Use of electrical resistivity as complementary tool for controling the concrete production

Resumen del trabajo presentado en el XIII International Congress on the Chemistry of Cement, celebrado en Madrid (España), del 3 al 8 de julio de 2011The control of the concrete production is one of the key factors for getting a robust material to guarantee a homogenous quality of the structure and, hence, of its reliability. The compliance of the hardened concrete with that established in the project, is checked, according to standard regulation, by means of the experimental determination of compressive strenght on two or three specimens from different batches and cured under specific climatic conditions during an assessed period of time. Nonetheless, the above-mentioned procedure presents as principal disadvantage the economic cost that implies all the process, from the acquisition of the necessary equipment, the contracting of specialised hand-of-work, and the treatment of the volume of debris generated by a destructive method. These aspects lead to the necessity of creating a complementary system of auto-control, which could being checked by greater frequency and greater number of samples, what could represent a closer assessment of real properties of the concrete. Thus, the electrical resistivity is proposed in the current work such as a tool of complementary control to the experimental compressive strenght assessment required by the standardization. It has been checked by statistical analysis more than 250 pairs of experimental data the correlation between the resistivity and the compressive strenght in different ages, from 1 to 91 days. Empirical equations are generated from the statistical tool of linear regression, taking the age of measument as input variable in addition to the electrical resistivity. It is concluded that, in addition to the ability of electrical resistivity to evaluate the durability of the reinforced concrete, as it has already been presented in several works, it is a suitable tool for the production control for its good correlation with the mechanical strenght over the time and for its non-destructive character and economic low cost