mudbed
 

Today I did a mudbed for a fireplace hearth. Didn't really need it, but I built the 2x4 hearth framework 1.5 inches too low, so took the opportunity to try a mudbed for the first time.
After reading in Fine Home Building how to do a shower mudbed I mixed the concrete the same way. Very Dry.
After placing it I realized I couldn't see any reason for mixing it so dry, especially now, that it is partly cured and the corners seem somewhat friable. Maybe tomorrow it will be different.
In any event, WHY is the concrete mixed so dry?
Thanks

Your right! For "flatwork" it isn't necessary, but, when building a sloping floor it is. The dry mud can then be scraped and shaved and dressed and made really purdy.:)

You could wet yours a little if you want in hopes of "setting-off" any portland that didn't "go" the first time. It may harden it some.:)

Thanks, Bud, for such a quick reply
So, it is sort of like making a surfboard? Put the styrofoam on and then contour it with an abrasive(trowel) to make it perfectly flat? That makes sence!
thanks again

Hi Stef, Welcome. :)

Besides what Bud said, water in concrete causes shrinkage, so less is better. The mud bed is designed to be covered with tile, and when it is, you'll have a very hard and durable hearth.