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Introduction:
Lightweight concrete has extreme importance to the construction industry. Most of current
concrete research focuses on high-performance concrete, by which is meant a cost-effective
material that satisfies demanding performance requirements, including durability. Lightweight
concrete can be defined as a type of concrete which includes an expanding agent in that it
increases the volume of the mixture while giving additional qualities such as lessened the dead
weight. It is lighter than the conventional concrete. The use of lightweight concrete has been
widely spread across countries such as USA, United Kingdom and Sweden.
The other main specialties of lightweight concrete are its low density and thermal conductivity.
So its advantages are that there is a reduction of dead load, faster building rates in construction
and lower transport and handling costs.
Lightweight concrete maintains its large voids and not forming laitance layers or cement films
when placed on the wall. Sufficient water cement ratio is vital to produce adequate cohesion
between cement and water. Insufficient water can cause lack of cohesion between particles, thus
loss in strength of concrete. Likewise too much water can cause cement to run off aggregates to
form laitance layers, subsequently weakens in
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What is the light weight concrete?
Light weight concrete (foamed concrete) is a versatile material which consists primarily of a
cement based mortar mixed with at least 20% of volume air. The material is now being used in
an ever increasing number of applications, ranging from one step house casting to low density
void fills.
Light weight concrete has a surprisingly long history and was first patented in 1923, mainly for
use as an insulation material. Although there is evidence that the Romans used air entertainers to
decrease density, this was not really a true Light weight concrete. Significant improvements over
the past 20 years in production equipment and better quality surfactants (foaming agents) has
enabled the use of foamed concrete on a larger scale.
Lightweight and free flowing, it is a material suitable for a wide range of purposes such as, but
not limited to panels and block production, floor and roof screeds, wall casting, complete house
casting, sound barrier walls, floating homes, void infill, slope protection, outdoor furniture and
many more applications.
Not everyone knows that density and compressive strength can be controlled. In the light weight
concrete this is done by introducing air through the proprietary foam process which enables one
to control density and strength precisely.
Normal concrete has a density of 2,400 kg/m3 while densities range from 1,800, 1,700, 1,600
down to 300 kg/m3. Compressive strengths range from up to 40 MPa down to almost zero for the
really low densities. Generally it has more than excellent thermal and sound insulating
properties, a good fire rating, is non-combustible and features cost savings through construction
speed and ease of handling.
The technology is the result of over 20 years of R&D, fine tuning the product and researching the
possible applications. It is used in over 40 countries worldwide today and has not reached the
end of its possible uses. Lightweight concrete is concrete weighing substantially less than that
made using gravel or crushed stone aggregates. This loose definition is generally agreed to cover
a broad spectrum of concretes ranging in weight from 12 to 120 pounds per cubic foot. Many
types of concrete fall within this range; some are cellular concretes made with foam or foaming
agents; some are made with lightweight aggregates; and some cellular concretes also contain
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lightweight aggregates. Other lightweight concretes may contain some normal weight sand. The
compressive strength of these concretes covers an even broader spectrum, with structural
lightweights at 6000 psi and higher at one extreme, and cellular fill concretes at 5 psi at the other
extreme Lightweight aggregate concrete is usually chosen for structural purposes where its use
will lead to a lower overall cost of structure than would be expected with normal weight
concrete. The generally higher unit cost of lightweight structural concrete is offset by reduced
dead loads and lower foundation costs. There may be a special advantage when existing
structures are being altered or expanded. For example, four stories were added to an existing
Cleveland department store without modifying the foundation. When the Tacoma Narrows
Bridge was replaced, the original piers were able to carry the load of additional traffic lanes,
thanks to the use of structural lightweight concrete in the bridge deck.