5 Ways to Prevent Concrete Cracks—and 1 Simple Fix
Concrete is one of the most durable construction materials available, making it a perennial choice of builders and do-it-yourselfers alike for creating patios, walkways, driveways, and other structures. Concrete may retain its excellent looks and strength for years if put properly, but avoiding a few frequent mistakes—both before and after the concrete pour—will lessen the likelihood of cracks in the near future. Cracks are not only ugly, but they are also vulnerable to water penetration, which may cause the crack to grow and compress continuously, causing it to worsen. Water may enter the fracture and undermine the soil underneath the concrete, worsening the situation.
Fear not: the problems highlighted are easily avoided. First, watch this video guide on pouring the ideal slab from Quikrete’s concrete specialists. Then, before you undertake your next concrete job, whether it’s a little planter or a large patio, brush up on how to do things correctly, and you’ll finish up with enviable results.
1. Cure properly.
While it takes 28 days for concrete to fully cure, the procedures you take in the initial few days following the pour are critical for creating a durable, crack-free surface. Cement (the binding element in concrete) cures gradually and requires moisture retention to acquire full strength. Concrete is less prone to break if moisture evaporates slowly, therefore spraying it with water a few times each day for the first week after pouring the project will make it considerably stronger. The more frequently you should spray the new concrete, the hotter and drier the weather.
To avoid having to water the concrete, mix Quikrete Acrylic Cure & Seal into the mixing water before combining with the concrete. It not only speeds up the drying process, but it also shields the concrete from dirt, oil, and other stains.
Keep an eye on the forecast for possible cold fronts within the same seven-day timeframe. If temperatures are expected to fall below 50 degrees Fahrenheit, cover the new concrete with a concrete insulating blanket or at least four millimeters thick polyethylene sheeting to prevent the new concrete from becoming too cold, which can weaken its internal structure and contribute to future cracking. If you must cover the concrete to protect it from the elements, don’t do it only to rinse it down. Wait until the temperature rises over 50 degrees Fahrenheit before exposing and spraying.
Spraying and covering the concrete after a week is no longer essential; at that time, it has hardened enough to not be impacted by excessive temperatures.
2. Include control joints.
Even if you cure your concrete slowly as mentioned above, a big slab, such as a patio or sidewalk, may break due to concrete shrinkage caused by temperature changes and water loss throughout the hydration process. Concrete slabs will ultimately break due to the natural movement of the earth underneath. That is why control joints are so important. In order to foresee and guide future fractures, these purposeful weak points are carved into the slab down to roughly a fifth of its depth. Cracks are likely to form in these weakest areas.
Control joints may be created in three different methods.
1. Use a concrete grooving tool to form them in still-pliable wet concrete.
2. During the pouring process, insert Quikrete Expansion Joint Strips, which are made of flexible wood fibers.
3. Use a circular saw equipped with a concrete blade to cut them into the concrete slab the day after you pour it.
To get the best results, multiply the planned concrete thickness (in inches) by 2.5 to get the maximum spacing between joints (in feet). For example, if you’re building a 4 inch-deep patio, multiply 4 by 2.5 to get a distance of 10 feet between joints. Place them closer together for further crack prevention, and consider splitting huge concrete slabs with perpendicular connections as well.
3. Combine the appropriate amount of water.
One of the most typical errors newcomers to concrete make is adding too much water to the dry concrete mix for easier mixing, which results in weak concrete with a significant breaking risk. Even one quart more water can reduce the strength of concrete by up to 40%! Wet concrete should be totally soaked (no dry spots) but not watery when properly mixed. Concrete that sloshes about in the mixer or wheelbarrow is too wet, while crumbly and crumbly concrete is too dry.
A regular 80-pound bag of Quikrete Concrete Mix takes about three quarts of water to get the desired consistency, similar to oatmeal. If the mixture is little crumbly, add additional water sparingly until all of the dry particles are mixed. If the mixture is excessively moist, add more dry concrete.
4.Consolidate the base.
You’ll need a compacted foundation to properly hold the new slab before you mix up any concrete to create a slab, such as a sidewalk or patio. If the foundation under the slab is not compacted, it might sink and form a void beneath the slab, leading to cracking. Gravel, such as Quikrete All-Purpose Gravel, is the greatest sort of fill since it’s simple to compress by tamping down three to four inches until you have a level, solid foundation.
The manner in which you dig the earth influences the possibility that fractures may form over time. A good rule of thumb is to only dig out as much soil as is required to accommodate the desired depth of the concrete and a few inches of gravel. For a four-inch-thick slab, for example, dig down seven inches and then fill the forms with three inches of sand before pouring. Don’t dig too deep and then fill with a few inches of dirt; the earth will ultimately settle and cause the slab to split.
5. Call in reinforcements.
While concrete is strong on its own, a little steel reinforcement can make it even stronger. For patios and pathways, this may imply installing rebar in a grid pattern, with bars spaced roughly two feet apart and halfway through the slab. Smaller projects, such as concrete vases and other ornamental pieces, might benefit from the use of wire mesh during the pour to increase strength and decrease cracking.
It does not have to be difficult to provide reinforcement. Get inventive if you don’t have rebar or wire mesh. Anchor bolts, for example, may provide a bit additional support for the legs of a concrete chair, as seen in this video from the Quikrete team. Simply place the reinforcing material in the middle of the concrete so that it is not apparent after the job is finished.