Searle,
Re: You, yourself, have remarked on the showers of shiny, reinforcing steel fragments which were produced. To my understanding, this can only have come about as result of a considerable explosive force --- a force other than gravity or fire -- being applied to the reinforced concrete.
As a former general contractor who has worked in high rises, I would like to clear up some imprecision in this discussion.
First of all, it is important to understand that it would have been highly unusual for their to have been any reinforcing steel (rebar) in the concrete floors at the WTC towers. Generally the way that the floors are constructed is that there are bar joists overlain with sheet steel pans into which about 4 inches of lightweight concrete are placed. Frequently, there is a six inch by six inch mesh of 1/8" steel wire which is incorporated in the pour in order to prevent minor cracks from spreading in the floors. The concrete is made with vermiculite as one of the aggregate components and the compressive strength is very low, on the order of 300-500 psi, as opposed to normal concrete which ranges anywhere from 2,000 to 4,000 psi compressive strength.
I've got some fairly high quality photographs of the WTC towers as they are collapsing:
erichufschmid.net
The steel which is ejected from the building appears to be much larger than rebar segments. In fact, some of the pieces being ejected appear to be on the order of several hundred pounds in weight. This would be consistent with the sort of steel components that went into the structure.
I don't have a good scientific explanation for the pulverization that occurred on 9/11 in those three buildings. Having demolished or witnessed others demolishing dozens of cubic yards of concrete in my career, I have never experienced anything remotely similar to the pulverization that we witnessed at the WTC complex. This pulverization cannot be explained by mere gravitational forces, I've seen far too many concrete demolitions that yielded results that were nothing like what we saw at the WTC.
Controlled demolition is my best guess, but my real question is when, if ever, will we get a testing agency to try to replicate the results that we saw on 9/11. My guess is that the U.S. government will absolutely refuse to pay for or authorize any such testing. Sadly, we've already seen what happened when an Underwriter's Laboratory manager attempted to alert a NIST manager that there is something rotten in the state of Denmark. |
