I've posted this to the reflector several times before and it is in the
archives, but here
it is once again!
Concrete is a mixture of two components, aggregate and paste. The paste is
comprised of portland cement and water while the aggregate is made up of
sand and crushed rock. The chemical processes involved in the curing
(setting) and hardening of concrete, the resultant compressive strength and
tensile, flexural, and torsional strength, and freeze/thaw resistance of
the cured product are directly dependent upon the ratio of these components
and how they are mixed, transported, handled, entered into the construction
project (foundation) and controlled during the curing process).
NEVER, NEVER pour concrete into a foundation of any type with standing
water as you will uncontrollably alter the cured structure. You are going
to pay some good hard earned $$ for the ready-mix company to deliver
concrete to a specified performance level, so do everything you can to
maintain those properties after it arrives at your site!
Contact your local ready-mix company's engineering staff, a PE, or the
Portland Cement Association for professional advise on your specific
73, Dave, K1FK
Fort Kent, ME