Experimental and numerical analysis of the effects of different repair mortars on the controlling factors of macro-cell corrosion in concrete patch repair

In reinforced concrete structures, the increase in the corrosion rate in the vicinity of the repair zone, due to galvanic cell formation, is known as the incipient anode effect. This study aims to investigate the effect of different repair mortars on the controlling factors of macro-cell corrosion current, induced by patch repair. Therefore, slab samples with different repair mortars, including mortar with ordinary Portland cement (OPC), repair mortar containing 5 and 9% micro-silica, and latex-modified cementitious mortar are investigated. Moreover, corrosion potential and macro-cell current between the substrate concrete and repair mortar are measured in this study, followed by determining the driving force, anodic and cathodic polarization resistance, and the ohmic drop. Using numerical simulation, a more extensive range of repair mortar resistivity and the driving force has been applied to evaluate their effects on the controlling factors of the macro-cell current. As demonstrated in the experimental results, despite the change in resistivity of the repair mortar, cathodic polarization resistance is always controlling the macro-cell current. An ohmic drop of approximately 5% will have the lowest contribution to controlling macro-cell current. In addition, simulation results illustrate that by increasing the resistivity of the repair mortars to 500 Ω m and the driving force to 500 mV, the ohmic drop contribution does will not increase significantly, while the cathodic polarization is always dominant.