Evaluación experimental de la fisuración del hormigón producida por la corrosión de las armaduras

Experimental evaluations of concrete cracking due to reinforcement corrosion

Among the different distressing consecuences of rebar corrosion the best known is the cracking of concrete cover. However, very few data have been reported in the literature of the amount of corrosion neded to induce this cracking. Due to this gap, the prediction of service life lacks of a proper quantification. In present paper it is summarized the results obtained under Brite / Euram funding which try to contribute to quantify the relationship between amount of corrosion and cover cracking. The variables studied were: cover / diameter ratio, proportions of cement, w/c ratio, position of the bar, stirrups presence and corrosion rate level. The corrosion is simulated by applying constant currents making the rebar to act as anode. The results indicate that the process develops in two steps: generation and propagation of the crack. The propagation evolves first following a behaviour of the type: w (crack width) = a + bx (radius lost), with slopes between 0,003 and 0,018, depending on the corrosion rate, until a certain attack level is achieved. Radius losses of about 15 - 50 um are necessary to generate the first vissible crack (0,05 - 0,1 nm width).