Concrete FAQs – Frequently Asked Questions

Do I really need to seal my type of concrete?

Exposed aggregate concrete is designed to be sealed, usually with a high-gloss sealant to create that “Wet Look”. One of the reasons it must be sealed is because of the open-pore design of the surface. If it is left unsealed, water and contaminants can easily enter the concrete and cause damage from freeze/thaw cycles as well as staining the aggregate. Stamped concrete is also designed to be sealed, and like all designed concrete, it will require maintenance to protect its finish. The colour coat is extremely thin, so be very careful not to do irreparable damage with a pressure washer.

What about all the other types of concrete?

It makes sense to maintain your concrete and avoid the substantial expense and hassle of replacing it after it becomes damaged. For concrete, sealing is a good preventative action to help prevent stains and damage from freeze/thaw, as well as environmental hazards.

All types of concrete can be sealed with several different types of sealant to choose from. Even the mostly overlooked garage floor is a great candidate for protection. Your garage floor takes most of the punishment during winter months because your car drops salt and debris collected from the road and deposits it on the concrete, where it attacks the surface, often resulting in pitting, chalking, and flaking. If you own a vehicle that leaks oil, you know how hard it is to clean off after a winter of leaking, even with a good pressure washer.

One popular type of finish for garage floors is an epoxy-based product that comes with a very long service life and is available in many colours, It can be installed with a grip surface to dramatically improve traction when wet. This type of finish is resistant to all oils, battery acid, brake fluids and of course salt.

How do I care for my concrete in winter?

You can help maintain concrete by shovelling the snow from your driveway, sidewalk and steps. By keeping the snow cleared, there is less chance it will compact down freezing into the surface and accelerate the freeze/thaw cycle. However, if you park on your driveway in the winter, do not shovel your driveway totally bare. The reason is that the salt that’s on your car is actually a very corrosive road gel that will eat your driveway when it falls off or melts. With a little bit of snow on the driveway, at least the snow will dilute it a bit, but if you can manage parking in the garage or on the road, that is your best bet.

Once spalling occurs, you really can’t do anything. It usually gets worse because water in the capillaries of the concrete expands when frozen and contracts when it thaws. Thus, making the concrete flake and break off, unfortunately, spalling is almost like cancer; once you have it, you can only slow it down; total eradication is impossible in most cases. The less number of times that water enters concrete and freezes, the less likely that it will become damaged. Use a plastic shovel instead of a metal one. Bent/sharp corners of a worn metal shovel can damage the surface of certain types of concrete.

Is it okay to use salt as a de-icer?

The short answer is NO. Salt is very corrosive to concrete and will eventually, if not immediately, cause damage to many types of concrete. As for de-icers, they all have their flaws and can damage your concrete. Do your homework.

What about environmentally friendly de-icers?

There are four primary types of de-icing salts that all have different characteristics and are each designed to work in certain temperature ranges.

1. The most common de-icing salt is regular rock salt or sodium chloride. It is widely available and can melt snow and ice until the temperature drops below -8 °c. Below these temperatures, the rock salt stops melting snow and ice. Rock salt also releases the highest amount of chloride ions when it dissolves. Chloride can pollute waterways, rivers, and lakes, and can also cause metal to corrode.
2. Calcium Chloride is another de-icing salt that is commonly marketed in tiny white pellets. It can melt snow and ice well below -17 °c. It can cause skin irritation if your hands are moist when using it, and it will chemically attack concrete.
3. Potassium Chloride is another de-icing salt that is now available. It is not a skin irritant and will not harm vegetation, but will only melt ice and snow when the temperature is above -9 °c.
4. The newest de-icing salt is Magnesium Chloride. It will continue to melt snow and ice well below -25 °c. This salt releases about 40 percent less chloride into the environment than either rock salt or Calcium Chloride. It can be less damaging to concrete surfaces of unknown or questionable quality.

Other De-Icing Problems

The common property of all different types of de-icers is that they all seem to have the potential to damage concrete, and some are harmful to the environment. Another potential problem with using a de-icer of any kind is the damage caused by increased freeze/thaw cycles.

For example, when a product rated for -9 °c melts snow and ice, it will enter the pores of the concrete as salty water. When the temperature drops below the rated temperature for that particular salt, it can refreeze and expand in the pores of the concrete, causing damage. Many types of salt de-icers are marketed as “Environmentally Friendly,” but still will damage your concrete. Be careful when using these products and read the directions carefully.

Have a Question Still?

If you still have a question about concrete repair, sealing, or restoration that wasn’t answered in this concrete FAQ, please call us anytime at (604) 690-7023 or email us. We would be happy to answer them for you.