Salt Resistant Concrete 2

JAE...unless you have a concern with rebar corrosion, I would stick with good quality, dense concrete using either Type I or Type II portland cement. In my opinion the key is the quality of the concrete (good dense graded mix, quality hard aggregates, air entrainment, and proper placement, finishing and curing)as compared to the type of cement for this application.

In my experience with a failure investigation of a similar application (brine processing plant)and designing concrete mixes for similar high chloride environments, the concrete quality will prevail.

If you have any embedded steel, you might consider a corrosion inhibitor in the mix (nitrite type). This along with dense mix, will help reduce the potential for corrosion. You can check the effectiveness of the finished product by doing chloride permeability testing on the concrete.

Good luck.
Ron

Gracias, Ron
We have no rebar - using fiber reinforcing instead along with 6% air.

JAE

I want to second the vote for dense, well placed concrete. If you have easy access to Type I/II or II Cement, that would be a plus.

Special care has to be taken when troweling a hard, smooth finish with air entrainment. The surface may undergo significant delamination. This is described in an excellant article in ACI Concrete International, about 3 years ago.

I would recommend that you review ACI 201.2R-77 (Reapproved 1982) titled "Guide to Durable Concrete". It contains recommended air contents for frost-resistant concrete. For example,according to this guide: IF nominal maximum aggregate size is 1 1/2 inch the average air content should be 5 1/2 percent for outdoor exposure in a cold climate where the concrete may be in almost continuous contact with moisture prior to freezing, or where deicing salts are used (e.g., pavements, bridge decks, sidewalks, and watertanks).

Note: The ACI guide states that there is conflicting opinion whether air contents lower than those given in its recommendation table (which the above example came from) should be permitted for high strength (5500 psi) concrete.

The ACI guide has another table that recommends for seawater exposure, concrete with Type II, IP(MS), or IS(MS) cement.

In the "Proposed revision of: Guide to Durable Concrete" (ACI 201.2R-92), section 2.3-Seawater exposure, states (in part) ...concrete should reach a maturity equivalent of not less than 5000 psi at 28 days when fully exposed to seawater."

The FEMA Coastal Construction Manual (FEMA 55, June 2000) recommends (for construction in area subject to saltwater flooding) using 5000 psi minimum compressive strength (for durability).

You should also check-out your local building code and your regional building code (e.g., IBC).

In my very limited experience with concrete, I have only seen concrete with Type V cement used in fishing-piers that are constantly exposed/submerged in saltwater.

Thanks everyone.

Shouldn't use Type V, it has less resistance against chloride attack than Type I and is more costly. The use of Type V for seawater exposure may be attributed to the trace amounts of magnesium sulphate commonly present in seawater.

Another item to watch for is the leaching of salt into the groundwater. Am aware of one instance where the 'saltdome' affected wells approx 1/2 mile down gradient.