Title: Natural Weathering Exposure Station for Concrete and Concreting Materials--Treat Island, Maine

Author(s): Henry T. Thornton, Jr.

Publication: Symposium Paper

Volume: 65

Issue:

Appears on pages(s): 83-94

Keywords: concrete durability; exposure; field tests; freeze-thaw-durability; marine atmospheres; performance tests; sea water; weathering.

DOI: 10.14359/6347

Date: 8/1/1980

Abstract:
The ultimate test of the durability of concrete is its performance under the exposure conditions in which it is to serve. Although laboratory tests yield valuable indications of probable durability, the potential disrupting influences in nature are so numerous and variable that actual field exposures are highly desirable to assess the durability of concrete when exposed to natural weathering. The exposure station located at Treat Island in Cobscook Bay near Eastport, Maine, has been in use by the U. S. Army Corps of Engineers since 1936. Its location makes it ideal for exposing concrete and concreting materials to severe natural weathering. Its effect is to provide a natural field laboratory where no size limitation is placed on the exposed specimens. The specimens are installed at mean-tide elevation and the alternating conditions of immersion of the specimens in sea water, then exposure to cold air, provide numerous cycles of freezing-and-thawing of the concrete during the winter. The effect of the relatively cool summers is to lessen, in general, autogenous healing and chemical reactions in the concrete. There are currently 36 active research programs in progress at Treat Island involving the exposure of some 1700 concrete specimens. The annual testing and continuous monitoring of these programs yield valuable data on the durability and performance of concrete and concreting materials.