The idea that thermite or similar preparations were used exclusively or in combination with other methods to destroy the Twin Towers remained unexamined for several years after the attack, despite its merits.
Aluminothermic reactions are exothermic chemical reactions in which aluminum is oxidized while an oxide of another metal is reduced. Although high temperatures are required to initiate such reactions, they are easily self-sustaining once started due to the heat they generate. The most common example of an aluminothermic reaction is thermite, in which powdered aluminum reacts with an iron oxide. Because aluminum has a greater affinity for oxygen than iron, oxygen is transferred from the iron oxide to the aluminum, releasing a great deal of energy and leaving behind molten iron and aluminum oxide.
Professor Steven Jones has noted that a number of features evident both before and after the falls of the Towers fit the theory that thermite was used. These include:
– A spout of orange molten metal seen just before the South Tower’s fall in videos of the Tower’s north face around the crash zone
– Reports of molten metal in the remarkably hot rubble of Ground Zero
– High levels of metals found in aluminothermic incendiaries — such as manganese, zinc, and barium — in samples of World Trade Center dust.
– Remains of the Towers’ structural steel showing severe corrosive attack involving sulfur
– Minute solidified droplets of previously molten iron in samples of World Trade Center dust
– Pieces of active nano-engineered aluminothermic chips in samples of World Trade Center dust
Basic thermite preparations can be modified and augmented in various ways to change their properties. The fineness of the aluminum powder determines the speed of the reaction. The use of ultra-fine aluminum powder gives the reaction an explosive quality, resulting in ‘super-thermites’. The addition of sulfur in preparations called thermates enhances the ability of the reaction to cut through steel.
Findings reported in Appendix C of FEMA’s World Trade Center Building Performance Study seem to fit the thermite theory remarkably well.
–Evidence of a severe high temperature corrosion attack on the steel, including oxidation and sulfidation with subsequent intergranular melting, was readily visible in the near-surface microstructure. A liquid eutectic mixture containing primarily iron, oxygen, and sulfur formed during this hot corrosion attack on the steel.
The severe corrosion and subsequent erosion of Samples 1 and 2 are a very unusual event. No clear explanation for the source of the sulfur has been identified.–
Because there are many possible types of pyrotechnics that exploit the energy-dense thermite reaction, the architects of the World Trade Center demolition might have relied entirely on such materials to attack the structures in several different ways, as is suggested by this hypothetical blasting scenario.
Building 7’s Collapse:
The total collapse of WTC 7 at 5:20 PM on 9/11/01 shows all of the features of an implosion engineered through controlled demolition.
Controlled demolition is the use of pre-positioned explosive charges to destroy structures. Depending on the nature of the structure and constraints imposed by its surroundings, a controlled demolition may require a great deal of precision in its planning and execution. That is especially true of tall steel buildings in urban settings, given the natural tendency of such structures to topple. Controlled demolitions of buildings in cities are designed to implode the structures, making them sink into their footprints and fold in on themselves into a small consolidated rubble piles
Observing the collapse of 47-story WTC 7 shows it to have all of the features of an implosion engineered by controlled demolition.
– The collapse of the main structure commences suddenly (several seconds after the penthouse falls).
– The building sinks in a precisely vertical manner into its footprint.
– Puffs of dust emerge from the building’s facade early in the event.
– The collapse is total, producing a rubble pile only about three stories high.
The main structure collapses totally in under 7 seconds, only about a second slower than it would take a brick dropped from the building’s roof to reach the ground in a vacuum.