How to Resurface Worn Concrete
Trowel concrete resurfacer over your worn walkway, and you'll have a brand new, durable surface with uniform color. Before you get started, check out this how-to video on working with concrete:
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.
Clean the Concrete
While wearing heavy boots and protective glasses, blast off surface dirt with a gas-powered pressure washer that can reach at least 3,500 psi. Fit the wand with a 25-degree fan tip, and hold it 6 to 8 inches from the surface as you clean the concrete with slow, even sweeps. To remove mildew or algae, use a concrete wash.