De tous temps, les Pinacées ont été utilisés pour leur résine ou le goudron que l’on peut en tirer, principalement dans le domaine maritime (calfatage, protection des cordages) et pour le poissage d’amphores. Ces travaux ont été consacrés au développement de nouveaux outils moléculaires et isotopiques pour la caractérisation de tels matériaux trouvés en contexte archéologique (distinction goudron / résine, origine taxonomique et géographique, modes de fabrication). Sur la base des outils développés, il apparait que l’utilisation de goudron prévaut dans ce contexte sur celle de résine et que les Pinus, dont les espèces peuvent être partiellement discriminées, sont les principaux Pinacées utilisés. Il a aussi pu être montré que les matériaux de calfatage et d’enduits de cordages sont globalement issus d’une cuisson moins poussée que ceux utilisés dans le poissage de récipients. Une distinction des échantillons archéologiques sur la base de leur composition isotopique en D a été proposée. / Resins and tars of Pinaceae have been used in the past mainly in the maritime field (caulking, protection of the ropes) and for the waterproofing of jars and amphorae. This study was devoted to the development of new molecular and isotopic tools for the characterization of such materials found in archaeological context (discrimination between tar / resin, taxonomic and geographical origin, manufacturing methods). Based on the detailed molecular and isotopic investigation of diterpenic compounds, in particular, it appears that the use of tar prevails in this context over that of resin and that trees from the genus Pinus, which can be partially discriminated in terms of species, have been preferentially used. It could be shown that the caulking material and the tar protecting ropes result overall from a less intense heating process than the material used to waterproof containers. A distinction of the archaeological samples on the basis of their isotopic composition in D was proposed.

<p>As of 2013, the damage caused by corrosion on highway bridges has been estimated to cost approximately 14 billion dollars annually, and this cost has been increasing over the years. Corrosion is one of the natural phenomena that has been slowly deteriorating infrastructure systems across the United States. One of the most problematic types of corrosion is crevice corrosion, which is defined as the formation of rust between overlapping surfaces such as the case of a splice connection where flanges are attached by splice plates. A significant number of steel bridges in Indiana have developed crevice corrosion in splice connections. Therefore, this research focuses on the crevice corrosion, or “pack rust”, occurring in these structural elements. The application of coatings alone has not been enough to stop pack rust at these connections. In an attempt to look for approaches that can effectively mitigate this problem and maintain the designed service life of bridges, different strategies have been studied and tested. The first objective of this study is to determine the strength reduction as a function of the time of exposure to salt misting. To do this, specimens that simulate the bottom flange splice connection have been exposed to a corrosive environment for different periods of time and later tested under tension to assess the reduction in strength. The second objective is to evaluate the effectiveness of the mitigation strategies under different conditions. First, the mitigating products were initially applied before exposure to salt misting. Second, the mitigating products were applied as a repair, and in this case, the specimens corroded for a given period of time and were then repaired to evaluate any further deterioration. The assessment of the strategies’ effectiveness is based on the strength reduction and visual inspection of the specimens. The ultimate outcome of this study is a series of general guidelines to slow down crevice corrosion based on the results of the laboratory testing. </p>