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Concrete Pitting, Flaking & Staining

The way your concrete looks says a lot about the health of your home. Spotting the signs of concrete pitting, flaking & staining can save you a lot in home repairs.

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For many homeowners, concrete is more than just a building material. It’s an integral part of their home’s aesthetic. That is why it’s so incredibly devastating for many homeowners to see the surface of their concrete begin to deteriorate. Concrete does not stay smooth and evenly colored forever. Discoloration, staining, flaking, crumbling, and pitting is unavoidable, especially for the concrete that is outside your home. 

Homeowners who wish to sell their properties should still invest in locating and repairing deteriorating concrete since it brings down the home’s value. Even if the way the concrete looks doesn’t bother you as a homeowner, concrete pitting, flaking, and staining should. This is because concrete deterioration can point towards a serious structural and drainage issue around your home. Like a runny nose in humans, concrete deterioration indicates a problem with a home’s health. 

How Concrete Starts Pitting, Flaking and Staining

Concrete may seem like one of the toughest materials in the world but, as you examine it closer, you’ll realize that it has one major flaw: its porosity. By allowing water to seep through, concrete makes itself vulnerable to erosion. Water is an erosive element capable of displacing concrete particles. At first, the damage done by erosion is trivial, but as time goes on, things get more and more severe as the concrete gets weaker. 

Weak concrete cracks a lot easier, and the cracks only serve to allow even more water through. For the concrete that’s a part of your foundation, this is a major problem. As your foundation concrete and slabs weaken, they lose their ability to support your home properly. This, of course, leads to structural issues like bowing walls, slab and foundation settling, and flooding problems. 

What Is Concrete Pitting? 

Concrete pitting is when the surface of a concrete structure begins to deteriorate. It’s defined by a cluster of small holes that appear on the surface of the concrete. It’s an extremely common problem in construction that occurs because of a problem with the way the concrete was produced. It usually happens on concrete that has a low psi (pounds per square inch). 

When a concrete structure begins to pit, it indicates a problem with the concrete’s internal structure. Concrete is made up of rock aggregate, sand, water, and Portland cement. When making concrete, you can add and subtract certain materials to make the concrete firmer, less porous, or stronger. However, creating concrete doesn’t end with the mixing. After pouring, the concrete can be periodically to help with the curing process. 

If something goes wrong while the concrete is being mixed or while it’s curing, then there’s a potential for future pitting. This isn’t always the contractor’s fault as concrete doesn’t always display problem signs while it’s being made. This means that even the most experienced contractors won’t notice something wrong with the mix.

Concrete pitting is extremely dangerous; because it indicates a problem with the concrete’s integrity, it means that your concrete is structurally weak. Concrete gets stronger as the years go by, so pitting spells trouble for the concrete’s strength. This can be detrimental to your home’s health, especially if the pitting is found on your foundation’s concrete. You definitely don’t want your home to be supported by weak concrete, so you need to act fast as soon as you notice the problem. 

Concrete Pitting Problem Signs 

Pitting can be visually identified by the tiny, rough craters that appear on the surface of the concrete structure. Sometimes, the craters will be spread out throughout the surface. Other times, it will be a cluster of craters of different sizes and depths. Concrete pitting often looks like a very thin layer of the concrete’s surface was scraped and torn off. The edges of the craters are almost always jagged, though smooth edges can be found on concrete that is constantly used or walked on (driveways, basement floors). 

When the concrete begins to pit, the craters will be small. As the pitting advances, and the structure weakens, the craters will clump up together and might even get big enough to form a single large crater. The state of the craters along the concrete surface depends on various factors: how old the concrete is; the materials used for the mixture; the curing process; and how often encounters water and ice. Concrete pitting usually starts less than five years after the concrete has been poured. 

Another visual sign of concrete pitting is uneven textures. Concrete is not naturally smooth. Contractors use tools to smooth out concrete after pouring it. This means that as the concrete pits and the top layer wears down, the concrete’s rough, natural texture gets exposed. 

You can test your concrete for concrete pitting by lightly tapping it with a hammer. If the hammer forms another crater, then it means the concrete is weak. If the hammer bounces off the concrete, then it’s still strong. 

What Is Concrete Flaking? 

Concrete flaking (sometimes called concrete spalling) is very similar to pitting. It also refers to the deterioration of a concrete structure’s surface. The difference between concrete pitting and concrete flaking lies in the different causes and in how the concrete itself is affected. Concrete pitting is caused by a problem with the concrete’s structural integrity, but concrete flaking is caused by water exposure and the freeze-thaw effect. 

Water is an erosive element capable of displacing all kinds of particles, even the ones that make up concrete. Freeze-thaw, on the other hand, is capable of displacing particles by expanding freezing moisture. The freeze-thaw effect is so impactful on concrete that, after years of damage, it can deteriorate the structure until the rebar is visible. 

Besides water and the freeze-thaw cycle, concrete pitting can also be caused by human tampering. When something heavy drops on a concrete slab or when you use a shovel for your snow and it hits the concrete—that can also cause some flaking. 

