Common Types of Concrete Sidewalk Cracks and Effective Repair Methods

Cracked sidewalks are not only an eyesore but a safety hazard. Whether hairline cracks, shrinkage cracks, expansion cracks, or deep cracks, these imperfections can be dangerous for the life of your sidewalks and cause people to trip and fall. These cracks let the water seep into the soil, leading to freeze-thaw cycles and soil erosion. If you want to save your sidewalks from extensive damages, learn about different types of sidewalk cracks and the best sidewalk repair methods.

Understanding the causes and types of sidewalk cracks is essential to choose the appropriate repair technique. Whether it's a minor patch-up or a complete sidewalk installation, addressing these issues early can prevent larger structural problems. By employing the right fixing process, you can extend the lifespan of your sidewalks and ensure safety for pedestrians.

 

Hairline Cracks

Hairline cracks form during the curing process when the concrete is settling. They are usually thin but can go deep in the slab. As these cracks run deep, they can cause more serious damage once the concrete has hardened.

Water and moisture can seep through these cracks in the soil and can freeze during the winters. The frozen moisture expands and causes the cracks to widen after every freeze-thaw cycle.

Shrinking Cracks

Shrinking cracks are common to occur in the freshly poured concrete during the natural drying and curing process. These cracks usually occur during the dry weather when the concrete doesn’t get enough time to cure and dries up quickly. 

These cracks are usually small and don’t impact the structural integrity of the surface but they may not look good. Proepr curing practice and use of shrinkage-reducing additives can help in avoiding the crack formation.

Settling Slab Cracks

If the soil beneath the concrete slab is poorly compacted before the new concrete is poured, the soil will continue to settle over time. The settling soil will also bring down the slab with it. However, this issue not only arises when the new concrete is installed. 

For example, if the utility company digs near your property and doesn't settle to soil after installing the new lines, the soil will keep settling and leave new voids behind. Soil movement leaves unsupported weak spots in the slab and these spots are more prone to cracking.

Heaving Slab Cracks

Freeze-thaw cycles and tree roots are two main reasons why heaving slab cracks occur. 

Freeze-thaw Cylces

If the soil has moisture in it, during winter it will freeze and expand, pushing the concrete and causing structural damage to it. During the freeze-thaw cycle, the ground can expand and lift a few inches before it thaws and lowers back to its original position.

The soil movement due to temperature fluctuation can erode the soil and weaken the concrete structure, leading to extensive cracks in the surface. It shows the importance of installing expansion and control joints during the construction of sidewalks.

The presence of these joints helps in controlling cracks and allows for the free movement of slabs during freeze-thaw cycles.

Tree Root Invasion

Tree roots growing in an upward direction near the sidewalks can push the concrete slabs, causing the cracks to appear. While installing trees near sidewalks, you must consider installing root barriers and also try to pick the trees whose roots have natural downward growth.

Moreover, if you notice root growth, you can request NYC parks to inspect the tree and trim the roots that require cutting. 

Different Ways to Fix Concrete Cracks

There are many ways to fix concrete cracks and some of the most common and effective methods include:

Flexible Concrete Caulk

Concrete caulk is specifically designed to flex with natural expansion and contraction of the concrete and adhere to its rough surface. Self-leveling concrete caulk and non-sag are two options that are often used together to achieve a better-looking final result. If you are planning to achieve a good result.

Polyurea Crack Filler

Polyurea is a semi-rigid repair liquid that mends cracks in concrete and repairs spalled or damaged joints. Filling cracks with polyurea can help reinforce the breaks and give strength to the concrete.

Epoxy

Epoxy filler is similar to polyurea but an interesting thing about it is that it can reinforce the cracks rather than sealing them up. If you opt for epoxy products to fix the cracks, keep in mind to take professional help as the prep work can be more complicated as compared to traditional caulking products.

Concrete Patch

Concrete patch products are another option to fix the cracks. These options are inexpensive but are only temporary. Rigid concrete cannot property bond with the existing concrete and as the concrete expands, it cracks and chips off. 

Mortar or Grout

Just like a concrete patch, using mortar or grout is a temporary fix. When the concrete moves and shifts with changing temperature, rigid mortar doesn’t flex, causing it to crack off or crumble away.

Repair Methods Based on the Extent of Damage

Fixing minor cracks is different than the major cracks, which are not only deep but also wide. 

Minor Cracks

Cracks less than 1/4 inch wide can easily be repaired using concrete caulk. Usually small cracks aren’t exposed to water and freeze-thaw cycles and don’t need extensive repairs.

Major Cracks

Major cracks that are wider than ¼ inches can also be caulked and repaired; often they will need a filler to go in the crack before applying repair material. If these cracks have been exposed to water and there are signs of a freeze-thaw cycle, complete replacement is essential to ensure soil sturdiness.

Conclusion

Cracks, whether minor or deep, require immediate attention to save the concrete surface from extensive damage. If left unaddressed, small cracks can allow the water to seep in and lead to major issues like freeze-thaw cycles, soil erosion, and uneven surfaces.

This deterioration on sidewalks poses trip hazards, leads to legal liabilities and violates DOT regulations. By addressing these issues timely with the help of professionals, you can save yourself from expensive repairs and comply with city codes.