Title: Standardization, to a Reference of 25 °C, of Electrical Resistivity for Mortars and Concretes in Saturated or Isolated Conditions
Author(s): Marta Castellote, Carmen Andrade, and Mari Cruz Alonso
Publication: Materials Journal
Appears on pages(s): 119-128
Keywords: concrete; mortar; temperature.
Electrical resistivity is a parameter that can be used to characterize pore connectivity and inform on the moisture content of the concrete. Its measurement is an interesting way to assess concrete durability, mainly from the point of view of assessing transport properties. Electrical resistivity, however, is dependent on temperature. In general, an increase in temperature leads to a decrease in resistivity due to the variations in ion mobility and ion-ion and ion-solid interactions. In this paper, standardization of resistivity to the value corresponding to 25 °C, for specimens in the range of temperatures from 3 to 55 °C, in saturated or isolated conditions has been carried out. Two different ranges of temperature have been identified (T < 25 and T > 25) for making the correction to the values of resistivity. In addition, it has been deduced that it is necessary to take into account the composition of the cementitious matrix. As a final result, a second-degree equation for each range of temperature has been found. These equations allow calculation of the resistivity at 25 °C as a function of the concrete composition, the temperature, and the measured value of resistivity.