Signs of cracks appearing in any concrete structure can be alarming, but while they should never be ignored, some are inevitable and require less attention than others.
Read on to help you decipher the type of cracks your concrete structure is suffering from, and what action – if any – you should take to fix them:
Plastic shrinkage cracking
Before concrete hardens, it’s known to be still in a plastic state. Full of water, when the liquid eventually goes, voids are left between the solid particles, that can weaken the concrete and make it more likely to crack. Because concrete is incapable of shrinking around a corner, the concrete will crack from that point, and likely extend throughout the thickness of the entire slab.
A concrete mix that’s too wet, or hot weather can cause plastic shrinkage cracks.
To prevent plastic shrinkage cracking, control joints can be incorporated into the slab by a qualified masonry contractor.
Expansion cracks
When concrete expands in the heat, it will push against brick walls or slabs that are in its way, and when the wall or the slabs can’t flex, the force of expansion often causes cracks in the concrete.
To help prevent such cracks, a masonry contractor will use expansion joints made from a compressible material such as asphalt or rubber, to act as a shock absorber that relieves the stress placed upon by concrete by expansion.
Heaving cracks
Ground movement caused by the freezing and thawing cycle concrete often experiences during the winter months, can cause cracks to appear, and if the slab cannot move freely with the ground, cracks in the concrete are inevitable. In some instances, big tree roots can have the same affect.
These cracks will need to be assessed by a local masonry contractor to determine the best course of reparatory action.
Settling cracks
Usually occurring when a void is created in the ground below the surface of the concrete, settling cracks can be caused should a large tree be removed nearby and the roots begin to decompose, or when work is undertaken to dig up a trench for a pipeline, for example.
A masonry contractor will examine the extent of the damage to help them decide what course of action to take.
Overloading cracks
Concrete is exceptionally strong, but as with most materials, it has its limits. When placed under extreme pressure from a heavy weight, concrete slabs can crack, such as after heavy rain or snowmelt, or when a large vehicle like a dumpster is placed on a driveway.
A badly cracked driveway may need to be replaced, while structural damage may need to be fortified by a stonemason.
Premature drying cracks
If a concrete slab loses a lot of moisture too quickly, you’ll likely see crazing cracks appearing; fine, surface cracks that look a bit like spider webs or broken glass. Fortunately, these don’t present a threat to a concrete structure.
Crusting cracks are also not structurally worrying, but aren’t aesthetically pleasing, and can happen during the concrete stamping process; a way of adding texture or pattern to concrete surfaces.
Cracks in concrete can vary in severity, and some may require no further action. However, cracks are always easier to rectify if they’re examined and treated by a masonry contractor as soon as they occur, and in some cases, early intervention can prevent the problem from becoming any worse.