Primers to the reinforcement in mortars : Effectiveness as a function of primer type, exposure conditions, and amount of sodium chloride

• Published in: Corrosion (Houston, Tex.) Tex.), 2007-03, Vol.63 (3), p.231-239
• Main Authors: CASTRO-BORGES, P, BALANCAN, M, MORENO, E. I, CHAN-CABRERA, J. H
• Format: Article
• Language: English
• Subjects: Applied sciences; Cathodic protection; Concrete; Concrete structures; Corrosion; Corrosion environments; Corrosion mechanisms; Corrosion potential; Corrosion prevention; Corrosion resistance; Electrical resistivity; Electrochemical analysis; Electrochemistry; Electrode polarization; Exact sciences and technology; Exposure; Metals. Metallurgy; Mortars (material); Primers; Protection; Rebar; Reinforcing steels; Repair; Sodium; Sodium chloride; Structural damage; Submerging; Tropical climate
• ISSN: 0010-9312; 1938-159X
• DOI: 10.5006/1.3278347

Primers are customarily used to prevent further corrosion of rebar during the repair process for corrosion-damaged concrete structures on the coast of Yucatán. However, there are not enough data about their effectiveness in this environment. This work presents laboratory data of mortar specimens where primers to the reinforcement were used as they are currently in localized repairs in tropical marine coasts. Four different, locally available primers were used according to their hypothetical protection mechanism (barrier, cathodic protection, inhibition, and repassivation). Primers were applied to the rebars and then embedded in mortar and subjected to two exposure conditions: partial immersion to different solutions of sodium chloride (NaCl; 0.4, 2.0, and 5.0%) and wet and dry cycles (12 h wet and 12 h dry) to a NaCl solution (3.5%) at 50°C. The electrochemical behavior of the specimens was followed through polarization resistance, corrosion potential, and electrical resistance. In practical terms, the use of primers proved to be a good option for economical and fast repairs or in cases where concrete was of bad quality (for example, concrete with a water-to-cement [w/c] ratio higher than 0.5). A degree of primer effectiveness was obtained according to the electrochemical behavior of the repair. Barrier-type primers were more degradation-resistant than the others. Although primers proved to be a reasonable option for localized repair, future behavior must be followed carefully.