Timber vs steel vs concrete piles in marine application 1

[GSI2722]

My project is on the NH Coast and involves a pile supported structure in the V zone. The piles will bear into bedrock at 20 feet and there will be about 5 foot stick-up above mudline. Capacity requirement is 50 tons. I favor 10-inch tip timber with 2.5 pcf CCA. My second choice is Prestressed-Precast concrete with DCI. Another engineer proposes steel H-piles covered with a PCV sleeve and concrete encasement above mudline.

There seems to be no consensus among the several engineers that I've talked to regarding corrosion protection. My question for you all is what are your comments and experiences with regards to corrorion resistance of the listed piles.

Thank you

 

[civilperson]

Wood pile life is less than fifty years at the splash zone, longer below water and above water. Steel encased in concrete and liner may last centuries. Use 1/16" of extra corrosion thickness for each twenty years for bare steel in marine air. I never used concrete, but should be fine with good density and cover.