Imagine building a beautiful covered patio area off the back of your house. You have dreams of entertaining family members and friends for years to come. But within weeks of finishing the project, you notice cracks in the concrete slab. What happened?
Concrete is essentially artificial rock. It is made up of a mixture of aggregate, sand, Portland cement, and water. It is the chemical reaction between the water and cement that turns concrete into a rock-like substance. Yet as strong as it is, concrete is obviously not impervious to cracking.
There are many reasons a concrete slab, foundation, or set of steps can crack. Below are the top four. If you have cracked concrete on your property, it is likely due to one of these four issues.
1. The Concrete is Sinking
Perhaps the most common cause of cracks in large slabs is sinking. A newly poured slab should be one solid piece if it was installed correctly. If just one area starts to sink, it puts the entire slab under pressure. The thing about sinking is that it can cause cracks even before it is noticeable. Just a quarter inch of sinking can cause cracks.
Sinking itself is the direct result of soil underneath giving way. Perhaps the contractor didn’t properly compact the soil before pouring. Maybe the property has a larger drainage issue. In either case, Salt Lake City’s Concrete Raising Company says that raising the concrete back to a level position is an effective repair in most cases.
2. Loads Are Too Heavy
Concrete slabs sometimes crack because the loads being placed on them are too heavy. This is rarely a problem for a backyard patio, but it could be for a driveway or sidewalk. A concrete slab driveway can easily support a typical passenger vehicle. But what if you back a heavy truck onto the driveway to accommodate a furniture of or appliance delivery? The weight of the truck might be too much.
3. Water Evaporates Too Quickly
A phenomenon known as plastic shrinkage occurs when water evaporates from curing concrete too quickly. Plastic shrinkage usually occurs when humidity levels are too low or the weather is particularly hot or windy. All three conditions lead to uneven curing.
Contractors attempt to avoid plastic shrinking by keeping the top surface of freshly poured concrete moist. The idea is to maintain adequate water content to ensure consistent curing.
5. Dry Shrinkage Occurs
Even when sinking and plastic shrinkage are not a problem, concrete can crack due to another phenomenon known as dry shrinkage. This condition usually occurs where concrete meets another substance. For example, your new patio may have a joint where the slab meets the foundation of the home. Your contractor may have installed rebar to strengthen the slab.
The contractor may have done everything correctly and yet you still have cracks. Why? Reinforced concrete is put under stress as it cures and shrinks. The problem is that the reinforcement material, rebar in this case, doesn’t shrink. As the concrete shrinks around the rebar, it creates pressure that can lead to cracks.
The Concrete Raising Company says there is no reason to panic over newly poured concrete that cracks. The root causes of most cracks are easily identifiable and repairable. And whether you live in Salt Lake City or elsewhere, concrete repairs are easier and more cost-effective than total replacement.
If you notice cracks in any concrete on your property, do not ignore them. Either fix them yourself or hire a contractor. Unaddressed cracks can lead to bigger problems you really want to avoid.