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Void Form bolts on concrete


GROUNDWORK contractors have often complained of the difficulties involved in casting concrete pads around the connection bolts that fix steel columns to the foundations.

Traditionally, paper cones have been placed around the bolts to allow some freedom of movement after the foundations have been poured, ensuring the bolts line-up correctly with the column connection plate.

But these can collapse, causing deformation in the bolt box and should be removed from the foundation after casting.

Now a Darlington-based company has developed a sacrificial bolt box formwork system that it claims will slash installation and labour time by up to 60 per cent.

Dean Brown, who, alongside partners Saul Charlton and Simon Johnson, developed and patented the Void Form, said the seed of the idea came after he experienced delays on a small industrial site.

He said: 'We experienced problems with the paper cones and thought there must be a better and more time efficient way of achieving alignment.'

Following trials, the team eventually came up with the final design, a rigid polypropylene version of the traditional cone.

The Void Form is slipped over the bolts and set into position by the groundworkers, a cap slips over the top of the formwork to ensure no water or debris can reach the steel bolts before the foundations are cast.

Steel erectors position the column connection plates and voids are grouted up, leaving the polypropylene form in situ.

Mr Brown said the form had been trialled on a site in Thirsk, North Yorkshire, by steelwork contractor Severfield Reeve, and claimed it saved 60 per cent in time and labour costs.