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Stirling Lloyd Stop The Rot on Major US Causeway
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The Eliminator® system from Stirling Lloyd, the market leaders in structural protection, has recently played an important role in extending the life of one of New York's most distinctive structures.
Named after its initial proponent and main advocate, arguably New York's most famous state and municipal officer who is credited for probably the largest creation of public works in US History, the Robert Moses Causeway forms part of the route to the South Shore beaches along the Great South Bay of Long Island and the Atlantic Ocean.
Originally known as The Captree Parkway and Causeway, the Robert Moses Causeway carries approximately 30,000 vehicles each day. It is a route which sees a marked increase in traffic levels during the summer months as New Yorkers strive to escape the oppressive heat of the city and the surrounding suburbs by visiting the resorts of Jones and Fire Island Beaches.
The Fire Island Inlet Bridge, which is an integral part of the Causeway, is a two lane, steel arch span and causeway with a concrete deck that carries Route 908 over Fire Island Inlet. Construction of the Bridge was completed in 1964 and although a relatively young structure, less than 40 years old, its concrete deck has suffered from severe chloride ingress resulting in cracks, spalling and the formation of pot-holes.
Studies carried out on the substrate and the evident alarming level and rate of corrosion indicated that no protective waterproofing system was used on the deck when the bridge was built. The extent of the deterioration is such that New York State Department of Transportation (NYSDOT), who took over responsibility for the maintenance of structure in 1977, are soon to begin design studies to replace the bridge, highlighting the importance and cost-effectiveness of installing such a system during the initial construction.
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Any new structure built as a result of these design studies, in the longer term, will give the opportunity to alleviate some of the congestion at this well known choke point as the increasing recreational activity on Fire Island generates more traffic. However, in the meantime NYSDOT were keen to extend the life of the current structure by preventing further chloride ingress and slowing the rate of corrosion.
To achieve these goals a complete refurbishment of the deck was vital. The design engineers on the project, Hardesty & Hanover, to meet the Client’s brief specified the use of an effective, proven spray applied waterproofing membrane used in conjunction with a ¾” micro-surfacing overlay. This combination was specified as not only would it achieve the Client’s goal of extending the life of the structure, but by milling off ¾” of the concrete surfacing and replacing it with the same depth of micro-surfacing would ensure matching with existing joint elevations. More importantly the specified system would be lightweight - reducing dead load, could be applied rapidly so minimizing disruption to traffic and would be very cost effective. It was also paramount that the waterproofing system provided an excellent bond to the concrete deck, could follow the contours of the milled deck and had no vulnerable seams or joints. Crucial to the success of this strategy was the use of the correct waterproofing membrane that could provide the benefits listed above. Hardesty & Hanover specified the use of Stirling Lloyd's Eliminator® system. Eliminator® is a rapid curing, seamless, spray applied waterproofing membrane based on methyl methacrylate resins that has an unmatched track record with approvals from Road and Bridge Authorities around the world.
The Eliminator® system was selected for a number of reasons, not least for its past performance in similar circumstances. The shear forces exerted on the waterproofing / wearing course interface when using micro-surfacing are far greater than those associated with "normal" surfacing depths, however the Eliminator® system has proved that such is the bond it achieves to micro-surfacing it can easily withstand these forces. For example the system had already been very successfully used in conjunction with micro-surfacing on the Manhattan and Queensboro Bridges in New York City which are subjected to much heavier loads and much higher traffic densities. The Eliminator® system, being liquid applied, would also easily cope with the contours of the rough, milled concrete deck and its rapid, spray application and fast cure would ensure that the maintenance work would cause the minimum disruption possible, a major consideration on such a major route. The contract to apply the Eliminator® system was awarded to Venture Construction of Pembroke, New Hampshire, USA., one of Stirling Lloyd Products Inc. trained and authorised contractors.
Once the deck had been correctly prepared, Venture Construction would spray apply Stirling Lloyd’s PAR1 methyl methacrylate primer to the substrate. This sealed the deck and enhanced the adhesion of the subsequent membrane to the deck. Once the primer had cured, typically in well under one hour, the Eliminator® membrane was spray applied in two colour contrasting coats to aid quality control and ensure the integrity of the membrane. As part of the unique on-site Quality Assurance programme with the Eliminator® system, adhesion tests were carried out to confirm that the adhesion to the concrete was greater than the 100 psi (0.7 N/mm²) required by the specification and wet film thickness checks were used to constantly monitor the thickness of the membrane to ensure that the required thickness was achieved. The first coat, pigmented yellow, was applied to give a thickness of 80 mils (2mm). Once this had cured, typically in under one hour, the application of the second coat would begin. Pigmented grey, this was applied to give a thickness of 1mm. Whilst still in its liquid state aggregate was broadcast into the membrane to provide a mechanical shear key, enhancing the bond to the subsequently applied micro-surfacing.
Such is the speed and ease of application of the Eliminator® system that Venture Construction were able, despite the work restrictions imposed by the traffic management system and the work schedule of the micro surfacing operation, to apply the complete system to the 111,000 SF (10,225m²) of deck in just 12 days. Once application had taken place the system could be trafficked in under one hour enabling the micro-surfacing system to be applied without delay. The use of the Eliminator® system in conjunction with a micro-surfacing overlay has not only enabled NYSDOT to extend the life of the Fire Island Inlet Bridge but also succeeded in ensuring the successful strategy was completed in a timely and cost-effective way - adding another success to the hundreds of structures already waterproofed with the Eliminator® system throughout the USA.
[ Stirling Lloyd Press Release PR03-17 : 05/2003 ] |
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