Getting Red Dirt Off Concrete

[alohatim]

I was at Long's the other day looking at cleaning products. I started reading the label on a bottle of CLR. I just realized the "R" stands for Rust! I started thinking about the red dirt stuck on my brand new garage floor. My garage has no cars--it is like a second living room and office. I was hoping I could restore the color to the nice mottled gray. Since I knew it is rust that makes the red dirt red, I thought I would give CLR a try (actually, I used Lime Away--figured it is the same thing).

I tried it on an inconspicuous spot. Just squirted it on, brushed it in, then sponged off with clear water. It seemed to work really well! It took out the red brown color that nothing else managed to budge.

I wondered if I could be damaging the surface. I seem to remember that lime is somehow involved in the making of concrete. Am I dissolving away some kind of bonding agent in the concrete?

Also, anybody know of a good clear sealer to use on concrete? What does Costco and Home Depot do to their floors? Is that buffed wax?

[craigwatanabe]

Re: Getting Red Dirt Off Concrete

The cement flooring at Home Depot is pure concrete. It's just buffed to a remarkable smoothness. It's a very expensive process as I'm told by the guys who laid the foundation and did the finish work on it.

There is no wax on the floor because it needs to stay porous.

As for CLR, I've used muriatic acid to acid wash the concrete back to "like new" condition. There are concrete sealers out there but be aware that most sealers will make to concrete slippery when wet.

[alohatim]

Re: Getting Red Dirt Off Concrete

Thanks... I thought of muriatic acid too. Does it etch the surface and make it rough? I found a bottle that last painters left. I may try it. Use it straight or dilute it?

[craigwatanabe]

Re: Getting Red Dirt Off Concrete

Thanks... I thought of muriatic acid too. Does it etch the surface and make it rough? I found a bottle that last painters left. I may try it. Use it straight or dilute it?

Do not dilute Muriatic acid. Water will neutralize it. Just use it straight out of the bottle, pouring it over the stain. The fumes will be intense so don't use it indoors unless WELL Ventilated.

Muriatic acid will lightly etch the surface but in most cases will bring back the concrete to practically "just poured" condition.

If the concrete surface is highly pitted from years of erosion, Quikrete makes a product that when poured and floated will yield a nice surface...it's called a concrete resurfacer and runs just under $30 a bag. It's basically high strength cement minus the aggrigate, it's a great way to bring a damaged sidewalk or driveway back to life.

[WindwardOahuRN]

Re: Getting Red Dirt Off Concrete

How about trying a power washing first?

We have a power washer and it does a fairly decent job. I think power washers can be rented from tool rental places here, too.

Maybe worth a shot?

[buzz1941]

Re: Getting Red Dirt Off Concrete

If the concrete surface is highly pitted from years of erosion, Quikrete makes a product that when poured and floated will yield a nice surface...it's called a concrete resurfacer and runs just under $30 a bag. It's basically high strength cement minus the aggrigate, it's a great way to bring a damaged sidewalk or driveway back to life.

Can it be used to level a slightly low floor? Like 1/4 inch.

Yeah, a power washer can really blast the dirt out.

[alohatim]

Re: Getting Red Dirt Off Concrete

First I tried brushing in Simple Green with a stiff bristled broom, then blasting with the hose. It removed very little.

I tried my electric pressure washer--was a afraid if I got the nozzle any closer than 6 inches that I would damage the concrete. The color still remained. What people tell me is that since it was a fresh pour, the dirt has penetrated a little ways down and is now cured inside the concrete.

I am hoping these chemicals will allow me to wash out the dirt with the least damage to the concrete. Then I can seal it so it doesn't penetrate anymore.

[craigwatanabe]

Re: Getting Red Dirt Off Concrete

Can it be used to level a slightly low floor? Like 1/4 inch.

Yeah, a power washer can really blast the dirt out.

Yes this can up to a half inch I believe.

[MrHydro]

Re: Getting Red Dirt Off Concrete

Some years ago I was trying to clean antique glass bottles with muriatic acid and I spilled some onto the concrete and when I washed it away with some water it left a spot on the concrete looking clean and bright gray while the untouched concrete nearby was dingy and dirty looking. Over time the difference faded and I can no longer tell where the muriatic acid was spilled.

Be careful! You don't want to risk any acid landing on your feet or hands! Yikes!