Structural Fill - Raising Existing Slabs

Need Polystyrene Fill or Structural Polystyrene to raise an existing concrete slab?

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PolyVoids are extensively used as structural fill or to raise existing concrete slabs in South Africa. PolyVoids sheets or blocks are placed directly on the existing concrete slab and then a new slab is cast on top of the polystyrene layer.

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Real Life Example:

In this picture, they are using our Highest Density PolyVoid blocks and sheets to raise an existing slab by 1m at the Nelson Mandela's Children Hospital in Johannesburg.

Engineering Design Considerations:

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• We don't design concrete slabs so you will have to consult with your structural engineer on what density PolyVoids will be required.

• Low Density PolyVoids are generally used where the polystyrene layer is not going to carry the final weigh of the new concrete slab. The polystyrene in this case is just present to fill a void and carry the wight of the slab until the slab has cured.

• Our High Density & Extra High Density PolyVoids are generally required when the polystyrene layer is going to carry the full weight of the new concrete slab and live loads after the slab has been cast.

• The new concrete slab should be structurally reinforced and a mimumum of 100mm thick.

Cost Considerations:

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• The higher the density, the higher the cost of the PolyVoids.
• Standard sheet & block sizes are more cost effective.
• Avoid special cut blocks if possible. Wastage can increase costs significantly.

Installation Considerations:

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• Thinner sheets packed on top of each other are easier to handle, cut and pack on site.
• PolyVoids are easily cut with a knife or hacksaw blade.