Moisture expansion as a deterioration factor for sandstone used in buildings

The expansion processes that develop in building stones upon changes of moisture content may be an important contributing factor for their deteriorations. Until recently, few data could be found in the literature concerning this parameter and weathering processes. Moreover, the processes that may be responsible for the moisture related expansion of natural building stones are not yet completely understood. To further elucidate this process, extensive mineralogical, petrophysical and fabric investigations were performed on eight German sandstones in order to obtain more information regarding the weathering process and its dependence on the rock fabric. The analysed sandstones show a wide range of pore size distributions and porosities. A positive correlation with the fabric and the pore space can be found for all studied petrophysical parameters. The intensity of the expansion and related swelling pressure cannot be attributed only to the swelling of clay minerals. The investigations suggest that the micropores and the resulting disjoining pressure during wet/dry cycles also play an important role. The results obtained suggest that the mechanism is related to the presence of liquid water within the porous material

Rettung für das Markttor von Milet: Schadensanalysen an Marmor, Mörtel und Stahl

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Geowissenschaftliche Bedeutung von Mikrorissen in Kristallingesteinen

In Kristallingesteinen (Magmatite, Metamorphite, Migmatite) sind Mikrorisse allgegenwärtig. Ihre Entstehung ist auf unterschiedliche treibende Kräfte (i.W. Tektonik, Thermik) und Mechanismen wie z.B. volumetrische Verformung oder plastische Rissinitiierung zurückzuführen (z.B. Vollbrecht et al. 1999). Die heute in oberflächennahen Kristallingesteinen zu beobachtenden Mikrorisspopulationen repräsentieren i.d.R. die Summe verschiedener geologischer Ereignisse in unterschiedlichen Krustenstockwerken, wobei generell die jüngsten Generationen das höchste Erhaltungspotential besitzen. Abhängig von den jeweiligen stofflichen Rahmenbedingungen (Wirtsminerale, Krustenfluide) zeigen die Mikrorisse unterschiedliche Ausbildungsformen (offen, verheilt, versiegelt), die häufig gemeinsam in einem Gestein auftreten und damit komplexe, mehrphasige Entwicklungen dokumentieren. Analysen von natürlichen und experimentell erzeugten Rissen belegen, dass die überwiegende Anzahl als Zugrisse zu interpretieren sind, d.h. sie werden primär senkrecht zur kleinsten Normalspannung angelegt. Zusätzlich ist bekannt, dass Mikrorisse innerhalb größerer Gesteinsvolumina meistens in Form von mehreren richtungskonstanten Scharen auftreten und damit den Gesteinen ein Anisotropieelement aufprägen. Das Beispiel zeigt zusätzlich, dass die Bildung der verheilten und offenen Mikrorisse unter verschiedenen Spannungsrichtungen stattfand. Aufgrund der genannten Eigenschaften besitzen Mikrorisse sowohl für die Rekonstruktion geodynamischer Entwicklungen als auch für die Interpretation der physikalischen/mechanischen Gesteinseigenschaften besondere Bedeutung. Das Vernetzungsschema zeigt, welche Informationen aus Mikrorissen durch Verknüpfung verschiedener analytischer Methoden gewonnen werden können...conferenc

Self‐injurious behaviour: limbic dysregulation and stress effects in an animal model

Background  Self‐injurious behaviour (SIB) is prevalent in neurodevelopmental disorders, but its expression is highly variable within, and between diagnostic categories. This raises questions about the factors that contribute to aetiology and expression of SIB. Expression of SIB is generally described in relation to social reinforcement. However, variables that predispose vulnerability have not been as clearly characterised. This study reports the aetiology and expression of self‐injury in an animal model of pemoline‐induced SIB. It describes changes in gross neuronal activity in selected brain regions after chronic treatment with pemoline, and it describes the impact that a history of social defeat stress has on the subsequent expression of SIB during pemoline treatment. Methods  Experiment 1 – Male Long‐Evans rats were injected on each of five consecutive days with pemoline or vehicle, and the expression of SIB was evaluated using a rating scale. The brains were harvested on the morning of the sixth day, and were assayed for expression of cytochrome oxidase, an index of sustained neuronal metabolic activity. Experiment 2 – Male Long‐Evans rats were exposed to a regimen of 12 daily sessions of social defeat stress or 12 daily sessions of handling (i.e. controls). Starting on the day after completion of the social defeat or handling regimen, each rat was given five daily injections of pemoline. The durations of self‐injurious oral contact and other stereotyped behaviours were monitored, and the areas of tissue injury were quantified. Results  Experiment 1 – Neuronal metabolic activity was significantly lower in a variety of limbic and limbic‐associated brain structures in the pemoline‐treated rats, when compared with activity in the same regions of vehicle‐treated controls. In addition, neuronal activity was low in the caudate–putamen, and in subfields of the hypothalamus, but did not differ between groups for a variety of other brain regions, including nucleus accumbens, substantia nigra, ventral tegmentum, thalamus, amygdala, and cortical regions. Experiment 2 – All the pemoline‐treated rats exhibited SIB, and whereas the social defeat regimen did not alter the total amount of self‐injurious oral contact or other stereotyped behaviours, it significantly increased the severity of tissue injury. Conclusions  A broad sampling of regional metabolic activity indicates that the pemoline regimen produces enduring changes that are localised to specific limbic, hypothalamic and striatal structures. The potential role of limbic function in aetiology of SIB is further supported by the finding that pemoline‐induced self‐injury is exacerbated by prior exposure to social defeat stress. Overall, the results suggest brain targets that should be investigated further, and increase our understanding of the putative role that stress plays in the pathophysiology of SIB.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/91181/1/j.1365-2788.2011.01485.x.pd

