are for applying the waterproofing system. Many liquid waterproofing systems are highly sensitive to moisture. Unfortunately, this means applicators have to wait around for the right weather conditions before they can apply the waterproofing. This puts added pressure on bridge owners, who may face complaints from the public the longer construction or lane closures go on. Choosing a waterproofing system that is less moisture sensitive helps avoid these delays. This can also be highly beneficial for contractors, who are often rewarded or avoid penalisation based on completion time. 2. How do I ensure the waterproofing membrane is applied correctly? Your waterproofing system is only as good as those who are applying it. Ask potential bridge deck waterproofing manufacturers if they have an approved contractor program and how their contractors are selected. Be sure to get references for projects that are similar to yours. It’s equally important to find out how and when quality control mea- sures are taken. For example, spraying on the liquid waterproofing at the right thickness is essential to performance. Applying too thin a layer will compromise the physical performance of the membrane while applying too thick a layer may stress the bond of the paving. Applicators using the ELIMINATOR® bridge deck membrane follow on-the-spot quality control measures, so they can quickly identify and resolve any issues. It is important to ensure you have the appropri- ate film thickness, measurable at the time of application. A two-coat system makes it easy to spray at the correct thickness. Tensile adhesion test, wet-film thickness tests, and electrical integrity testing are also performed throughout the application process. 3. How easy is it to repair the bridge deck waterproofing membrane? Bridges are busy sites that have open exposure to a host of contami- nants, not to mention multiple trades working together simultaneously. It’s best to choose a bridge deck waterproofing system that can be re- paired on-the-spot if the membrane does get damaged. This helps keep the bridge construction on track. 4. How do you test the performance of your waterproofing system? In many regions, there are independent organizations that validate the performance characteristics of bridge deck waterproofing systems. 5. Can you demonstrate that your bridge deck waterproofing membrane stands up over the years? Ask manufacturers for both references from long-term bridge projects as well as accelerated age testing data to see how the membranes have performed over the ensuing decades since they were applied. Products in Practice Historic bridge requires bridge deck waterproofing One landmark bridge structure in the Czech Republic tackled these challenges by choosing a bridge deck waterproofing system that could both resist unforgiving environmental conditions and be applied vir- tually year-round. Flooding as well as wear and tear from weather required the 650-year-old Charles Bridge to face a major renovation, including repairing the upper bridge section, replacing the old concrete
deck, installing new waterproofing system, replacing stones in sills, adding new drainage, and repairing the structure’s pillars. To extend the life of the bridge, the engineers on the project were keen to use an innovative and long-lasting solution for this work. GCP Ap- plied Technologies’ ELIMINATOR® system was chosen due to its ability to provide a tough, durable membrane that achieves the required bond strength. Based on its unique ESSELAC® technology, the ELIM- INATOR® system can be applied in a wide range of temperatures and climatic conditions, which meant that installation of the waterproofing could be carried out throughout the year, a feature which the competing systems were unable to offer. Europe’s busiest bridges seek swift repair solution The Second Bosphorus Bridge in Istanbul took a similar approach. Made up of two elegant, steel deck structures, the bridge joins Eu- rope and Asia across the narrow straits of the Bosphorus while the Haliç Bridge carries the O-1 Highway over the Golden Horn Estuary. Between the pair they carry 330,000 vehicles per day, making them Europe’s busiest road bridges. To reduce traffic disruption during waterproofing and resurfacing of the bridge decks, the project team needed a waterproofing solution that was fast to apply, rapid curing, durable, and tolerant of difficult site and climatic conditions. Based on their previous experience, KGM (the Turkish General Directorate of Highways) selected the ELIMINA- TOR® bridge deck waterproofing membrane to protect the two bridges. The ease of application of the cold, spray-applied ELIMINATOR® system helped speed up the contract. The waterproofing system was rapidly applied using portable, simple-to-use airless spray equipment, and the liquid waterproofing solution fully cured in under an hour, at which point it could be trafficked. The ELIMINATOR® system’s tolerance of climatic conditions, ability to bond to itself, and to accept full site traffic after only one hour, allow other trades to access the bridge at all times. These benefits enabled the 33,600m² deck of the Second Bosphorus Bridge and the 40,000m² deck of the Haliç Bridge to be completed 30 days ahead of schedule. Bridging the gap deliver long-term results In summary, a careful considered approach to specifying bridge deck waterproofing is crucial in today’s world where extreme and often vari- able weather conditions are on the rise, causing an increase in cases of bridge deterioration. Growth in population in urban environments is also putting increased pressure on bridges, so protecting structures to ensure a longer service life is more important than ever. Not all wa- terproofing solutions are the same, however, so it’s important to look for systems with a proven track record, accreditation, and fast-curing systems that will enable quick and smooth installation to facilitate the wider construction work at play. Finding a company with experts on hand to guide you through the specification is a good way to ensure the plans are fool-proof and tailored to the specific project.
JASON ARMSTRONG is the Product Marketing Manager at Liquid Waterproofing EMEA at GCP Applied Technologies.
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