Void formers are used to separate concrete slabs from unstable soils that can exert significant pressures on structural foundations.
Biodegradable void formers are designed to provide temporary support for concrete during curing. Furthermore, they are designed to break down as the product biodegrades naturally. This is in contrast to other void forming materials such as foam which merely deforms under pressure.
mastaVOID is a honeycomb cardboard sacrificial formwork. It is manufactured using 100% FSC Certified material. This means it is much more environmentally friendly than foam void formers.
Developed to create space between the soil and building’s foundation, mastaVOID reduces the upward force transmitted to the structure due to ground heave. The cardboard absorbs moisture from its surrounds and is eventually broken down completely, leaving behind a perfect void in the concrete construction.
It is designed for large-scale commercial and residential projects, specifically those located on reactive soil sites.
How strong is mastaVOID?
mastaVOID void former is extremely strong and able to withstand high-pressure loading. Not only does it absorb direct impact forces, but it also has the ability to support the concrete load during pouring.
Sheets are available in thicknesses from 50 mm to 200 mm, which have been independently tested for compressive strength. During testing, the 50 mm sheet resisted an average peak load of 106.6 kN of force, equivalent to 30,172 kg of peak load per square metre. Test results for all thicknesses of mastaVOID are listed in the table below.
Reliable, predictable performance
mastaVOID is the premier void forming solution for engineers and builders.
Having a genuine void under the concrete reduces the risk of the impact of the reactive soil on the structure. Damage from soil movement and pressure placed on the slab will be reduced. Plus, the large panel format makes for quick installation on site.
Supplied unpacked, bagged individually, or bagged as a pallet, mastaVOID sheets are delivered to you however you choose. Bagging protects the void former sheets from moisture and premature degradation until you are ready to use them. Concrete should only be poured over void formers if they are dry and in good condition.