[Re: Spider Tie Concrete Wall Forming, Spotlight, October issue]
Why would AQUA magazine print such a blatantly false claim that structural concrete is five times stronger than gunite (should say shotcrete)? Gunite/shotcrete process done properly yields values from 4000-8000 psi and is the ideal placement technique for concrete (velocity, compaction, density etc).
Mr. McDonagh's claim is obviously made without any knowledge of the shot process but that's not what concerns me. What concerns me is that five times a shot product would yield 20,000 psi to 40,000 psi. This is stronger than most geological stone formations. I would like to see the ASTM or ACI testing methods that substantiate this claim. Again, my question is why would you print such nonsense? An industry voice like AQUA should know better. I realize these are not your words and they're from a supplier but come on, to concrete installers this is very dangerous verbiage.
William T. Drakeley, Jr., Drakeley Industries
