Foam Concrete Weight Reduction and Flexural Strength

Weight Reduction in Foam Concrete

One of the main advantages of foam concrete is its weight reduction (up to 80%) compared to conventional concrete. Unlike conventional concrete, air bubbles are evenly distributed throughout the body of the foam concrete and their size ranges from 0.1 to 1 mm.

The density of foam concrete depends on the amount of foaming agent and varies between 400 and 1600 kg/m3. It is ideal for structural, partitioning, insulation and filling applications with excellent acoustic/thermal insulation, high fire resistance, lower raw material costs, easier pumping and finally no compaction, vibration or leveling [1].

Flexural Strength

The compressive strength of foam concrete depends on the type of foaming agent used and the hydration regime. In addition, the elasticity modulus of foam concrete is also dependent on the density and a number of other factors.

Foaming agents and surfactants must be diluted with water before being agitated through a "cigar" to produce stable foam. A typical expansion for a protein based dry foam is 20 times the fluidity of the surfactant.

Water reducing agents and plasticisers do not mix well with foaming agents. To avoid this, a superplasticizer is usually used in foamed concrete mixes.

It is essential to ensure that the entrained air is contained in stable, tiny, uniform bubbles which remain intact and isolated and do not increase the permeability of the cement paste between the voids. This is achieved by ensuring that the foaming agent has been diluted at a low 3% - 5% ratio with water before it is agitated through a "cigar". The presence of air voids does not reduce the elasticity modulus and the concrete complies with all requirements for a load bearing structure.