3 ms·
I'm no expert, but I've read that their use of volcanic rock is a major factor - since "pumice" has a swiss-cheese like surface, and that tends to add strength
by MrTonyD 9y ago
I'm no expert, but I've read that their use of volcanic rock is a major factor - since "pumice" has a swiss-cheese like surface, and that tends to add strength to concrete. Also, they used incredibly little water in their mixtures - there are descriptions of them pounding in the concrete (as opposed to the way we "flow" it.) I understand that studies have shown that concrete mixed with very little water is much stronger. I also read that fast-setting concrete has been found to be very weak - and was never actually tested in any significant way before it was approved. So very long curing times result in much stronger concrete.
Obviously, all these discoveries are being fought by the building industry - so none of these things are reflected in current code. Instead, they just argue about rebar while ignoring the other discoveries.
- peterwwillis 9y agoJust because it's stronger doesn't mean it's more durable, which the article points out. Portland concrete has higher compressive strength but doesn't last as long.
- MrTonyD 9y agoWell, old concrete, even pre-"quick set" has been found to be much more "durable" (colloquially speaking - not really an engineering term.) And in most applications it isn't concrete's compressive strength which causes failure - for either old concrete or new concrete. So I would hesitate to defend current building practices based on the lone metric of compressive strength. But, again, I'm not a structural engineer (though I do know one who works for the state, and he isn't allowed to express his real opinions about the danger of our current infrastructure - many building failed in earthquakes which they should have survived easily.)
- snovv_crash 9y agoFrom my experience with epoxy, thicker viscosity and slower-curing is well known to result in a stronger end material. I'm not saying this is also true with concrete, but there is a parallel precedent.