Aggressive water on concrete

[RMPE]

Looking at a 10 year old clearwell that has been exposed to an aggressive water with a Langlier Index of -1.3, Alk of 76 (mg/l as CaCO3), Hardness of 160(mg/l as CaCO3), and CO2 of about 50 mg/l. After 10 years the cement paste has been "dissolved" to about 1/4" in depth and only the sand remains. Has anyone seen this before and remedied the problem??

 

[Ron]

Yes, have seen similar deterioration. Several ways to fix, either synthetic (epoxy or other polymer bonded to concrete) or cementitious (bonded "mortar" patch). Both will require draining, sandblasting the surface then repair.

 

[RMPE]

My first thoughts too but not cheap. Alternative is to fix the water. The water has very high CO2 that creates carbonic acid in a slow moving water (around baffle walls).
PCA "Design and Control of Concrete Mixes (& ACI 515)says "Waters with pH greater than 6.5 may be aggresive if they contain carbonates. Carbonic acid solutions with concentrations between 0.9 and 3.0 ppm are considered destructive to concrete." Our pH is 6.7 and not sure what the carbonic acid concentration is, but not favorable.

There is an air stripper system designed to reduce the CO2 but not in place yet. Could also add lots of caustic soda to compensate, at a cost.

Also have a lift station with severe hydrogen sulfide gas deterioration. Is there a concrete repair forum????