Corrosion Damage Analysis and Material Characterization of Sherman and Centaur - The Historic Military Tanks

A study of corrosion damage and material characterization of two historic military tanks, the Sherman and Centaur is reported. Experiments were conducted to analyse surface corrosion and corrosion propagation from surface to sub-surface. Significant surface corrosion was found, this phenomenon was further facilitated by delamination failure mechanisms. Corrosion depth for the Sherman was approximately 110 µm, where sulphide inclusions were detected in the sub-surface analysis. The Centaur’s analysis showed corrosion pits at 100 µm depth. These pits possess random geometrical configurations with evidence of sulfur, sodium and calcium

Non destructive assessment of in situ concrete strength: comparison of approaches through an international benchmark

Strength assessment of concrete in existing structures is a key issue. Many non destructive techniques (NDT) are available which can provide information about the material condition and several approaches can be used to derive strength estimates from NDT test results. However, common practice suffers from many drawbacks: (a) it is difficult to ascertain the level of accuracy/confidence of concrete strength estimates, (b) one lacks established guidelines for estimating the concrete strength variability, (c) the best way to combine NDT methods and coring remains an open issue. The RILEM TC 249 "Non destructive in situ strength assessment of concrete'' is addressing these problems. A benchmark was carried out in order to compare (a) how experts define and can carry out an NDT investigation program and (b) how experts derive strength values from the NDT measurements. The benchmark was based on synthetic simulations which reproduced a synthetic data set corresponding to a grid of twenty 3 m-high columns defining a single-storey building structure. The comparison of the various strategies and the analysis of results enabled identification of the most influential parameters that define an investigation approach and influence its efficiency and accuracy. A special emphasis was placed on the magnitude of the measurement error. A model of the investigation strategy is proposed, that will be detailed in future guidelines. The reader is invited to refer to a companion paper (Alwash et al. in Mater Struct, 1. doi: 10.1617/s11527-016-0962-x), based on more extensive Monte-Carlo simulations of the same case-study, which analyzes and quantifies the efficiency of the investigation strategies with respect to both average strength and strength variability assessment, in order to draw conclusions based on rational analyses rather than on the element of chance