The measurement of surface roughness to determine the suitability of different methods for stone cleaning

Trabajo presentado a la EGU General Assembly 2011.In order to select the best bead blasting based method to clean the stone masonry of specific areas of the Cathedral of Segovia (Segovia, Spain), measurements of the roughness of the stone surface were performed, before and after cleaning processes.Peer reviewe

Los revocos de cal de las fachadas de la plaza de la Corredera de Córdoba

The causes of the pathologies found on the lime renderings from Plaza de la Corredera façades are analysed in this study. For this purpose, the mineralogical and chemical analyses of the building materials -brickwork and rendering mortar- has been carried out, as well as their physical, hydric and mechanical properties have been determined. The obtained results from both unaltered and altered materials, and the analysis of the rendering's raw materials, have allowed us to establish that rendering deterioration is connected to the presence of saline compounds (gypsum, halite), which existing in the brickwork substratum, have been removed due to the water saturation of such brickwork. The main cause responsible of the alteration forms - efflorescence, crusts, grain-disintegration, bulging, flaking found on the renderings, has been the salts precipitation (halite, hexahydrite, epsomite) in their way towards the external surface.En este estudio se analizan las causas de las patologías de los revocos de cal de las fachadas de la Plaza de la Corredera. Para ello se ha realizado el análisis mineralógico y químico de los materiales de construcción - fábrica de ladrillo y mortero de revestimiento- y se han determinado sus propiedades físicas, hídricas y mecánicas. Mediante la comparación de los resultados obtenidos en los materiales inalterados y en los alterados, así como una vez analizadas las materias primas utilizadas en la realización del revoco, se ha podido establecer que la alteración de este último está relacionada con la existencia de compuestos salinos (yeso, halita) que, presentes en el substrato de fábrica de ladrillo, se han exudado por saturación de agua de la misma. La precipitación de las sales (halita, hexahidrita, epsomita) en su migración hacia el exterior ha sido la principal responsable de las formas de alteración -eflorescencias, costras, arenización, abombamientos, descamaciones- que aparecen sobre los revocos de estudio

Polygonal cracking associated to vertical and subvertical fracture surfaces in granite (La Pedriza del Manzanares, Spain): considerations for a morphological classification

The area known as Pedriza de Manzanares forms part of the Upper Manzanares River Basin and of the recently (June 2013) listed Sierra de Guardarrama National Park, located in the Spanish province of Madrid. The region is home to Late Palaeozoic granites characteristic of the Spanish Central Systam, which were intruded during the Variscan Orogeny and uplifted to their present position during the Alpine Orogeny. Previous studies of polygonal cracking in granite suggest several possible control mechanisms. Some authors contend that weathering patterns are governed by internal geodynamic factors, such as the final stages of magmatic consolidation or differential movements in fault planes as a result of their structural position. Others claim that climate-related external factors, specifically insolation rates and thermal differences, can explain the predominance of a given orientation in such patterns. The present paper is a study of the effect of case hardening on polygonal cracking, and the role of variables such as temperature and rock surface hardness in granite weathering. It also aims to establish a general systematic classification for polygonal cracking, focusing particularly on the cracking associated with the sub-vertical planes of fracture at Pedriza de Manzanares. The morphometric parameters associated with cracks and fractures, including strike and dip, are analysed, along with the height of occurrence and shape of polygonal cracks.La Pedriza de Manzanares forma parte de la cuenca alta del río Manzanares en la provincia de Madrid, y desde junio de 2013 forma parte del Parque Nacional de la Sierra de Guadarrama. La zona está formada por granitos característicos del Sistema Central Español que intruyeron a finales del Paleozoico durante la orogenia Varisca y sufrieron un levantamiento hasta su posición actual durante la orogenia Alpina. Trabajos previos sobre agrietamientos poligonales en granitos sugieren diversos posibles mecanismos de control. Algunos autores mantienen que los patrones de meteorización están controlados por factores geodinámicos internos relacionados con estados tardíos de consolidación magmática, o por movimientos diferenciales de planos de fractura, como consecuencia de su posición estructural. Otros autores apuntan que los factores externos tales como el clima, específicamente por diferencias térmicas debido a la insolación, pueden explicar la abunadancia de estas formas de acuerdo con un patrón de la orientación del afloramiento. En este trabajo se estudia la influencia de los endurecimientos superficiales en la evolución de los agrietamientos poligonales, y se analizan variables como la temperatura y la dureza de la superficie rocosa en el proceso de meteorización del granito. Además, el trabajo trata de presentar una clasificación general de los agietamientos poligonales, incidiendo en los agrietamientos asociados a planos de fractura subverticales identificados en La Pedriza de Manzanares. Los parámetros morfométricos estudiados de los agrietamientos poligonales, incluyen la dirección e inclinación de la pared rocosa, la altura de aparición y su forma

