C+S September 2020 Vol. 6 Issue 9 (web)

ELIMINATOR ® Waterproofing System Protects Landmark New York Bridge

By Tom Carter and Greg Laugeni

Designing bridges to stand the test of time is no mean feat at the best of times. When it came to replacing the old Tappan Zee Bridge with a new 3-mile twin span bridge across the Hudson River, the New York State Thruway Authority (NYSTA) and design-builder Tappan Zee Con- structors (TZC) needed to ensure the highest level of protection was achieved. With the added challenge of variable and extreme weather conditions, restricted working hours, and short possession times, the choice of waterproofing solution was crucial. Here we explore how these challenges were tackled, and review the results following the project’s completion. A massive fast-tracked waterproofing project The Governor Mario M. Cuomo Bridge is the largest single design- built contract for a transportation project in the U.S. and the longest bridge in the State of New York. Constructed of precast concrete deck panels that sit atop steel girders, the bridge is designed to achieve a 100-year service life. Both the scale and the construction schedule of the $3.98 billion project are noteworthy. This extends to the waterproofing of the bridge, which required surface preparation as well as the application of two layers of liquid waterproofing over 1.2M square feet in just three months. Early design support When it came to selecting the waterproofing solution, the specifiers were looking for a product with a proven track record on long span bridge decks. This led them to discover GCP Applied Technologies’ ELIMINATOR® system from Stirling Lloyd (now GCPApplied Tech- nologies). This liquid waterproofing membrane system has been used to protect the deck of many of the world’s biggest steel and concrete deck bridges for more than 25 years. After conducting an in-depth site visit, including inspection of the bridge deck, GCPApplied Technologies’Design Support Team worked closely with the project team to develop the waterproofing specifica- tions. This called for a solution that would provide speed and ease of installation, minimizing traffic disruption and facilitating contract pro- gression. The ELIMINATOR® waterproofing system satisfied these requirements, as it is spray applied and cures quickly (typically within the hour) to form a highly durable, seamless membrane. GCP also conducted compatibility testing of the bridge deck with the ELIMINATOR® membrane, and realized exceptional adhesion

Overcoating of ELIMINATOR® waterproofing can be done at any time, giving contractors greater flexibility.

results. The specifications also called for the use of a thin asphalt wearing course. Veteran waterproofing applicators working together Due to the massive scale of the waterproofing operation, a site visit by pre-selected certified ELIMINATOR® applicators was scheduled by TZC. It was recognized that only a select few, highly experienced, well-trained and well-equipped applicators would be able to perform all the work required within the parameters of the project construc- tion schedule. A shortlist of experienced ELIMINATOR® applicators visited the site to get a hands-on view of the scale, scope and timeline for waterproofing. TZC selected a joint venture led by Venture Con- struction, the largest ELIMINATOR® applicator in North America, and Thomarios, the applicator with the longest track record in North America, to install the ELIMINATOR® system. Supported by Venture’s large fleet of surface preparation machines and multiple crews from Venture and Thomarios, the applicators were able to cover 250,0002 feet a week, including surface preparation and ap- plication of the tack coat. Contractors were able to quickly apply ELIMINATOR® waterproofing to the Mario M. Cuomo Bridge using special spray machines.

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september 2020

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