What is foam concrete?

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Foam concrete, also known as lightweight aerated concrete, variable density concrete, cellular concrete, and lightweight or ultra-lightweight concrete, is defined as a cementitious material with a minimum of 20% by volume of mechanically entrained foam in the plastic mortar.

 

As mostly no coarse aggregate is used for production of foam concrete the correct term would be called indeed mortar instead of concrete. Sometimes it may also be called as “foamed cement” or “foam cement” because of mixture of cement and foam without any fine aggregate. However, foam concrete is not to be confused with autoclaved concrete, which is manufactured offsite using entirely different methods.

 

The density of foam concrete usually varies from 400 kg/m3 to 1,600 kg/m3. The density is normally controlled by substituting fully or part of the fine aggregate with foam.

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Displacing concrete with air

 

The variable density is normally described in kg per m3, where regular concrete is 2,400 kg/m3. Variable density can be as low as 300 kg/m3, although at this density it would have no structural integrity at all. By replacing the dense heavy concrete with air, the variable density reduces strength to increase thermal and acoustical insulation.

 

There are many competing products, e.g. foaming agents that resemble shaving cream, to mix air bubbles in with the concrete, but all accomplish the same outcome: to displace concrete with air.

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Applications

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Foam concrete can be produced with dry densities of 400 to 1,600 kg/m3, with 28-day strengths of approximately 1 to 10 N/mm2 respectively. Foam concretes are fire resistant and, their thermal and acoustical insulation properties make them ideal for a broad range of purposes, from insulating floors and roofs, to void filling. It is also particularly useful for trench re-instatements. Applications of foam concrete include, but are not limited to:

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• Blocks and panels for walls

• Levelling Floors

• Road subbases and maintenance

• Bridge abutments and repairs

• Ground stabilisation

• Roof insulation

 

Foam concrete is a highly versatile material, featuring benefits like:

• Weight reduction of superstructure using foam concrete walls: less steel reinforcements required for slabs, columns, beams and foundation due to lesser load.

• Reduced cost of raw materials: By adding air, enclosed in foam bubbles, the volume of concrete can be increased at very low cost.

• Environmentally-friendly / Energy savings: Compared to autoclaved aerated concrete (AAC), air curing is possible for foam concrete. This saves up to 9 m2 of gas for curing one cubic meter of AAC and therefore protects our environment.

• Cost reduction for transportation and storage: Less raw materials, very efficient foam concentrate.

• Faster construction using cast in-situ application improved thermal insulation: Foam concrete can achieve the same insulation results as normal concrete with only 20% of the weight and 10% of raw materials.

• Improved fire protection: A wall of 13 cm thickness and 1,250 kg/m³ can withstand a fire for 5 hours. A wall of 10 cm thickness and only 400 kg/m³ achieves the same result, due to the air enclosed in the foam concrete. Easy to use/produce/handle.

• High flowing capability: Can fill hollow spaces.