EPS Concrete vs Perlite Concrete for Floor Fills, Sunk Fills and Screeds

Viraj Kulkarni

Oct 8

2 min read

EPS concrete is cement mortar with expanded polystyrene (EPS) beads mixed in. The beads are very light, so the mix is light. It is widely sold as a filler for sunken slabs and floor fills.

Perlite concrete is also light, but its aggregate is expanded perlite, an inorganic volcanic mineral. That one difference changes how the two behave in a fire, on site, and under a finish.

Side-by-side comparison

Property	EPS bead concrete	Perlite concrete
Lightweight aggregate	Polystyrene (a plastic)	Expanded perlite (a mineral)
Behaviour in fire	Beads melt and burn	Non-combustible
Segregation in the mix	Beads tend to float up	Aggregate stays distributed
Surface	Beads can show at the top	Hard, smooth, monolithic finish
Holding a screw	Poor	Drywall tracks screw straight in
Laid to slope	Difficult	Yes, levelled with a straight edge
Heat insulation	Good	Good; k as low as 0.08 W/m·K in insulating grades

Fire

Polystyrene is a plastic. In a fire, the beads melt and burn, leaving voids in the fill. Perlite is volcanic glass that fuses above about 1,260 °C, so it does not add fuel to a fire. For hospitals, data centres, airports and high-rises, that is a material difference worth putting in the specification.

Source: Perlite Institute (USA) published technical information. Keltech Energies Ltd is a member of the Perlite Institute.

Segregation and finish

EPS beads are far lighter than the cement paste around them. During mixing, pumping and vibrating they tend to rise, leaving a weaker bottom and beads at the surface. Perlite granules are bound into the paste and stay distributed, giving a consistent fill and a hard, smooth top that takes tiles, vinyl, carpet or waterproofing directly.

On office and commercial floors

Drywall partitions are fixed into the floor screed. Perlite concrete holds a screw; bead-filled concrete generally does not, because the screw meets plastic beads and voids instead of a solid matrix.

Where each fits

Perlite concrete: terrace slopes and insulation, floor screeds that take finishes directly, sunk fills, podium fills, and any building where fire performance matters.
EPS concrete: low-cost void fills where fire, surface hardness and finish are not part of the brief.

Frequently asked questions

Is perlite concrete as light as EPS concrete?

Perlite concrete can be made as light as about 300 kg/m³ for insulation, and up to 2,000 kg/m³ for harder fills. Tell us the density your structural consultant allows and we will match it.

Does perlite concrete contain any plastic?

No. The lightweight aggregate is expanded perlite, a natural volcanic mineral.

Can it be used in sunken toilets?

Yes, as a lighter filler replacing brickbat or other fills. Waterproofing of the sunk area is a separate layer and should be specified as usual.

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).

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