Concrete Resurfacing Tutorial
This was a concrete resurfacing project we did in Lakeworth, TX to help a homeowner create a more common theme throughout the area.
The pool deck had a “cool deck” overlay on it that had faded a bit and was looking a little dated. It also had cracks everywhere that really detracted from its appearance.
At the same time patio and sidewalks had an exposed aggregate finish that was hard on the feet. This type of finish has small stones sticking out of the concrete surface, and if any of them have sharp edges, it can be hard to walk on barefoot.
Our homeowner was looking to make the entire area blend in together instead of a hodgepodge of floor finishes.
We started this concrete resurfacing project by applying a crack fill epoxy to all of the major cracks after opening them up first with a diamond blade mounted on a grinder. This allows the crack fill material to penetrate deeper into the crack so that it can “glue” the sides of the crack together.
While the epoxy is still wet, we sand it so that when we apply our resurfacing material it has something to grip as an epoxy surface is very smooth and without it the material might peel off.
As were were doing this we noticed a couple of ducks watching us. It wasn’t too surprising since we were right by the lake, but these guys hung around for a good reason, as we found out later.
The most important step in concrete resurfacing is proper floor preparation. This almost always requires grinding the surface to roughen it up. This gives the resurfacing material something to “bite” into.
When we grind, we use a shrouded grinder that is hooked up to a vacuum system. This pretty much eliminates any dust created by the grinding process.
Sometimes, instead of grinding, we may use an acidic etching solution to open up the pores. It works but you have to be careful with the residue left over from this process as if it drips anywhere it will etch the floor and burn your skin. For these reasons we prefer to grind.
Next we power washed the entire slab to clean off anything that might prevent our concrete resurfacing material from sticking tightly to the floor.
Now it’s time to apply the concrete resurfacing material to create our first skim coat overlay. We call it that because we are laying or skimming a coat of concrete over the floor. So just what is this overlay material anyway? It basically a combination of cement, sand, and a special polymer (fancy word for glue) that allow it to stick to the floor in a thin coating.
If you just mixed up a batch of cement, sand, and water and put it down in a thin coat it would peel right up in a few days. The polymer is the key. It’s incredibly sticky and its adhesive strength increases with time.
This resurfacing material leaves the floor with a somewhat sandy texture which is excellent for abrasion resistance. We pour this special cement into a few quarts of water, add some pigment to it (in this case a beige), stir it up and then squeegee it on the floor.
We spray a light coat of water on the bare concrete before applying the overlay, which helps keep the mix wet. Concrete is very absorbent so if we didn’t do this, the concrete floor would suck all the water out of our overlay mix as we apply it, making it drier and thicker, eventually reaching the consistency of chewing gum.
At this point it’s unworkable. Wetting the floor prevents that. We also try to lay it down as smoothly as possible that way we don’t have to sand it as much with a rub brick later.
After applying the first coat we need to wait for it to dry before putting down the second. This really depends on the environment. If it’s really cold outside, it can take six or seven hours for it to completely dry. In that case we will come back the next day; normally though, it’s two to four hours.
If the floor was in really bad shape (lots of divots and other issues) we may apply a third coat of resurfacer to cover these problems up. However, most floors only require a couple of coats of the concrete resurfacing material, so the second is usually the final one.
Since part of this project had exposed aggregate we used the material to fill in the areas between the stones. As you would expect this takes more material but it does it create a smoother finish.
Our Lakeworth homeowner wanted a stone pattern in the floor, so once the second skim coat had dried we chalked out the pattern. That means we take a piece a chalk and draw out a stone pattern on the overlay. If something doesn’t look right or we change our mind we can easily erase these chalk lines without damaging the floor.
One neat trick we do if a client has chosen a stone pattern is to incorporate the existing cracks into the design. Though we are using a crack fill epoxy to help stabilize these cracks there is no guarantee that they might not come back. If they do it usually shows up as a thin line in the floor.
As we are chalking the pattern on the floor we can use these cracks as part of the stone pattern. When we cut the pattern, we do so over the crack so if it does move it will be in the already cut portion of the floor making it pretty much invisible.
Once we get it just right, we can start the actual scoring. Scoring is where we use a round diamond cutting blade, usually mounted on a small right angle grinder to cut the floor.
We always cut completely through the concrete resurfacing material and down into the original concrete floor; that way we have a consistent looking score line as we expose some of the sand, cement, and stone that make up the original floor.
After scoring we have one more step to do before the staining process. We need to protect all exposed areas from overspray.
We do this with a pre-taped plastic drop cloth. We will first apply some blue painters tape along the area we are trying to protect the apply the pretaped plastic drop cloth over it and extend it up about 20” tall. That completely protects any areas from overspray.
At long last we could get down to staining. Here, we had two choices: acid or dye staining. Lately we’ve been doing much more dye staining than acid staining on concrete resurfacing finishes for a couple of reasons.
First, it’s easier to control. Acid staining is reactive while dye staining is pigment based. Reactive staining is much harder to control. The stain will create a lot of variegation but we don’t have much control on what colors it creates. With dye staining, we consistently get the same result because we just mix the pigments to the proportions we need.
The second reason is speed. Acid staining takes time to do its thing and it requires an additional neutralization step to stop the color from continuing to darken. Dye staining just requires for it to dry and we are ready to start sealing.
Lastly, dye staining gives us a much wider palette of available colors than acid staining which has about eight primary colors, some of which, like greens and blues, cannot be used outdoors as they will turn black after a few months.
For this project I went with the dye stain. We mixed up a batch and then started spraying it down when we found out why those ducks were hanging around.
Just as we were staining the sidewalk, a duck suddenly exploded out of a small bush of Japanese grass right next to it. It was a nest with some small eggs! Don’t worry, we didn’t poke around in it; we were just amazed at how well hidden she had been in there.
We got back to work. It normally takes two coats to get the right color combination. It went very fast and by the time we finished spraying the first coat on the floor it had dried so quick that we could immediately start the second coat.
We wrapped up our Lakeworth concrete resurfacing project with two coats of sealer, all under the watchful eye of our mama duck, who stuck around for the duration of the project.
We usually spray it on as it goes on faster and more consistently than rolling it. Our homeowners were very pleased with the final result, and we have to agree it came out rather nice.
Here is a video from our youtube channel that shows the entire concrete resurfacing process from start to finish.