Concrete may look tough, but it’s a rather delicate material that requires considerable preparation to pour and cure. Like many building materials, it is highly susceptible to both water damage and shifts in the soil. While it’s solid strength is its greatest asset, its inflexibility is its Achilles heel. That strength is also what makes concrete crack prevention a bit of an art form.
Concrete can crack for a number of reasons. One of the most common is because of excess water being used in the concrete mix. When excess water is introduced it dilutes the mix and weakens the strength of the concrete. As the concrete hardens and the moisture evaporates it will shrink. As it shrinks, it cracks. In fact, a concrete slab 100 feet long can shrink up to 1/2 an inch as it dries.
Another common cause of cracks is rapid drying of the concrete. This typically happens when concrete is poured on a hot day. When concrete is poured it requires several days, to several weeks to fully dry. If this happens too rapidly, it affects the chemical reaction taking place within the mix.
Sometimes, concrete will crack because insufficient, or inappropriate control joints are used. Control joints are intentional cracks that allow the concrete to break where you want it, instead of where it wants to crack. Its like a pressure valve that helps release the tension that builds up in the concrete as it dries and settles.
Avoiding cracks can be tricky, but concrete crack prevention isn’t a mystery. It simply requires taking proper care to ensure the following conditions are met:
In cold weather, never pour on frozen ground or over snow or ice. Further, be sure to use concrete curing blankets to prevent freezing as the concrete cures.
Try to schedule your pour so that it takes place in dry weather that is between 40-80 degrees. This is the ideal pouring range and represents a minimal risk of weather related cracking.
Prepare the soil properly. Make sure it is properly inspected and compacted, and that the forms are set properly for the pour.
Carefully plan control joints. Be sure they are sufficient for the size of the slab you are pouring.
Contact us here at Master Markings to learn more.
