전화: +41-44-872 40 50
All’s well and good at the Welland Canal in Canada – particularly in relation to the new POLYFLEX-ADVANCED flexible plug expansion joints of its Lock 2 Road Bridge
The Welland Canal connects two of North America’s great lakes, Lake Ontario and Lake Erie, providing an alternative route to the nearby Niagara River which the mighty Niagara Falls, with their 51-meter (167-ft) drop, make unnavigable for shipping. The canal – a key element of the St. Lawrence Seaway which makes the Great Lakes navigable from the Atlantic Ocean – has eight locks, which enable the total level difference of approximately 100 m (328 ft) between the two lakes to be negotiated safely. A bridge at Lock 2 carries Niagara Regional Road 83 across the canal, with one section of the bridge rising when required to allow ships to pass as they transport roughly 40 million tonnes of cargo along the canal each year.
In early 2017, as part of an overall bridge renovation project, new POLYFLEX® ADVANCED expansion joints, for SLS movements of 30 mm (1.2 inches), were installed at four structure axes, replacing bituminous plug joints that had proven unsatisfactory in the past. Such bituminous/asphaltic plug joints have long been plagued with durability problems, especially at low or high temperatures. Inconsistent quality due to improper mixing and incorrect temperature during installation (high temperatures required) also frequently cause problems.
POLYFLEX®ADVANCED flexible plug expansion joints, with a flexible driving surface of high-performance polyurethane, might be thought of as the modern version of bituminous plug joints. Like the traditional plug joint type, they create a smooth, safe, low-noise surface, and offer great adaptability and easy installation, but they additionally offer greatly improved reliability, strength, elasticity and durability. They also offer greater movement capacity, uniform material behavior at very high and very low temperatures, and easier installation at ambient temperatures. And the speed of installation and curing of the material is particularly beneficial when the joint is installed on an existing structure to replace an old expansion joint – as was the case in this particular project.
With this far superior type of expansion joint now installed in the structure’s deck, the bridge’s owner can be confident that the joints will perform well for many years to come.
Cross section of the new carriageway joint, showing an optional polymer concrete base that may be used as required – e.g. to form a suitable subsurface for the poured POLYFLEX® material or to reduce the depth of POLYFLEX® material required (and also forming an ideal connection to the bridge deck’s waterproofing membrane at each side)