I've had multiple conversations recently about applying salt during the winter months to our boardwalk system. I decided to post an email exchange about this topic for those who are considering a boardwalk application in an area with harsh winter climates.
An email from Nicole in Cincinnati, OH:
"Jason,
It was good meeting you yesterday and learning more about Permatrak. We were all happy with what you shared with us. The more we think about the product the more questions are arising that we will continue to follow-up on with you. One such question has already surfaced. We have some concerns about the product’s durability to withstand salt. Can you provide some insight on this concern? It seems the answer to snow removal in our area is to heavily salt it. So it is likely the boardwalk and pedestrian bridge will have a lot of exposure to salt. Are there any installations that you know of that have endured salt exposure and what do they look like? The installation in Beckett Park in West Chester, OH would be a good local example but do they salt it during inclement weather? Has it been installed long enough to experience winter conditions? Or are there other examples?
Any follow-up you can provide us is appreciated to help address our concerns.
Thank you.
Nicole"
Nicole brings up a lot of great points, common areas of concern for designers and owners living in states with snowy winters. Below is my response:
"Hello Nicole,
I hope all is well and you are moving along with your project.
Here is a little “food for thought” about durability, specifically about corrosion due to salting. I mentioned to you during our meeting that my background was with CONTECH as an engineer designing bridges (both vehicular and pedestrian). Those bridges were typically more in the critical salt paths. In deciding where to salt, owners typically go where the demand is first….so they salt the roads (main arterials first, then secondary roads etc, and then possibly pedestrian pathways). Therefore, the vehicular bridges had to deal with salting issues with every snow storm. The most common form of defense against corrosion due to salting was to require epoxy coating on the precast concrete's steel reinforcing. I recall several northern state DOTs requiring epoxy coated steel on certain structures. A second defense would be to increase the concrete earth cover so that the path for salts to the steel is a longer path. Longer path = longer time until corrosion sets in.
As we looked at the pedestrian bridges, salting was not very common. It was deemed less likely they would salt these crossings, but it did come up. For example, salting on a steel truss bridge is not a very good idea and I recall CONTECH’s warranty specifically requiring no salting. In lieu of salting, owners look at alternate solutions such as brine solutions, CMA, urea, etc. Here is an article with some ideas for salt alternatives.
Another thought I have on salting is to do what you normally would do for sidewalks. Our boardwalk is more likely to shed the salts (joints every 10” or 24”) than a concrete sidewalk. Also, reinforcing in sidewalks is typically wire mesh which is all interconnected. This provides a path for corrosion no matter how or where salt reaches the steel. Reinforcing in PermaTrak is not interconnected and if one bar began to corrode in a PermaTrak member, it would be unlikely to cause structural failure. In speaking with several owners of PermaTrak boardwalks, their response to the question ”Do you salt your boardwalks?” was either "No we don’t" or "We use a brine solution."
The town of Glastonbury, CT does not use a salt based solution for their snow icing process. FYI, we have PermaTrak projects installed in northern Ohio, CT, Northern California, Northern Indiana, and Massachusetts.
I hope this helps your thought process, and please let me know how progress is coming on your project. Sounds like a great project for Cinci!
Best Regards,
Jason"
If you have any further questions on salting or snow removal best practices for PermaTrak pedestrian boardwalks, feel free to email me or leave a comment on this post.
Photos:
1st photo of PermaTrak boardwalk in progress construction - Windsor, CT
2nd photo by tstadler
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