M60 Palatine Road Bridge
Balvac is Principal Contractor delivering the structural concrete repairs and impressed current cathodic protection (ICCP) works to pier crossheads supporting the M60 Palatine Road Bridge, for Highways England in Area 10. The bridge carries 80,000 vehicles per day over the River Mersey and Palatine Road in Manchester.
Each carriageway is constructed from 11 pre-stressed reinforced concrete beams, supported by 15 pier crossheads. The beams sit on bearings in a hidden half-joint detail, and leaking bridge deck joints have resulted in chloride contamination and corrosion within the half joint. The original reinforcement design led to a structurally vulnerable detail that is not visible or easily accessible.
The permanent works solution involves the phased breakout of defective concrete by hydrodemolition, and repair using flowable and dry spray concrete materials (class R4 mortars). The repaired crosshead is protected by an ICCP system to limit further corrosion, using a standard mesh anode and sprayed concrete overlay to the accessible beam surfaces. An innovative string anode protects the inaccessible upper beam reinforcement, which requires a 16m long, 50 mm diameter hole, to be cored longitudinally through the crosshead. All repairs have so far been undertaken with the pre-stressed concrete deck beams propped to relieve the load from the crossheads. This is carefully controlled and monitored to ensure a tolerance in differential movement of <0.5mm between adjacent beams.
Concrete Repair materials supplied by CRA member Weber, and the original CP design was by CPA member Mott MacDonald.