It's my understanding that the fire might have not been as bad if the Towers had been built using asbestos.
Asbestos was used but was stopped about 1/2 way up. After that, different fire proofing was used.
As to whether or not asbestos would have made a difference, it is hard to tell. Most of the fire proofing was blown off by the force of the impact and asbestos probably would have been as well.
It's my understanding that the fire might have not been as bad if the Towers had been built using asbestos.I don't know that you would have bought all that much time in this case; the aircarft coming in laterlly literally 'blew off' and blew out a lot of material that would otherwise 'protect' the building/steel from the effects of fire. Much of the sheet rock used in lieu of other 'wall' materials blew out when the jet(s) hit.