THE INFLUENCE OF MORTARS ON THE CORROSION OF REINFORCEMENT BARS

ANGEL VICO; LUIS TRAVERSA; MARCELA VÁZQUEZ

Sao Pedro, Brasil

Congreso; 54th. Meeting International Society of Electrochemistry; 2003

Concrete structures that are built close to the sea are frequently damaged bypathologies associated to the corrosion of the reinforcement steel bars (rebars).When small sectors need to be repaired, mortars replace concrete. In thisinvestigation we are interested in the influence of the presence of these mortarpatches. A standard mortar composition (water to cement ratio 0.4) is studied withno curing and 7 days curing (C0 and C7 respectively) and with the addition of latexin the formulation (latex:water = 1:2, labeled L) and compared with the performanceof standard and good quality concretes, water to cement ratios 0.4 and 0.65 (labeledH1 and H2).Samples with rebars combine concrete and mortars and are immersed inaerated 3.5% in weight NaCl. The corrosion potential and the resistivity weremonitored regularly over a period of more than 100 days. Twice along the period thecorrosion rate was also determined from polarization resistance measurements. Thequality of the mortars was also determined evaluating physical properties such asporosity, absorption, compressive strength and others.The corrosion potential values analysed according to ASTM C876 show theimportance of the curing stage (usually disregarded) and the positive effect ofadding latex to mixture, as the potentials clearly move into the passivity range(Ecorr> -200 mV vs. CSE) both with curing and latex incorporation, see Fig. 1. Theelectrical resistance and the polarization resistance values also support the benefit ofincorporating latex into the mixture, even if no curing will be provided (Fig. 2 and3). The mechanical properties are also in good agreement with these results.