Digital image processing techniques as a tool for evaluating and mapping patinas on granite monuments

Monument conservation is related to the interaction between the original petrological parameters of the rock and external factors in the area where the building is sited, such as weather conditions, pollution, and so on. Depending on the environmental conditions and the characteristics of the materials used, different types of weathering predominate. In all, the appearance of surface crusts constitutes a first stage, whose origin can often be traced to the properties of the material itself. In the present study, different colours of “patinas” were distinguished by defining the threshold levels of greys associated with “pathology” in the histogram. These data were compared to background information and other parameters, such as mineralogical composition, porosity, and so on, as well as other visual signs of deterioration. The result is a map of the pathologies associated with “cover films” on monuments, which generate images by relating colour characteristics to desired properties or zones of interest

Mampostería de las viviendas históricas de Maracaibo en base a la Grauvaca “piedra de ojo” = Historical masonry dwellings Maracaibo based Greywacke “eye stone”

Se analizan los materiales de la mampostería de “piedra de ojo” de las viviendas del casco histórico de Maracaibo con fines de reposición y de conservación. Se expone la metodología del análisis petrofísico a partir de probetas para determinar los componentes y las propiedades escalares, mediante la inspección visual, difracción de rayos X, microscopía óptica de transmisión, porosimetría, así como medición ultrasónica y ensayos mecánicos. Los resultados demuestran que la piedra procedente de la formación “El Milagro”, es una grauvaca ferruginosa, de color rojizo, con abundante porosidad (huecos) de tipo móldico, fenestral, e intergranular apreciable a simple vista y que sustenta la denominación popular de “piedra de ojo” . Presenta una baja succión capilar, densidad aparente de 2.889 kg/m 3 y una baja resistencia a compresión, no llega a 5 MPa, disminuyendo considerablemente en húmedo y condicionada por las cargas orientadas, tanto en paralelo o perpendicular a la superficie de estratificación

Geomorphological evolution of the Rimac River’s alluvial fan, Lima, Peru

The alluvial fan of Lima is a complex landform, resulting from the sediment contributions of the Rimac River and the coalescence of the alluvial fans of the tributaries of the Rimac River. Depositional zones in the fan and changing main channel and distributary channels are influenced by the palaeo-relief inherited from a semi-arid climate and by the climatic changes. The upper sedimentary sequence of the fan, dominant on the Costa Verde, is of Upper Pleistocene–Holocene age. The sediments forming it are non-cohesive and are highly mobile during floods and earthquakes. The dominant features in this sequence, intertwined channel facies and laminar flows, were influenced by the Pleistocene–Holocene postglacial marine transgressions. A deeper understanding of the evolution of the Lima alluvial fan provides insight in to the fan’s future evolution in the framework of active tectonics and climate change. The Lima fan is an area with high human population density and is subjected to floods and debris flows resulting in subsequent loss of human life and properties. Therefore, the improved understanding of the fan’s evolution, resulting from this study, will contribute to a better definition of high risk areas of potential human disaster caused by these natural processes. Cyclic-fandevelopment, presently controlled by glacial sea level lows and palaeo-topography will continue regardless of human intervention in attempts to prevent natural disasters in Lima

Drª Rosa Esbert Alemany. La humanidad de las piedras = Drª Rosa Esbert Alemany. L'humanité des pierres

Drª Rosa Esbert Alemany. La humanidad de las piedras = Drª Rosa Esbert Alemany. L'humanité des pierre

EL tratamiento digital de imagenes como una herramienta de evaluación y análisis en la restauración y conservación del patrimonio arquitectónico = DIGITAL IMAGE MAPPING AS An Analisis and Evaluation Tool in Heritage Conservation and Restoration Process

AbstractTwo monuments representative of the pre-Romanesque style are analyzed by digital image mapping integrating the results in a GIS. These buildings share various characteristics and have in common the pathologies (dark patinas, sugaring) and mainly the present fragmentary state they show. Regarding thisanalysis the areas of affection are quantified and mapped, establishing a cause-effect link between the petrophysical parameters of the materials (lithological varieties) and the changes developed. In addition, on one of the monuments, the missing original volumes are recreated by inferring the measurements from the preserved parts of the building. This process is based on the algorithms of texture generation, bymathematical morphology, and by the geometrical proportions on which the aesthetic pattern of the monument is based

Properties of the Ignimbrites in the Architecture of the Historical Center of Arequipa, Peru

The petrographic and petrophysical characteristics of three varieties of ignimbrites used in the architectural heritage of Arequipa (southwest Peru) are analyzed. The modal classification QAFP and TAS diagram discriminate their dacitic nature. Mercury injection porometry revealed very high porosity: 46.5% for white and beige ignimbrites, and 35.5% for the pink variety. Ignimbrites contain intrusions of vulcanodetrital fragments and vacuoles that influence their predominantly non-linear mechanical behavior. The results of water absorption by capillarity (C) and ultrasound pulse velocity (UPV) demonstrate a slight anisotropy for the beige variety and near isotropy for white and pink ignimbrites, which justify the randomness of the application of the ashlars in the masonry and in the selection of the faces to carve. Surfaces with hollows in the white and beige ignimbrites are the result of the erosion of the acicular pumice that fills the vacuoles

Reinterpretación del tallado plano del patrimonio cultural de Ignimbrita de Arequipa

El patrimonio arquitectónico del centro histórico de Arequipa (Perú) ha sido construido aprovechando las coladas volcánicas de la propia ignimbrita que le dan belleza y singularidad. La labra dócil de la piedra favoreció la decoración barroca de las portadas de los inmuebles religiosos y casas señoriales y el trabajo escultórico plano que se denomina “arquitectura textilográfica”. Se expone que el tallado es plano porque está condicionado por la albañilería más que por el diseño escultórico. Se realiza en la cara de los sillares, lo cual origina una variedad de dimensiones de la testa y del canto, aumentando también el grueso para contribuir al dibujo del tallado y ensamble de las piezas, alterando por consiguiente la altura de la hilada del aparejo. Contribuyen al tallado planiforme las limitaciones de la baja resistencia mecánica de la piedra con presencia de intrusiones duras y de vacuolas. Además los continuos seísmos, en particular después del terremoto de 1868 en la fase post colonial, incidieron en la reducción del vuelo de ménsulas y molduras en las posteriores reconstrucciones

Aplicaciones del analisis digital de imagenes

Centro de Informacion y Documentacion Cientifica (CINDOC). C/Joaquin Costa, 22. 28002 Madrid. SPAIN / CINDOC - Centro de Informaciòn y Documentaciòn CientìficaSIGLEESSpai