Cracked concrete sidewalks look shabby, and they are more prone to quick decay. Further, cracks can pose a tripping hazard and a liability. There are a few common causes of cracking, which can usually be avoided or repaired.
1. Moisture Damage
Moisture, whether from rain, snow, or lawn sprinklers, is the most common cause of cracks on older sidewalks. The concrete has lasted many years, providing that it was installed well on a firm base, but eventually, small cracks begin to form. The culprit is moisture seeping into the pores of the concrete, where it erodes the material and makes it more prone to cracks. Sealing the concrete every few years can protect against moisture cracks.
2. Soil Movement
Concrete needs a firm, immobile base if you don't want it to develop cracks from movement stress. When cracks form on a sidewalk that is less than a couple of years old, soil movement in the base material is the likely culprit. Some soil types are simply more fluid, but over-irrigation or poor drainage near the sidewalk could also impact the base. Repair requires rebuilding the sidewalk from the base up while addressing the cause of soil movement.
3. Tree Roots
Tree roots are powerful things. If they raise toward the soil surface beneath a paved area, they can put sufficient pressure on the concrete and cause crack formation. Installing root barriers between the sidewalk and any landscape trees can help. If a root has already caused concrete uplift and cracking, your concrete contractor may be able to cut out the damaged slab, trim back the root, and settle the slab back into place with a new joint to repair the crack.
4. Load Constraints
Sidewalk concrete is mixed and poured to a depth made to handle standard foot traffic. If you drive or park vehicles or heavy equipment on the sidewalk, there is more of a chance of cracks developing. Know the load constraints for your sidewalks and avoid any type of traffic that could lead to cracks. Alternatively, have reinforced sidewalks poured if you know they will be subjected to heavy loads.
Snow, ice, and freezing temperatures are the likely cause of cracks that form in winter or early spring. Damage on the concrete surface allows moisture incursion. The moisture then freezes, expands, and cracks the concrete. Moisture incursion below the concrete can also cause cracking as it causes frost heave in the soil that lifts and cracks paving. Proper snow removal, sealing, and managing runoff around the sidewalk will minimize cracks caused by weather conditions.
Contact a concrete contractor to learn more.