Basic Methods of Monitoring of Corrosion Processes of Cement Structures and Their Implementation for Projecting of Possible Mineralogical Changes in Matrix Composition: Review

Abstract

Long time service of concrete constructions is accompanied by continuous impact of environment on its structural integrity and capability to carry project capacity of constructions. This influences are able to change not only chemical composition of cement matrix but itself activates corrosion processes that have place to occur on the joints of metal rebar and cement matrix in reinforced concrete (RC). Chemical initiation in the reinforced concrete begins due to the migration of water with parts of molecular oxygen in the thickness of concrete via porous structure of material. The same can be said about the injected compounds of either SO4 2- or Clcomponents that both can be present either in environment or concrete itself due to the modifications of slurry. Such occurrences usually accompanied by changes of pH of the environment that is crucial for the electrolytic environment to appear. Therefore, the process of the reduction of water/ proton may begin at rebar surface wich is the cause not only of the reinforced concrete rebar corrosion but also are reason of accelerated cement matrix degradation. Also, must be noted, that steel corrosion in RC accompanied by changes in current flow. Thus, by understanding the chemical processes and changes that occur in cement matrix of concrete and basics of steel corrosion initiation under the influence of aggressive solutions, the list of non-destructive methods of monitoring (NDM) based on electrical methods of monitoring are reviewed. Different approaches using electrical methods of corrosion monitoring has shown that the use of any of the technics either measurements of the corrosion potential or concrete resistivity or polarization resistance provides different results in mapping of areas with high corrosion risks, monitoring of the heterogeneity of concrete and insights on transport phenomena (e.g. water and salts ingress) in the material. Moreover, advances in potential monitoring without connection to the rebar as non-destructive measurements have shown their effectiveness. Nevertheless, colligation of the results of both numerical and NDM methods is necessary for assortment the results to provide a better data of the worktime of RC structures.