Foam Concrete vs Perlite Concrete: Which Lightweight Concrete Should You Specify?
Foam concrete (also called cellular lightweight concrete, or CLC when cast as blocks) gets its low weight from air bubbles made with a foaming agent. Perlite concrete gets its low weight from expanded perlite, a volcanic mineral that has been heated until it pops into light, glassy granules full of tiny cells.
Both are lightweight. They are not interchangeable. Here is how they compare on the things that matter on a roof or floor.
How each one is made
Foam concrete: cement slurry plus a pre-formed foam. The air bubbles are what make it light. If bubbles collapse during mixing, pumping or placing, density and strength change.
Perlite concrete: Kelite expanded perlite (made by Keltech Energies Ltd) mixed with cement, or cement and sand, plus an admixture. The lightness is in the aggregate itself, so it does not depend on bubbles surviving the pump.
Side-by-side comparison
Property | Foam concrete | Perlite concrete |
Source of lightness | Air bubbles from foam | Expanded perlite aggregate |
Density range | Wide, depends on foam stability | About 300 to 2,000 kg/m³ |
Drying shrinkage | Can be high, risk of cracks | Very low |
Surface | Often soft or dusty at low densities | Hard, monolithic, table-top finish |
Levelling | Self-levels, hard to hold a slope | Laid to slope, levelled with a straight edge |
Holding a screw | Poor at low densities | Drywall tracks screw straight in |
Fire | Non-combustible | Non-combustible (perlite fusion point above 1,260 °C) |
Heat insulation | Good at low densities | Good; k as low as 0.08 W/m·K in insulating grades |
Fire data: Perlite Institute (USA) published technical information. Keltech Energies Ltd is a member of the Perlite Institute.
Shrinkage and cracking
Foam concrete loses a lot of water as it dries, and that shows up as shrinkage cracks, especially over large floor areas. Perlite concrete has very low shrinkage, so the screed stays sound under waterproofing, tiles or vinyl.
Surface and finish
On a roof or floor, what goes on top needs a hard, flat base. Perlite concrete finishes to a smooth, monolithic surface that takes carpet, tiles, vinyl, wood or a waterproofing membrane directly. Low-density foam concrete tends to leave a softer surface that may need a separate topping.
Screw holding: the office-floor test
In offices and data centres, drywall partitions are fixed to the floor with tracks. We have filmed drywall tracks being screwed straight into a perlite concrete screed. Most other lightweight concretes, foam included, will not hold a screw at low densities, so the track has to go on a separate hard topping.
Slope
Foam concrete flows and self-levels, which is useful for flat fills but makes it hard to hold a slope on a terrace. Perlite concrete is laid to the slope you need and levelled with an aluminium straight edge, so it does the job of brickbat coba and insulation in one layer.
Which one should you use?
Choose perlite concrete for terrace slopes, roof insulation, floor screeds that take finishes directly, office floors with drywall partitions, and anywhere surface hardness matters.
Foam concrete can suit deep void fills where finish and surface hardness do not matter.
Frequently asked questions
Is perlite concrete stronger than foam concrete?
At the same density, perlite concrete gives a harder, more monolithic surface. For a specific project we will give you the compressive strength of the grade proposed.
Can perlite concrete be pumped?
Yes. It can be delivered by RMC and pumped, mixed on site, or supplied in pre-mixed bags.
Is perlite concrete used for structural work?
No. It is used for non-structural fills, screeds, insulation and plaster.
Related reading: EPS concrete vs perlite concrete · What is perlite concrete?
About Perlite India. Perlite India designs and lays perlite lightweight insulating concrete for roofs, floors, sunk fills and podiums, with 3M+ sq.ft laid across India. Supported by the Perlite Construction Division of Keltech Energies Ltd, a member of the Perlite Institute (USA).
Or WhatsApp us: +91 98600 63626
Comments