Leeds City Council has selected Sika’s carbon fibre wrap system for Phase 2 of the refurbishment and strengthening of the Matthew Murray Tunnel in Leeds, UK.
The reinforced concrete tunnel is 160 metres long and was built in 1974 as part of the dual carriageway A463 Ingram Road Distributor that runs between Junction 2 of the M621 and the Armley Gyratory. To keep traffic disruption to a minimum, work was carried out during night hours, with a contraflow operating in the northbound tunnel.
Over the years, continuous attack from de-icing salts has contaminated the pier between the two carriageways, leading to corrosion of the steel reinforcement and spalling of the cover concrete.
To bring the tunnel back up to strength, particularly in relation to accident impact damage, the tunnel has been refurbished in two phases.
Phase 1 was completed in 2003 and involved the removal of all defective concrete and reinforcement in the northbound tunnel, and replacing with new reinforcement and sprayed concrete.
For phase 2, which has been recently completed, Leeds City Council chose a more radical solution.
Deterioration of the southbound tunnel had not been so extensive, but some repairs and additional strength was required to complement the work completed on the northbound side of the pier. Balvac Limited were appointed main contractors to carry out repairs and install the Sika fabric wrap reinforcing system.
Following removal of any defective concrete, local repairs were completed using SikaCem 133 Gunite, a one part, dry spray micro repair concrete. Up to seven layers of SikaWrap carbon fibre fabric wrap were then bonded to the intermediate wall by Balvac Limited, using the SikaDur range of epoxy resins. Sika said that this process adds considerable strength to the wall, helping to contain the concrete and retain the integrity of the structure in the event of impact forces being applied.
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