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While huddling around the fireplace this winter, are you thinking about your next concrete project? I know I am! The winter months are not only hard on us; they can also seriously shorten the life of concrete that’s exposed to salt (chlorides) or not placed with the right mix design. Whether you’re a DIYer, contractor, or simply a knowledge seeker, following a few guidelines will protect your project for many years to come.
The four aspects of long lasting concrete to withstand freeze thaw cycles and the effects of deicing chemicals are Mix Design, Proper Placement, Concrete Sealers, and Deicing Choices.
Mix Design: The best resistance to chloride resistant concrete is an air entrained low-permeability mix. The recipe can have lots of ingredients, including silica fume, fly ash, concrete additives, and the right amount of Portland cement. Seem like a lot to think about? Not really; just tell your concrete supplier what you’re building and they’ll set you up with the right mix design.
Proper Placement: The point here is that 70-80% of spring, summer, and fall days are great for pouring concrete. Just stay away from excessively windy and hot, sunny weather. Cloudy days are best so that the set time can be extended and you’re not pressured into adding water to finishing operations. Excess water and paste on the surface of your freshly placed patio is a sure fire way to get premature surface scaling. Cure the concrete for at least 7 days.
Concrete Sealer: After it’s cured, seal your project with a silane water-based product. There are many great sealers on the market and they really help to resist attack by deicing chemicals. Reseal the surface as recommended by the manufacturer. Usually every 2-3 years does the trick.
Deicing Choices: This has changed a lot since the days of just good old rock salt. Stop using that for projects that you care about. Calcium chloride is not a great choice, either, because it also attacks concrete. There are many high-performance de-icers on the market today that are much friendlier to our environment and the life of our concrete patios or sidewalks. Some of these products won’t tell you what’s in them exactly, but will typically work down to between -10 and -20 degrees. Look for a product that says it won’t damage your concrete. While these higher performance products do cost more, that’s pennies compared to replacing your concrete.
Now throw another log on the fire and plan your project!