Siemens SINUMERIK 840D Maintenance Manual page 37

SIEMENS MAINTENANCE MANUAL
thicker with # 4 rebar 18" on center three inches off the ground.
For stress lines in the concrete make sure they are such that they do not go under any
of the machines. (If they do, this will eventually defeat the purpose of the pad.)
The top of the felt, if used, should be sealed with a caulking compound to prevent oils
and coolants from penetrating the ground. (Compound must be resistant to oils and
coolants of course). A recommended product is Volcum.
Concrete to use for the pad should be rated at least 3000 psi. It should also contain 3/4"
(1" nominal) crushed rock. Curing time should be at least 7 days. The longer foundation
is allowed to cure, the better. If accelerants are used to cure the concrete in less time,
cracking is more likely to occur.
OCTOBER 2005 PRE-INSTALLATION PROCEDURES 31