Suchergebnisse

Uniaxial compressive strength (UCS) is the most used parameter to measure rock strength. However, restrictions in sampling large volume of material, the need of very large set of results and onsite characterisation of UCS non-destructively are requirements in many scientific and engineering investigations. The estimation of UCS from a single non-destructive or minimally invasive technique (NDT) may result incomplete because each NDT is sensitive to different compositional and textural factors. This paper combines open porosity, P-wave velocity, Leeb hardness and micro-drilling resistance force to estimate USC for a wide range of carbonate sedimentary rock types with different petrographic characteristics. Results reveal that mineralogical composition significatively affects micro-drilling resistance force profiles and P-wave velocity values, especially for quartz-bearing rocks. In addition, texture controls substantially the reproducibility of tests sensible to rock surface properties, such as Leeb hardness and micro-drilling resistance force. Fifteen simple and multiple expressions for UCS are fitted. Linear expressions have shown better coefficients of determination (R2) than non-linear equations because of the linearity shown by individual parameters. Curve fitting improves as the number of petrophysical parameters increase in the multiple linear regression analysis. The best correlation is found when the equation incorporates all the mechanical parameters obtained non-destructively as well as open porosity (R2 = 0.910). Leeb hardness is always the most significant variable of the fitted regressions and its addition into multiple linear equations causes an increase of R2. Open porosity also improves R2 whereas drilling force and P-wave velocity have a lower statistical weight in the expressions. The UCS estimation from all NDT, without considering open porosity, shows a good correlation (R2 = 0.899), which presents the advantage that they can be obtained non-destructively with portable equipment and can provide a numerous set of results at relatively low cost. ; This work was supported by the Spanish Government [grant number RTI2018-099052-B-I00] and Regional Government of Madrid (Spain) [Top Heritage, grant number S2018/NMT-4372].

O objetivo deste trabalho é analisar a relação entre a coordenação da política fiscal e monetária com os multiplicadores fiscais na Argentina, Brasil, Chile e México. A contribuição deste trabalho consiste em uma análise comparativa desses países sobre as experiências de coordenação entre a política fiscal e monetária, juntamente com uma estimativa de multiplicadores fiscais. O referencial teórico do conceito de multiplicadores de coordenação e fiscais levanta primeiro, depois as tendências nos quatro países de variáveis como consumo, investimento, gastos do governo e a taxa de juros são analisadas para ver se houve efeitos expulsão (crowding out) nos quatro países. Finalmente uma estimativa com variáveis representativas de gastos multiplicadores e o impacto da coordenação em matéria de crescimento económico é apresentado. ; RESUMEN: El objetivo de este artículo es examinar la relación de la coordinación de la política fiscal y monetaria con los multiplicadores fiscales en Argentina, Brasil, Chile y México. La contribución de este trabajo consiste en un análisis comparativo de dichos países sobre las experiencias de coordinación entre la política fiscal y monetaria junto con una estimación de los multiplicadores fiscales. Se plantea primero el marco teórico del concepto coordinación y de los multiplicadores fiscales, después se analizan las tendencias en los cuatro países de variables como el consumo, la inversión, el gasto de gobierno y la tasa de interés para saber si han existido efectos expulsión (crowding out) en los cuatro países. Por último, se presenta una estimación con variables proxy de los multiplicadores del gasto y del impacto de la coordinación en el crecimiento económico. ; ABSTRACT: In this study we search the relationship of fiscal and monetary policies coordination with fiscal multipliers in Argentina, Brazil, Chile and Mexico. Our contribution is focused in the comparative analysis on experiences of fiscal and monetary policies coordination and fiscal multipliers. We start with an analytic issues analytic on coordination and fiscal multipliers theory. Then we present the trends about consumption, investment, government spending and interest rate to know if these four countries had have crowding out effects. Finally, we show an estimation with proxy variables of spending multipliers and the influence of coordination on economic growth. ; N/A

