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Re: z factor for crack control

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Wade -

Two thoughts.

First, I would waterproof the slab and walls.  We used a Bentonitte produce
(Paraseal, or something like that) here in Southern California for a project
which was below the water table and have hade no problems that I have heard
of going on five years.

Second, we have developed a set of notes for concrete at the beach which is
exposed to salt water, which I am attaching below.  We use these for piles
and grade beams or slabs which cannot be effectively waterproofed.  I have
been told it increases the material cost of the concrete 60% to 70%, but it's
worth it if it keeps your concrete from blowing apart over time.  I also have
some literature in my office on glass fiber-reinforced plastic rebar, but
I've never used it.

Good Luck, 

Bruce Resnick


NOTES FOR CONCRETE IN A MARINE ENVIRONMENT

1. MINIMUM CONCRETE STRENGTH F’c SHALL BE 4000 PSI. (DESIGN CONCRETE STRENGTH
F’c = 3000 PSI)

2. A CALCIUM NITRATE CORROSION INHIBITOR, SUCH AS DCI-S MANUFACTURED BY W. R.
GRACE & COMPANY, SHALL BE ADDED TO THE CONCRETE MIX, AS PER THE
MANUFACTURER’S RECOMMENDATIONS.

3. A WATER-REDUCING POZZOLAN ADMIXTURE SHALL BE ADDED TO THE CONCRETE MIX AS
PER THE MANUFACTURER’S RECOMMENDATIONS.

4. THE CONCRETE MIX DESIGN SHALL BE DESIGNED BY A LICENSED ENGINEER AND
SUBMITTED TO THE STRUCTURAL ENGINEER FOR REVIEW PRIOR TO ITS USE.

5. ALL REINFORCING STEEL IN THE CONCRETE SHALL BE EPOXY COATED.

6. THE MINIMUM CONCRETE COVER OVER THE REINFORCING STEEL SHALL BE 4”.

7. THE WATER-TO-CEMENT RATIO SHALL NOT EXCEED 0.40.

8. ALL CONCRETE TO BE PLACED BELOW THE WATER LEVEL SHALL BE PLACED BY A
TREMIE STARTING AT THE BOTTOM OF THE EXCAVATION.  AS THE CONCRETE RISES, THE
TREMIE SHOULD BE KEPT 12” BELOW THE LEVEL OF THE CONCRETE.

9. ALL OTHER CONCRETE AND REINFORCING STEEL NOTES SHOWN ON THESE PLANS SHALL
BE CONSIDERED VALID UNLESS SUPERSEDED BY THE NOTES ABOVE.