Lessons Learned from the Treat Island Marine Exposure Site

Abstract

The marine exposure site on Treat Island near Eastport, Maine, was built more than 75 years ago and during this period a wide range of concrete types have been placed on the site. Treat Island represents a very severe exposure condition with the highest tides in the world, salinity typical of the Atlantic Ocean and approximately 100 freeze-thaw cycles per annum. The various research programs that have used this facility have investigated the effects of numerous parameters including fibre-reinforcement, polymer-impregnation, supplementary cementing materials, sulfur concrete, high-alumina cement, ettringite-based rapid-set binders, w/cm and strength, ultra-high-performance concrete, corrosion-resistant reinforcement, impact of load and cracking, “mechanical air-entrainment”, and use of corrosion-inhibiting admixtures. Performance has been evaluated in a number of ways including visual assessment, pulse velocity, dynamic modulus, chloride profiling, and electro-chemical corrosion monitoring. The paper presents an overview of “lessons learned” with detailed information on factors affecting the rate of chloride ingress.