Composition And Porosity Study Of Original And Restoration Materials Included In A Coastal Historical Construction

The materials used for the building constructions can suffer during their life numerous deterioration processes induced by different anthropogenic and natural factors. For this reason, optimal restoration works are vitally necessary for a correct Built Heritage preservation process. One of the most critical environment is the marine atmosphere (marine aerosol impact following dry and wet depositions) where the climatic conditions are very aggressive. For this reason, the new building materials that will be used for a restoration must be selected taking into account the possible deterioration sources that are present in the vicinity of the building or construction. Among marine aerosol, other factors such as biodeterioration, water infiltrations, physical stress, even pollutants than can be deposited from the surrounding environment must be taken into account. This work is focused on the analytical and physical study of the different building materials used for the restoration works carried out in 2014 in the Tower of La Galea Fortress (Getxo, Basque Country, Spain), a historical construction placed in front of the sea. The analyzed materials were the weathered sandstone (original sandstone) and the one used to replace it (restoration sandstone), as well as restoration joint and rendering mortars. The results presented in this work offered a global idea of the correct material selection, taking into account the different factors that can affect the integrity of the whole building in the future. In order to test the durability of these materials against the surrounding environment, different analyses were carried out. On the one hand, X-ray Diffraction (XRD), Raman spectroscopy and Wavelength Dispersive X-ray fluorescence (WD-XRF) were used for chemical characterization of the materials. On the other hand, Mercury Intrusion Porosimetry (MIP) was used to understand the porous system and the thermal behavior was studied using Infrared Thermography (IRT). Finally, the thermal fatigue test was carried out to determine if temperature cycles could have impact in the structural integrity and aesthetic appearance (i.e. color changes) of these materials during time

Salivary biomarkers of HPA axis and autonomic activity in adults with intellectual disability with and without stereotyped and self-injurious behavior disorders

Salivary levels of biomarkers for the hypothalamic–pituitary–adrenal axis (HPA; cortisol) and sympatho-adreno-medullary system (SAM; α-amylase) were measured in 51 adults (57% male) with neurodevelopmental disorders associated with intellectual disability (i.e., mental retardation) and chronic self-injurious behavior (SIB) and compared with matched controls without SIB. Cortisol levels differed significantly (p < 0.01) between the SIB and control group (SIB > control). Within-group analyses showed significant differences (p < 0.05) in levels of salivary α-amylase between individuals with SIB and those with SIB meeting criteria for stereotyped movement disorder (SMD; SIB + SMD > SIB). Salivary α-amylase was significantly correlated with frequency of stereotypy among the SIB group (r = 0.36, p < 0.05). These preliminary findings warrant further exploration into the role of the SAM system in the pathophysiology of SIB and related repetitive behaviors among individuals with neurodevelopmental disorders associated with intellectual disability

Bullet impacts and built heritage damage 1640–1939

© 2018, The Author(s). Conflict damage to heritage has been thrust into the global spotlight during recent conflict in the Middle East. While the use of social media has heightened and enhanced public awareness of this ‘cultural terrorism’, the occurrence of this type of vandalism is not new. In fact, as this study demonstrates, evidence of the active targeting of sites, as well as collateral damage when heritage is caught in crossfire, is widely visible around Europe and further afield. Using a variety of case studies ranging from the 1640s to the 1930s, we illustrate and quantify the changing impact of ballistics on heritage buildings as weaponry and ammunition have increased in both energy and energy density potential. In the first instance, this study highlights the increasing threats to heritage in conflict areas. Second, it argues for the pressing need to quantify and map damage to the stonework in order to respond to these challenges

On-site monitoring for better selection of stone repairs: a case study

Weathering of clay-bearing sandstones does not only depend on material properties but also on the environmental conditions they are exposed to. The same is true for repaired stones, in which the compatibility of the repair mortar should be studied not only in terms of material properties, but also in terms of the climatic conditions it will be sub- jected, in order to maximize this compatibility. This paper proposes a methodology to quantify the thermal and hygric stresses in clay-bearing sandstones and their repair, based on the measurement of temperature and relative humidity at the surface and at several depths in a repaired and a non-repaired stone, as well as wind-driven rain and absorbed water. This is illustrated by a case study in an historical building. The data are used to quantify the stresses in the mate- rials and to propose possible degradation mechanisms.ISSN:2050-744