A few questions about building things with concrete

General Questions
#1

The wife and I have decided that we need some seating for the back yard, and just to try something new, I thought I’d make a bench or two out of concrete. I plan on using pre-mixed sakrete or its equivalent, possibly with a little colored aqarium gravel mixed in for texture. My questions are as follows:

  1. How thick do the surfaces need to be? The basic design is a flat bench, 36" x 18", with a roughly 12" lip on all four sides. The base will be a seperate piece. I am planning to reinforce the concrete with wire mesh of some kind. Is a 3 or 4 inch thickness OK?

  2. Do I need to use some kind of releasing agent on the formwork? I’d like to be able to re-use the forms if possible.

  3. How long do the pieces need to cure before I can remove the forms?

#2

Three inches thick with reinforcing should be more than adequate.

The 12" lip doesn’t make sense. Did you mean 2" ?

A releasing agent is a must. Wood forms, motor oil soaked in and surface wiped dry.

Colored aquarium gravel is a bit pricey to just add to the mix. Why not scatter on the seating surface and work in slighty while mix is fresh. When patially or neary set broom off the mix and then hose off with water.

Check out: <diynet.com> for more suggestions.

#3

Or brush on diesel fuel.

What is this, the third or fourth concrete question this week? How very odd…