Home » Projects » Void Filling beneath a gas sub-station – Romford, UK


Geobear was contacted to use it’s geoopolymer material to fill a void beneath a gas substation. The substation is situated on a slab supported at both ends by concrete rafts, visual inspections indicated the presence of a void beneath the centre of the slab. The void, caused by a combination of wash out and burrowing animals, would be a significant safety issue if left unattended.

The primary concern was any bowing or sinking of the slab. Housing very sensitive pipe work for the gas substation meant a significant bow could cause a fracture of one of the pipes either above or below the slab, which would be a significant safety threat.

Geobear solution

The substation is housed on a small concrete slab with limited access. A key feature of using Geobear is that our solutions can be applied within small confined spaces.

Our void filling process requires the drilling of small 16mm holes through the concrete slab, steel tubes are then inserted into the holes which allows for a geopolymer material to be injected into the void. The geopolymer material is pumped directly from the Geobear vehicle stationed adjacent to the site through hoses connected to the steel tubes.

The material used is formed from two liquid components. When the components mix a reaction occurs in which the materials ‘polymerise’ and expand to fill the voids. The size of the void dictates the amount of material required and both visual and laser monitoring is used to ensure the void is completely filled and there is no lateral movement of the slab.

Why Geobear?

This project was completed by one of our technical teams within one day with the voided area completely filled with the geopolymer material. The lightweight nature of the material also meant no additional loads were on the soil below.

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We deliver projects on any sort of building or structure – from conservatory extension problems to 80,000m2 warehouses and road infrastructure. In most cases we will have the best solution, so get in touch today.

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