Posted 6/11/2019 13:29 (#7553380 - in reply to #7553355) Subject: RE: how thich should the concrete be
I designed many secondary fertilizer containments using mafia blocks (2 by 2 by6 ft.) assembled 2 high on a foundation of 3/4 inch crushed limestone 1 ft. deep and 4 ft. wide with filter fabric between the excavated earth and the crushed stone. Most have been in place for 20 to 25 years with no movement.
Several manure storages were built with 2 layers of mafia blocks on 6 inch, 3500 psi concrete with 1/2 inch rebar on 24 inch each direction, they are also still in place. Our design limitation of 2 blocks in height had to do with the resistance to sliding with a concrete to concrete interface if the structure were filled with water to a level of 6 inches of freeboard.