Concrete Countertop Cement Choices

Advice on materials choices and some tips on technique for a first-time concrete countertop job. June 12, 2014

I am going to build some concrete countertops for my own house. I am completely, 100% confident in my abilities to do what I want done. I did some looking and found a company that produces white cement and white marble sand for the finish coat on Gunnite swimming pools. Both companies claim their cement has additives that bring the psi up to 7,000 pounds in 28 days, both advertise ASTM testing, etc. I know concrete can be tricky stuff. I can buy the pool companies sand and cement (with additives) separately and I'll have $7.70 invested per 70 pounds. The pool company is out of Arizona and has been serving the pool industry (and countertop builders) for many years. I need 20 bags - $160 vs $1,200. Am I missing something here??

Forum Responses
(Laminate and Solid Surfacing Forum)
From contributor J:
I am not a guru at all, but I did concrete counters for my own house several years ago. I made my own mix using sand and gravel from a big-box store, and type III Portland cement which I had to get from a specialty building supply. It's the type III, or high early strength Portland cement component that makes it get stronger sooner. I would guess that both Rhodes and the pool people use Type III to bind their other ingredients together. Not that you asked, but one thing I would do differently is that I'd make sure the top edges of the counter were either rounded or had a decent chamfer (3/16" or better). I used square-edged molds with caulk beads in the corners, and ended up with a fairly crisp pencil-edge. Those sharpish edges chipped rather easily during the first year or so.

From contributor B:
White Portland cement is white Portland cement. The expensive place is charging you for their name and system. I would suggest that you buy a bag of the cheaper stuff and do a test sample of the thickness and edge detail that you are planning. You will work out some details that you might not have thought about.

From Contributor Z:
I use Quickreet 5000, available at a big box store for about $6 per 60 or 80 lb bag. Then it needs additives. It has lots of fiber, water reducers, color and other additives. The water reducer allows you to use about 1/2 as much water, so it will shrink less as it dries. The shrinkage is what causes cracks in your countertop, so you want the lowest water content you can manage.