ash Bricks
1-Appearance
❖These bricks have a pleasing colour like cement, are uniform in
shape and smooth in finish, also, they require no plastering for
building work.
❖The bricks are of dense composition, uniformly shaped
with/without a frog, free from visible cracks, warp-age, organic
matter, pebbles and nodules of free lime.
❖ They are lighter in weight than ordinary clay bricks and less
porous too.
❖The colour of flyash bricks can be altered with the addition of
admixtures during the process of brick making.
❖ They come in various sizes, but generally are similar to the sizes of
clay bricks.
2-Structural Capability
These bricks can provide advantages being available in several loadbearing grades, savings in mortar plastering, and giving smart looking
brickwork.
❖High compressive strength eliminates ,breakages/wastages during
transport and handling, the cracking of plaster is reduced due to lower
thickness of joints and plaster and basic material of the bricks, which is
more compatible with cement mortar.
❖ Due to its comparable density the bricks do not cause any extra load
for design of structures and provides better resistance for earthquake
loads due to panel action with high strength bricks.
❖Compressive strength of fly ash sand lime bricks is av. 9.00 N/mm2 (as
against 3.50 N/mm2 for handmade clay bricks).
3-Thermal properties
•Thermal conductivity is 0.90-1.05 W/m2 ºC (20-30% less than
those of concrete blocks). These
bricks do not absorb heat; they reflect heat and gives
maximum light reflection without glare.
•Sound insulation
•It provides an acceptable degree of sound insulation.
•Fire and vermin resistance
•Flyash bricks have a good fire rating. It has no problems of
vermin attacks or infestation.
4- Durability and moisture resistance
These blocks are highly durable, after proper pointing of joints, the
bricks can be directly painted in dry distemper and cement paints,
without the backing coating of plaster. Rectangular faced with sharp
corners, solid, compact and uniformly Water absorption is 6-12% as
against 20-25% for handmade clay bricks, reducing dampness of
the walls.
5-Toxicity and Breath-ability
There are no definite studies on the toxic fume emissions or
the indoor air quality of structures built with fly ash bricks,
though claims of radio active emissions by these blocs have
been made at some scientific forums.
Fly ash as a raw material is very fine and care has to be taken
to prevent from being air-borne and causing serious air
pollution as it can remain airborne for long periods of time,
causing serious health problems relating to the respiratory
system.
Though block manufactured from fly ash has no such
problems.
6-Sustainability
Environmental Impacts
Fly ash is a cocktail of unhealthy elements – silica, aluminum, iron oxides,
calcium, magnesium, arsenic, mercury, and cadmium, and poses serious
environment and health hazards for a large population.
But the brick is better off, for flyash changes into a non-toxic product when
mixed with lime at ordinary temperature as the calcium silicate hydrates
and forms a dense composite
inert block.
Thus having the potential as a good building material, while off setting
about 100million tonne’s of flyash annually produced in pakistan by the
numerous thermal power plantsand sugar mills which could cause serious
contamination of land, groundwater and air.
7-Buildability, availability and cost
•The blocks have an easy workability and high compressive
strength eliminates breakages/wastage during handling giving
a neat finish, with lower thickness of joints and plaster. The
construction technique remains the same as regular bricks
ensuring easy change of material, without requiring additional
training for the masons.
• Though these bricks are abundantly available closer to
thermal power plantsand sugar mills all over the country for
obvious reasons, finding dealers in all major cities and towns
wouldn’t be a problem.
8- Applicability
The blocks being available in several load bearing grades
are suitable for use: • Load bearing external walls, in low and medium size
structures.
• Non-load bearing internal walls in low and medium size
structures.
• Non-load bearing internal or external walls in high-rise
buildings