Evolution of the alteration process in time of granitic materials from Valdemorillo quarries used in built heritage, Madrid, Spain

Depto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasTRUEpu

Influencia de la anisotropic en la durabilidad de las dolomías Cretácicas de la Comunidad de Madrid frente a la cristalización de sales

The behaviour of dolostone exposed to the effects of salt crystallization processes was studied on materials from Redueña and Torrelaguna in the province of Madrid, Spain. Much of the region's architectural and monumental heritage was built with the materials from these two sites. Stone specimens were selected for testing on the basis of ultrasonic wave propagation velocity (Vp) measurements taken in around one hundred cubic samples of each variety. The anisotropy indices were calculated and the samples were clustered on the basis of the results. Two representative samples of each class were taken and characterized for their petrographic and petrophysical properties before and after exposure to salt crystallization cycles. Ageing was evaluated in terms of weight loss and the visual deterioration observed. The pattern of decay found varied substantially in the two materials: the Redueña material exhibited more intense deterioration, with scaling and spalling, while the Torrelaguna dolostone tended to generate fragmentation and rounding at corners and edges.Depto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasTRUEComunidad de MadridMinisterio de EducaciónUnión Europeapu

Ruta Geomonumental: materiales de construcción Conjunto Médico Ciudad Universitraria de Madrid.

Itinerario científico didáctico en el que se muestran las piedras y materiales cerámicos empleados en la construcción de las facultades de Medicina, Farmacia y Odontología de la Universidad Complutense de Madrid (UCM)

Definition of analytical cleaning procedures for archaeological pottery from underwater environments: The case study of samples from Baia (Naples, South Italy)

This work is focused on a multidisciplinary study of 13 pottery fragments collected in the submerged archaeological site of Baia (Naples, Italy). Founded by the Romans in the 1st century B.C., this archaeological area represents one of the greatest evidences of Roman architecture and it includes ancient ruins whose structures range from maritime villas and imperial buildings. Several diagnostic tests were carried out in order to characterize the archaeological materials, their structure and properties, as well as the alteration and degradation products. Degradation forms in seawater imply not only a variation in the physico-mechanical and chemical properties of the material but also an aesthetic damage, due to superficial deposits, which can lead to the illegibility of the artefacts. In this context, it is crucial to determine to what extent these decay factors, mainly attributable to biological growth, could affect the durability of pottery and what are the effects of cleaning procedures. The work offers further elements to obtain new insights into the underwater cultural heritage field and in the function of ceramic matter, especially related to several applications in technology and in the adoption of strategies for suitable conservation procedures. (c) 2020 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Archaeometric approach for the study of mortars from the underwater archaeological site of Baia (Naples) Italy: Preliminary results

This work was aimed to evaluate the features of mortar samples taken from the underwater archaeological area of Baia (Naples, Italy), an important site, where the remains of the ancient Roman city of Baiae and Portus Iulius are submerged after bradyseism events, started from 4th century AD. Several architectural structures are still preserved into the submerged environment, such as: luxurious maritime villas, imperial buildings, private houses, thermae, tabernae and warehouses. In particular, some samples were collected from the masonry walls belonging to a building of the underwater area called Villa a Protiro. A first archaeometric approach has been applied to analyse twelve archaeological mortars samples in order to define: textural features, chemical composition and raw materials used for their production. For this purpose different analytical methods were used, such as, polarizing optical microscope (POM) and scanning electron microscopy (SEM-EDS).This work was financially supported by national national research project “COMAS” (Planned COnservation, “in situ”, of underwater archaeological artifacts), funded by the Italian Ministry of Education, Universities and Research (MIUR).Peer reviewe

Investigating the effects of lightning on cultural heritage: Characterization of the resulting fulgurite

On average, about 100 lightning discharges occur every second on the Earth. When lightning strikes soil, sand or rock, the high temperatures reached (about 30.000 ºK) promote the formation of melted glass tubular structures known as fulgurites. In the case referred here, lightning stroked a soil (granitic sand plus angular stones of thick-grained two-mica granite) and allochthonous materials supporting the platform of an electric tower. The intense melting produced a cylindrical rod, from which, as if they were roots of a tree, several bifurcating horizontal and subhorizontal branches of decreasing thickness were attached (see figure below).Peer reviewe