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Re: Water Retaining Concrete

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Unforturnately, I don't have a good source for you.  However, my quick calc of
eqn (10-4) of ACI 318 for the situation you described above seems to indicate
the design has a 'z' value roughly twice that allowed by code.  Thus twice the
corresponding limiting crack width of 0.013 = 0.026 should be expected.  Seems
like that is what may be occuring.  If it is not to late, you may need to
roughly double the reinforcing for the remainder of the job.  Hope all turns
out well.

Dan Huntington
KJWW Engineering

Chance, Acie P. wrote:

> I am designing retaining walls which will form the edges of a lagoon. The
> first two walls we poured have cracks which go completely through the wall.
> The cracks appear to be shrinkage cracks. The mix design uses 4000 psi
> concrete with flyash, super P and well graded aggregate. The walls are
> between 10 and 20 ft. high and 2 ft. thick. Vertical steel is # 7 @ 12 back
> side and  #5 at 12 water side. Horz. steel is # 5 @ 12 both faces. Crack
> control joints are located at 25 ft. O/C. This follows ACI 350
> recommendations. I am worried about the damage to the rebar from the
> chlorinated water moving through the cracks. We do not intend to waterproof
> the lagoon but we do need to insure the structural integrity of the wall.
> The existing cracks are from .002" wide to .035" wide and will be injected
> but I have a lot of wall left to pour. If any one knows of a good authority
> on cast in place concrete for water retention I would be interested.