Reading through replies and notables for the cement plants I do not see mention of the actual process of making cement, the base product. Stone is cooked in a furnace until it breaks down. way hotter then cremation requires. The bodies are not disposed of in the wet mix, it's the hot furnace. :

"The crushed rock is combined with other ingredients such as iron ore or fly ash and ground, mixed, and fed to a cement kiln.

The cement kiln heats all the ingredients to about 2,700 degrees Fahrenheit in huge cylindrical steel rotary kilns lined with special firebrick. Kilns are frequently as much as 12 feet in diameter—large enough to accommodate an automobile and longer in many instances than the height of a 40-story building. The large kilns are mounted with the axis inclined slightly from the horizontal.

The finely ground raw material or the slurry is fed into the higher end. At the lower end is a roaring blast of flame, produced by precisely controlled burning of powdered coal, oil, alternative fuels, or gas under forced draft."

http://www.cement.org/cement-concrete-applications/how-cement-is-made