Mirage Landscaping of Calgary is a full-service landscape design, maintenance, and construction firm. Over the years, we have been involved in a lot of concrete and paving stone jobs as we help people beautify their residential and commercial properties.
During the winter, our constant cycles of Chinook-driven thaws followed by more snow and freezing makes low spots in concrete or paved areas very obvious. Shallow areas puddle with snow and condensation, and periodically become foot traps of slick ice to trip up the unwary.
Ice presents the most recurring and difficult problem to combat during our winters. Whether in the form of ice dams in your gutters, icicles, glaze ice on your asphalt or walks, or low spots that freeze, ice shouldn’t be left untouched.
Bad News First
If you want to correct a low spot in concrete during the winter, there are a couple options available.
Sub-freezing temperatures effectively end the hydrological balance concrete needs to arrive at its proper tensile strength. The weather freezes water into the concrete rather than allow it to evaporate out. The concrete will be hard, but only in the way that frozen mud is.
If you can’t wait for spring for Mirage Landscaping of Calgary to come by and give you a free quote on building up or replacing a low concrete spot, you really only have two options available—liberal ice melt applications to the area, or drilling a drain into the low spot.
We have covered ice melt salts before. Normally, we advocate a sparing application, but if you have a hazardous spot that threatens life and limb, it’s worth considering making the non-draining low spot so briny that the most water can do is form slush. Sodium chloride content drives down the freezing point of water. If you can create a local solution that is greater than 16 grams of salt per kilogram of water present you can drive down the freezing point of water by 0.8 degrees Celsius for every additional gram of salt added. Just make sure that this hyper-saline solution cannot readily run off into your grass or the street drains.
Another quick fix strategy is to use a drill and bit suitable to the task and punch a hole through the lowest spot of the depression to bite as deeply into the soil as possible. Then, when the water is in its liquid state, it drains into the unfrozen soil. There are possible drawbacks to this approach. The first is likely ice blockage of the hole requiring your periodic attention. Secondly, if you have a large volume of water draining beneath a concrete pad, you could be inducing erosion of the soil beneath it, causing more subsidence. Drilling should be considered a last resort.
The Good News
If your walk or driveway uses pavers, even if those pavers are hundreds of pounds each for a driveway, low spots in those installations can still be corrected during winter. Most paving stone projects are suspended upon a prepared foundation of compacted gravel and sand fill. When a settling of the earth beneath this drainage substrate occurs, it can create a water trap between pavers and the compacted soil beneath, which affords little or no effective drainage.
As unpleasant as the job may seem, lifting out problem pavers and repairing the drainage/fill matrix underneath is entirely possible in the depth of winter if the repair doesn’t require any concrete work. It is advisable, however, to wait for a thaw period to begin such a project, if for no other reason than to make it easier to dig below the known freeze line in the soil to shore up the drainage layer to ensure the pavers don’t resettle low once again.
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