Concrete-epoxy interface can be found in many strengthened or retrofitted structures, especially
in Hong Kong where concrete structures are the majority. In practice, epoxy is usually used in
repairing concrete structures because of its excellent adhesion, chemical and heat resistance,
good mechanical properties and electrical insulating properties. The bond between concrete
and epoxy has been found to be strong enough such that failure does not occur at the interface
under dry condition. However, prior research studies have indicated that moisture-affected
debonding in a concrete-epoxy bonded system is a complex phenomenon that may often
involve a distinctive dry-to-wet debonding mode shift from material decohesion (concrete
delamination) to interface separation in which concrete-epoxy interface becomes the critical
region of failure. Such premature failures may occur regardless of the durability of the individual
constituent materials forming the bonded material systems. In this paper, a review on moisture
degradation of concrete-epoxy interface is presented, followed by an explanation of such
phenomenon using an atomistic approach which can fundamentally describe the interaction
between the bonded system and the surrounding water molecules. It is highly recommended that
the durability of concrete-epoxy interface should be carefully considered in the design stage due
to the detrimental moisture effect.
