I assume you will be using the premixed bags of concrete? Most bag products are designed to meet some ANSI code bla-bla-bla, don’t know what that means, what I do know is that they use the least amount of cement as possible, so do yourself and the project a favor by buying an extra bag of pure cement. Add in about a three-pound butter tub of the pure cement to each 80# bag of premix. This will richen the mixture and make for a longer lasting project.
I did this at my home over five years ago and it still looks like it did the day it was completed. I know of other people who didn’t richen the mixture and had failures after a few years. Too much work not to get the maximum bang for the buck.
Edited by Bmerf, September 28, 2012 - 01:48 PM.