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Re: Water Retaining Concrete

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Is the crack in vertical or horizontal direction?  If it is vertical,
has it occured at the control joint? Is there any way you can determine
the crack width through the thickness of wall? What curing method did
you use?  Was the backfill in place when you started seeing the crack?

As a general rule, I do not use flyash or any other pozzalona with
concrete used for structural purposes, mainly because of a wide
variation in their properties.  By the way, did you have any concrete
tests done on field samples?  What was the pressing need for using super
placticizer?  With 2' thick walls and the amount of reinforcement you
have, compaction with conventional vibration should have been possible.

Please, furnish answers to my questions, and I will come with a solution
to your predicament.


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.