The worst has happened – you’ve just noticed a crack in your freshly laid concrete. You inspected it when the asphalt company had finished the job and it was perfect.
So, how did it happen? And what can you do to fix it?
Rest assured, the unfortunate reality is that concrete cracks are very common, and even inevitable at times.
Below, we’ll walk you through some of the most ordinary types of concrete cracks, and what you can do to fix them.
Extreme weather can take great strain on concrete. Hot temperatures cause concrete to expand; in response, it exerts force by flexing and pushing hard enough that the concrete cracks. On the opposite side of the spectrum, sharply plummeting temperatures that quickly thaw back out again result in substantial ground movement.
Understanding how concrete reacts to changes in moisture and temperature, homeowners should plan ahead by placing control joints or pre-planned cracks within their concrete. Ultimately, these control joints take the impact of the crack rather than the concrete slab. If the slab still cracks, it can be repaired and stabilized with the help of epoxy injections and sealing techniques.
Rapid drying of the concrete causes it to crack. During concrete stamping, the top of the slab has the potential to dry out more quickly than the bottom, in a process known as plastic shrinkage. When this occurs, the top slab becomes crusty, changing from a liquid to a plastic state and correspondingly pulling away from the bottom.
This can be combated by curing the slab to maintain water moisture, though bear in mind that improper curing can also lead to problems. Overall, curing is a recommended practice to improve the strength and longevity of a concrete slab. The usual curing process is conducted over a period of seven days.
By contrast, excess water raises the probability of concrete cracks. Avoid adding any more water to a concrete mix, as it will evaporate and lead to shrinkage.
Settlement, which occurs when the ground shifts, signals danger to the health of concrete. The ground may move as a result of poorly compacted soil, overgrown tree roots or water erosion. Avoid planting trees too close to sidewalks to prevent roots from growing underneath, and replace any poor soil with crushed stone before pouring the concrete.
Because some concrete contains steel rebar as a means of fortification, this means that rust is a concern. Oxidation begins when cracks occur and allow water to seep into the slab’s surface. As the steel rusts, it expands and encourages even more cracks. To minimize the potential of corrosion cracking, homeowners should fix all cracks before they expand further.
Concrete is one of the world’s strongest man-made materials, but that doesn’t mean it is infallible. In fact, concrete can only handle so much weight. Sidewalks and residential driveways are equipped to handle the load of one or two cars, and shouldn’t be tested, as placing too much weight on a concrete surface may cause it to crack. Check with your building code department for assurance that concrete will perform under the pre-approved loads.