Concrete structures: on-site electrochemical techniques and concrete resistivity to predict service life Part 2: Service life of structural concrete, present and future challenges

Abstract

Concrete protects the steel of the reinforcements in a similar manner than do the paints but with the particularity that it is a material chemically active and evolving for decades. Concrete provides a very alkaline electrolyte encapsulated in its pore network. The steel may remain passive indefinitely but chlorides and atmospheric carbon dioxide penetrate the pores and reaching the reinforcement promote corrosion, which impairs the concrete structural properties inducing the cover cracking and the loss in steel-concrete bond. Calculation of service life is becoming an important subject in engineering terms due to the increasing demand to produce buildings and infrastructures with service life beyond 100 years. In the paper focus will be devoted to two main areas: 1) the measurement techniques in concrete and permanent probes, including on site methods for large structures and contactless (inductive) methods 2) the illustration of the corrosion resistance control exerted by concrete resistivity which enables the calculation of the diffusion of ions through the concrete and the prediction of the corrosion rate in function of the climatic conditions.