It is nevertheless interesting to check the amount of explosives that would be required to
produce all of the pulverized concrete dust found on the ground. Explosives are notoriously
inefficient as a comminution tool. At most 10% of their explosive energy gets converted into the
fracture energy of comminution, and only if the explosive charges are installed in small holes
drilled into the solid to be comminuted. Noting that 1 kg of TNT releases chemically about
4 MJ of energy, the total mass of TNT required to pulverize 14.6 × 107 kg concrete material
into dust of the sizes found on the ground would be 316 tons. So, in order to achieve solely by
explosives the documented degree of concrete pulverization, about 1.36 tons of TNT per story
would have to be installed into small holes drilled into the concrete slab of each story, and then
wired to explode in a precise time sequence to simulate free fall.
Given the uncertainty of input parameters, computer calculations have been run for the
full range of their realistic values. In comparison with all these calculations, the claim that
the observed fineness, extent and spread of pulverized dust could be explained only by planted
explosives has been found to be absurd. Only gravity driven impact could have produced the
concrete dust as found on the ground.
wtc7lies.googlepages.com/Bazant_WTC_Collapse_What_Did__Did_No.pdf
Journal of Engineering Mechanics, American Society of Civil Engineers
