Why Does Concrete Turn White? Interesting Facts About Efflorescence

Concrete floors make an industrial statement, but with the rise of stained concrete floors, there’s a spotlight shone on efflorescence. While efflorescence may sound lovely, in truth, it can ruin the appearance of your floors – especially if it’s under a sealer. If you’ve noticed your concrete turn white, you’ll want to know whether it can be restored and what you can do to prevent it from turning white again in the future.

Here is what you need to know about efflorescence and your concrete. 

Why Does Concrete Turn White?

concrete turn white efflorescence

In many cases, this is because of efflorescence. Efflorescence is that white powdery substance on the surface of your concrete that can appear over time. It can occur on anything containing portland cement and is commonly seen on concrete floors. It’s what happens when soluble salts and water-dispersible materials rise to the surface of your concrete due to a variety of factors. 

On unsealed concrete, it can either wear off or be removed in most cases. If the concrete is sealed, the efflorescence can be trapped under it, leading to delamination and unsightly discoloration.

What Causes Efflorescence?

When soluble salts, moisture, and migrating channels combine, you can get efflorescence. As moisture rises to the surface of the concrete, it carries with it the calcium salts from within the concrete. These react with CO2 at the surface, forming that white powdery dust. It can be worsened by exposure to moisture, such as rain. 

With no moisture movement, there is no efflorescence. When it is a mere cosmetic issue, it typically results from moisture evaporating from when the concrete was laid down. However, it can also indicate problems, like moisture intrusion.

Can You Prevent Efflorescence?

It’s difficult to prevent efflorescence due to the factors that contribute to its formation. A surface can be efflorescence-free for months, and then it forms. It can also show up quickly, depending on the conditions. Waiting for the concrete to cure before sealing or coating it is generally advised, in order to give efflorescence time to form and be cleaned away. 

This is because cured concrete is denser, so it is harder for moisture to move through it. However, when concrete is not cured and placed at a high slump, this creates many pathways for moisture to move through. 

High-quality mixes, consistent pours, appropriate subgrade conditions, proper draining, and mindful finishing practices can all help to prevent efflorescence. Testing for vapor transmission can tell you whether or not efflorescence is a problem you’ll probably deal with or not. 

These are but a few of the considerations to keep in mind when trying to prevent efflorescence. 

Does Efflorescence Go Away?

concrete turn white efflorescence

Once your concrete has turned white, it’s only natural to want to know if this will resolve itself on its own or whether you need to take action. In most cases, efflorescence will go away with normal weathering, as the salts leading to it are mostly water soluble. It typically goes away after the first year and stops developing in about 18-24 months. 

It will stop on its own after the salts in the surface have dissipated. If you repeatedly struggle with efflorescence, this can be an indicator of an underlying problem that needs to be repaired before it causes permanent damage, such as a water leak. 

Can You Remove Efflorescence?

In most cases, you can indeed remove efflorescence – and typically, with ease. This can be done by dry-brushing the concrete and then flushing it with water. Light sandblasting can work if dry-brushing doesn’t cut it. Be very careful with sandblasting, as you don’t want to roughen or damage your concrete.

There are also some commercial cleaners that can help with removing efflorescence. You could also try an acid solution, but this can change the appearance of your concrete. On average, you want to wait about 2 months before applying a cleaner, in order to determine the severity of the efflorescence. You will also want to test it on a patch, in case it alters the appearance of your concrete.

While most types of efflorescence can be removed, this isn’t always the case. Calcium carbonate efflorescence is an example of one that is very difficult to remove without altering the surface. Sandblasting and water jets may help with this. If you are ever in doubt about how to remove efflorescence, it is best to consult with experienced professionals. 

A crucial factor here is that you need to know what caused the efflorescence to occur. You will want to address the problem. For instance, if you have efflorescence that appeared later on, this could have been because of a water leak. You typically want to fix the problem before removing the efflorescence. 

Does Concrete That Turned White Need To Be Replaced?

Why Does Concrete Turn White? Interesting Facts About Efflorescence

If your concrete turns white, it’s only natural to be concerned. You may wonder if the concrete has been ruined or if the white substance is dangerous and a health hazard. While efflorescence in and of itself isn’t dangerous, it can be an indicator of moisture problems that can lead to structural damage. 

As such, if you notice your concrete turn white, it’s important to determine the underlying cause. You will want to know whether this is something that will just go away on its own or whether it’s an indicator of a larger problem. Your certified Stone Edge Surfaces contractor will be able to help you with this.

Stone Edge Surfaces is here to help with your concrete needs. Our high-quality products are ideal for both commercial and residential use. Contact us today to learn more.

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