The Mace Group who operate as project managers on behalf of the NHS Trust called in specialist contractor Cemplas Waterproofing and Concrete Repairs Ltd to survey a 25m high redundant external concrete chimney which had been subjected to years of carbonation resulting in the re-enforcing steel to rust and cause large areas of concrete to spall.

Based on the survey by Cemplas, together with Cambell Reith Engineers Cemplas put together a specification together with a quotation based on fully scaffolding the chimney and undertaking the remedial works.

The specification and remedial repair costs submitted by Cemplas were accepted and a order was placed to undertake and complete the works over a four week period.


Due to the nature of the works Cemplas were requested by the Hospital to erect the scaffold to the full height of the stack over two weekends. Once erected the scaffold was encapsulated with monaflex sheeting.

Work commenced by hammer testing the entire area of the stack together with breaking out all defective areas, and to ensure there was noise disruption to the hospital patients, all breaking out works were undertaken over a single weekend.

Cemplas operatives then applied Sika Ferroguard 903 corrosion inhibitor, and primed the reinforcement with Sika Monotop 610 rust inhibitor prior to reinstating the defective broken out concrete with Sika’s Monotop 615. Once all repairs had been completed the stack was jet washed to leave a clean substrate for the application of three coats of SikaTop 107 slurry coating.

Cemplas applied the first coat of SikaTop 107 protective slurry coating, incorporating mesh reinforcement which was followed by two further coats of 107 slurry.

Once the slurry had cured, two coats of steel protection paint was applied to the steel restraining bands around the perimeter of the chimney.

All works undertaken by Cemplas were completed on time, and on budge to the client’s complete satisfaction,.

www.cemplas.co.uk