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Tue, Sept. 17

Ice melts can have an impact on concrete

Most concrete is damaged by water seeping in, freezing, then thawing. Removing snow helps. (Metro Creative Graphics)

Most concrete is damaged by water seeping in, freezing, then thawing. Removing snow helps. (Metro Creative Graphics)

Do de-icers or ice melts damage concrete?

Winter brings the most picturesque scenes, but it also brings a rise in weather-related problems. Of these, ice and its removal are among the most critical. Unfortunately, there are a small percentage of those who crack their ice dilemma only to face another problem when spring arrives; damaged concrete. There is much confusion surrounding this damage which is mostly caused by the freeze/thaw cycle. Too often people attribute concrete damage to the ice melt that was used.

There are several chemicals, some of which are used in ice melt that actually attack concrete and are best avoided. They are: Aluminum chloride, ammonium sulfate, calcium sulfate, magnesium chloride, ammonium nitrate, ammonium chloride, magnesium sulfate and sodium cyanide.

By far the most risk of damage to your concrete during the winter months is attributed to the freeze/thaw cycle. This is the build up of water (melted ice) being absorbed into porous concrete, which then freezes and expands. This expansion within the concrete causes pressure to build up and eventually this build up will exceed the limit that the concrete was built to withstand. When the pressure becomes too much for the concrete to withstand, scaling generally occurs.

The freeze/thaw cycle is a natural process and there is no way of eliminating it. However, to reduce the damage caused by this cycle, it is strongly recommended that after applying the ice melt and when the ice turns to slush, that the slush be removed from the pavement, sidewalk or driveway to reduce the amount of water that may penetrate the concrete, thus reducing the pressure build up.

Using an ice melt that contains calcium chloride tends to re-freeze more quickly compared to using ice melt containing potassium chloride. By using potassium chloride, you extend the time available for more melted ice (water) to drain off your concrete or evaporate, resulting in less water being absorbed by the concrete.

Here are some types of damage that can be attributed to the freeze/thaw cycle:

▶ Popout: Popouts occur due to internal swelling in the concrete causing small fragments of concrete to break away from the surface. Popouts are usually caused by highly absorbent rocks that are not capable of holding a lot of pressure. When freezing occurs under moist conditions, the rock will swell and break from the concrete surface.

▶ Mortar flaking: A type of scaling where the top layer of concrete will break away from the foundation upon freezing when it is saturated with water.

When pouring concrete, ensure that your concrete is of the highest quality and standard. A high grade and durable concrete mix should be used. The concrete should be properly sloped to ensure that water drains away. Proper finishing practices are also important for the creation of a strong concrete surface. The concrete must be cured promptly and followed by an air-drying method.

Do not use ice melt on already damaged concrete. Damaged concrete will only absorb the water more readily since its seal has already been broken and therefore is more susceptible to damage. For concrete that is less than 12 months old, you should not use any ice melt. Newly poured concrete needs time to cure and settle and using ice melt may weaken the structure making it more susceptible to damage in the future.

It is important to understand how various ice melt products will affect the concrete and their immediate environment.

Sodium chloride for example, will attack the metal rebar contained within the concrete when it is soaked up into the concrete and also damages surrounding vegetation, soil structure and ground water.

Calcium chloride, which tends to leave an oily residue on the concrete surface, will actually discolor concrete.

Magnesium chloride, ammonium nitrate and ammonium sulfate will attack and disintegrate concrete and should be strictly avoided.

There is a company called XYNYTH Manufacturing that makes organic natural ice melt which is potassium based. It actually reduces the change of damage to surfaces by preventing refreezing of the melted ice longer than other ice melts and does not leave a residue. It is also good for the plants and is safe for our eco-system.

Sandy Griffis is executive director of the Yavapai County Contractors Association. Email your questions to her at ycca@cableone.net or call 928-778-0040.

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