Bridge Collapse

[xoxoxoBruce]

Yes, it's an epoxy paint like we use on airframes. Concrete doesn't stick to the iron work, it get it's purchase from the shape of (bumps on) the rebar.

1~When normal people see the school bus the normal reaction is, Oh, innocent children... an emotional response.
2~Then a normal person would move on to concern for the other victims.
3~The normal progression would be to then move to how and why this happened.
This sometimes happens all in one post, but more often in a progression of subsequent posts.

The problem tw has, is he doesn't acknowledge your point and add his own, or even ignore your point and add his own... he often condescendingly belittles other people for stopping at #1 or #2 and not moving on to #3 immediately.
I suspect it's because he feels his point is more important due to his superior knowledge.
It's exceedingly annoying, but he sloughs off this flaw as being unemotional, in his own condescending style, which just pisses people further.

[yesman065]

Originally Posted by xoxoxoBruce

Yes, it's an epoxy paint like we use on airframes. Concrete doesn't stick to the iron work, it get it's purchase from the shape of (bumps on) the rebar.

That was my initial impression (bumps/grooves on the rebar being that which the concrete"grips upon") If I recall correctly they are in a diamond pattern running the length of the rebar...annnywayyyyy... if the rebar is rusting those grooves intended to hold it together would be greatly diminished and that, coupled with the vibration of years of automobile, could lead to some type of faulty structure. I cannot imagine the engineers not accounting for this when the bridge was built. Unless that nifty de-icer they installe increased the degradation of the supporting rebar exponentially.

Does anyone know if this has been the reason for replacing/rebuilding a bridge of similar structure in the past?

[xoxoxoBruce]

The biggest problem with rebar rust is that it splits the concrete, weakening the structure. On the W-35 bridge, I'd be more concerned with the effect on exposed steelwork of the nasty road clearing chemicals. But keep in mind this is wild speculation and we'll have to leave it to the experts to cover... uh, make the final determination that it's nobody's fault.