Originally Posted by BluTaco
I've never heard that concrete rots wood. That's ridiculous. When people talk about concrete most of the time they don't know what they are talking about. Concrete is a mixture of cement, sand, gravel & water. When CEMENT is mixed with water it creates a chemical reaction and cures hard. Sand and gravel are just put in as a filler to minimize the cement required. Cement is what is expensive. Concrete does not have moisture in it to rot wood. Concrete is porous and allows water to pass through that can eventually rot wood. If you use pressure treated wood it will last for years and years (I'm talking 30-40 years). Building code does not allow for structures to bury PT wood for the fact that it will eventually rot out but if you are building a fence then you are just fine. Also, as for installation most people pour in dry concrete for the posts. Level the post and tie them together with 2x4's to ensure they are all straight then go back with the water hose and wet the concrete.
You're right , concrete doesn't rot wood , water does that , it's the concrete that holds the moisture ( originating from precipitation or moisture content in the soil ) against the post , causing rot
Pressure treated posts , whether CCA or ACQ can also fail , especially in concrete and I've seen them rot off here in 10 years