Dealing With Winter Concrete Damage in the Spring
by TRP Ready Mix on March 11, 2019
Concrete Contractors & Suppliers Offer Concrete Repair Tips for Winter Damage
Winter weather will wreak havoc on your driveway, pathways, stairs, and any other exterior concrete slabs around your property, especially with the severe weather Ottawa is experiencing.
Moisture, the freeze-thaw cycle, de-icing salts, and blades from shovels and snow plows means your concrete had a lot thrown its way this winter. So, come spring, you’ll have to assess the damage and make necessary repairs.
To help you understand how winter can damage concrete, how to fix it, and the preventative measures you can take, read on.
Types of Winter Damage
Scaling is the most common type of damage for exterior concrete slabs. It occurs when the top layer of the concrete fails, which is also known as delamination. Scaling on concrete often looks like thin sheets or small scales are peeling off.
Scaling can vary in depth, from a thin layer that is thinner than a sheet of paper to deeper surface damage that exposes the fine and coarse aggregate in the upper layers of the concrete slab. And in mild cases, it may only appear as light-coloured specks, especially on painted, stained, coloured, and sealed surfaces.
While not always the case, scaling is often found in the middle of the slab and away from the slab’s joints and edges.
A combination of factors contributes to concrete scaling, with the most important factor being the quality of the finished concrete. How the concrete is mixed and installed will affect whether or not the concrete can withstand harsh winter damage. In other words, the concrete production method—the water-cement ratio of the concrete mix, the addition of water, air-entrainment, finishing practices, and curing conditions.
The depth of the damage is what differentiates scaling from spalling. Scaling is superficial while spalling is deeper.
Spalling is damage to the concrete’s surface that also extends deeper into the slab, exposing coarse aggregate. This damage can be found throughout the slab—at joints, cracks, edges, and mid-slab—and at depths between 1/8 of an inch to several inches.
Spalling can be caused by not repairing scaling on concrete. Poor mixing and placement methods, along with the freeze-thaw cycle in winter, also cause spalling—specifically, a high water-cement ratio, low air-entrainment, and poor finishing practices.
Expansion and control joints are supposed to be engineered to prevent damage during substrate movement. But when movement at a joint exceeds tolerance, the adjacent sections of the slab may shift, spall, and crack.
Concrete cracking is unavoidable. But the location and severity of the cracking can be controlled. Pouring concrete in cold weather can lead to cracking in unplanned locations. As concrete expands and contracts during the winter, it can crack in unsightly locations.
But control joints can help control cracking. Control joints are cuts in the slab where cracks will most likely occur. These provide relief when concrete contracts, allowing cracks to form more evenly in preferred locations.
Failing to address these issues can lead to the damage spreading and becoming irreparable larger-scale sheet delamination issues. So be sure to:
Concrete crack repair is simple and essential to prevent water from getting into cracks and causing more damage. Use a waterproof concrete crack sealant to fill the crack. This sealant will retain a flexible bond with both sides of the crack and restore the surface.
For larger cracks, first, remove any loose concrete with a soft bristle brush. Then place a backer rod into the divot before filling with sealant.
Making the necessary repairs to your concrete, such as concrete driveway repair, will prevent further damage and keep your concrete looking great for longer.
Preventative Measures to Take
The right amount of air-entrainment is the most important preventative measure to protect concrete from winter damage. Air-entrained concrete has air pockets for water to expand into when frozen. These air pockets help relieve internal pressure that causes damage.
To find out how much air-entrainment your concrete should have, speak with the ready-mix experts.
Too much water will lead to damage caused by freezing and expanding in winter. So trust that your ready-mix concrete supplier has used the right amount of water content in your professionally-mixed concrete and avoid adding more.
Additives can help protect concrete from winter damage. But these should only be used properly—with the right knowledge.
- Avoid Carbon Black pigments for exterior decorative concrete and stick with Iron oxide pigments;
- Use fiber reinforcement as a secondary reinforcement for crack prevention in winter; and,
- Avoid adding water-reducers, retarders, and accelerators to your concrete mix if you are inexperienced. Instead, leave this to the pros.
Use a wood or canvas-resin float when finishing concrete, and do not trowel-finish air-entrained concrete. Also, avoid over-vibrating concrete slabs with a power screed.
The proper installation of control and expansion joints will reduce stress on the concrete as it cures and when the temperature drops. And be sure to properly prepare the ground (sub-base) to prevent cracks from sub-base settlement.
Avoid De-Icing Salts
De-icing salts are a major cause of concrete damage in winter. These salts melt snow and ice, causing a salty slush to penetrate concrete slabs. Not only will this freeze and expand, causing damage, but the salt will also absorb more water in the concrete.
So, instead of de-icing salts, use sand or fine gravel to provide traction on slippery surfaces in winter.
Use a Plastic Shovel
When clearing off snow and ice from your concrete, use a plastic shovel to prevent damage. Metal shovels and snow blowers will cause damage to concrete. Also, only clear snow off concrete if necessary. For patios and other areas you don’t use in the winter, there is no need to clear the snow. Snow can actually provide a protective insulating layer for concrete in winter.
Re-Seal in Spring
To keep your concrete protected year-round, apply a sealant every two to three years. Re-sealing is also highly recommended to preserve the appearance of decorative concrete.
A penetrating sealer that bonds to the surface of the concrete can prevent water from penetrating the concrete. As a result, it can prevent cracking from water freezing and expanding in concrete.
Take steps to prevent winter damage. And if you notice damage come spring, be sure to repair your concrete as soon as possible to avoid further damage.
Contact concrete contractors and supplier for more help with your concrete project needs.