Isotope Tracers to Investigate Reactive Zones in Stones from Built Cultural Heritage

AbstractThis work aims at identifying the reactive zones inside limestone used in monuments exposed to fog. The location of these zones and the depth of the water penetration front is of primary relevance to evaluate the transport of aggressive species and the influence of environmental conditions on alteration mechanisms and kinetics of limestone exposed to the atmosphere. We report herethe results of weathering experiments conducted in a deuterium-enriched environment and the characterization of reactive zones analyzedby NanoSIMS. It was determined that water penetrated several hundred micrometers inside the limestone and that only the first micrometerswere significantly altered

Structures de porosité et propriétés de transport dans les grès

Mertz Jean-Didier. Structures de porosité et propriétés de transport dans les grès. Strasbourg : Institut de Géologie – Université Louis-Pasteur, 1991. 170 p. (Sciences Géologiques. Mémoire, 90

Role des structures de porosite dans des proprietes de transport : application aux gres du Buntsandstein et du Brent (Alwyn, mer du Nord)

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

Les structures de la porosité de grès hydrothermalisés

The porosity variations between moderately buried Buntsandstein sandstones and equivalent units submitted to hydrothermal fluid circulation are studied with resin impregnated stained thin sections. Hydrothermal fluid circulation increases porosity heterogeneity on various scales. By the study of porosity structure in one typical sandstone submitted to strong silicification and/or dissolution, we are able to justify the total porosity decrease or increase, to show the free or trapped-porosity development and to predict permeability variations.Les variations des structures de porosité entre des grès du Buntsandstein, ayant été faiblement enfouis, et des grès équivalents, ayant été en plus hydrothermalisés, peuvent être analysées à partir de lames minces dont la porosité a été imprégnée de résines colorées. Pour un faciès gréseux donné, les circulations de fluides hydrothermaux accentuent à toutes les échelles l'hétérogénéité du réseau poreux par des silicifications et/ou par des dissolutions intenses. A partir des modifications des structures du milieu poreux, il est possible de justifier la diminution ou l'augmentation de la porosité totale, des porosités libre et piégée et de prévoir les variations de la perméabilité.Jeannette Daniel, Liewig Nicole, Mertz Jean-Didier. Les structures de la porosité de grès hydrothermalisés. In: Bulletin de Minéralogie, volume 111, 6, 1988. pp. 613-623

Influence of Clay Minerals Nature on the Hydromechanical and Fracture Behaviour of Stones

International audienceElastic properties and fracture behaviour evolutions of two sedimentary stones are under study to estimate their influence on scaling effect of monumental stone heritage. Young moduli and toughness of Villarlod molasse and Thüringer sandstone are measured under moisture content variations with respect to their natural anisotropy. Several relative humidity levels are considered to investigate their effect upon humidification and drying. The stone property evolution is in close correlation with the identified clay phases of the matrix. It appears that clay minerals as smectite and glauconite influence the stone properties at very low moisture contents, whereas less swelling clays have impact only when high moisture contents are reached. This is in close correlation with the inherent deformation ability of these minerals. It is observed that nature and distribution of clay phases largely influence on the macroscopic behaviour under natural exposure conditions, as they modify the stone properties and represent the weakness planes of the stone

The pink staircase of Sully-sur-Loire castle: Even bacteria like historic stonework

International audienceRosy discoloration has affected the stone steps in the main spiral staircase of the Sully-sur-Loire castle donjon for many years now. This study monitors the development of the coloration and the environmental climatic conditions in the staircase to understand the conditions favoring the presence of this rosy discoloration. High-throughput sequencing was performed on healthy stone and on pink pigmented stone to identify the agent responsible for this discoloration. The results suggest that the rosy discoloration is the mark of a former degradation process which is now inactive, and that bacteria were the main agent of the pink patina formation. Nitiliruptor was the main genus identified in the pink parts of the staircase. This is the first time that this bacterial genus has been linked to a cultural heritage biodeterioration process. There was no evidence that this bacterial genus was responsible for the development of the pink patina, but it could have replaced it as a subsequent evolution of the process

Comparaison en laboratoire de l'altération par gélivation et par dissolution d'une roche calcaire

Le but de cette étude est de caractériser l'altération générée par la gélivation d'une part et par la dissolution d'autre part sur un calcaire oolithique. Des observations locales par porosimétrie au mercure et microscopie électronique à balayage et des mesures globales de fréquence de résonance et perméabilité sont confrontées pour déterminer les effets de ces deux phénomènes

Intrinsic Parameters Conditionning The Formation Of Mn-rich Patinas On Luneville Sandstones

International audienc

Strengthening mechanisms of clay building materials by starch

International audienceEarth has a renewed interest in eco-friendly building materials. Starch is a promising additive, but its strengthening origin needs understanding to promote better solutions according to soil variability. This multiscale study examined natural clays and starches interactions. Clays and starches were evaluated based on mechanical and rheological properties. Kaolinite was found to be better reinforced by starches. At microscopic scale, starches modified the arrangement of grains and clays, but the role of botanical origin is unclear. At molecular scale, the ratio between amylose and amylopectin led the interactions with kaolinite. These results help to understand how bio-additives affect earth-based building materials

Swelling inhibitors for Clay Materials : comparison of Industrial and Natural Surfactants. In : Monument future : Decay and Conservation of Stone

14th International Congress on the Deterioration and Conservation of Stone, GOTTINGEN, ALLEMAGNE, 07-/09/2020 - 12/09/2020Humidity variations due to the climate of Western Europe induce many problems in clay-rich building material. Indeed, the repetition of wet/dry cycles leads to swelling and shrinkage phenomenons. Thus, cracks and material loss may appear. A solution to limit the volume change of bulk material consists of using surfactants. This study focused on the behavior of swelling montmorillonitic clay mixed with a series of 9 surfactants: 3 diaminoalkanes with different carbon chain lengths, polyethylenimine and triton X-100 (industrial surfactants) were compared to natural products (bio-inspired/ bio-sourced) such as lawsone, pork gelatin, saponin and dopamine. The swelling at the clay sheet scale before and after treatment was observed on powders using X-ray diffraction analyses after conditioning at low and high relative humidity, while the swelling deformation at macroscopic scale was assessed on specimens submitted to imposed hygric conditions via the continuous measurement of axial deformation. In complement, the microstructure was investigated by mercury intrusion porosimetry. Diaminoalkanes appeared to be the more efficient swelling inhibitors for the crystalline swelling, in particular, those with long carbon chains. Nevertheless, some of natural additives also showed a high capacity to reduce swelling at both macroscopic and microscopic scales which would suggest the possible use of less toxic additives/natural as swelling reducer