Can I use nonshrink 1585 precision grout hearth slab

I wanting some input on the hearth slab. The materials list states 5000psi concrete however my local store doesn’t here it. They recommend using 1585 non shrink precision grout. Is this something that I could use? Getting mixed reviews on the web. Any help thanks

Hi Stasher, and welcome to the BrickWood forums!

I’m really sorry for the long delay in responding to your question. It was posted in a section of the forum that doesn’t always notify us when there are new threads. I’m going to answer it, even though i suspect you’ve long since moved forward, as a guide for others.

It turns out that 5000psi concrete is not a common item at the retail level. What is common is 4000psi concrete, and you can definitely use that. Either one will give you a ridiculously strong slab structure, and you can use it for any place in the build that calls for concrete. (Filling the voids in your concrete blocks, for example, will pretty much yield a bomb-proof structure.)

The Quikrete 1585 product is about 3 times as strong as either of those materials. BUT… It is grout, not concrete. It is meant to “glue” concrete together, or to anchor stuff into concrete. And it is at least twice as expensive as 4000psi concrete, and over 4 times as expensive as standard concrete (which you should not be using). Grout has sand in it, but no aggregate (crushed stone). Over the expanse of a slab, it’s more likely to crack because there’s nothing in it to relieve structural stress except a little lime.

I’ll bet your local store special-ordered a delivery of 1585 to accommodate a contractor who needed some of it, and now the remainder is a hammer in search of a nail. Which would be your project. “High-strength? Oh, you could use this!”

You can readily substitute 4000psi concrete for 5000psi concrete. But 14000psi grout is not a good substitute material, and at $17 a 50 lb bag it’s going to weigh down your construction budget, too.

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