Concrete polishing

[KChurch1]

We started polishing the concrete counter today....messy! It's a bbq surround... the homeowner had the concrete poured... he said it was plastic cement agregate with sand...and then he did a slurry of portland cement with black tint top coat and sides. It looked pretty smooth, but with a few rough spots. We tried to polish an area with just polishing powder and hog pad... it brought up the shine, but the rough areas had to go, so I got out the diamonds and started grinding... started with 220 grit... went through the top coat slurry very fast and exposed the agregate.... the problem is that the agregate is not being exposed evenly... after we started grinding he said that a chunk of the top had fallen off and he replaced it with the tinted portland cement... no sand. There's really no way to get a consistant finish with just polishing. What would you suggest? Should we just finish polishing what we can and put a concrete stain to even out the color? The guy is not real picky and he knows it's our first concrete polish, but we would like it to look nice...

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[doitright]

Hi Karen :)

After speaking with Maurizio several weeks ago, it sounds like you and I are tied for 1st place for these unique "Why me?" jobs. :D

I have only done concrete floor polishing, with large planetary head floor machines. A typical concrete floor has a nice blend of aggregate, sand, and cement. It is usually tamped to bring the cement cream to the top. After the initial cut, the sand and aggregate are exposed, and the subsequent grits are used to polish. It sounds like that is basically the procedure you used.

Since this is a poured top, this is probably where the problem lies. I'm not familiar with plastic cement aggregate. (I'm familiar with the term "plastic" cement, only)

It doesn't make sense to apply a black top coat, then to grind and polish. :confused:

What were you trying to achieve as an end result?

[flatfloor]

How about a stain and then 2-3 coats of a concrete sealer such as L&M Sealhard. http://www.lmcc.com/products/prodinfo.asp?id=49&lang=

[KChurch1]

We went back today and tried a few things... one of the things we tried was TYW Stone Beauty tinted with a black tint.... it worked well to even out the color, but the texture of the surface was not acceptable to the client.... combination polished concrete with aggregate and polished black tinted slurry coat..... there was really nothing we could do to give the client the finish he wanted... if the concrete counter had been installed correctly, we could have made it beautiful... the only alternative is for him to apply another slurry coat... we recommended four coats and then repolish... originally he only put one coat and it came off with the first grind.... it would have been okay if we could have exposed the aggregate over the entire suface and polished it, but there were areas where there was only slurry and no aggregate. We finally ended up using 50 grit to rough up the surface and remove the Stone Beauty to ensure whatever he decides will not have a bonding problem. It was a fun learning experience and the client paid us for our time.... I think he's going to have another company come in and color coat the counter with a concrete topping and forget about the polished concrete look....

[doitright]

Hi Karen :)

Thanks for the update!

He may have had better results had they put the tint in the orginal mix, not just by adding a top coat slurry. I don't know if it will ever be right. I'm glad to hear you got reimbursed for your time. ;)