Concrete is one of the most commonly used building materials in residential projects. It's widely used because it can be adapted and molded to build a huge variety of structures, it's durable and it's relatively inexpensive compared to other materials.

Like with many other materials, concrete has drawbacks as well.

One of the most common problems with concrete is cracks developing in them. Cracks are unsightly and can mean that ground or soil is structurally unsound or weakened over time. It can also mean that a problem has developed with the way the concrete was poured.

Excessive Water

Water makes concrete easier to mix and pour. This is why it's common to see find that too much water has been added during do it yourself concrete projects. However, too much water in the concrete mix weakens the concrete.

Aside from weakened concrete, too much water in the mix leads to shrinkage.

Concrete shrinks when it dries. This is because water evaporates from the concrete and makes it shrink. If the concrete mix is too soupy , the shrinkage will be greater. Concrete slabs can shrink as much as 1/2 inch per 100 feet which causes the force to pull it in different directions, causing cracks.

Improper Curing

The most common cause of cracks is improper curing. The concrete needs time to cure before it can be left alone, otherwise problems like cracking are bound to arise.

Poor Workmanship

Another major factor in the development of a crack is poor workmanship or just plain bad luck with structural integrity and moisture-related issues. An experienced concrete contractor will be able to spot any potential issues and fix them as they work so there are no long-term negative effects on the concrete work.

Shifting Ground

Another common cause of cracks in concrete is sub grade settlement. This happens when the ground shifts or moves and causes a change in grade through natural movement. However, this can also occur when the ground isn't properly prepared and compacted before pouring the concrete.

No Control Joints

Control joints are used for concrete masonry, so it doesn't crack. Control joints are filled with mortar but have a bond breaker on one side to stop the tensile stress. If control joints are not provided, concrete may crack as it shrinks over time. Control joints should be installed at intervals to ensure the concrete has the space to expand and contract as needed.

Aging Concrete

There are many things that can age concrete prematurely like salts in the water or using low quality aggregate which weakens the strength of the material. The most common cause for cracks developing on aging concrete is freezing and thawing cycles. Temperature really impacts concrete because it causes it to contract and expand. If water seeps through, it can cause larger cracks in the concrete.

It's important to understand that not all cracks are a reason to remove the concrete and start over. Some cracks appear as part of the natural aging process and are not a cause for worry.

Hairline cracks can easily be patched and some larger cracks can be filled in and polished. Unless a crack is causing a tripping hazard, or unless it continues to spread, you should be okay doing the repair work on your own.

Otherwise, it's time to call for professional help--preferably an experienced contractor who specializes in cement work or has experience repairing concrete.