Comparative analysis for the assessment of restoration treatments on stone material from the roman theater of Merida (Spain)

The overall goal of the project is the study of effects of conservation treatments applied on stone material from archaeological sites, i n terms of superficial changes, effectiveness and durability. In this sense, one of the first premises is characterize the surface of the treated and untreated material in order to determine changes in physical and chemical properties

Evolution in the use of natural building stone in Madrid, Spain

Many types of stone have been used for construction in Madrid. In historical times, their use was determined by the proximity of the geological resources, the ease of quarrying and transportation links to the city. More recently, as transport connections and quarrying techniques have improved, quality and durability have become key determinants of building stone selection. Local flint was used intensively from the ninth to the eleventh century, when it was replaced by Redueña dolostone, used in turn until the seventeenth century. Granitic rocks from the Guadarrama Mountain Range that crop out in the northern and western area of the province increasingly began to be used in the city from the sixteenth century. Traditionally known as Berroqueña stone, this building stone was quarried in a number of areas; the primary point of supply was Zarzalejo, and from the eighteenth century the granite used was mainly quarried in the Alpedrete area. Eighteenth century advances in underground quarrying made it possible to extract a limestone (Colmenar stone) located in the southeastern part of the region. Together with Berroqueña stone, this limestone became one of Madrid's traditional building stones, and both, highly esteemed for their excellent petrophysical properties and durability, are still used today

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

The resistance of dolomitic limestone to 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 degeneration pattern found varied substantially in the two materials: the Requena material exhibited more intense deterioration, with scaling and spalling, while the Torrelaguna dolostone tended to generate fragmentation and rounding at corners and edges. The anisotropy of these stones does not appear to clearly govern salt crystallization-mediated deterioration. Although no clear relationship could be established between the intensity of deterioration and the initial anisotropy indices, total anisotropy was observed to increase as a general rule, and normally more than the relative anisotropy index. No specific anisotropic group was found to undergo greater variation than any other.En este trabajo se estudia el comportamiento de las dolomías de Redueña y de Torrelaguna frente a los efectos de la cristalización de sales. Ambos materiales han sido ampliamente utilizados en la construcción del Patrimonio arquitectónico y monumental de la región de Madrid. Para la selección de las probetas pétreas a ensayar, se midió la velocidad de propagación de ondas ultrasónicas (Vp) en cerca de un centenar de muestras cúbicas de cada variedad. Se calcularon los índices de anisotropía y se realizó un proceso de clustering para su clasificación en función de niveles de anisotropía. De cada clase se tomaron dos probetas representativas y se procedió a su caracterización petrográfica y petrofísica antes y después de someterlas a ciclos de cristalización de sales. Para la evaluación del envejecimiento se registró la variación de peso y se documentó el deterioro visual observado. El patrón de degradación para cada uno de los materiales frente a los ciclos es bastante distinto: la dolomía de Redueña es la que presenta un deterioro más intenso con descamaciones y desplacados mientras que la de Torrelaguna tiende a generar fragmentaciones y formas redondeadas. La anisotropía de los materiales pétreos estudiados no parece controlar de forma clara el proceso de su deterioro por cristalización de sales. Aunque no ha sido posible establecer una relación clara entre intensidad de deterioro e índices de anisotropía iniciales, en general, se observa un incremento del índice de anisotropía total, por lo general algo menor para el índice de anisotropía relativa, sin poder apreciar que las variaciones sean mayores en un grupo de anisotropía específico

Petrophysical-mechanical behavior of Grisolia stone found in the architectural heritage of southern Italy

Grisolia is one of the building stones most commonly found in the architectural heritage of southern Italy. Also known commercially as “gold stone” for its yellow intrusions, Grisolia was employed by the leading Calabrian schools of stonemasons, principally in the southern Italian regions of Calabria and Basilicata. It is an Upper Triassic crystalline carbonate quarried in the Verbicaro Unit on Calabria’s northern Tyrrhenian coast. Possessing petrographic, physical and mechanical properties that ensure stone strength and durability, it is a high-quality building material suitable for structural and ornamental uses. These properties can be attributed to its low open porosity and excellent hydric behavior (low capillary water absorption), as well as to its high mechanical strength and low anisotropy. These characteristics make it recommendable as a building material for both restoration and new construction

The conservation state of the Sassi of Matera site (Southern Italy) and its correlation with the environmental conditions analysed through spatial analysis techniques

The current study aims to analyse the conservation state of the Sassi of Matera site (Southern Italy), a place inscribed on the UNESCO World Heritage List since 1993 (the Sassi and the Park of the Rupestrian Churches of Matera) and recently awarded 2019 European Capital of Culture. Furthermore, the article considers the influence of some of the causative factors controlling the Matera building conservation state, paying particular attention to the site microclimatic conditions such as the insolation and winds. We studied this subject through a new methodology that makes a combined use both of stone decay data gained from the extensive field assessments of the visible weathering forms catalogued in an ad hoc questionnaire and GIS advanced spatial analysis techniques such as Map Algebra and Kernel Density Estimation. The research puts into evidence that the Sassi of Matera shows a fair state of conservation that is conditioned by the wind/rain actions and sun exposure. Besides, just the already well known facts that the surfaces facing north seem to be most influenced by the wind/rain actions; and that, on the contrary, the decay of the walls facing south seems to be guided mainly from the sun exposure, put into evidence the importance of locating the intensities of the decays in any urban tissue or any site in order to plan conservation interventions and prioritize actions and the usefulness of the spatial analysis techniques and data processing

Determination of anisotropy to enhance the durability of natural stone

Received 30 November 2010 / Accepted for publication 8 July 2011 / Published 23 August 2011 /Online at stacks.iop.org/JGE/8/S132 Copyright © 2011, Oxford University Press © 2011 NanjingGeophysical Research InstituteAnisotropy is a petrophysical property of natural stone and other construction materials thatdetermines their quality and resistance to decay due to a variety of agents, such as water. A studywas conducted on nine types of stone widely used in Spain’s built heritage, using six previouslydefined anisotropy indices. These indices can be used to determine the degree of anisotropy,which helps explain the differential decay observed in stone materials quarried in the same bedand used to build the same structure. The conclusion reached is that anisotropy should bedetermined in the natural stone used both to restore the architectural heritage and in newconstruction, since the appropriate choice of material quality ensures greater resistance to decayand, therefore, increased durability. Materials with the lowest possible anisotropy should beselected, as this property governs their hydraulic behaviour: the lower the anisotropy in amaterial, the better its behaviour in relation to water and the longer its durability.Comunidad de Madrid (España)Ministerio de Educación y Ciencia (España)Depto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasTRUEpu

Limestone on the 'Don Pedro I' facade in the Real Alcázar compound, Seville, Spain

This paper discusses the research conducted prior to restoring the 'Don Pedro I' facade on the Real Alcázar or royal palace at Seville, Spain. The different types of stone on the facade were located and characterized, and their state of decay mapped. Although other materials (brick, rendering, ceramics, marble) are present on the facade, its main elements are made from two types of limestone: palomera and tosca, each in a different state of conservation and exhibiting distinct behaviour. Colour parameters, real and bulk densities, compactness, open porosity, water saturation coefficient and total porosity were determined to characterize the two varieties. In addition, ultrasonic techniques were used to map the various levels of decay on the facade, stone by stone, for future interventions. The findings show that owing to its petrographical and petrophysical properties, palomera stone is of a lower quality than tosca stone, and has undergone more intense deterioratio