Fire is a major decay agent of rocks and can generate immediate catastrophic effects as well as directional and anisotropic damage that affect long-term weathering processes. Temperature increase is the most relevant factor, among other components in a fire, generating mineral transformations and bulk mechanical damage. Mineralogical changes at high temperatures are key to understanding the overall mechanical behaviour. However, most studies to date were carried out after rock specimens were heated to a target temperature and cooled down to room temperature. Therefore, these studies are missing the observation of the actual mineral processes during heating. This paper aims to compare mineralogical changes in crystalline rocks during heating by means of XPS and different XRD techniques. Samples of four different granitoids were heated to several temperatures up to 1000 °C to evaluate their chemical and structural changes. Results show how standardised thermal expansion coefficients are not a suitable indicator of the bulk effect of high temperatures on rocks. Results also show how thermal expansion estimations from XRD lattice measurements may be an alternative to bulk dilatometric tests, as they can be performed with limited sampling, which may be necessary in some studies. Nevertheless, XRD and XPS results need to be interpreted carefully in relation to the bulk effects of temperature increase in the rocks, as the structural behaviour may seemingly contradict the macroscopic effect. ; This research was funded by "Top Heritage (P2018/NMT-4372) programme from the Regional Government of Madrid (Spain)", "Grants PIC2020-116896RB-C21", "PIC2020-116896RB-C22" funded by MCIN/AEI/ 10.13039/501100011033," Grant AICO/2020/175" by the Regional government of Comunidad Valenciana (Spain).

The complexities of evaporation from structurally and mineralogically heterogeneous sandstone (Locharbriggs Sandstone) are investigated through a laboratory-based experiment in which a variety of environmental conditions are simulated. Data reported demonstrate the significance of material-environment interactions on the spatial and temporal variability of evaporative dynamics. Evaporation from porous stone is determined by the interplay between environmental, material and solution properties, which govern the rate and mode by which water is transmitted to, and subsequently removed from, an evaporating surface. Initially, when the stone is saturated, evaporation is characterized by high rates of moisture loss primarily controlled by external atmospheric conditions. However, as drying progresses, eventually the hydraulic continuity between the stone surface and subsurface is disrupted with recession of the drying front and a decrease in evaporation rates which become reliant on the ability of the material to transport water vapour to the block surface. Pore size distribution and connectivity, as well as other material properties, control the timing of each stage of evaporation and the nature of the transition. These experimental data highlight the complexity of evaporation, demonstrating that different regions of the same stone can exhibit varying moisture dynamics during drying and that the rate and nature of evaporative loss differs under different environmental conditions. The results identify the importance of material-environment interactions during drying and that stone micro-environmental conditions cannot be inferred from ambient data alone. These data have significance for understanding the spatial distribution of stone surface weathering-related morphologies in both the natural and built environments where mineralogical and/or structural heterogeneity creates differences in moisture flux and hence variable drying rates. Such differences may provide a clearer explanation for the initiation and subsequent development of complex weathering responses where areas of significant deterioration can be found alongside areas that exhibit little or no evidence of surface breakdown. ; Madrid's Regional Government Geo-materials Programme (S2013/MIT-2914) ; Peer reviewed

Knowing the maximum temperatures attained by stonework during past fires in historical buildings is important to understand the damage caused to the materials and the subsequent weathering history after the fire. Thermoluminescence (TL) provides a tool to assess such temperature but different protocols exist. TL has been tested to assess the maximum temperature reached by a past fire on the surface of calcitic sandstone (frequently used in historical buildings in Saragossa, Central- Eastern Spain). We have prepared subsamples of this sandstone annealed from 200°C to 700°C. Quartz extracts from such samples were used for testing different TL protocols, from measuring the erosion of the whole TL glow curve of quartz extracted to test the Thermal Activation Characteristic (TAC) and other more recent approaches, such as comparing the sensitization of the integrated 110, 200 and 250-400°C peaks at different irradiation doses or a full predose protocol. The erosion of the TL glow curve of quartz seems to underestimate the attained temperature while the other tested protocols indicate that the temperature reached was 400°C. ; This research was partly funded by Regional Government of Madrid Geomateriales S2009/MAT-1629/GEOMATERIALES and by a PICATA postdoctoral fellowship of the Moncloa Campus of International Excellence (UCM-UPM, CSIC). ; Peer reviewed

