The strengthening process used stress bar post tensioning and carbon fibre reinforcing strips. Associated works included crack sealing, construction of extensions to the bridge piers and replacement of bearings, of both elastomeric and fixed disktron types. Scope also involved fabrication and supply of 29mm bars for installation and tensioning at the soffits, and 32mm bars at the deck-top.
Features of Abergeldie’s approach were controlled hydro-demolition of the existing concrete bridge deck surface to expose the installation points for the new 32mm bars. Careful attention to environmental controls was required to manage the collection and disposal of slurry spoil from the process. A temporary holding tank was used to collect the slurry, which was later pumped out and disposed of away from the site. Carbon fibre geotextile fabric reinforcing strips were applied using chemical anchors. For the placement of new concrete to make good the bridge deck, stiff PVC board was used to create sacrificial formwork.
Traffic management was a significant issue, with careful planning needed to limit lane closures and minimise disruption of normal vehicle flows, particularly during peak hours.
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