How Can I Etch New Concrete Flatwork?

A pressure washer will do!

Thanks, doc! I ended up doing another acid etch with an abrasive floor sanding setup and the result looks pretty good. Thanks again for the excellent suggestion.

A sand blaster with adjustable pressure will also produce a similar effect. Just be careful when you first start out and use a low setting.

Muriatic acid simply loves to devour masonry products--good etcher.

The easiest and more typical way to achieve a sand or rock finish is the method mentioned by previous owner, to acid wash the surface of the concrete a few days after placement. Use hydrochloric acid, diluted for a sanded surface. Acid washing is just a matter of placing the acid, somewhat evenly on the surface and then washing it off. Hydrochloric acid when reacted and/or diluted is not of concern for disposal (since it would become calcium/magnesium/aluminum chloride and water). You can Acid wash at any time after you have a good set on the surface. Hydrochloric acid actually dissolved the cement, so it dissolved the cement at the surface and leaves the sand remaining. Just be careful about the concrentration and pouring on a concentrated point as it would eat a hole then. The trick is to achieve a reasonable dilution to still react rapidly enough, I would try a mix in the pH 2 to 3 range first and let it sit until the tops sand particules were clearly visible then wash, and make sure to spread evenly as it begins to react and neutralize the acid as it contacts the cement, else you can end up with areas of excessive removal of cement and uneven surface while other areas didn't react enough. It is not a technically hard task, just takes some care in application and attention in timing.

Glad you got the job done.

For the record, HCl reacts mainly with the lime liberated in cement hydration. 6 days after pouring is not too long at all. The actual delay isn't critical.

As has already been pointed out, just wait until you start to see the sand then wash off and finish with a stiff broom.

Of course, a pressure washer is an even better way to achieve your finish, as you have already found out.

Enjoy your concrete!

I'm afraid your hosed for this job, but for next time, the way to get the nice non-slip finish is to float it, then take a course garage broom and brush the surface lightly. For that professional finishing touch, you go around the edge with a finishing trowel that puts a nice radius on the outside edge and makes a smooth border about 3 inches in, leaving the rough part in the center. I just talked to a general contractor relative of mine and he said that if you try to acid etch concrete you can get a more or less non-skid surface but it won't be even and it won't look nice. You could try painting the old and new sidewalks with an epoxy concrete floor paint that has sand mixed in it. At least that way, they would match in color and properties. Good luck.

Actually salt, exposed sand, exposed rock finishes are all architectural surfaces meant to look better than a rough broomed standard concrete finish like you'd apply on a house slab or cheap driveway. It can also provide for better local surface drainage and higher friction against slipping, like a salt finish does. Pools will typically use something like a salt finish or similar other surface textures to control slipping potentials and provide aesthetic quality of pool decks. I have acid etched many concrete surfaces for exposed rock or to weahter the surface. The trick, if you are competent with concrete work and reasonably (high school chemistry) knowledgeable of the concrete and acid, is to control the concrentration of the acid and spread it evenly. Too concrentrated burns holed locally where applied. A sanded epoxy paint surface would be expensive, but is one way to treat the surface, much like the concrete liner of some expensive pools.