Concrete cracks are a relatively normal occurrence; however, they are quite preventable. There are various steps that you can take in the very beginning to prevent any unsightly concrete cracks from occurring in the future.
If you want to learn more about how to prevent concrete from cracking, then please keep on reading below.
Why Does Concrete Crack?
It is important to understand why concrete cracks in the first place.
Concrete can crack due to a number of reasons. A common reason is known as drying shrinkage. When concrete is in its plastic state, it is also at its largest volume. Once the concrete starts to set and harden, it begins to shrink. On average, concrete can shrink ⅛ inch for every twenty feet.
Concrete has both compressive strength and lower tensile strength. If the internal tensile stresses become greater than the tensile strength then a crack may develop.
Excess water in the concrete mix can also increase the chances of cracking. This is because it can evaporate from the concrete and increase the probability of shrinkage.
Poor subgrade preparation can also lead to concrete cracks. It is important that the subgrade is smooth, uniform, and has positive drainage. A smooth subgrade can reduce restraints once the concrete shrinks, hence reducing the chances of cracking.
Improper curing is another crucial reason why concrete cracks. Curing maintains concrete moisture by preventing rapid loss. If concrete loses moisture, it will shrink faster, causing what is called map cracking.
While map cracking does not affect the concrete’s structural integrity, it can affect the concrete’s aesthetics. Lack of curing is especially dangerous for concrete cracking. As such, it is important to actively cure concrete beforehand to prevent defects such as map cracking and scaling.
Preventing Concrete Cracks
There are many steps you can take to avoid your newly poured concrete from cracking. Here are just a few of them:
1). Properly Cure The Concrete
Concrete takes 28 days to completely cure, and so the steps you take in the first few days are crucial for a strong and crack-free concrete surface.
Cement cures slowly and needs moisture retention to be strong. Concrete will be less likely to crack if the moisture slowly evaporates. As such it is important to spray the concrete with water a few times each for the first week. This is because the hotter and drier the weather, the faster moisture can evaporate and the more likely you will get cracks.
2). Introduce Control Joints
Curing is an important precaution, but even large slabs can crack due to shrinkage from temperature changes and water used in the hydration process.
The natural movement of the soil underneath the concrete can make the concrete slabs crack. With control joints, you can create intentional weak spots cut into the slab.
Control joints are made by cutting a quarter of the concrete slab’s depth to anticipate the possibility of future cracks. Essentially, introducing control joints is to gamble on the odds that cracks can happen in these weak parts.
3). Mix In The Right Amount Of Water
Adding too much water is a common mistake when it comes to concrete mixing. This can lead to weak concrete and higher chances of cracking.
Therefore, to avoid cracking ensure that you add in the right amount of water. Wet concrete should be thoroughly saturated but not watery. Make sure to read the manufacturer’s instructions carefully before mixing concrete.
4). Compact The Base
Before pouring your concrete, it is important that the base you pour it on is compact. If the base beneath the concrete is not compact, it can settle and create a void underneath the concrete slab. This, of course, can lead to cracking.
Gravel is usually the best type of fill. Try not to dig out more soil that is necessary. You should lay out a few inches of gravel and ensure that you do not dig too far into the soil before laying it out.
5). Add Steel Reinforcements
Concrete can be stronger when you add steel reinforcements. If you are constructing patios or footpaths, you can add rebar in a grid pattern that has bars two feet apart from each other and sitting halfway through the slab.
There are also alternatives to rebar or wire mesh depending on your concrete project. However, make sure that the reinforcing material you are using is located in the centre of the concrete, or ensure that it is not visible once the project is complete.
Summary
There are several reasons why concrete will be prone to cracking; however, these reasons are easily avoidable as long as you take the proper steps.
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