Excerpt that mentions the reinforced-concrete core of each WTC tower: "The WTC towers weren't built of massive I-beams and other large steel; they used a lot of smaller beams around the perimiter and a reinforced concrete core. The floors were also reinforced concrete, contributing to ridgidity." ************************************************************ From: gheston@HiWAAY.net (Gary Heston) Newsgroups: talk.bizarre Subject: Re: You gotta love engineers, sometimes... Date: Fri, 14 Sep 2001 03:16:03 -0000 Organization: HiWAAY Internet Services Message-ID: References: X-Newsreader: trn 4.0-test75 (Feb 13, 2001) Originator: gheston@HiWAAY.net (Gary Heston) X-Complaints-To: newsabuse@supernews.com Lines: 42 According to Thom Rounds : [ ... ] > One of the prime ingredients in concrete is water. Without a >suspension of water in the mix, concrete would turn right back into powder >again. What happens to water when you heat it up to about 180 degrees or >so? And if it's in the middle of a chunk of conrete, what will the result >be? > Hint: where I spilled about a pint of molten metal, the concrete >exploded and left a crater about two feet across and several inches deep. > Softened steel? I don't think it ever got to that. No, it didn't. In these situations, the differing expansion rates of steel and concrete are what causes the structural failure--rebar expands a lot faster than the concrete around it, causing the concrete to start fracturing; once it breaks into enough small pieces, it all comes down. The WTC towers weren't built of massive I-beams and other large steel; they used a lot of smaller beams around the perimiter and a reinforced concrete core. The floors were also reinforced concrete, contributing to ridgidity. Once enough of the concrete crumbles away from the rebar, it folds. Once one floor collapses, the rest will go from the impact stress. In your case, you created a steam explosion in a relatively damp slab. Floor slabs pick up a lot of moisture from the ground they're resting on, and you superheated it in a fraction of a second to an extremely high temperature. No suprise that it popped out a chunk of the surface; hope you didn't get splashed. Gary -- Gary Heston gheston@hiwaay.net This item has been intercepted by the Echelon Project. So have all of yours....