Deterioration of existing piers on the Congleton Road and Malkins Bank Bridges between junctions 16 and 17 of the M6 motorway was caused by the use of de-icing salts on the M6 and constant saturation.
Erosion of the concrete and the degeneration of the passive film around the reinforcement allowed the corrosion process to take hold. Subsequent expansive rust caused severe cracking of the concrete which further increased the corrosion.
CCL was commissioned to complete essential concrete repairs to the supporting piers of the bridges across this very busy carriageway. Using hydrodemolition and grit-blasting techniques, the company removed any concrete contaminated by chloride and reinstated it using sprayed concrete. To protect the reinforcement against further corrosion CCL installed sacrificial galvanic anodes.
Collection and disposal of the high volumes of water generated during the hydrodemolition works was carried out using a specialist water treatment system to filter the water and re-oxygenate it in order to neutralise the pH value, before it could enter the drainage system.