Evaluación del impacto de la caducidad de los epóxicos en la resistencia a la extracción de anclajes en concreto según la norma ASTM E488M y su viabilidad técnica para el refuerzo estructural

Abstract

In civil engineering, chemical anchors with epoxy adhesives are widely used in the reinforcement and rehabilitation processes of concrete structures. These two-component structural adhesives—composed of epoxy resin and hardener—ensure mechanical and chemical adhesion between the anchor and the concrete, in accordance with ASTM C881 (ASTM, 2019). Their high adhesion and versatility in application have favored their widespread use in Colombia, especially in projects with complex geometries or in areas with limited access. However, these products have a relatively short shelf life, between 12 and 18 months, after which manufacturers do not guarantee their structural performance (Hilti Corporation, 2023). This condition poses a recurring problem on construction sites: the disposal of expired adhesives without technical evidence confirming the loss of their properties, which translates into economic losses and the generation of hazardous waste (Ministry of Environment and Sustainable Development, 2017). This study evaluated the effect of epoxy adhesive expiration on the pullout strength of post-installed anchors in concrete using tests conducted according to ASTM E488M. Three groups of adhesives were used: current, five-month expired, and eighteen-month expired. The results indicate that, under controlled storage and application conditions, expired adhesives maintain structural behavior similar to those within their expiration date, presenting failures in the concrete and without evidence of a significant decrease in adhesion. These findings provide relevant technical evidence to support decisions regarding the use of expired epoxy adhesives, contributing to more efficient and sustainable materials management in infrastructure projects.