Experimental study of the ageing of building stones exposed to sulfurous and nitric acid atmospheres

During the last few decades, due to remediation procedures, SO2 emissions in the atmosphere have decreased, unlike NOx. Air pollution has changed. Indeed, the aim of this research is to assess the effect of NOx and their interactions with SO2 on stones, particularly on limestones used in Champagne-Ardenne (France) during the restoration processes. Three French building limestones (Courville, Dom and Savonnières) and one reconstituted stone were exposed during 28 days to four strong acid atmospheres i.e. two H2SO3 solutions with different concentrations and two mixed atmospheres with different proportions of HNO3 and H2SO3. These tests produced an intensive acid attack on the stone, allowing the observation of short-term salt precipitation and the evolution of stone properties. Each day, one sample was removed from the acid atmosphere to measure the concentration of SO4(2-) and NO3(-) by ion-chromatography. The surface changes were assessed before and after the tests by 3D scanning and observations with electron microscopy. X-ray microtomography has been performed in the Centre for X-ray Tomography (UGCT) and the Department of Geology at Ghent University (Belgium) in order to observe the penetration of salts and the consequences in stones porosity. First observations showed that exposure to acid atmosphere, led to gypsum efflorescences. Obvious colour changes occurred in all tests. Salt crystallization entailed a change in the porous system, which was evidenced by 3D, mercury porosimetry and X-ray microtomography. Difference between weathered and fresh stone was highlighted by Ion chromatography analyses

Impact de l'humidité et des solutions salines sur le comportement dimensionnel de grès du Buntsandstein (contribution à la sélection de faciès de restauration)

L'objectif de ce travail est d'appréhender l'altérabilité des grès en s'appuyant sur la définition de paramètres physiques pertinents. Il est appliqué à l'évaluation de grès du Buntsandstein afin de contribuer à la sélection de faciès de restauration des monuments historiques du nord-est de la France et, plus particulièrement, de la cathédrale Notre Dame de Strasbourg. Pour y répondre, l'étude expérimentale comparative s'est fondée sur cinq faciès de carrière dont les sensibilités à l'altération doivent être appréciées et sur deux faciès mis en œuvre qui ont montré des cinétiques et des états d'altération divergents. La considération de ces faciès exposés a constitué un garde-fou qui permet d'apprécier la différence de tenue entre ces grès. Les caractéristiques des structures de pores et des matrices argilo-ferrugineuses impliquées dans la réponse dilatométrique des grès ont souligné la forte incidence de la quantité, de la nature et des propriétés de surface des argiles sur les comportements hydrodynamique et mécanique, à l'origine de leur fatigue. L'application de tests en laboratoire de résistance aux sels a mis en évidence l'implication des interactions minéraux-solution saline dans la réponse des grès à une contamination en NaCl et Na2SO4. La discrimination des faciès selon leur sensibilité à l'altération par les sels a pu être établie et un indice de sensibilité aux sels a été formulé. Les propriétés des matrices argileuses et la qualité des contacts de grains jouent un rôle déterminant dans la réponse des grès à l'altération par les sels.The aim of this study was to highlight relevant stone parameters on which the durability of Triassic siliceous sandstones could be predicted in order to contribute to the selection of the potential restoration stones in the built heritage and especially on the cathedral of Strasbourg. An experimental comparative study was made on 5 quarry sandstones to discriminate and 2 exposed sandstones from the monument. The two exposed pieces showed opposite weathering behaviors and states of cohesion that could allow a better definition of the parameters involved in the salt weathering of sandstones. The pore structures and the clay coating properties of sandstones underlined the major role of the clay minerals (quantity, nature and specific surface area) in the dilation behavior under humidity variations as well as in hydrodynamical and mechanical behaviors of sandstones. Three types of salt weathering test were carried out on sandstones. The clay-salt interaction was emphasized by the modifications of the dilation behaviors after salt contamination upon salt nature, NaCl or Na2SO4. A classification of stone susceptibility to salt damages had been proposed as well as an index of salt susceptibility of sandstone had been formulated. The mineralogical and mechanical contributions could justify stone susceptibility to salt damage.REIMS-SCD-Bib. electronique (514549901) / SudocSudocFranceF

De l'importance des dissolutions partielles dans des ooïdes calcaires : Exemple des oolithes hauteriviennes de Suisse

In the Canton of Vaud (Switzerland), two Hauterivian oolitic units were penetrated by a borehole. In both units, the ooids are partly leached. More specifically, the ooid cortices were partly leached and some ooid nuclei appear suspended in the middle of cortical moldic cavities created by leaching, rather than having fallen to the bottom of these cavities before the final cementation take place. We demonstrate that these ooids were originally calcitic, not aragonitic, not "two-phase" nor "bimineral". This leaching is not an early diagenetic feature related to subaerial exposure, but a late diagenetic feature, possibly related to the migration of acidic pore waters, brought about by Alpine tectonics and/or karstification

