Tom Clancy wrote a novel about a group inside the US that was using a concrete mixer full of ANFO, the OK city truck had an estimated 6,000lbs. of it though I think thats a stretch because it was only a 1 ton chassis but getting to the point I absolutely do know what a mixer can haul, I’ve been driving them for 13 years, my latest truck has a max capacity of 12 cubic yards or about 48,000 pounds, 8 times what McVeigh had.
I would think the density would be the major factor of weight.