How to Diagnose Problems With Your Concrete Slab
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How to Diagnose Problems With Your Concrete Slab

May 14, 2018

Cracking, crumbling, sinking, settling...there is so much that can go wrong with concrete over time, particularly if it wasn't poured properly in the first place. These slab problems are more than just an eyesore; they can be dangerous for pedestrians or — if you own a business — prevent customers from wanting to visit your location.

 

Lucky for you, most of these common issues are pretty easy to diagnose! And with a quick visit from our concrete lifting team here at Ward Insulation, you can be back up and running in just a day's time. Here's what you should be looking out for (we'll explain each specific issue in further detail later in this post):

  • Dusting

  • Scaling

  • Water intrusion

  • Shrinkage cracks

  • Frost heaves

Let's explore these further. . .

 

 

Dusting

 

What is it?  Dusting is characterized by a soft, chalky film on a slab that can be rubbed off with your finger. It's often caused by "overtroweling" or accidental carbonation of the concrete during the setting process, resulting in constant abrasion. 

 

What can be done about it?  Apply a surface hardener or densifier which includes lithium silicates or sodium and potassium silicates. This will seal in the eroded particles and prevent further abrasion — at least for a time. 

 

 

Scaling

 

What is it?  Scaling happens when the air content of the concrete is less than the proper percentage (between 5 and 8 percent). It can also be caused by deicing salts getting onto the surface before it has dried and stabilized fully. Concrete that is scaling will look bumpy and uneven, with aggregate (loose rocks/material) clearly exposed. 

 

What can be done about it?  Not much, unfortunately (you can't get air back into concrete that's already sealed). That said, it's possible to heal surface damage by breaking down the upper layer till you reach sound concrete, then applying an overlay. 

 

 

Water intrusion

 

What is it?  It's not uncommon for water from a drain, spout, or broken pipe to intrude the surface underneath a concrete slab, eroding the soil and causing it to sink over time. Water intrusion is usually quite obvious, signaled by one particular section (often a corner) sinking, while the rest remains intact.

 

What can be done about it?  Make sure that all spouts and drains are releasing water a good ten feet from your concrete. Already have a sunken section? Call a concrete lifting specialist in your area (Wyoming and Colorado, that's you!) and they'll raise it right up.

 

 

Shrinkage cracks

 

What is it?  Shrinkage cracks, while only cosmetic, are still indicative of an imperfect slab. They're recognized by a tight, thin pattern of very thin cracks which form if the concrete surface dries too rapidly. 

 

What can be done about it?  Not much. While you may think that polishing the surface would get them out, this just isn't the case. That said, the performance of the slab shouldn't be compromised by shrinkage cracks alone. Don't worry about this one!

 

 

 

Frost heaves

 

What is it?  One of the biggest overarching problems associated with concrete is its propensity to crack in various circumstances. One of the most common is thermal contraction — of which frost heaving is a specific type. Frost heave happens when water is drawn from unfrozen soil to the freezing zone where it attaches to and forces soil particles apart. 

 

While it can be difficult to distinguish between frost heave and settlement due to shifting or eroding soil, frost heave bears a few distinct qualities: evidence that the movement is recurrent or cyclical (happens often in the same place), evidence of water intrusion or poor drainage (see above), and absence of backfill or site fill problems. 

 

What can be done about it?  Left untreated, cracks due to frost heave can spread quickly, making them more vulnerable to failure. Remedy the issue either by concrete lifting or by replacement, and consider the problem to be urgent. 

Do you notice any of these signs and symptoms in your own concrete?

Give us a call!