Long-Term Performance of Adhesive Bonded Anchors

Post-installed adhesive anchors used for fastening nonstructural and/or structural elements to concrete structures are prone to creep under sustained loads over their service life, which may considerably affect their long-term performance. In this study, the influence of various in-service conditions and sustained loading levels on the long-term performance of adhesive anchors was experimentally examined. The tested adhesive was an unsaturated polyester resin and the bonded anchors were subjected to sustained loads of 23, 47, and 70% of their mean ultimate short-term capacities for up to 10,376 days (28.4 years). The tested in-service conditions were indoor temperature, outdoor temperature and humidity variations, wetness, and presence in the concrete of salt additives. Results indicate that the tested bonded anchors did not fail indoors when subjected to sustained loads up to 47% of their mean ultimate short-time capacity. However, the long-term performance was substantially impaired outdoors, presumably due to temperature and humidity variations, leading to failure for sustained loads higher than 23% of the anchors' mean ultimate short-term capacity.