As good as new

The five storey building at New Inn Yard in Shoreditch, had been constructed in the 1950s using a reinforced ring beam design, and consisted of exposed concrete floor edges on each level which had been filled in with brickwork and masonry-style panels.

Stone Refurbishment was called in to complete a full concrete repair scheme, including joint sealing works to concrete window sills and protection and stabilisation of the brick work panels.

Stone had to implement a very specific style of technical design for the project due to the nature of the closely surrounded property, nestled among several other properties, as is common in this area of London, with access to the property a huge issue.

Stone Refurbishment’s experts recommended that the client, a resident himself in the upper floor apartments of the building, opted for a comprehensive concrete repair scheme to avoid the necessity of a further maintenance programme at a later date.

All of the work was carried out in compliance with BS EN 1504, the comprehensive British standards introduced for all concrete repair work. Stone’s started with the breaking out of all defective concrete elements which were then repaired using Sika MonoTop concrete repair products, highly-regarded for use on older buildings.

All concrete surfaces were cleaned using very high pressure water blasting to remove any unseen delaminated, weak or deteriorated concrete. Areas in need of repair were identified and were mechanically cut out. It was of paramount importance that no feathered edging or nails were left behind and that any tying wires found were fully removed.

Concrete on the exposed steel work of the building was removed to allow coating and compaction of repair material.

Once fully exposed, the steel work was cleaned using an abrasive blast technique, leaving the steel bright and free from any rust, scale, mortar or dust.

Before it could be used for the repairs, the reinforcement concrete had to be tested for contamination. It was then cleaned using a low pressure water blast to remove any further contaminates that could cause future corrosion and to roughen up the surrounding concrete in preparation for the repair mortar.

The now cleaned reinforcement was then coated twice with Sika MonoTop 610, a type of bonding primer and reinforcement protection, allowing adequate drying times between coats. Sika MonoTop repair mortar was then applied by hand to the pre-wetted areas of repair and compacted, again by hand, to ensure there were no air pockets whatsoever.

In some deeper areas of repair locations, some layers of the repair mortar were required to be layered promptly, after the previous coats of repair mortar were given time to have sufficiently stiffened.

In some locations this was not possible and so to avoid slumping or sagging these areas were allowed to dry for 24 hours. At this stage Sika MonoTop bonding bridge was applied to the previously dried mortar with top layers then applied again by hand. These were then finished with a float to achieve a smooth and neat finish in line with the existing building line.

Once all of the repairs were completed, Stone’s technicians applied the corrosion inhibitor, Sika Ferrogard 903, to all of the concrete elements of the repairs to absorb onto the surface of the embedded steel to reduce the corrosion rate and delay any future corrosion.

The final step in the concrete repair process was to apply the final protective coating of Sikagard 680S to the brickwork panels, a clear glaze providing an anti-carbonation coat.

Stone Technical Services was established in 1998 by brothers Dave and Grahame Stone.
www.stoneservices.co.uk