Photo: Ryan Benyi
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Q: Our concrete walk has pits and seems to be crumbling. How can we fix it?
—Jace Laakso, Missoula, Mont.
Tom Silva replies: Spalling, the pits that form in concrete, happen when too much water is used in a concrete mix, weakening it.
As long as your walkway isn't cracked all the way through, you can coat the slab with a concrete resurfacer, a no-shrink blend of Portland cement, sand, and polymer additives that fills divots and makes a uniform finish. Its natural color is dark gray, so buy enough to cover your entire walk. One 40-pound bag coats about 35 square feet. If you want a different color, just add a concrete tint.
Before resurfacing, strip off any paint or sealers and watch the weather. Temperatures should remain above 50 degrees F for 8 hours after the pour and above freezing for 24 hours after that.
Resurfacing takes most of a day, but your walkway will be back in pristine shape once you're done.
—Jace Laakso, Missoula, Mont.
Tom Silva replies: Spalling, the pits that form in concrete, happen when too much water is used in a concrete mix, weakening it.
As long as your walkway isn't cracked all the way through, you can coat the slab with a concrete resurfacer, a no-shrink blend of Portland cement, sand, and polymer additives that fills divots and makes a uniform finish. Its natural color is dark gray, so buy enough to cover your entire walk. One 40-pound bag coats about 35 square feet. If you want a different color, just add a concrete tint.
Before resurfacing, strip off any paint or sealers and watch the weather. Temperatures should remain above 50 degrees F for 8 hours after the pour and above freezing for 24 hours after that.
Resurfacing takes most of a day, but your walkway will be back in pristine shape once you're done.
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