Corrosión por cloruros del acero de refuerzo embebido en concreto con agregado grueso reciclado y materiales cementantes suplementarios

Abstract

In a regular concrete mix, aggregates correspond to approximately a 70% of its volume. Therefore, great amounts of crushed stone, gravel and sand are extracted, processed and transported thus generating important economical and environmental costs. Recycling concrete from demolition works and construction´s waste materials have been studied since the 50`s, however only ten years ago the number of researches have been increased on this subject (Ajdukiewicz and Kliszczewicz, 2002; Chen et al.. Nevertheless, most of them have focused their studies on RCA´s physic-mechanical properties and concrete made from Recycled Aggregate Concrete [RAC], not considering so far the RCA corrosion effect of embedded reinforced steel on RAC exposed to adverse environmental conditions, such as marine environment. Nowadays, the most important pathology suffered by reinforced concrete structures is corrosion damage, which is caused by chloride penetration into concrete and, also concrete carbonation at a lesser extent. Corrosion, which limits duration of reinforced concrete structures, has even reported economical losses of about 276 billion dollars a year (Federal Highway Administration, 2002). On the other hand, concretes with SCM addition are reporting a proper acceptance for this purpose (Ann et al., 2008; González and Martínex, 2008; Kou and Poon, 2008; Berndt, 2009; Corinaldesi and Moriconi, 2009), highlighting the positive impact of SCM on resistance and durability behaviors, as well as the environmental benefits they provide. Concretes elaborated from recycled materials (SCM or RCA) have different micro-structure. In the case of RCA concrete, it has greater porosity than conventional concretes (Gómez, 2002; Poon et al., 2004; Tam et al., 2005; Etxeberría et al., 2007). On the other hand, it has been demonstrated that concrete electric resistivity is associated with the micro-structure of cement matrix (pores distribution) and with the corrosion rate of reinforced steel (Tumidajski et al., 1996; Tumidajski, 2005; Polder et al., 2000). Therefore, the electric resistivity is used as a parameter to evaluate concrete durability. The purpose of this research is to analyze electric resistivity and the electro-chemical response of reinforced concrete to obtain the RCA and SCM effects on the reinforcement corrosion beginning and rate induced by the accelerated chloride penetration. On reinforced concrete specimens tests of Electro-chemical Impedance Spectroscopy (EIS) were carried out in order to determine the electric resistivity and loading transfer resistance, so as to evaluate the corrosion process. Additional parameters were employed by characterizing the mechanical behavior and the ion chloride penetration resistance by means of compressive resistance tests and chloride rapid chloride permeability tests, respectively.