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Historically, foamed concrete has been perceived to be weak and non-durable with high shrinkage characteristics. Unstable foams have in the past resulted in foamed concrete having
properties unsuitable for reinforced, structural applications. Unprotected reinforcement in aerated concrete in which the voids are interconnected would be vulnerable to corrosion even
when the external attack is not very severe.
2.2.2 Lightweight Foamed Concrete
Presently the construction industry has shown significant interest in the use of lightweight foamed concrete LFC as a building material due to its many favorable characteristics such as
lighter weight, easy to fabricate, durable and cost effective. LFC is a material consisting of Portland cement paste or cement filler matrix mortar with a homogeneous pore structure
created by introducing air in the form of small bubbles. With a proper control in dosage of foam and methods of production, a wide range of densities 400
– 1600 kgm3 of LFC can be produced thus providing flexibility for application such as structural elements, partition,
insulating materials and filling grades. Lightweight concrete is a versatile material which consists primarily of a cement
based mortar mixed with at least 20 of volume air. LFC is a cementations material having a minimum of 20 by volume of mechanically entrained foam in the mortar slurry in which
air-pores are entrapped in the matrix by means of a suitable foaming agent. The air-pores are initiated by agitating air with a foaming agent diluted with water; the foam then carefully mixes
together with the cement slurry to form LFC. The material is now being used in an ever increasing number of applications, ranging from one step house casting to low density void
fills. 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. Mix design used due to material that required for 1m
3
concrete:
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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. To calculate the compressive strength of concrete can use the formula below:
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Where: f’c
= compressive strength MPa P
max
= maximum load N A
= cross sectional area mm
2
Density =
V W
3 Where:
W = concrete weight kg
V = concrete volume m
3
Normal concrete has a density of 2,400 kgm3 while densities range from 1,800, 1,700, 1,600 down to 300 kgm3. 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.
2.2.3 Precast Lightweight Foamed Concrete