Water-repellent and biocide treatments: Assessment of the potential combinations

International audienceIt is a common practice to use several chemical products during restoration projects of monuments or sculptures. However, care must be taken when combining the products to avoid a misuse. For example, it is well-known that applying a biocide on stone before a water-repellent leads to a diminishment of the hydrophobic effect of the treatment. But the application of biocide after a water-repellent treatment has been poorly analysed, although studies have proven that the stone looses its hydrophobicity after the application of the biocide. Henceforth, this study investigates the effects of biocide application on a water-repellent film and focuses on the possibilities to restore the efficiency of the previous water-repellent treatment (after the application of the biocide). At first, the tests were performed on glass slides to understand the mechanisms, with the subsequent results revealing that the biocide product deposits on the water-repellent film. Then, the study focuses on determining methods to remove the remains of biocide on limestone samples, previously treated with a water-repellent. The water-repellent used in the study is an alkylpolysiloxane, Rhodorsil H224 from Rhodia

Cathodoluminescence Instrumentation for Analysis of Martian Sediments

International audienceThe morphologic study of the surface of Mars reveals that liquid water existed during the first few hundred millions of years of the planet's history (e.g. Smith et al. 1999). The flow of water produced extensive erosion in some place, but also large sedimentary basins. With a long enough duration of the presence of liquid water and the oxidation of basalts, the emergence of biological activity may have eventually occurred, as on Earth. The detection of biomarkers at the surface of Mars is one of the main challenges of current and planned planetary exploration missions (e.g. Westall et al. 2000). Looking for a fossil or present biological activity may be approached by the search for cells, but also by the study of the results of their activity and their interface with the sedimentary environment. Such bio-sedimentations are known among the oldest terrestrial fossils and testify to the earliest terrestrial bioactivity. A discovery of such bio-sedimentations on the Martian surface would be of prime interest for addressing some of the key goals in exobiology. Cathodoluminescence (CL) is a method relevant to the search for life, as it is in line with these analytical goals of detecting bio-sedimentations (Barbin et al. 1999), and it fits well with robotic facilities usable in modern space missions (Blanc et al. 1999, Thomas et al. 2002. 2005). An established technique, cathodoluminescence is a newcomer to Martian exploration, whereit is expected to contribute to the mineralogical characterisation of sedimentary rocks, to the search for biomarkers revealing past biological activity, and to identify past geochemical conditions (Melezhik et al. 1999; Denson et al. 2007). CL is one of the best methods when the growth dynamics, microstructure, and origin of minerals need to be determined, such as with Martian sediments. CL has become an important standard technique for studying geological materials, offering a wide spectrum of applications (Marshall 1988; Barker and Kopp 1991; Barbin and Schvoerer 1997; Pagel et al. 2000). However, it is in the field of sedimentology and petrography that CL has proved to be especially valuable

Infrared thermography monitoring of the NaCl crystallisation process

In this work, we describe the growth of NaCl crystals by evaporating droplets of aqueous solution while monitoring them with infrared thermography. Over the course of the evaporation experiments, variations in the recorded signal were observed and interpreted as being the result of evaporation and crystallisation. In particular, we observed sharp and transient decreases in the thermosignal during the later stages of high-concentration drop evaporation. The number of such events per experiment, referred to as “pop-cold events”, varied from 1 to over 100 and had durations from 1 to 15 s. These events are interpreted as a consequence from the top-supplied creeping (TSC) of the solution feeding the growth of efflorescence-like crystals. This phenomenon occurred when the solution was no longer macroscopically visible. In this case, efflorescence-like crystals with a spherulite shape grew around previously formed cubic crystals. Other crystal morphologies were also observed but were likely fed by mass diffusion or bottom-supplied creeping (BSC) and were not associated with “pop-cold events”; these morphologies included the cubic crystals at the centre, ring-shaped at the edge of droplets and fan-shaped crystals. After complete evaporation, an analysis of the numbers and sizes of the different types of crystals was performed using image processing. Clear differences in their sizes and distribution were observed in relation to the salt concentration. Infrared thermography permitted a level of quantification that previously was only possible using other techniques. As example, the intermittent efflorescence growth process was clearly observed and measured for the first time using infrared thermography.This work was partially funded by the BQR call from the University of Reims Champagne-Ardenne (project Transels)

The Ursinus Weekly, October 2, 1975

Meetings on Perkiomen Valley growth • In memoriam • Gene Shue presents: Year of the Sixers • City planner speaks • Ursinus College appoints Assoc. Prof. of Education • Kane earns Doctorate • Editorial: A different year? • Is there more to life? • New dorms renovated • Saturday Lunch • Forum series opens: Nina Deutsch • Musical notes • Chris Hillman rated • New events at Walnut • Nancy Drew revisited • Alumnus is named to Library post • British history specialist joins Ursinus faculty • Instructor returns to Ursinus • Pa. Dutch Program is success • Instructor appointed to Biology Dept. • Lindback Award presented • Soccer season opens • Ursinus allies with area • Balloons! • Ursinus named a \u2776er • Register now! • Grads elect officers • Yes we can gang didn\u27t • NFC forecast • MAC report • F & M stings Bears 35 - 21https://digitalcommons.ursinus.edu/weekly/1041/thumbnail.jp

