How To Grind Concrete Floors For Epoxy

Welcome to!  In this lesson we cover how to properly grind a concrete floor, getting it ready for epoxy.

Tools Needed: -18 inch Floor Grinder -Hand-held Grinder -Diamond Grinding Wheels - Orbital Sanders - 100 Grit Sandpaper

- Concrete Vaccum - Shop Vac - Mop and Bucket - Crack Filler - Measuring Cup - Masking Tape

First we decide on which way we are going to exit.  This is the door way we will exit after rolling out epoxy.   Make sure you do this first, or you may literally paint yourself into a corner.

We start by grinding the entire floor with the floor grinder, making sure we stayed away from the walls to avoid damage.

At the same time, we grind the edges near the walls with a hand-held grinder.  It gives you more control and gets into hard to reach places.

This is what the concrete looks like BEFORE we grind it.  It's pretty smooth with a shiny finish.  Epoxy will NOT stick to shiny surfaces.

This is what the concrete floor should look like when it's properly ground.   This concrete is ready for epoxy.

After the floor is properly ground down, it's time to vaccum up all the dust.

We blow out any remaining dust with a dust blower.

Grinding and vaccuming reveals many cracks in the concrete.

All cracks in the floor must be filled.  The reason is because epoxy is so viscus (liquidy) that it will enter a crack and "gravity feed" all of the epoxy down the hole.  

We widen the cracks with an angle grinder and vaccum the dust at the same time.

We widen the cracks so we can fill it with sand.

Next, we level the sand in the cracks with a trowel.

Then we mix up a batch of PurEpoxy Polyurea Crack Filler. It's a 1 to 1 ratio.  It sets off fast, in about 2 minutes.  So, we mix only 8 ounces at a time.

The sand gives the crack filler something to grab onto as it sets up in the crack. In about 2 minutes, it will turn hard as a rock, so work fast.

After the crack filler hardens, the remaining overflow must be ground flat.   We use hand-held grinders and orbital sanders for this.

For any remaining holes in the floor, we spakle them with a skim coat of cement. Then we sand that flat when it dries.

After all the grinding is done, it's time to vaccum one last time. Then we mop the floor with water to pick up the remaining dust.

The final step is to tape off areas we don't want epoxy to get on.   So, we tape the front of the garage where we want the epoxy to stop, and along the edges of the walls.

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