Concrete Floor Cracks and the Importance of Repairing Them

Have you noticed cracks emerging in your recently laid concrete floor? As well as being unsightly, you might be worried that these cracks could present lasting damage to your floor’s surface. 

This article looks at why concrete floors crack, why you need to fix cracks when they appear, and how to prevent concrete cracks in the future. 

Let’s begin by understanding some of the reasons why concrete cracks in the first place. 

Why Does Concrete Crack? 

We see cracks in concrete everywhere we look, but it’s not always clear to everyone why these cracks emerge. If cracks have started to appear in concrete at your home or within your commercial property, it might have been caused by one of the following reasons:

Rapid drying:

Concrete that has dried too quickly can crack and potentially cause “crazing.” Concrete crazing refers to a network of hairline cracks in concrete that result from the presence of too much or too little moisture.

Change in climate:

Perhaps the main reason why concrete cracks is due to changes in the climate. As air humidity and temperature change, concrete expands and shrinks. Too much variation in the climate can cause the concrete to crack. 

Excessive water:

Concrete is a composition of water and cement. If too much water is added to the mixture, it causes laid concrete to shrink, which is likely to cause cracks within the concrete soon after it has been laid (within thirty days). 

Ground movement:

Particular movements in the ground can cause concrete to crack. For example, heaving, which usually results from growing tree roots, can push up into the concrete and split it. Settling can also cause concrete to crack, which is when water damage causes concrete to sink. 

Too much weight:

If your concrete is too thick and heavy, it might crack under pressure. It’s incredibly important to get the composition of your concrete right. 

What Are the Different Types of Cracks in Concrete? 

You might have recognised that not every concrete crack is the same, as they vary in width, depth, and even shape. Four of the most common concrete cracks include: 

Structural cracks:

As the name suggests, structural cracks are problematic. They tend to be wide and run through an entire slab of concrete. If you notice structural cracks, you will need to replace the concrete. 

Hairline cracks:

These appear at the surface of concrete and are unsightly. Hairline cracks should be repaired if they begin to widen, as they can collect dirt and debris, which can compromise the structural integrity of the concrete. 

Shrinkage cracks:

Resulting from improper joint placement, shrinkage cracks tend to occur while the concrete is curing and can be rectified if noticed in time. 

Settlement cracks:

If you notice that a section of your concrete sinks, you may also recognise some settlement cracks appearing. These result from ground that wasn’t properly compacted before the concrete was laid.

Why Do I Need to Fill Concrete Cracks? 

Cracks in concrete are a sign that it has been poorly laid or that there is an issue with the surface below or surrounding the concrete. If you don’t repair cracks in your concrete floor, you face a range of maintenance issues in the future, and your concrete floor may be further affected in the following ways: 

Increased size of cracks:

If you ignore cracks in your concrete, they will only get worse over time. As mentioned, temperature and humidity changes and several other factors can cause the cracks in your concrete to widen. 

Water damage:

As water seeps into the cracks in your concrete floor, it can affect the structural integrity of the entire surface. If your concrete floor is outside, water in the cracks can turn to ice, which will increase the severity of the cracks.

Unsightly:

Cracks in your concrete don’t look great and give off the impression of poor workmanship. As well as affecting the structure of your concrete floor, cracks should be fixed for aesthetic purposes, as nobody wants to have a floor that is covered with cracks and gaps. 

Issues when laying floor:

If concrete is serving as the base layer of your floor, you will need to fill the gaps before laying a surface on top of the concrete. If you don’t take the time to fill the cracks, then your floor’s surface will be uneven and may be ineffective. 

Ultimately, filling concrete cracks is important in most instances, as leaving them untreated can cause you further issues in the future and will affect the appearance of your floor. You can repair concrete cracks with durable caulk, which can be undertaken as a DIY project or by calling in a professional. 

How Can I Prevent Concrete from Cracking Outside?

While you can’t control the elements, there are certain things you can do to prevent concrete from cracking outside in the future, including: 

Use a good subgrade:

The subgrade is the area below your concrete. The thicker the subgrade, the more load your concrete can support. Whatever it is composed of, the subgrade should be flat and appropriate for concrete to be poured on top. 

Modify the concrete mix:

Getting the composition of your concrete right is vital. Concrete that is too thick or thin is likely to crack, so ensuring your water to cement ratio is optimum is important before laying concrete.  

Install joints when laying concrete:

Utilising and laying control joints will allow for movement caused by temperature changes and drying shrinkage, which gives you an element of control over how and where cracks in the concrete might form. 

Cure the concrete properly:

Allowing your concrete sufficient time to cure properly will prevent crazing (hairline cracks) and will increase the strength of the concrete. 

As you can see, preventing concrete from cracking outside is all about laying and curing it properly, so you don’t want to cut any corners when it comes to preparing and installing your concrete floor. 

Final thoughts

There are many reasons why concrete cracks, but by controlling the conditions in which it is laid and being diligent, you can do your best to prevent cracks. If you notice cracks in your concrete floor, it’s essential to repair them, as they will only get worse in the long term.