This paper describes the investigation and rehabilitation of Mewata Bridge in Calgary, Alberta, Canada. Mewata Bridge is a 152.40 m long, three span, multicell reinforced concrete boxgirder bridge with a deck area of 2800 m² approximately, over the Bow River. Detailed diagnostic tests confirmed extensive deterioration of concrete deck with large areas of the deck showing active corrosion. The four lane bridge required to be repaired, with at least two lanes open to traffic throughout the repair process. The key elements to the repair process were the following: 1. Use of ultrahigh pressure hydrojetting, to avoid microcracking of the structure during demolition of poor concrete; 2. Use of high performance concrete, i.e. Pyrament Cement Concrete, guaranteeing high bond strength and very high compressive strength at an early age; 3. Staging of items 1 and 2 above in a strip pattern to eliminate premature overstressing of the bridge. Hydromilling is a state of the art demolition technique guaranteeing overall safety of the demolition process and lending itself to the repair of the bridge in precise longitudinal strips. Pyrament Cement Concrete performed the crucial function of developing high bond strength with the main flexural steel over the piers and was specified to have a minimum compressive strength of 24.0 MPa in 12 hours. Full traffic could be allowed on the repaired strip in 24.0 hours. Pyrament Cement Concrete also allows hydromilling adjacent to a strip that has been poured only 12 hours earlier without debonding. (A)
Samenvatting