Random Cracking Cracks that radiate across a concrete surface are unsightly and unsettling. In time, water can enter a crack and freeze, which causes further damage and widens the rack.
Fix It Cracks can be repaired with injected, two-part epoxy. Done right, this restores the concrete’s strength to original or better. Another option is to fill the crack with siliconized acrylic latex. This does nothing to restore strength, it is intended only to keep water and debris out. Bear in mind, neither of the above will correct a deeper structural problem. Also, it’s nearly impossible for a repaired crack to look like anything but what it is.
Avoid It The goal, since all concrete cracks, is to provide a planned place for that to happen, called a contraction joint. Parameters include: spacing of 8 feet or less in each 90-degree direction; create while the concrete is still green—within 12 hours of placement; depth of one-quarter to one-third the slab’s depth. Three types include: saw cut; tooled joint; and proprietary joint strip. Adjustments, such as a low water/cement ratio, can be made to the concrete mix to limit shrinkage and, in turn, cracking.