74,000 Concrete Ties from 1966 - What's the life expectancy?

http://www.cement.org/transit/tr_concre ... ssties.asp

The first major use of the modern precast, prestressed concrete tie was in 1966, when 74,000 were installed on the Florida East Coast Railway.

Does anyone know what the life expectancy has been for the original 1966 concrete ties on the FEC? What's the annual replacement rate? Obviously, they aren't exposed to freezing and thawing cycles, for the most part, and the granite ballast is yet another factor favoring longevity?

A lot of those original ties are still in track. However, FEC used their own concrete tie design (at that point, there wasn't a "standard" AREA design) and they chose to use a threaded rail fastener with a spring clip. They have had fastener problems, and have been retrofitting ties with a specially designed plate that has shoulders for Pandrol clips. Other than that, though, the ties are holding up quite well.

However, it's worth noting that FEC had to import blue granite ballast from north Georgia to replace the limestone ballast that FEC had previously used. Limestone will NOT provide adequate support for concrete ties.

Many of the premature concrete tie failures on Amtrak and elsewhere result not from freeze/thaw cycles but from an "alkali-aggregate" reaction that occurs usually because of manufacturing problems. FEC does not seem to have had problems of that kind.

In the northeast, they're usually good for about 30-40 years. However on the NEC Amtrak has found that many were defective after only 20 years of service.

Much less than 20 on the NEC in NJ. I think pretty sure 10 at most. I think it was the alkali problem, the manufacturer (low bidder?) screwed up. JS

Just some numbers from a conference earlier this year: since the 1970's over 300 million concrete ties have been installed in the United States. Of those between 5-10% have failed due to "chemical degredation".