DIY Tips For How To Repair Cracks In Concrete
Cracks! Most of us panic at the sight of a crack in the concrete. Is my house falling to pieces? Does it need replacement of the foundation? Lots of questions and few responses. This article is meant to give you some clear explanations of why such cracks occur and answer some of your questions.
Why Does Concrete Crack?
Most cracks occur as a consequence of concrete shrinkage. Shrinkage is simply a reduction in concrete volume as it hardens. If this volume drop were unrestricted, then there would not be a crack. However, ground friction and several things like structural ties inhibit free shrinkage and thus cause cracks.
How much is natural for shrinkage? A 100-foot-long standard concrete slab will usually shrink by around 3/4 inches. In other words, in every 100 feet of concrete, you can find cracks totalling in widths of up to 3/4 inches. Lightweight concrete shrinks more. It is necessary to remember that concrete is cracking and this is natural. An unsightly and excessive number of cracks is what is not natural.
Nonstructural Cracks
Not every crack threatens the structural safety of a building. In fact, in many instances, cracks are merely cosmetic. These cracks are typically seen in flatwork such as walkways and curbs.
Typical causes of these cracks are:
- Poor workmanship
- Inappropriate joint detailing
- Higher shrinkage of concrete
Sometimes, in driveways and sidewalks, such nonstructural cracks become more than just an eyesore. Tree roots and vehicle impact can cause ravelling and vertical and horizontal offsets at the cracks. When these offsets become trip hazards, repairs are needed.
Structural Cracks
A majority of structural cracks occur as a result of the following conditions:
- Design deficiency
- Construction deficiency
- Settlement or heaving of soil
- Reinforcement corrosion
Sometimes, with some side effects, structural fractures manifest themselves. Doors and windows do not readily open and shut. The floors sound irregular—vinyl flooring tears as a result of the movement of cracks. Stucco starts to display new cracks, and new cracks can form even inside corners. Longitudinal cracks may grow as a result of corrosion of reinforcement along the length of the foundation.
What Do I Do Next?
When in doubt, consult a professional concrete engineer to investigate the cause of distress and evaluate the condition of the concrete.
As a homeowner, you could assist such a professional by keeping a periodic log of:
- Crack progression
- Crack widths
- Landscape irrigation schedule, especially big tree removal dates
Removing a large tree next to a house will cause abrupt changes in soil moisture level and cause the movement of the soil.
A correct diagnosis is, as in medicine, a must for an effective cure. It is necessary to investigate the cause of the concrete distress to suggest a suitable repair material.
A variety of repair materials are also available, and each has a particular use, as in medicine. Any fractures, for instance, are caused by movement in the structure. Repairing such cracks with epoxy could cause a crack to recur in a nearby location in the future. Not only does the use of a suitable material and procedure save repair costs, but it can also guarantee a durable concrete/structural repair.
In summary, concrete does crack; however, not every crack is a structural threat to a building. The cause of a crack should be investigated before performing a repair.
