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 the salt and even worse, anti-icing agent (calcium chloride) and ice break down the surface of your slab (or curbs) causing pits, spalls and sometimes we see complete surface failure.
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, Rusty Spurr Coatings 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. 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 not getting a good bond. The sealer may not penetrate- just laying on the top, and peeling more easily and appear cloudy or milky. We use a proven product that is not sold to the public and we actually had to be trained on its use. The slab needs to be CLEAN and DRY. So the first step is we pressure wash it with a 4200 psi /4.0 GPM wash gun and get dirt and even old sealer off down to the pours. If the slab is not cleaned properly the sealer will not absorb properly and create problems. We like to wait until the next day to install the sealer and at a time when it’s sure to be dry and the temp is between 15-25 degrees Celsius is ideal.
Sealant is applied (for the homeowner) most economically by using a (solvent resistant) roller on a long handle. For the DIY’s Just keep a wet edge so you don’t see roller lines. Sprayers can be tricky as it’s hard to get it thick enough and not have it pool. Sprayers that handle the strong solvents are expensive. DO NOT use a cheap garden sprayer. You will wreck it. The rubber seals can’t handle the strong solvents. AND NEVER USE A SOLVENT SEALER INSIDE, AS THE VAPORS ARE VERY VERY FLAMBLE.
If all this sounds like too much hassle for you, we would be glad to take care of it. Contact Rusty Spurr Coatings for supply and install options.