An inspection of the concrete soffit above the suspended ceiling of a leisure complex swimming pool found severe corrosion of the reinforcement and extensive spalling of the concrete. The complex was housed in the basement of a converted building in North London and had structural steelwork installed some years ago during the conversion which had corroded with the resultant rust delaminating in layers.
Following a full concrete survey by a specialist consultant, we provided methods and budgets for the client and the Main Contractor and were able to negotiate the subcontract for the repair.
With the pool close for in excess of 6 months, the client required the remedial works and fitting out completed as soon as possible to limit revenue loss.
Weekly planning meetings, led by the hands-on client, were held with the all the specialist subcontractors and designers. These were essential as limited as-built drawings and details were available. A repair plan was agreed at negotiation stage and final details agreed as the areas were opened up.
The severity of concrete degradation resulted in the need to install major propping prior to removal of defective concrete. Over 1200 sacrificial anodes in strings of 10 were then installed to the soffit and beams to control corrosion together with monitoring anodes and boxes.
Preparation of the surfaces by open grit blasting was followed by repair using 7 tonnes of hand placed mortars and 30 tonnes of spray concrete. A cementitious fairing coat and elastomeric coating were applied to both the repaired and existing concrete to enhance protection to the structure.
The structural steelwork was also cleaned by grit blasting followed by the application of a high performance coating system.
Strict controls were put into place to reduce the risk to the health and safety of the operatives. These ranged from forced air to control dust and labour rotation for limiting exposure time to vibration from power tools.
Upon completion of the structural repairs, a high performance ceiling was installed to provide a moisture and temperature controlled environment for the structure with access made available to check the anode monitors.
Despite the many unknowns at planning stage the project was completed on time.