Quikrete is fine. W Tex, like Lower Az has minimal ground movement
Make your pier ftgs 6" bigger than your columns, 16" column = 28" sq footing, 12" thick concrete. Rebar, use #4 (1/2") 2 ea way as stated before as a mat in the ftg and 2 #4 verticals coming out. Pre wire your mats and after pouring concrete center them on top and take a shovel or stick and push them down about half way, 3" min from the bottom is code, measure and jab the verts, don't make it too hard by pre installing them since you will not have an inspection, at least here in Az nonstructural/nonbearing walls don't.
As far as your 16" tall panel between columns to apply the rock, there is almost no weight per sq inch so you only need an area a little wider than 4" and 4 to 6 in thick, no rebar, basically a landscape curb size.
Sounds like a cool project.
Kent
Last edited by krp; 04/15/10.
