Efflorescence on Concrete: What is it and Why Does it Happen?


Efflorescence. It sounds pleasant – beautiful even. And that makes sense because it comes from a French word that means ‘to flower.’ But when you walk outside, look along the foundation of your house, and notice patches of white and grey crystals, you won’t be thinking that they’re beautiful at all.

Efflorescence is a common problem any time you have porous building materials like brick or concrete mixed with water that’s carrying salt. As the moisture works its way through that material, it will eventually evaporate, leaving all of that salt to crystallize on the surface. This is what creates the white streaks and patches that most people think of when they hear the word efflorescence.

As we’ve already noted, efflorescence isn’t something that only affects brick surfaces. It can just as easily hit a concrete wall or foundation. However, concrete is often susceptible to this issue for unique reasons…

Why is Effloresence on my Concrete?

You can end up with efflorescence on concrete for several reasons – and not just because you’ve been having more rain or snow than normal. The actual production of concrete can lead to efflorescence showing up shortly after it’s cured.

Consider these factors that can go into the presence of efflorescence on your concrete…

  • If your concrete mix has a high salt content, it can wind up being pulled out by moisture once your concrete has been poured and is in place.
  • If, after pouring, your concrete isn’t cured properly, moisture may be left in the concrete which can lead to efflorescence.
  • If the atmospheric temperature is low enough to slow the evaporation rate of any moisture in your concrete, it may wind up drawing salt to the surface of your building material.
  • If your concrete has too much water in it, it can cause the final product to be more porous than normal which may allow greater levels of salinized water to collect in the concrete. This could easily lead to efflorescence down the road.
  • The use of Portland cement can increase the probability that your concrete will end up with efflorescence since it contains higher levels of alkalis which make efflorescence more likely.

Any of these factors (along with several others) may contribute to a higher probability that your concrete will experience efflorescence over the course of its lifetime.

Preventing Efflorescence on Concrete

Fortunately, there are a number of ways that you can mitigate the issue of efflorescence on concrete. In particular, you can use a water repellent or acrylic coating to keep water from absorbing into the surface of your concrete. Adding a sealant like this is simple and only requires three steps…

1. Clean the Concrete. First, you’ll want to rinse the surface of your concrete with water. You can use a hose, a power washer, or a spray bottle depending on the location of the concrete and how large the area is.

2. Apply the Sealer. Once your concrete space is clean and free from any debris or efflorescence, you’ll want to evenly spray the sealer or other solution onto the surface of the concrete. Once you’ve covered it, allow it to set until it’s completely dry. Check the instructions on the sealer to make sure that you apply the proper number of coats.

3. Rinse the Concrete. After the sealant is dry, it’s a good idea to rinse the concrete off one more time. Once you’ve given it a good rinsing, use a dry rag to remove any moisture.

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