Concreate, Inc. delivers concrete polishing and custom staining for both commercial and residential projects primarily in Virginia and Maryland (but also up and down the East Coast). We work hand in hand with with designers, architects, project managers, general contractors, tradesmen, and home owners alike from start to finish. We welcome the opportunity to serve your polished concrete needs in every way possible.

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What Is Concrete Guard?

What Is Concrete Guard?

A worker’s hand applying a polyurethane coating to a floor as a concrete guard.

Learn more about how these easily applied layers work hard to protect concrete surfaces and why they’re not universally required.

Key Takeaways:

  • Concrete guards can help protect against stains and UV light damage
  • These are simple to apply with a microfiber mop
  • The right guard can also provide antimicrobial protection
  • Guards with low volatile organic compounds are a healthier option
  • Not every job will require a guard to be completed

Concrete is often overestimated as being an indestructible material. Why bother adding any kind of coating when it has a reputation for being durable and long-lasting? The reality is that concrete frequently requires some type of shielding if you want it to perform optimally in both practical and visual terms. Additionally, proper shielding also ensures the overall longevity of your concrete. 

It’s often best to apply a guard to protect the slab against stains and give it a little shine. However, this isn’t the case with every project. Contractors need to use their best judgment based on the goal of the final project. Here’s what to look for in a good concrete guard, how to apply it, and what might happen if you don’t.

Just what is a concrete guard?

A concrete guard is a semi-permanent, semi-topical water-based coating that is typically a blend of acrylic and polyurethane. It can also be a critical final step in a successful concrete polishing process, though it’s not tied exclusively to polishing.

Guards provide what the pros call a “sacrificial coating,” or a layer designed to take the brunt of any harm so the concrete doesn’t have to. They can be thinly and easily applied to the slab using a microfiber mop. Once it’s down and bonded to the concrete, the surface has a tough extra layer of protection. This creates a barrier that defends against stains, scrapes, and spills due to the guard filling in the concrete’s pores.

How to know if a guard is right for your site

Guards can be a non-negotiable if the site deals with frequent spills or accidents. Businesses working with a lot of liquids, oils, or chemicals should add a guard to protect their concrete. Other businesses, such as restaurants and breweries, should also have a guard in place to protect their concrete from damage. 

Some guards can even include antimicrobial performance, which goes that extra mile in protecting areas such as a food preparation environment. Bacteria lodged in porous concrete can be a problem on multiple levels – for example, they create a biofilm on concrete which leads to chemical biodeterioration, and their four-stage process of bacterial decomposition can lead to the production of acids, carbon dioxide, nitrogen, and sulfide gas. 

Bear in mind that guards do not make your concrete indestructible. However, they do buy you time to quickly clean up any spills immediately – do not make the mistake of thinking that you can leave spills indefinitely. 

Another important note is the difference between concrete guards and sealers. Guards provide superior acidic protection, while sealers penetrate more deeply into the concrete to strengthen bonds and provide a better shield against the freeze/thaw cycle.

How guards supply solar protection for concrete

Concrete is prone to damage from ultraviolet (UV) light. The sun’s radiation can wear down bond chains and polymers in untreated concrete, weakening the slab to cause spalling, cracks, or a powdery buildup on the surface.

A polyurethane guard can effectively protect exterior and interior slabs from this kind of harm. UV radiation can also cause guards to yellow and colored concrete to fade dramatically in tone. Sites with surfaces handling direct sunlight will therefore want a guard with significant UV resistance.

Enclosed spaces and curing times

The smaller the site is, the bigger concern volatile organic compounds (VOCs) become. VOCs are present to some degree in concrete guards and can release toxic gasses or vapors. These are a health threat in any space, but especially in small and/or poorly ventilated ones.

It’s best to use a guard with low VOC at or below 150 g/L (grams per liter) or a guard with ultra-low levels (below 50 g/L). This precautionary step ultimately applies to all site sizes. Any guard you use should be USDA/FDA compliant and meet ADA requirements. Verify that any guard you consider meets these standards to ensure the best outcome.  

Polyurethane guards cure relatively quickly. Just how quickly is determined by several factors. Two important considerations are the local temperature and humidity levels, which, if too high or too low, will extend the curing time. The precise blend of the guard must also be taken into consideration.

Reapplying a concrete guard

These sacrificial layers will need to be replaced sooner or later, and this needs to be done delicately by experienced contractors. Sometimes, it’s as easy as adding another coating to the existing guard. More complex cases may require polishing down the old guard and reapplying a fresh layer.

This process can be risky, as there’s a chance that the underlying layers could be damaged. A slow and steady wet process with a lighter grit may be needed to assess the situation. Here’s a quick guide on how varying grit levels work and how they are applied.

When can the guard be skipped?

Concrete floors that have been densified and polished are extremely difficult to scratch, so applying a guard could be considered overkill. Adding a guard – which is scratchable – could end up ruining the overall effect of a polished floor. On the other hand, the acidic protection offered by guards could save that polishing job from a serious stain.

Again, this depends on the site and each unique circumstance. The best contractors will take the time to listen to the customer’s needs, applying their expertise to help the customer find the best way to achieve their goal with the condition of their concrete in mind. 

Explore more of our top tips

Looking to learn even more about concrete skills and terminology? Visit our learning center, where you’ll find blogs and podcasts from our in-house experts and hand-picked guests sharing professional insights on many aspects of the concrete industry. We can also help you complete any concrete job except pouring the stuff, so get in touch to learn more!