How To Patch Cracks in Concrete Floors & Walks
As tough as concrete is, it
can easily crack or chip due to temperature changes and because it naturally
absorbs moisture. And what starts out as a little hairline crack can
quickly escalate to serious, costly damage because water and debris is
able to penetrate deeper into the concrete. Fortunately, these simple
techniques can help you repair damage before things get expensive, protect
your investment and prolong the life of your concrete structures. Note
that these repairs are not appropriate for structural concrete, such
as perimeter foundations.
Prepare the repair surface
Before you start patching damaged concrete, make sure the area to be
repaired is clean and dry. Remove all loose concrete and debris with
a stiff wire brush. If the crack is larger than 1/2", use a chisel
and enlarge the base of the crack (see Fig. 1). Then, wash away any dirt
and foreign materials, such as the oils and greases commonly found on
driveways, with a concrete cleaning solution. Finally, let the area dry
Applying the patch
Masonry crack filler is available in caulking cartridges, which are
ideal for getting deep into small cracks. Simply load the cartridge into
your caulking gun, squirt the filler into the crack, and smooth the patch
with a small putty knife.
Vinyl-reinforced patching compound is better suited to larger cracks.
Mix according to the manufacturer's directions, then, using a pointed
trowel, fill the crack with the compound and tamp it to get any air bubbles
out before you smooth it and admire your handiwork. The larger the crack,
the more important tamping is because trapped air bubbles will weaken
Variation: Using forms to repair edges and corners
Chips and cracks in concrete steps, stairways and walkways can be dangerous
as well as unsightly. To fix a the corner of a stairway or the edge of
a walkway, you might need to build a wooden form to support the patch
as it dries to full hardness.
For a small repair on a step or stairway, a straight board can be supported
by a heavy brick (see Fig. 2). Just make sure the board doesn't move
throughout the drying period.
For a walkway repair, you might have to dig a small trench parallel
to the walkway, then place your board next to the area to be repaired.
Drive a few stakes in the ground to support the board, or, if the repair
area is small enough, stabilize the board by loosely refilling the trench