A. Murray MacKay Bridge, Canada
Eliminator® system of choice for A. Murray Mackay Bridge refurbishment.
In a major refurbishment during the summer of 2001, the orthotropic steel deck of the MacKay Bridge was given new, long-term protection with the installation of the Eliminator® sprayed bridge deck waterproofing membrane.
Nova Scotia, Canada
Halifax-Dartmund Bridge Commission
Duron Atlantic Limited
- A. Murray MacKay Bridge, Nova Scotia, Canada
In 2000, the structure’s owners, the Halifax-Dartmouth Bridge Commission, employed O’Halloran Campbell Consultants to carry out a complete survey of the bridge deck. The study had shown that the 30-year-old bridge was exhibiting significant corrosion caused by the ingress of water and de-icing salts through the epoxy-asphalt surfacing.
Extensive laboratory and on-site testing was commissioned with a wide range of products including elastomeric membranes, skid/slip resistant surfacing and bituminous sheets.
Tests included freeze-thaw cycling, fatigue and bond strength tests. Following the evaluation of the results, the Bridge Commission selected Eliminator® membrane for protection of the critical suspended spans, an area of 39,000m2. In addition to its performance in the tests, the Eliminator® system also possessed an excellent proven track record on steel orthotropic decks in both cold and hot climates.
The bridge was vacuum-blasted to SP10 standard and then primed with the MR6 acrylic reactive primer, which incorporates zinc phosphate pigment to provide additional corrosion protection. Two distinct colour-coded coats of Eliminator® were then sprayed, the first at 80 mils and the second at 50 mils. Each of the coats can be over coated within 40 minutes of application and can be trafficked within an hour.
The Engineer specified an aggregate scatter into the freshly applied second coat to provide a shear key for the asphalt on the gradients. The seamless membrane system was completed with the application of Stirling Lloyd’s proprietary polymer modified bitumen tack coat, SA 1030, to provide a strong bond between the Eliminator® and the surfacing. The Bridge Commission intends that the Eliminator® system will allow the milling of the asphalt alone and its recapping when necessary, rather than removing the entire system down to the steel deck, saving both the steel deck and traffic disruption.
The Eliminator® waterproofing system was chosen from a range of products due to superior performance on a number of tests. Two colour coded coats of Eliminator® were spray applied, creating a seamless layer which will continue to protect the A Murray Mackay Bridge for the future.