The effect of moisture on bonding behaviour of epoxy on concrete

Corrosion of concrete sewer pipes as a result of microbial actions is known as microbiologically induced concrete corrosion (MICC). Failure of sewer structures as a result of MICC causes extensive damage posing health risks and rehabilitation costs. Protective polymeric linings (e.g., epoxy and epoxy mortars) have been used widely in larger distribution pipes and manholes as MICC mitigation strategy due to their high resistance to acid attack. The main challenge, however, in the use of polymeric coating is their premature failure by delamination. Failure can occur within two years or less, when coating service life is expected to be 20-50 years. Our current studies suggest coatings provide sufficient resistance to acid migration, negating the potential role of acid attack to delamination but highlighting other potential pre-cursors to this phenomenon. This study examined the effect of moisture on epoxy bonding. Moisture is maintained on the wall and crown of concrete pipes as a result of humidity and rising tidal zones. It is known moisture can disrupt epoxy curing and when adsorbed could contribute to losses of mechanical properties attributed to the disruption of interchain hydrogen bonding by water molecules. To examine the effects of moisture, concrete cylinders with moisture vapour evaporation rates (MVER) of 100 to 1000