CCSL protects A9 Cromarty Bridge

CCSL was awarded a contract by BEAR Scotland at the A9 Cromarty Bridge Invernesshire to undertake the impressed current cathodic protection (ICCP) design for Phase II.

Prior to the site works commencing, investigations were undertaken to assess the effects ICCP would have on the existing Macalloy bars. Once this was determined not to be an issue, an ICCP and galvanic anode system was designed and accepted. CCSL engaged the services of CPA member Corrosion Prevention Limited to assist in the design.

The ICCP system comprised of two anode types: NMT discretes anodes 1,300mm long were drilled and installed into the stem wall from above the deck; and 350mm long discrete anodes were installed to the bearing shelf. CNT anode mesh was used to protect the diaphragm walls, atmospherically exposed capping beam, sides, column tops to MHWS and to the columns at mid-tide level. Impalloy galvanic anodes were used to protect the pile cap and columns up to mid-tide.

The works package comprised of hydrodemolition by CCSL’s sister company AquaForce Limited to remove the delaminated/spalled concrete, followed by sprayed concrete repairs undertaken by Gunite Solutions Limited. CCSL’s parent company Freyssinet installed the system under CCSL supervision.

Three piers were repaired and protected. The remote monitoring and control system was developed by CPA member Cathodic Protection Company Limited. CCSL has the contract to monitor the systems for 56 weeks and to incorporate the Phase I piers into the monitoring programme.