Concrete is guaranteed do two things, it will get hard, and it will eventually crack. This is never truer than when winter comes knocking. Concrete can sustain damage as seasons change and temperatures begin to fluctuate. Of course, you want concrete to harden - that’s the point of concrete - but the cracking, flaking, and pitting, not so much. This creates an unsightly appearance and requires regular maintenance for property owners, as well as creating hazardous conditions for patrons and personnel.
Yes, you can prevent concrete damage by strategically cutting it, using additives, and by applying reinforcement upon installation, but did you know you can also take seasonal steps to further protect it from damage, and protect people from harm?
If you melt it … they can walk: Using salt to melt ice
The average winter temperature in more than half of the United States falls below freezing, and for those of us lucky enough to live in one of those states, we get to deal with subzero temps, blinding snow, and the ice that accompanies those freezes.
Ice is slippery and dangerous to traverse, and melting it is the most logical thing to thwart it, right? Most commonly we use salt for this application and, quite frankly, melting ice from concrete with salt works great! Just sprinkle a little on and watch ice magically melt away. Practical. Easy. No big deal. But the problem is, melting ice creates water, and as hard as concrete is, it is also porous, and the water from that melting ice will penetrate the concrete.
In warm weather, when concrete gets wet, the sun dries it out without incident. But when you add freezing temperatures to the forecast, adding salt, or any other type of ice melt, forces it to melt and causes what is called a “freeze-thaw cycle.”
The water that is absorbed into the concrete will freeze and expand. This will create a condition called “spalling,” making the top surface of the concrete detach and flake off from the concrete below. This can also cause the concrete to crack in areas that were left unprotected during installation.
Typical Concrete Spalling/Cracking
But doesn’t sodium chloride (salt) react with concrete?
No. It is a common myth that sodium chloride chemically reacts with concrete itself. It can, however, have other negative effects, and finding a “safe” solution to easily melt ice from concrete is a tricky prospect. While the sodium chloride has no effect on the concrete itself, if the melting salty water seeps into the pores of the concrete and reaches the cavities provided by the rebar reinforcement placed within, the freeze-thaw effect will occur and your concrete will most certainly spall or crack.
Save that salt for your water softener: Alternative Solutions
Probably the single best means to keep ice on concrete at bay is through good old-fashioned shoveling. Clearing walks following a snowfall prevents build up and keeps the freeze-thaw effect from happening. Take care what equipment you select, however, because new concrete (under one year old), can be damaged by scraping. Use a plastic shovel to minimize potential damage.
As any good mid-westerner knows, mother nature rarely sends lightweight, easy-to-shovel snow. Often, we get some ice, followed by heavy, wet snow, followed by winter sun which immediately begins melting just the top layer, while creating treacherous ice underneath. When this happens, no amount of shoveling will help, and sand can be a great alternative to salt. It provides traction on the ice, reducing the probability of slipping and falling, but a major downside is that it is messy and sticks to your boots, tracking in with you anywhere you go.
Grit is also a solution. This is more course than sand and can be applied in a lesser amount. Also, the darker color can assist with melting as the temperatures warm, but, just like sand, it is messy.
Another option is to seal concrete surfaces. This can be highly effective in protecting your concrete from winter, as it will prevent water from being absorbed into the concrete. There are two types of concrete sealers to consider: film-forming sealers and penetrating sealers.
Film-forming sealers will give concrete a wet, high gloss appearance. This is typically used on decorative concrete that is stained, colored, or exposed aggregate. It is recommended you reapply this type of sealer every two to three years to maintain the protection and appearance.
Film-forming sealer being applied
Penetrating sealers are just that; they penetrate the pores of the concrete to form a chemical barrier that will prevent water from getting in. They do not peel or wear off like film-forming sealers, and typical reapplication is once every three years.
Penetrating sealed concrete
Heated Sidewalks Keep Surfaces Dry, Safe, and Prevent Damage
Probably one of the best solutions is heated sidewalks. While there are upfront costs, it eliminates the need for any sort of de-icing and drastically reduces the freeze-thaw effect that is so damaging to concrete. These systems can be heated electronically, or through water piping in the sidewalk via heated water circulating from a boiler. While this may be impractical for large areas, such as in parking lots, it works very well on sidewalks and for entrances to buildings.
While we can’t control the weather, we can make conscious choices in how we mitigate its negative effects. Although ice melting agents are tempting to use because they are convenient, consider other options to ensure protection of your investment for many years to come. When you are looking at your next project, be sure to consider how you can make this annual nuisance less annoying and easier for you to manage.
If you want to know more about this, or want to talk more about other considerations to make when planning a build, be sure to contact us; we’re always happy to chat!
About the Author
Paul Block has been a project manager with Shingobee Builders for three years. He has over 20 years of experience in various facets of the construction industry, including work with concrete construction. In his time with Shingobee, he has managed retail, restaurant, financial, and telecommunications projects.