Resistance of concrete to carbonation and chloride penetration assessed on site through nondestructive test

The paper describes the main mechanisms of carbonation and chloride penetration into concrete and how the rate of penetration can be measured with laboratory tests. It is also discussed why nondestructive test (NDT) methods for measuring directly the resistance of aged field concrete to carbonation or chloride penetration are not available. Only destructive tests are applicable which, given the very high-spatial variability encountered, become prohibitive in terms of costs and damage. The only way to assess the resistance of aged field concrete to carbonation or chloride penetration is through surrogate tests measuring variables that are linked to it. There are two standardized test methods with potential as surrogate tests, as they are fast and entirely nondestructive: the coefficient of air permeability kT ("Torrent" method) and the electrical resistivity rho ("Wenner" method). Data obtained on-site with both methods are presented, confirming their potential to assess the resistance of aged field concrete to carbonation or chloride penetration.