Interesting theory. This still doesn't explain the delivery mechanism. How would this explosive aluminum get strategically placed close enough and uniform enough to dislodge enough of the columns to bring down the building? The author even said the aluminum was molten and would fall between the cracks. This is a dissipating effect that would dissipate the energy in a vertical fashion rather than in a horizontal fashion. The energy would need to be distributed horizontally to enough columns to cause collapse. Seems unlikely. The only way this would work is if the sub-floor could withstand these kind of temperatures long enough and there was enough molten aluminum to cause a pooling effect that would cover an area of at least half an acre 3-4 inches deep (to compensate for the unevenness of the floor) that would allow the molten aluminum to flow and make contact will enough of the columns while maintaining the heat required to penetrate the column. I don't think there was that much molten aluminum especially considering the fact that the plane ended up spread across several floors which makes it less likely. And if there were any leaks in the sub-floor, the molten aluminum would tend to dissipate its energy to the floors below reducing the pooling effect and limiting the horizontal flow.

Add to this, that this supposedly happened three times two three different buildings, one which didn't even have a plane hit it? It's hard to fathom the odds.  

 WHILE IT IS TRUE THAT AN ENGINEER CAN MAKE IT SOUND MORE PLAUSABLE.................BUT IT DOES NOT SHOW ALL THE FACTS EITHER.MY ARGUMENT IS BETTER THAN YOURS.....SIMPLY BECAUSE I "KNOW"  AND YOU JUST CALCULATE.  WANT TO CONTINUE TO THEORIZE OR DO YOU WANT THE TRUTH?  FACT IS NOT THEORY!

'LAND TO LAND,INVESTIGATIONS. INC.  WE COVER THE WORLD.