Slump is a measure of consistency. Too high a slump will prevent the
concrete from flowing properly, while too low a slump can cause problems of
high pressures in the form, outflow of mortar (through the form seams, etc),
and improper adhesion (such as to the tower legs), and the delay between the
completion of the pour and finishing (troweling the surface).
The term 3000 # (that's 3000 pounds per square inch) relates to the
compressability of the concrete after a 28-day cure period. General
conventional concrete mixes are in the 7000# or less category, while
high-strength concrete ranges from 7000# to about 15,000#.
73, Dave, K1FK
Fort Kent, ME