C+S January 2020 Vol. 6 Issue 1 (web)

Protecting Bridges in Extreme Climates By Jason Armstrong

Harsh weather conditions can be a challenge for bridge construction and renovation projects, in more ways than one. Both concrete and steel bridges are susceptible to corrosion from water and waterborne contaminants, which can impact their service life. This means selecting the best waterproofing solution is crucial. However, knowing what to look out for when selecting a waterproofing system isn’t always easy. The view from the bridge Crumbling roads and bridges are causing deep concern for government officials and transportation agencies around the world. Aging infra- structure, combined with increasing traffic growth, put into question the long-term viability of many rail and road bridges. Corrosion of reinforcement due to chloride-ion contamination in reinforced concrete bridge structures is known to be one of the major causes for deteriora- tion in highway bridges. Extremes in cold, heat, and even humidity are a major factor in bridge construction and renovation — often throwing project schedules off course. Some bridge waterproofing membranes are extremely sensitive to moisture and have a limited temperature and humidity application window. This can leave work crews waiting around at the mercy of the weather, leading to lost productivity, delays to construction schedules and revenue loss. Getting to the root of the problem Increasing traffic levels, the increased size of today’s vehicles as well as increases in carbon dioxide, sulphates, sulphuric acid and chloride ions from de-icing salts are all contributing to the deterioration of exist- ing bridge infrastructure.  Both refurbishment and new bridge projects must be designed with this in mind.    Concrete bridge deck deterioration is one of the most extensive bridge maintenance problems affecting the service life of bridges. The use of waterproofing membranes is one strategy to prevent moisture and chlorides from reaching the concrete by providing a barrier on the top of the concrete deck. The waterproofing membrane is then protected With new structures come high expectations and pressure to achieve greater than 100-year service life and limit the need for frequent and disruptive repairs. The need for future proofing against increased com- plexity of design and anticipated traffic volumes are all factors adding to the challenge of bridge protection.   from the traffic by an asphalt overlay. A forward thinking approach

To reduce the risk of deterioration, quality waterproofing should be considered at the early stages of the project. The bridge deck, water- proofing membrane, and surfacing need to be considered together. Achieving the optimum combination extends the life and reduces maintenance cycles, future disruption, and the overall project costs.    The closure of busy bridges for refurbishment work can cause major and costly disruption. Incorporating a quality waterproofing system to protect aging bridges for the long term is essential in reducing ongoing maintenance and subsequent bridge closures.    What to look for in a waterproofing membrane  The type of waterproofing membrane needed varies depending on several factors. For bridge refurbishments, typically there is a focus on reducing future maintenance and dead load and on choosing a mem- brane that’s quick to apply to reduce closure times. For new bridge construction projects, there is a focus on choosing a membrane that will offer long-term asset protection.     Key factors to consider when comparing waterproofing systems:   • Longevity of the waterproofing membrane  • Condition of the deck  • Type and depth of proposed paving  • Length of bridge closures and/or night possession • Phasing of works • Preventing costly overruns  When it comes to waterproofing bridge decks, it’s easy to assume that all liquid waterproofing systems are the same. After all, they may look very similar on paper. However, there are key questions to ask when specifying liquid waterproofing to ensure you get a system that’s du- rable and can be applied quickly, to help keep the bridge project on track. 1. How quickly can the waterproofing membrane be applied? Choosing a bridge waterproofing membrane that can be sprayed on fast and cures quickly is the first step. However, the real application time often comes down to what weather and temperature restrictions there Since the ELIMINATOR system cured quickly, multiple trades could finish their work on the bridge quickly. • Climate conditions and environmental challenges  • Availability of reference sites for similar projects 


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