London - slab re-levelling: Kentish Town City Farm
Kentish Town Farm is situated in the busy suburbs of London. It’s a free entry, charity farm whose objective is to provide families with access to see a live farm in the inner city.
The farm itself is built upon land around the main railway line into London, it features a main building constructed in the 1950’s. The original building was built off a concrete slab, that was now bowing, this had resulted in significant cracking on internal walls and was compromising the structural integrity. Furthermore, doors were not shutting correctly and there were large gaps between the floor and the skirting.
Uretek were called in to provide a geo-polymer injection solution that would result in the lifting and re-leveling of the bowed slab.
A key reason for using Uretek was the lack of disruption to the building and farm itself. We could station an isolated unit adjacent to the farm building for two days and solve the problem. Where we were not working inside, those areas of the building could remain in use, and public access to the farm itself remained open. This enabled the farm, its staff and the general public to maintain virtually a normal operating use of the site.
Our solution required the injection of expansive geo-polymer material beneath the slab throughout the building. A programme of work was designed by in-house engineers, which was then followed by technical teams on site. The works programme would see a pattern of drilling 16mm holes into the concrete slab throughout the site at 1.5m centres, technicians then insert steel tubes into the slab and pump geo-polymer material beneath.
The geo-polymer material works by expanding under the slab, a reaction takes place whereby the material which is injected in liquid form, expands and turns into a solid. As the material expands it fills voids underneath the slab and forces out any localised groundwater, once the material can’t expand any further beneath the slab, it follows the path of least resistance which means the pressure of expansion begins to lift the slab. We monitor the lift using lasers that record an accuracy of 0.25mm, this highly accurate monitoring enables us to stablise areas where no-lift is require.
In this case there were visible cracks to the wall and gaps to the skirting, so we injected material and lifted the slab until cracks closed and the floor met the skirting. The small drilling holes on the floor are resin filled, leaving minimal signs of any work having been done.
Please contact us if you have a concrete floor that has dropped or for any other queries.