Saltwater Corrosion

[haynewp]

I have a project where a contractor has questioned using helical anchors in a coastal region. There is a high water table at the site, and the geotech has recommended helical anchors. Anyone experienced with saltwater corrosion of helical anchors? The site is several miles inland.

 

[SlideRuleEra]

Of course it depends on the site geology, but in the Southeastern US, the coastal water table is high, but ground water is typically fresh (not necessary potable) unless you are very close to flowing salt water - say within a few hundred feet, or so from the ocean, tidal saltwater creek, estuary, marsh etc.

http://www.SlideRuleEra.net

 

[haynewp]

It is in South Florida. Looking more closely at the site, it is only a few hundred meters from a brackish/marine lake. Maybe this generated the contractor's comment.

I think the concrete caps on the anchors could be extended to below the water table fluctuation line, and corrosion be completely taken care of even if there is salty water at the site. One installer of the anchors believes the design life of the anchors to be in excess of 50 years without modifications to the concrete caps (part of the anchors experiencing saltwater table fluctuation).

 

[fndn]

You may test the soils for "soluble sulfates" and see if you're at severe range or at negligible range. Based on the test results, Type V cement may be needed or you may proceed without worries. Your local Geotechnical engineer would know more about your local variations.