Placing and finishing concrete during Colorado’s winters presents a unique set of challenges.
Freezing temperatures can compromise both the strength and appearance of freshly placed concrete. Concrete blankets are an essential tool for combating freezing temperatures, but without proper procedures, they can yield unsightly results.
In this post, we’ll explain the importance of concrete blankets and why they require the handling of an experienced contractor.
What Happens When Concrete Freezes?
When concrete freezes during the curing process, its strength is significantly reduced, and the surface becomes damaged. This often leads to delamination, which is when the top part of the concrete separates from the rest of the slab. You can spot delamination when chunks of the surface pop off or flake away. To prevent this kind of damage, the use of concrete/insulation blankets is essential during Colorado’s winter months.
How Do Concrete Blankets Prevent Freezing?
Concrete blankets are made of polyethylene with insulation sandwiched between layers. This design traps the heat naturally produced by concrete during the curing process- known as “The Heat of Hydration”.
Did you know that if concrete temperatures drop below 40°F, the cure process effectively stops? Concrete blankets ensure that doesn’t happen by holding in the natural heat produced during curing. Like a winter jacket for concrete!
Which Concrete Installations Require Blankets?
All concrete contractors rely on insulation blankets in cold weather, but they’re especially important for flatwork (like driveways, plazas, and decorative slabs).
Vertical pours, such as walls, often have wooden forms that provide enough insulation to protect against freezing, so blankets are generally reserved for open, exposed surfaces.
Other Winter Placement Techniques
Concrete blankets are just one part of a winter concrete toolkit. At Colorado Hardscapes, we also use:
- Hot water – This makes the most significant difference in keeping mix temperatures up during placement.
- Chemical accelerators – Used when extreme cold is expected, these compounds help speed up the curing process.
Downsides of Concrete Blankets
While essential, concrete blankets can cause issues if not handled properly:
- Poorly secured blankets can shift or blow off, exposing parts of the slab to freezing air.
- Surface marks: If placed too soon or applied unevenly, blankets can leave drag marks or indentations.
- “Blanket marks”: Unavoidable creases in blankets result in uneven contact across concrete, creating visible discoloration and mottling.
How We Minimize Blanket-Related Issues
At Colorado Hardscapes, we’ve refined our cold-weather techniques over decades to maintain both durability and appearance. Here’s how we prevent these common problems:
- Apply a spray-applied membrane curing compound: This compound helps concrete cure at one rate. We apply this compound at all times of the year, but it especially helps get an even cure under the blankets.
- Add a breathable buffer: We place breathable sheet-goods as a contact buffer between the concrete/insulation blanket and the concrete. Typically, we use landscaping fabric because of its breathability.
- Time our coverage carefully: We only cover the concrete when it is pertinent, such as on cold mornings, evenings, and nights. During warm daytime temperatures, we remove the blankets and let the concrete breathe. This reduces the chance of discoloration and allows the heat from the sun to help the curing process. We also often rinse down the concrete during this time to mitigate discoloration.
- Monitor temperatures: We can put sensors into concrete that measure temperature and strength gain. That information helps us know when we don’t need the blankets anymore. This is particularly useful for structural concrete installations.
- Heated Tents: If necessary, put up a low or high tent with heat pumped inside as a blanket alternative.
- Adjust Pour Time: During winter, we pour early in the day to take advantage of the warmest temperatures and maximize curing potential.
Final Thoughts…
At Colorado Hardscapes, we know that quality doesn’t pause for winter. Our 77+ years of experience have taught us the importance of precision, timing, and craftsmanship in every pour. Using proven winter placement techniques, we deliver concrete that performs beautifully—even through Colorado’s harshest seasons.
