When carrying out repairs to reinforced concrete structures, epoxy resins are commonly used to produce a bond between the old and new concrete. The approach is generally adequate provided that the surface is properly prepared. However, since the epoxy resin is an electrical insulator, it nullifies cathodic protection when the latter is applied to these repaired areas. This paper reports on the evaluation of a commercially available resin product which was modified to produce a good bond
between the old and the new concrete, with minimum interference in the flow of cathodic protection current. To that effect, 12 cube specimens (15x15x15 cm) of old concrete adhered to new concrete by means of an epoxy resin with different concentrations of an electrically conductive material (3 samples each per concentration) were prepared. Shear - bonding and electrical resistivity tests were carried out. The effect of the conductive mixture was also evaluated by applying impressed-current cathodic protection to the samples under both dry and humid conditions. The results indicate that these mixtures increase the mechanical properties of the old/new concrete joint and also allow the application of cathodic protection to the system. The mixture prepared with 37 % of electrically conductive material showed the best pdormance.
Key Words:Cathodic protection, Conductive Resin, Corrosion of Steel in Concrete, Epoxy.