Winter Maintenance and De-icing

How to protect your investment through harsh Canadian winters.


If there is one question that remains in the minds of many people, it’s the question about the performance of paving stones during the winter. The question covers such concerns as durability, skid resistance, snow clearing and de-icing. Durability is one of the things that Unilock paving stones are known for. Unilock paving stones have some of the highest compressive strength and lowest water absorption levels in the industry. The advantage of this is that the concrete will not absorb and trap water in its micro-voids, minimizing the risk of any water freezing and expanding, ultimately damaging the concrete. Skid resistance is one of the greatest benefits of Unilock paving stones. Many styles of Unilock paving stones have excellent skid resistance because of their textured surface. If skid resistance is a concern because of a sloped surface, you should select a Unilock textured surface for all or part of the installation. Snow clearing on paving stone surfaces is much easier than you think. Almost all Unilock paving stones have a slight bevel around the edge of the stone. Not only does this facilitate the movement of rainwater across the surface, but it also protects the edges from potential chipping by snow clearing equipment. We recommend that you always use a plastic snow shovel for paving stones. This means that your snow blower should also be fitted with a plastic shoe on the adjustable gliders and on the scoop edge. Hint: If you hire someone to plow your driveway, you must have your snow clearing firm confirm in writing that it has protective edges on the snowplow to avoid scratching the surface. Although the metal on snow clearing equipment will not adversely affect Unilock paving stones structurally, the contact of any steel on concrete can potentially leave tiny particles of metal in the surface of the concrete which will rust and leave unsightly brown streaks after a couple of months. (A good example of this can be seen on the municipal curbs at the street. Take a close look and you will see what the snowplows have done.) De-icing substances, when used in proper amounts, will not damage good-quality concrete. They will, however, speed up the surface wear on some styles of pavers. Many of the exposed aggregate products and tumbled products are unaffected by virtue of their style.

There are three types of de-icing salts:

Sodium chloride (common rock salt) is the most popular de-icing salt. It is widely available and it will melt snow and ice at temperatures down to approximately 16° F (-9° C). Below 16° F (-9° C), rock salt stops melting snow and ice. Sodium chloride can damage adjacent grass, plants and metal. Apply with caution and use as sparingly as possible.

Calcium chloride is another de-icing salt. It generally looks like small, white, round, pellets. It will melt snow down to about 0° F (-18° C). It can irritate skin. Studies indicate that depending on the concentration, calcium chloride is less damaging to grass than sodium chloride is. Heavy concentrations of calcium chloride can chemically attack concrete.

Potassium chloride is a de-icing salt available in some markets. It will not hurt skin or damage plants.

However, it melts ice only when the air temperature is above 15° F (-9° C), but it can be combined with
sand to improve effectiveness. Hint: If you do not know what is in your de-icing material, do not use it on concrete surfaces; just use sand to prevent slipping and sliding.

Note: Fertilizers that contain ammonium nitrate and ammonium sulfate should not be used for de-icing since these substances attack the integrity of concrete. Always read manufacturers’ recommendations for use and heed all warnings and cautions.