Le Priabonien dans sa region-type (Vicentin, Italie du Nord) : stratigraphie, micropaleontologie, essai d'integration dans l'echelle chronostratigraphique

SIGLECNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Introduction

La tenue du second colloque consacré aux meules et plus particulièrement pour cette édition aux « meules à grain du Néolithique à l’époque médiévale : technique, culture, diffusion. Archéologie, histoire et technique » à l’Université de Reims Champagne-Ardenne est un événement particulièrement riche et significatif dont nous ne pouvons que nous féliciter. Riche, car notre région est bien connue pour ses découvertes archéologiques couvrant cette période, et nul doute que les présentations nous..

Le passage jurassique crétacé au Liban

Les travaux décrits dans ce mémoire ont été conduits dans le but de clarifier la succession des évènements géologiques s étant déroulés sur le territoire libanais de la fin du Jurassique au début du Crétacé. Classiquement attribués au Jurassique supérieur (Kimméridgien-Thitonien) les calcaires sommitaux des formations de Bikfaya et de Salima sont recouverts par des dépôts de grès azoïques : les Grès de base d âge incertain. Le sommet de ces grès contient de nombreux gisements ambrifères dont la faune devait être datée. L analyse sédimentaire et micro-paléontologique des échantillons récoltés lors du levé des nombreuses coupes effectuées sur l ensemble du territoire libanais à permis de révéler les diachronies variées du contact calcaire-grès. Ainsi, ce contact, qui pour les anciens auteurs correspondait à la limite entre le Jurassique et le Crétacé, souligne l histoire géologique ancienne et complexe d un territoire composite, contrarié par l activité tectonique plio-quaternaire qui modèle actuellement le Moyen Orient. Nous proposons que la partie Ouest du Liban (Monts Liban et plaine côtière) a évoluée pendant le Jurassique dans un contexte subsident de bordure de bassin losangique liés aux Palmyrides syriennes. Puis, consécutivement à une inversion des contraintes tectoniques, la partie Nord du Mont Liban a progressivement été soulevée. Ceci a induit un arrêt sédimentaire, une abrasion et une karstification des domaines émergés. Parallèlement, la région du Chouf et ses bordures ont accueilli une sédimentation carbonatée continue probablement jusqu à la fin du néocomien. Cette sédimentation très variable verticalement et horizontalement est le résultat de mouvements différentiels d un substratum en touche de piano. Puis, de l Anti-Liban, dont l histoire géologique étudiée ici de part et d autre du contact calcaire-grès présente un comportement totalement différent du reste du Liban, des flux réguliers de sables continentaux viennent combler les dépressions toujours actives tectoniquement comme le soulignent les nombreuses passées volcaniques. L arrivée des grès est diachrone sur le Mont Liban, progradante vers le Nord ; les quartz sédimentant dans un environnement carbonaté littoral puis progressivement exondéStudies described in this report have been realized in order to clarify of geological events series which took place in Lebanon between Upper Jurassic and Lower Cretaceous. Classically attribute to Upper Jurassic (Kimmeridgian Thitonian) Bikfaya and Salima formations top limestone are covered by azoicals sandstones : les Grès de base . Top sandstones are full of undated ambriferous deposits. Sedimentary and micropaleontological studies of sample collected upon all over Lebanon show various diachronies for limestone-sandstone contacts. For ancients authors, this contact means Jurassic-Cretaceous boundary. For us, it emphasize an ancient and complex geological history of a composite land, altered by Middle East Plio-Quaternary tectonic activity. We propound Lebanon s west border (costal plain and Mont Liban) evolutes during Jurassic as subsident lozenge basin border connected with Syrian Palmyrides. Then, consequently to reversal tectonic North part of the Mont Liban has been gradually uplifted, eroded and karstifed. In the same time, Chouf and is border receive continues limestone sedimentation probably until Late Neocomian. Vertical and horizontal variability of the limestone sedimentation resulted from differentials moves of a keyboard like substratum. Limestone-sandstone contact have been studying in Anti-Liban mount and show totally different geological history that the other part of Lebanon. Then, Anti-Liban mount sent continentals sand flows to Chouf depressions. Those depressions had regular tectonically and volcanic activity during their filling up by sand. Sandstone deposit is totally diachronic in Mont Liban, with a North progradation. Quartz deposit started in costal limestone environment and finished in continental s. At the end of tectonically activity Lebanon is covered by clayey and ambriferous sandstones depositsREIMS-BU Sciences (514542101) / SudocSudocFranceF