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Sat, Dec. 07

Ask the Contractor: How to handle weather-related problems outside your home

Winter can be hard on concrete driveways (Courier stock image)

Winter can be hard on concrete driveways (Courier stock image)

We are approaching our winter weather and, from experience, our weather can take a toll on more than just our cars and our attitudes.

Concrete walks, driveways and steps all take a pounding from the elements and the de-

icing chemicals that we apply. 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.

CONCRETE

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 buildup of water (melted ice) being absorbed into porous concrete, which then freezes and expands.

This expansion within the concrete triggers pressure to build up and eventually, over time, the pressure becomes too much for the concrete to withstand and 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, remove the slush from the pavement, sidewalk or driveway to reduce the amount of water that may penetrate the concrete, thus creating pressure buildup.

Using an ice melt that contains calcium chloride tends to re-freeze quicker compared with 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.

DE-ICER VS ANTI-ICER

Anything used to melt the ice is considered to be a de-icer or ice melter. It does not matter what the material composition is or what format it comes in. It can be in variety of solid formats, such as: granular, flakes, pellets, pearls, powder or even in a liquid format. Many people assume that the word “ice melter” means that it is somehow eco-friendly. This simply is not the case. Rock salt is an ice melter.

An anti-icer is any product that can be applied to a surface before a storm to help prevent ice buildup from occurring. It typically does not eliminate ice buildup, but rather just delays it enough that clearing equipment can be brought out to remove the slush accumulation.

Do not use ice melt on already damaged concrete. Damaged concrete will only absorb the water quicker 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, 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.

The most common winter damage to concrete is scaling, that is the flaking or peeling away of the surface mortar. Scaling can leave the concrete looking pock-marked, and will expose the stones in the concrete mix.

Minor scaling can be merely a cosmetic flaw, but if left unchecked, it can turn a smooth concrete walk into a rustic gravel path.

Scaling is caused by cycles of freezing and thawing. Water is absorbed into very fine capillary spaces in the concrete. When the temperature drops, this absorbed water freezes and expands. Such expansion creates pressure that forces flakes or mortar loose from the surface, and you can often see where mortar has “popped” leaving holes.

Removal of compacted snow and ice with shovels or snow blowers isn’t always easy or effective. In order to be effective, de-icers must first attract or come into contact with sufficient moisture to form a liquid brine.

The brine has a lower freezing point than water, which causes ice and snow to dissolve on contact. De-icing agents penetrate downward through the ice and snow layer until they reach pavement.

Once on the pavement, the brine spreads outward to break the bond between the ice and snow and the pavement. After sufficient loosening, the ice and snow can be removed by shoveling or plowing.

Calcium magnesium acetate, or CMA, is a salt-free de-icing agent made from acetic acid and dolomitic lime. Although this de-icing compound is more expensive than most salts or combination deicers, it is less damaging to the driveway surface and plants, making it suitable for use in environmentally sensitive areas.

There is a terrific product on the market that is sold at Ewing Irrigation in Prescott Valley. I use this- and the material has the proper recipe for concrete.

Remember to tune in to YCCA’s “Hammer Time” 7 a.m. every Saturday or Sunday morning on KQNA 1130 am/99.9 fm/95.5fm or the web kqna.com. Listen to Sandy to Mike talk about the construction industry and meet your local community partners.

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