Concrete Water Wall

[marinaman]

I've got a landscape architect who wants this office to design the structure for a concrete site retaining wall that will double as a decorative "water wall". In other words, water will cascade down the face of this wall, all the time.

I've designed the wall, footing, reinforcing, etc etc. I'm drawing it up....but I've raised questions in my mind regarding coatings, special admixtures, or something....to help keep the wall waterproofed.

I'm asking myself.....does this wall need a waterproof coating on the cascade face? Does this concrete need some sort of admixture to make it more waterproof or to better protect the wall reinforcing? Or, maybe it doesn't need anything and can just let water run over the face of it from now own....as heck.....bridge supports submerged in lakes or rivers aren't coated to my knowledge.

What do you guys think?

 

[TehMightyEngineer]

Remember that a cycle of wetting and drying is much worse than constant moisture. So, in some ways, this may do better than bridge supports that are exposed to varying levels of moisture. I'd say, if possible, go precast as it should give you a lot of compressive strength and limit the corrosion just by less concrete permeability alone. Lots of cover to keep any rust jacking or surface staining from occurring would be all I would use at a minimum. Corrosion admixtures and something like epoxy coated bars (I dislike epoxy coated bars but this is probably a good use for them) wouldn't be a bad idea but I'd only go that far if it doesn't overload the budget.

Another good option would be fiberglass rebar. It will cost more up front but the fact that it can't corrode and given the application (wall so probably no need for bent bars) it should be ideal. Probably cheaper than traditional when you consider the increased service life, the cost of maintenance, cost of epoxy coated bars and/or admixtures, and the slightly higher tensile strength of the bars.

Professional and Structural Engineer (ME, NH)
American Concrete Industries

http://www.americanconcrete.com

 

[rn14]

I worked at a big precaster for a few years (septic tanks, vaults, culverts, etc). In most cases nothing special was ever done or needed; the exception was usually sewage. I don't think you have anything to worry about.