Concrete surfaces have two layers: smooth and rocky. The smooth outer layer is the visible part of concrete and the most fragile. When this layer becomes chipped, scaled or flaked, this is called spalling. Spall refers to the flakes of concrete that break off from a larger slab or wall as a result of weathering, physical impact such as from projectiles, and other forms of stress on the concrete.
Spalled concrete on walkways, stairs, driveways and sidewalks can look unattractive. Although spalling usually affects the outer surface of structures, it also may happen to the interior of concrete. Concrete can be weakened by fire, corrosion of internal reinforced steel bars, chemical damage, bacterial corrosion, and expansion or settling of the structure after construction.
Exposure to extreme weather conditions such as heat from the sun, freezing of trapped water, and erosion by fast-flowing water can also cause spalling. Moisture entering brick, concrete or natural stone can force the surface to peel, pop out or flake off. In basements, moisture and salt pushes outward from the inside.
Though spalling can be a natural result of aging in concrete, it can also be a sign that the concrete cured improperly or was not mixed correctly. When too much water is used while mixing concrete, this will result in weak surfaces that may become pitted and flaky with age. This can be remedied by cutting away the surface and patching the concrete. If not repaired, spalled walls can crumble and bring down a structure.
How to detect spalling:
Spalling is a pitting reaction that causes concrete to crumble and chip away in thin shards. Walls look crumbly, flaky or chipping, and may have minor holes or voids on the surface. Fortunately, spalling is often just surface damage, and is not a sign of structural problems within the wall. This means that they can be repaired by replacing or patching the spalled portion.
The chimney is the one feature of a home that is constantly exposed to all the weather elements and more likely to suffer from damage. The entry of moisture through the chimney can cause spalling and deterioration to your home. When inspecting your chimney for damage, look for mortar joints in need of repair, spalled or broken brick surfaces, rusting inside the fire box or damper assembly. Regular inspection and keeping the chimney crown well maintained and free from cracking and deterioration will ensure good protection from water entry.
Brick material is porous and will absorb water like a sponge. The moisture can then wick right through to the interior. Water proofing or weather proofing will allow the brick to release moisture but not absorb it.
How to address the problem:
The best time to address spalling is when concrete is first poured. Steps should be taken to prevent spalling in the first place. Concrete should be mixed with the right amount of water, and ideally the mix kept as dry as possible because high water content can weaken concrete. Any concrete structure needs time to cure properly, and should be handled carefully during curing. Sealing is also commended to protect concrete from the elements. There are a number of sealants available for concrete and the sealant can also work with a decorative finish.
If signs of deterioration are spotted in a concrete installation, act quickly to address them. The longer concrete is allowed to crack, pit, chip and flake, the higher the risk of serious damage. Consult a reputable contractor or concrete professional to get advice and to perform any necessary repairs.
For more answers to your questions about spall repair, contact Freedom Restoration at 410-451-7110 or click here.