huangyhg

precast concrete panels in saltwater
we have a lagoon with 700' of 9' high existing concrete bulkhead which is old and spalding in areas.owner wants us to drill in dowels and attach 6"x6" wire and pour a new 8" face in front of old wall.to avoid pouring concrete in saltwater tides we want to use a 6" thick precast wall panel and anchor it to the face of the wall with a 1" spacer and then pour grout behind the precast panels to fill in the voids.question is what would be the best anchor system to use between precast panels and concrete wall,panel will be 10'x 9' x 6".secondly is this a viable solution to avoid casting inplace and what type of longevity would the precast give us?
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i consider the owner's recommendation to be better. the existing wall may not be uniform enough to allow a calculated gap (1 inch, per your proposal). wall irregularities could be from construction deviations during initial installation, settlement/bulging from earth pressure, or non-uniform deterioration.
the cast-in-place concrete will easily take care of any of these problems and the anchoring will be more or less continuous (in case there are unexpected weaker spots in the existing wall). also placing concrete in a tidal zone is not a problem for a contractor who knows what he is doing. suggest only inviting contractors that you have prequalified to bid on the job.
i like your precast suggestion. precasting in a controlled environment could get you great concrete quality which would give you a long service life.
the inaccuracies of the past constuction could be taken care of by making your spacing away from the wall more.
why not just leave a void behind the new precast? design the new precast "facing" to span between anchor points.
6 " precast probably does not give enough protection to steel in saltwater. usually 3 " min cover and 4 " at corners
intrusion prepakt

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