The use of E-glass/vinylester composites, fabricated by processes such as resin infusion and pultrusion involving low-moderate temperature cure regimes, in civil infrastructure applications is increasing. A major consideration in these applications is long-term durability in the presence of aqueous solutions ranging from water to alkaline environments such as would be seen from pore water of concrete in the case of a reinforcing bar in concrete, or from an alkaline rich concrete leachate due to water migrating through porous concrete to the surface of a composite overlay. This study characterizes mass uptake, tensile, and interlaminar shear response of a pultruded E-glass/vinylester immersed in deionized water, alkali solution, and concrete leachate solution for periods up to 75 weeks. The high pH solutions are seen to cause a greater degree of irreversible damage at the resin, interface, and fiber levels. (c) 2005 Wiley Periodicals, Inc.