Cutter Charges and WTC Cut Columns
Closeup of a cut WTC column below, click on the image to enlarge it, like most of the images on this page. Note the extensive slag dripping down the front and also inside the column in the back. Some have maintained that this column must have been cut by ironworkers clearing the rubble, but that would be a terribly messy cut for a cutting torch and why would an ironworker make a cut at such an angle when it is far less work to cut more or less straight across? Most of the edges are rounded and sloppy, especially the unevenness of the back of the column suggests this column was not cut by an ironworker, anyone who's every used a cutting torch would be embarassed by a cut so terribly sloppy. I believe this cut is good evidence of a controlled demolition.
Some more cut WTC columns below with some clearly showing similarly diagonal cuts which would be expected in a controlled demolition, and not likely cut that way by ironworkers.
Photos from Dr. Steven Jone's paper Why Indeed Did the WTC Buildings Completely Collapse?.