cement primer Getting Started Discuss cement primer in the Pizza Oven Design and Installation forums; Is there a good website to learn about working with concrete? I know nothin', and had a builder doing other ...

[jimkramer]

Is there a good website to learn about working with concrete? I know nothin', and had a builder doing other work form and pour the foundation. My first question - how long does it take for the foundation to cure before I can start on the base? We're about 1hr. north of NYC, and I assume temp has a lot to do with it. What about the hearth slab? I'll be using the FB board on top, so it will be 3.5", I think, according to the pompeii plans.

[dmun]

It's advised to let your concrete cure for a week before loading it. Keep it damp, which shouldn't be a problem in this weather.

It's advised not to work with concrete under freezing, it significantly reduces the strength of bond. You're cutting it close here in the northeast unless you enclose and heat your worksite.

[dmun]

Is there a good website to learn about working with concrete?

I was going to refer you to my concrete mixer primer, but photobucket has dumped my pics. I'll see what I can do to fix it, meanwhile, here's the text:

http://www.fornobravo.com/forum/f6/c...asics-790.html (Concrete mixer basics)

Edit: Pics Fixed.

[Neil2]

The thread that dmun has linked to above is a good treatment of this subject.

Most of the problems that crop up on this site have to do with the moisture content. Too wet or too dry. Too wet weakens the concrete. Too dry and the concrete may not work into the corners of the form, leave a lot of voids or, in a worst case, not hydrate fully.

The amount of water to add cannot be determined exactly. There are too many variables such as the amount of moisture already present in the aggregate. As a general "rule of thumb" you can test your slump as follows:

Get a shovel full of concrete. Tilt the shovel up at a 45 degree angle. The concrete should start to flow off the shovel at this angle.