Summer heat is so high it's cracking Ottawa sidewalks

National Post

16 hours ago

A sidewalk outside of the Goodlife Fitness gym at Heron Gate buckled last week amid the city's extreme heatwave.
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Two large concrete slabs outside the gym formed a frown-like arch several inches off of the ground, and were surrounded by caution tape and pylons earlier this week.
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The city received eight or nine reports related to similar sidewalk cracks or shifts, according to Bryden Denyes, area manager of roads services with the City of Ottawa.
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Sidewalks can crack for different reasons, according to Beatriz Martin-Perez, a University of Ottawa structural engineering professor who studies the durability of concrete.
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One reason, Martin-Perez explained, is when the top of the sidewalk in contact with sunlight is hotter than the cooler soil underneath. This tension in temperatures causes the concrete slab to bend and crack on the top.
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'Think of it as a sad face that it tries to create,' she said. 'Concrete is not that flexible, but eventually it cracks on the point where there is high tension.'
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The eight or nine reports he's received are spread out among 'random places,' including downtown, urban and suburban neighbourhoods.
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Sidewalk cracks 'don't happen suddenly,' according to Martin-Perez.
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There is also no precise temperature that needs to be reached for sidewalks to buckle, but prolonged direct sunlight on top of the concrete is what can create the tension causing a crack.
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Denyes' maintenance team typically only sees sidewalks impacted by cracks related to heat, he said.
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Other infrastructure, like bridges and parking garages can be affected, according to Martin-Perez, because they use similar horizontal concrete slabs. However, she said flexible rubber-like joints within these structures account for expansions and contractions due to changing temperatures.
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From there, Denyes' team waits to see if the shifted sidewalk returns to its normal position once it cools down. Then, the team comes up with a maintenance plan, which could be a temporary asphalt patch, or a more permanent repair like re-pouring the concrete and completely replacing the sidewalk.