Because of the exposure to rainwater and snow, concrete flaking is more likely to occur on your outdoor concrete like your patio, walkways, driveway, and pool decks. Concrete slabs that are near flowerbeds are also likely to flake due to exposure to plant insecticides and weed killers. The chemicals in those products can trigger reactions that cause flaking.  

Concrete Flaking Problem Signs 

Visually, concrete flaking and concrete pitting look very similar to each other to the point where many homeowners will not know how to distinguish between the two. However, flaking and pitting do have certain characteristics that make it easy to tell the difference as long as you look closely enough. 

With concrete flaking, there aren’t as many craters on the surface. As the name implies, concrete flaking has more to do with the surface of the concrete peeling off more than the surface breaking apart. 

Because concrete flaking has nothing to do with the way the concrete was produced, it happens to any concrete. A good way to differentiate between concrete flaking and pitting is to notice the depths of the surface damage. The craters formed by pitting will run deep, and the holes will still be there even after the surface has broken off. With flaking, on the other hand, if the surface has peeled off and the concrete lacks craters, it means that the concrete itself is strong and it’s flaking due to external factors. 

Like pitting, you can also use a tool to test the concrete for flaking. Use a tool with a sharp tip, like a screwdriver, and drag it across the concrete’s surface. If it creates a white line, then the concrete is sound. If some of the concrete flakes off, then you’ll know there’s some flaking going on. 

What is Concrete Staining? 

Just like concrete never stays smooth forever, concrete also will never stay the same color forever. Concrete, especially concrete located outside, goes through a lot of changes despite being immobile. These changes are sometimes due to external elements, but they can also be internal at times. 

The good news about concrete staining is that you can find it a lot faster than pitting or flaking. Unless the concrete encounters extremely harsh weather, concrete pitting and flaking is an incredibly slow process that can take a few years. Staining is a different story because concrete usually has an even, gray color; any stains will immediately catch anyone’s eye. Here are some of the things you should look out for with stained concrete:  

efflorescence on basement walls
Efflorescence 

Efflorescence is a white, powdery stain that is sometimes textured as rough patches of a gritty, mossy substance on the surface of concrete. Often confused for mold, efflorescence is nothing more than salt and minerals. 

There are two types of efflorescence: primary and secondary. Primary efflorescence occurs due to the way the concrete was mixed and the materials used for production. As the water content in the concrete evaporates and rises to the surface, it brings all the salts and minerals within the concrete to the surface. There, it forms the white stains associated with efflorescence. Primary efflorescence only occurs in concrete structures that are less than a year old and is most common in outdoor concrete. 

Secondary efflorescence is similar, but instead of being caused by the water that was used for the mixing, it’s caused by water that saturated an already existing concrete structure. For example, if your basement experiences flooding and efflorescence stains appear on the concrete a few weeks later, that would be secondary efflorescence. This kind of staining is most common in interior concrete like basement walls. 

Secondary efflorescence on structures over a year old indicates that there’s a moisture problem in your home. If you’re having efflorescence staining problems in your concrete, then you’re most likely having mold and humidity problems too.  

Mold 

Mold is a microorganism that feeds on organic matter. It may not seem like it, but concrete has organic matter in the form of salts and minerals. Mold on concrete looks like the typical black or black-green stains usually associated with mildew. The size of the stains depend on how long the mold grows on the concrete. 

Mold stains are more likely to appear in humid, dark places like your basement. It can also grow on the slabs that make up your patio or yard walkways if they are close to foliage. This is because the vegetation blocks out sunlight, allowing the mold to thrive. 

Mold on your basement concrete is pretty serious, and means that there is a humidity or leaking problem in your basement, which, if you live in a Mid-Atlantic city like Roanoke, VA, this is most likely the case. Your foundation likely has poor drainage can lead to foundation settling and other structural issues. 

Oil Stains  

Oil stains on concrete have a pretty straightforward cause: your car. They are most likely to happen on your driveway or on your garage floor and can be caused by motor oil leaking. 

Despite the simple explanation, oil stains do not have a simple solution. This is because concrete is a porous material that absorbs oil. Once that oil stain is there, it’s difficult to get rid of. 

Discoloration  

Sometimes, concrete will begin to show dark, spotty blemishes for seemingly no reason. These kinds of stains make it look like it rained, and the water was just beginning to dry. Unlike other stains, discoloration does not occur because of an external element staining the concrete but rather a specific ingredient used when the concrete was made. 

Calcium chloride is what causes discoloration. It’s an admixture that accelerates cement hydration, as well as reduce the settling time by over 50%. While very useful to save time during construction, there is a risk of causing discoloration.  

Rust Stains 

Homeowners often think that concrete has rust stains because of rebar. However, rust stains can still appear on concrete that has not been reinforced with rebar. Concrete without rebar can rust because it has iron in it. It depends on how much iron is in the concrete, but moisture can ferment the iron and cause the stains. 

Because rust stains are caused by a chemical reaction, they are extremely difficult to remove. The chemicals that eliminate the stains are exceedingly harsh, so don’t try to remove rust stains yourself. 

