I am a retired Mechanical Engineer (BME U of MN 1961) who practiced as a
Professional Engineer in Minnesota for 27 years.

I have witnessed the implosion of two high rise concrete-steel buildings in
person. My first thought when I saw the first WTC tower collapse was,
"That is a controlled demolition". I had second thoughts when I realized
how much smoke and dust had been created. The demolitions I witnessed did
not have all that smoke and dust.

I have since learned that the original steel and rebar in those building
was coated with special type of corrosion inhibitor that required special
contractors and high security during the coating. It turns out that
coating was the plastic explosive C4 that the Navy Seals use to blow up
underwater steel and concrete barriers. It turns them to powder and naked
steel just like the 3 WTC buildings.

I heard that submarine pens and missile silos used this construction in
case an enemy had captured one of these facilities. They could be
destroyed with one coded phone call.

I called a fraternity brother, Theta Tau - the largest engineering
fraternity in the USA, who had done work on the missiles silos in N. and S.
Dakota during the 1960's. He affirmed that such construction was used in
building those missile silos so that they could be "pulled" with a coded
phone call.

Was there any mention of the use of C4 on the steel in any of the videos on
9-11?