Advantages of Fly Ash Bricks


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.

flyash bricks

Structural Capability

These bricks can provide advantages being available in several load-bearing 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).

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.

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.

Toxicity and Breath-ability

There are no definite studies on the toxic fume emissions or the indoor air quality of structures
built with flyash bricks, though claims of radio active emissions by these blocs have been made at
some scientific forums.

Flyash 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 flyash has
no such problems.


(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 offsetting about
100million tonne’s of flyash annually produced in India by the numerous thermal power plants,
which could cause serious contamination of land, groundwater and air.

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 plants all over the country for obvious reasons, finding dealers in all major cities and
towns wouldn’t be a problem.


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.