What Is Foam Concrete?

Foam concrete is typically made by mixing water, cement and foam. It contains fewer chemicals and is a nontoxic, more environmentally friendly and lightweight alternative to standard poured concrete. Its high air content and fire-resistant properties make it ideal for insulation, soundproofing and filling in those awkward gaps around old, unused pipes or voids between bricks, for example. It has also been used for structural elements, such as partitions and floor panels, in house builds aiming to be more eco-friendly.

Prized for its high strength-to-weight ratio and resistance to cracking and shrinkage, foam concrete can often reduce building and labor costs. It's easier to transport, it's self-leveling, and it's typically more flexible than standard concrete. It's also more resistant to temperature changes and extreme cold or heat. Building work completed with foam concrete generally requires much less maintenance than when standard pour concrete is used.

The downside? It isn't as strong as regular concrete. Normal concrete – made with broken stone or gravel, sand, cement and water – can simply hold more weight and is a safer choice for supporting beams and building foundations. Mortar, meanwhile, typically has a higher ratio of water to cement to help it bond building blocks, such as bricks or slabs, together.

Foam concrete's strength and durability are determined by the components mixed into it. For example, the mix will be stronger if sand is included. Some foam concrete mixes include Portland cement, limestone and/or pulverized fly ash (the lighter ash that flurries into the air rather than gathering at the bottom of a furnace).

Foam concrete's lightweight properties make it ideal when large quantities are needed because it takes less energy and manpower to move it between locations. It's also easier to cut than standard concrete, so it's perfect in situations where holes for wiring and pipe must be cut into the concrete. Foam concrete contains no toxic substances that might be harmful to the environment, making it an eco-friendly building material too. Because it consists of up to 80 percent air, it has excellent insulation, sound-absorbing and fire-resistant properties.

Precast blocks of foam concrete are often used as insulating materials in roofs, walls and floors in residential and commercial buildings. Denser and more structurally sound forms made of sand, cement and foam work best in this capacity. Because it flows freely and spreads easily, foam concrete is also an ingenious solution to fill in gaps and voids of pretty much any size. This could be anything from a disused basement or cellar to some old pipes that need to be filled in.