engleski

PAG BRIDGE – INSPECTION & TESTING OF THE ARCH AFTER 40 YEARS OF SERVICE

The Pag Bridge over the Fortica strait provides the fixed road link from the mainland to the island of Pag. The open spandrel sickle shaped concrete arch of 193.2 m span and the rise of 27.6 m was built in 1968. The bridge is located in aggressive maritime environment, with frequent strong winds spraying sea-salt on the exposed concrete surfaces. Reinforced concrete arch was repaired in 1991 with removal of the damaged concrete cover by a hydrodemolition device, grouting of all visible cracks, placing shotcrete strengthened by anchored reinforcement mesh and protected by special longlasting elastic coating. Both the superstructure and piers deteriorated even more inducing serious functional difficulties. The reconstruction commenced in 1999 and comprised replacing the existing superstructure by new steel superstructure and strengthening the piers. Bridge inspection and condition assessment was called for in 2009, but it focused on steel portion of the structure. However, limited testing and visual inspection of the accessible parts of the arch were carried out as well. Testing included half-cell potential measurements at locations where visual inspection indicated active corrosion process, laboratory testing of physical and mechanical properties (concrete strength and modulus of elasticity), permeability properties (capillary absorption and gas permeability), alkalinity properties and chloride content on 19 extracted cores, and rebound hammer was used to support the assessment of concrete quality. These revealed substantial defects in the reinforced concrete arch protection system and that further rehabilitation works are necessary.

Arch bridge; chloride corrosion; inspection; testing

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