If you have exposed aggregate or stamped slabs on your property, I hope you are maintaining the sealant. These finishes look pretty but they need extra care. Even a plain slab will benefit immensely from being sealed if only once near the beginning of its hard life! Here are reasons and methods for sealing concrete.
Concrete is porous. It is basically a very hard sponge. When it is mixed, there is water between all the little grains and particles. Then it evaporates, leaving actual holes and pores for water and dirt to reabsorb. Just think of all those little holes full of slushy dirty salty ice and water. Then it freezes and thaws about 50 times every season. Have you ever seen a pail or pipe split open from the irresistible force of ice freezing solid inside? Well on a miniature scale, that’s happening in the surface of your concrete. Tiny fractures form, and the salt and ice break down the surface of your slab (or curbs).
Now you understand that sealant is not just cosmetic, especially for decorative concrete. The sealer penetrates the surface, filling those little holes and forming a uv resistant, salt, dirt and erosion resistant raincoat for your expensive slab or curb.
You can tell you need sealer when exposed aggregate looks dry and dusty. You can actually see that ice is popping off some of the pebbles. In stamped concrete, look for “freckles” where the release colour is popping off or wearing away from abrasion. When you see freckles and dry spots that absorb water, then it’s time to reseal!
In Alberta, contractors generally use petroleum based acrylic sealers. So if you don’t know what was used before, you should use that too. Do NOT buy or accept any advice to EVER use a water based sealer! Do NOT go to the nearest home improvement store! I have wasted a couple thousand dollars on the “latest greatest” water based sealers- consider it my sacrifice for your sake. Believe me when I say, they are ALL a waste of money and your valuable time.
Stamped concrete, especially needs TWO or three initial coats of sealer. Contractors (like us) often apply the primer coat very shortly after laying the concrete. Then it needs to breathe for a couple of weeks ( the manufacturers always say a month but that’s just the them covering their behind ) After that they usually leave it to you to apply the second coat but sometimes forget to tell you that important detail.
With one exception, you should only use under 20% acrylic solids petroleum base sealer like Conspec or Unicon or National Concrete house branded cure and seal. Yes you can go to the professional supply store and they will sell you the professional product. (Please understand, some sales people have never actually used sealant, so some might try to sell you on water based sealer . Don’t fall to their beguiling sales pitch! ) The reason for using light bodied sealers is that you will get a better bond and re-emulsify old acrylic sealant by having a higher ratio of solvents in the solution. If you use a heavier ( thicker) glossy sealant, you risk getting a good bond. The sealer may not penetrate- just laying on the top, and peeling more easily.
The slab needs to be CLEAN and DRY. So maybe pressure wash it and wait a day or two for warmish weather. 15-25 degrees Celsius is best.
This slab shows some worn areas even after reseal (top) it could have been touched up, but it’s not too far gone and looks ok.
If your stamped colours are badly worn down, the colour can be fixed somewhat , but I will leave that for another article. Just don’t reseal unless you are ok with how it looks, or you will permanently seal in the bald patches.
Sealant is applied (for the homeowner) most economically by pouring out puddles and using a brush and a fuzzy (solvent resistant) roller on a long handle. Just keep a wet edge so you don’t see roller lines. Sprayers can be tricky and the ones that handle the new solvents are expensive. DO NOT use a cheap garden sprayer. You will wreck it. The rubber seals can’t handle the strong solvents.
If all this sounds like too much for you, we found a very knowledgeable company offering a resealing service. DSO concrete coatings uses their own proprietary 30% solids petroleum base acrylic sealer. They have a great program you can register to get reminder calls every couple or three years, and they can take good care of your slabs and curbs too.
They know more about sealant than me, so outside the scope of this article, you can call them for advice too. 780-668-1894
They serve both the Edmonton and Calgary market areas. 
This photo shows some sealant problems with curb. It didn’t get resealed and went through winter with only the primer coat
So-you can buy their amazing sealer direct from DSO too. They don’t have a store, but call them to arrange a way to get their superior product at about the same price as the others. Just you will need to buy a 20 litre pail minimum, whereas you can get 4 litre cans from the others. We just met these folks but I’m very impressed. I’ll update this blog after some experience.
DSO coatings. 780-668-1894
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