Concrete Pitting, Flaking & Staining

FAQ's

Concrete pitting, flaking, and staining is something you definitely want to avoid as a homeowner. Not only do they make your home look old and ugly, but they also weaken the concrete. There are some forms of concrete deterioration and staining (like pitting and discoloration) that are out of the homeowner’s control. While there isn’t much that can be done in those situations, there are other situations that can be avoided by taking the proper precautions. The trick to preventing concrete deterioration is to simply limit its exposure to water. 

  • Indoor Concrete 

For indoor concrete, you’ll want to focus on improving the drainage and moisture control in your basement. You can do so by speaking to your local foundation experts about the different waterproofing measures they provide. At JES, we have a variety of installations for different kinds of foundations. This includes vapor barriers, sump pumps, dehumidifiers, and indoor drainage systems. 

Cities like Roanoke and Richmond, VA as well as Baltimore, MD see a lot of flooding due to tropical storms. While the storms themselves may not always be harsh, the storm surge raises the water level of the rivers and causes a lot of flooding. With such intense flooding issues, investing in good waterproofing measures can permanently protect your concrete and your foundation.  

  • Outdoor Concrete 

Outdoor concrete is a little more difficult to protect. There’s not much one can do to protect the slabs from the elements save for covering them all up in waterproof sheets. What can help is improving the drainage system around your yard so that water doesn’t flow towards your concrete slabs. 

Seasonal maintenance is a must, especially during the winter. Make sure to always shovel the snow off your property to avoid subjecting your concrete and soil from the freeze-thaw effect. Keep an eye out on your drainage systems, such as your gutters and downspouts, since any clogging will cause leaking problems that could affect your concrete. 

Concrete pitting, flaking, and staining can debilitate your concrete. But can it cause concrete settling? The truth is, it can’t. Concrete settling has nothing to do with the concrete itself and everything to do with the soil under the slab. It can accelerate the settling process but not actually cause it.  

  • How It Accelerates Settling 

Concrete pitting, flaking, and staining accelerates settling because it debilitates the slab. As the slab grows weaker and cracks, water is able to seep through and saturate the soil below a lot easier. The slab relies on the soil as a stable foundation, but soil can easily get displaced by water. 

In Virginia, the Washington–Baltimore combined statistical area, and West Virginia, the soil is sandy, loose, and fine-grained. This means that it will wash out if met with any water. A weak, porous concrete slab contributes to concrete settling by allowing water to wash out the soil further. It’s also more likely to break when settling against the loose soil.  

  • What You Can Do About It 

If your concrete slab has settled, there is a way to repair it. JES offers PolyRenewal™ as a solution. PolyRenewal™ is a concrete lifting method that involves injecting polyurethane foam under the concrete slab so that it replaces soil as a support for the slab. The polyurethane foam is capable of lifting the sunken slab back into place and evening out your driveway, patio, or pool deck. 

Polyurethane foam is impermeable, meaning that it does not allow water to seep through to the soil below. Unlike other materials used for concrete lifting, it does not erode with water, and it is not affected by the freeze-thaw effect, making it a permanent solution to concrete settling. 

Mold is more than just a cosmetic stain on your concrete. It’s a health hazard and can have a profound effect on the lives of you and your family members. If you spot a mold stain on your concrete, then you need to act fast because mold is a lot more dangerous than you might think. 

  • How It’s Harmful  

Mold is dangerous because of how it affects the respiratory system. Upon immediate exposure, it can trigger allergies and cause minor breathing issues. Mold releases spores that latch onto your lungs and sinuses when you breathe them in. Those with existing respiratory complications will have a harder time being in a space where there’s mold. 

Long-term, mold can cause severe health issues. Mold poisoning is one common consequence as well as problems with your respiratory system. Your sinuses, lungs, throat, and eyes can all be compromised when exposed to mold, so it is definitely not something you want in your home for too long.  

  • What to Do About It 

The moment you see some mold on your concrete, it’s time to call in the experts. Concrete that’s outside might be a little easier to get rid of because of sunlight exposure, but indoor mold requires a professional hand. Not only can professionals get rid of the mold properly, but also they can point out other places where mold might be growing in your home and take care of that as well. 

It takes really harsh chemicals to get rid of mold in a damp, dark place like a basement. The best mold-eliminating chemicals are so strong that they are not available for commercial use. If you attempt to get rid of the mold yourself, then you might end up missing some. As long as there is a single spore left to grow, the mold will come back.

Get in Touch with JES For Concrete and Foundation Repairs 

If your concrete is pitting, flaking, or staining, then you might need to take a closer look at your home’s structural integrity. At JES, we have the expertise needed to make these kinds of things easy for homeowners. Since 1993, we’ve been the leading local experts on concrete lifting and foundation waterproofing and repairs. We service Baltimore, MA, Washington, D.C., Charleston, WV, and Virginia (Appomattox, Richmond, Roanoke, Manassas, Virginia Beach). 

Give us a call, or fill out our online contact form to schedule an inspection, free of charge! We’ll send a JES field expert to your home, where you will be given a cost estimate and a rundown of everything you need to keep your home strong and safe.

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