Concrete
is a composite material produced after mixing aggregates and cement with water.
Concrete is the second-most commonly used construction material worldwide, next
to water.
Concrete
looks like stone but not. Stone is just one of its aggregates along with gravel,
sand, brick chips, and many other quarry materials.
Cement
accounts for around 10 to 15 per cent of concrete. It is manufactured through a
closely controlled chemical combination of calcium, silicon, aluminum, iron and
other ingredients. Common materials used to manufacture cement include
limestone, shells, and chalk or marl combined with shale, clay, slate, blast
furnace slag, silica sand, and iron ore.
Cement is
precious, reason why it is very important that in making concrete mix, the
exact ratio of cement over water is always achieved. Apart from cement wastage,
exact cement and water consistency impacts on the hardness, rigidity, and
strength of concrete. For this purpose, concrete manufacturers use appropriate
concrete mixing machines.
Concrete mix
vary. Based on the variations in concrete materials and purposes, concrete can
be classified into the following 3 basic categories:
1) Lime Concrete uses
lime as the binding material. Lime is usually mixed with surki and khoa or
stones in the proportion 1:2:5 unless otherwise specified. The khoa or stones
are soaked in water before mixing. Lime concrete is used mainly in foundation
and terrace roofing.
Use of lime concrete is advantageous because
it- a) is cheaper than cement concrete; b) is more workable than cement
concrete; c) has lower heat of hydration making it suitable for mass concrete
works; d) is more resistant to fire; and e) is more resistant to sulfate
attack.
Lime concrete, however, has its disadvantages
like- a) lower strength than cement concrete; b) not as durable as cement
concrete; and c) susceptible to frost.
2) Cement Concrete is
used in most engineering and construction works. It consists of cement, sand,
brick chips, or stone chips of the required size. The usual proportion is 1:2:4
or 1:3:6. After mixing the required amounts of concrete materials, the mix is
cured with water for 28 days for proper strength building.
Cement concrete is a versatile with a wide
range of applications. It can be used in structural applications such as beams,
columns, slabs, and foundations. It can also be used in non-structural
applications such as paving, curbing, and landscaping as well as in popular
choice for precast applications such as pipes, paving stones, and sewer
systems.
The main advantages of cement concrete are
its strength, durability, and fire resistance. It is also relatively low
maintenance and can be easily repaired if damaged.
Cement, however, is a relatively heavy
material and can be difficult to work with. It is susceptible to cracking and
can be damaged by extreme weather conditions.
3) Reinforced Cement
Concretes are steel reinforced for enhancing the tensile strength. It is sometimes
pre-stressed under compression to eliminate or reduce tensile stresses. The
resulting concrete is known as Pre- stressed Concrete.
The steel reinforcements used in reinforced
cement concrete are rods, bars, wires, meshes, other steel materials. The
concrete is cast around these steel reinforcements to form the desired shape of
concrete cast.