Pothole formation and development may be influenced by joint sets and other heterogeneities within bedrock, as well as by hydraulics. Previous research indicates that most potholes found in rivers of the mountainous Spanish Central System exhibit preferred orientations associated with dominant joints and correlate more strongly with variations in substrate resistance than with hydraulics. Weathering and erosion weaken rock surfaces, which leads to decreased mechanical resistance. We start from the hypothesis that different mechanisms of pothole formation may create around the pothole a distinctive signature in terms of ultrasound pulse velocity and surface hardness. We develop a conceptual model and test it using potholes for which we know the mechanism of formation, demonstrating that the spatial and statistical distributions of dynamical mechanical properties and surface hardness of a pothole may provide insight into its genesis. Copyright © 2016 John Wiley & Sons, Ltd. ; This research was partially funded by Geomateriales 2 programme (S2013/MIT-2914) funded by the Regional Government of Madrid (Spain). ; Peer reviewed

Mokattam limestone is the most frequent building stone used in the cultural heritage buildings in Historic Cairo (Egypt) and it is susceptible to the ongoing effects of salt weathering. A purpose-made simulation chamber was used to test in the laboratory the salt weathering on limestone samples from an active quarry at Helwan area (30 km, south Cairo) at different temperature regimes (20, 30 and 40°C). To assess the extent of the resulted decay, mechanical properties of the fresh quarry and tested samples after different regimes were investigated with non-destructive techniques (P-wave velocity and Leeb rebound hardness) and destructive techniques (uniaxial compression strength). The different mechanical measurements of the tested samples were notably affected after the different temperature regimes. Uniaxial compressive strength is highly correlated with Leeb rebound hardness while P-wave velocity showed a low relevance for the prediction of the strength of the tested samples. ; This study was supported by the Mission Sector of the High Education Ministry, Egypt and the Regional Government of Madrid and the European Social Fund under the project entitled Geomateriales 2 S2013/MIT-2914.

Morphometric characterisation is particularly relevant in the study of geomorphological heritage. 3D modelling techniques have been proven as very useful tools to recognise, characterise and valorise geomorphosites. Bedrock rivers account for one of the most outstanding aspects within geomorphological heritage due to the amount of distinctive and attractive geomorphological features associated to them and the high preservation of sculpted forms. Digital elevation models (DEMs) have made it increasingly possible to establish accurate morphometric indices and establish clearer connections between forms and processes. This paper reviews different methodologies to obtain DEMs on bedrock rivers. This review goes from DEM analysis at multiple spatial scales to introduce optical microrugosimeter as the latest technical development to facilitate micromorphometric analysis. Micromorphometric analysis opens the scope for improving the knowledge we have on trans-scale issues in bedrock rivers. Micromorphometric analysis also opens a new layer of information that enriches the public's valuation of geodiversity of geomorphosites by increasing its didactic and interpretative potential. ; This work was supported by Geomateriales 2 (S2013/MIT-2914) and Top Heritage (P2018/NMT-4372) programmes from the Regional Government of Madrid (Spain). ; Peer reviewed

Taphonomic processes play an important role in the preservation of small morphological features such as granulation or pits. However, the assessment of these features may face the issue of the small size of the specimens and, sometimes, the destructiveness of these analyses, which makes impossible carrying them out in singular specimen, such as holotypes or lectotypes. This paper takes a new approach to analysing small-morphological features, by using an optical surface roughness (OSR) meter to create a high-resolution three-dimensional digital-elevation model (DEM). This non-destructive technique allows analysing quantitatively the DEM using geometric morphometric methods (GMM). We created a number of DEMs from three populations putatively belonging to the same species of trilobite (Oryctocephalus indicus) that present the same cranidial outline, but differ in the presence or absence of the second and third transglabellar furrows. Profile analysis of the DEMs demonstrate that all three populations show similar preservation variation in the glabellar furrows and lobes. The GMM shows that all populations exhibit the same range of variation. Differences in preservation are a consequence of different degrees of cementation and rates of dissolution. Fast cementation enhances the preservation of glabellar furrows and lobes, while fast dissolution hampers preservation of the same structures. ; J.E. was supported by a Juan de la Cierva Grant (FPDI-2013-17337), and by project CGL2013-48877-P from Spanish MINECO. M.G.H. acknowledges support from the Programme Geomateriales 2 (S2013/MIT_2914) funded by the Regional Government of Madrid and the European Social Fund. ; Peer reviewed