Near-surface sensors for condition monitoring of cover-zone concrete

With more demands being made on reinforced concrete, 100-year guarantees of durability will become a necessity. Lifetime calculations, and prediction of the residual service-life of structures, require quantitative information on cover-zone properties and threshold values for corrosion initiation. It is clear that there exists a need to determine quantitatively those near-surface characteristics of concrete which promote the ingress of gases and/or liquids containing dissolved contaminants. In addition, in-situ monitoring of the temporal change in such properties could assist in making realistic predictions as to the in-service performance of the structure; likely deterioration rates for a particular exposure condition or compliance with the specified design life. This paper details covercrete sensor arrangements; format of data presentation and information that can be obtained from embedded sensors. Such sensors could, ultimately, form part of a high-level monitoring strategy and should be considered at the design stage.