71 research outputs found
La Torre inclinada de Pisa. Estructura, materiales de construcción e intervenciones de refuerzo
An exhaustive diagnosis of "anatomy, physiology and pathology" of the masonry body of the leaning Tower of Pisa has been carried out with the aim of integrate the knowledge of the structure features, mechanical conditions and decay processes of the building materials, necessary for correctly managing the therapy, temporary and definitive interventions.
The interventions already or being implemented consist of (i) outer circular slightly stressed steel tendons, (ii) inner stressed and/or passive strainless bars, and (iii) grouting by a specially devised cement admixture.
The paper will not be dealing with "materic" restoration works, and geotechnical interventions for reducing the progressive tilting and stabilizing the foundation/subsoil system of the Tower.Se ha realizado un exhaustivo estudio de diagnosis de la Torre inclinada de Pisa, con el fin de completar todo el conocimiento existente en torno a la estructura, condiciones mecánicas y procesos de alteración de los materiales de construcción, para proponer la terapia más correcta de intervención, ya sean éstas temporales o definitivas.
Las intervenciones ya realizadas o en fase de ejecución consisten en: (i) cables de acero ligeramente tensados rodeando la Torre, (ii) barras interiores tensadas y/o pasivadas, y (iii) relleno con una lechada de cemento con aditivo, especialmente preparado para tal fin.
El presente trabajo no se centrará en las restauraciones ni en las intervenciones geotécnicas realizadas para reducir la progresiva inclinación y estabilizar el sistema de cimentación de la Torre
Investigación arqueométrica de los ladrillos de las antiguas murallas defensivas de la ciudad de Pavía (norte de Italia)
A study was conducted on bricks sampled from the defense walls around the historic town of Pavia (northern Italy) erected during Roman (uncertain) and “Spanish”(sixteenth-seventeenth centuries) times. An analysis of colour, macro- and micro-chemical composition,mineralogical clusters and structural-textural features showed that similar raw materials were used in the manufacture of these bricks, although certain variations were identified: particle size is finer in Roman bricks, while the “Spanish” version contains ground carbonate and “chamotte” additives. The “Spanish” bricks,fired at lower temperatures, are more porous. The wide range of firing temperatures used to make “Spanish” bricks was very likely related to the intended use. The sporadic presence of maghemite is discussed in the context of the atmosphere prevailing in the kilns. The “Spanish” bricks are lighter in colour as a result of their carbonate content and lower firing temperature. These characteristics, which affect the weather resistance of the different types of brick, should be taken into account in restoration work.Se investigan ladrillos recogidos en las murallas defensivas de la histórica ciudad de Pavía (norte de Italia), que fueron construidas en tiempos romanos (no establecidos)y “españoles” (siglos XVI y XVII).En base al color, composición química tanto total como puntual, asociaciones mineralógicas y características texturales,se concluye que se utilizó una materia prima similar en ambas épocas, con algunas particularidades: granulometría más fina en los romanos, adición de carbonato molido y chamota en los “españoles”. Por su parte, la porosidad es mayor en los ladrillos “españoles”. El amplio rango de temperaturas de cocción observado para estos últimos debe estar relacionado con los distintos usos para los cuales fueron destinados. La presencia esporádica de maghemita se discute, además, en función del tipo de atmósfera imperante en el horno de cocción. El color de los ladrillos “españoles” es más claro, como corresponde a su mayor contenido en carbonatos y menor temperatura de cocción. Estas características ejercen una notable influencia en la resistencia a la meteorización de los distintos tipos de ladrillos y deben, ser tenidas en cuenta ala hora de elaborar posibles planes de restauración
Procesos de alteración asociados al contenido de minerales arcillosos en materiales pétreos
Stone alterability/durability is depending upon a number of intrinsic and extrinsic factors among which "clay minerals" constituents, either diffused throughout the stone framework or as coating-filling of void spaces, can play an important role.
Swelling-shrinking and aggregation-disaggregation phenomena occurring by interaction of argillaceous particles with water and other fluids can cause destructuration of the stone resulting in a variety of pathologies. Also salt crystallization which is depending on fluid transfer, moisture evaporation and ion concentration in the circulating solutions, can be influenced by clay mineral reactivity. Furthermore, saline solutions can drastically change the clay minerals behaviour, resulting in enhanced "osmotic" swelling and variations in clay aggregation geometry; these phenomena resulting in significant stone damage.
Case histories concerning several lithotypes used for monumental buildings and artistic manufacts are reported for showing the role of different clay mineral types in determining trend and intensity of decay processes.Varios factores, tanto intrínsecos como extrínsecos, pueden condicionar la alterabilidad/durabilidad de materiales pétreos. Entre ellos, la presencia de minerales arcillosos, bien como constituyentes difusos o recubriendo-rellenando huecos, puede jugar un papel importante.
El resultado de la interacción de las partículas arcillosas y el agua (u otros fluidos) da lugar a patologías que son consecuencia de una serie de daños internos producidos por las continuas variaciones plásticas, asociadas a parámetros físicos y cristaloquímicos de este tipo de minerales. Entre los que podemos citar la desestructuración de la piedra (bien por agregación-desagregación de las partículas arcillosas o por procesos de hinchamiento-contracción) que está asociado, por ejemplo, con la cristalización de sales, producida por la transferencia de fluidos a su través, o a variaciones de humedad, a concentraciones iónicas de la solución, en función de la reactividad de las arcillas presentes, o a efectos provocados por tensiones osmóticas que modifican la geometría de aglutinación de las propias partículas.
En este artículo se analizan diferentes litotipos utilizados en la construcción y ornamentación de edificios históricos, todos ellos con minerales arcillosos, así como sus patologías, definiéndose las tendencias y los procesos degradativos encontrados
The Influence of the Type of Lime on the Hygric Behaviour and Bio-Receptivity of Hemp Lime Composites Used for Rendering Applications in Sustainable New Construction and Repair Works
The benefits of using sustainable building materials are linked not only to the adoption of manufacturing processes that entail reduced pollution, CO2 emissions and energy consumption, but also to the onset of improved performance in the building. In particular, hemp-lime composite shows low shrinkage and high thermal and acoustic insulating properties. However, this material also shows a great ability to absorb water, an aspect that can turn out to be negative for the long-term durability of the building. For this reason, the hygric properties of hemp-based composites need to be studied to ensure the correct use of this material in construction and repair works. The water absorption, drying and transpirability of hemp composites made with aerial (in the form of dry powder and putty) and hydraulic limes were investigated here and related to the microbial growth induced by the water movements within the material. Results show that hemp-natural hydraulic lime mixes exhibit the highest transpirability and drying rate, the lowest water absorption by immersion and capillary uptake and the least intense microbial attack and chromatic change. A microscopical study of the hemp shives also related their great ability to absorb water to the near-irreversible swelling of their structure under dry-wet conditions.The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 326983 (NaturALiMe), and the Spanish project MAT-2012-34473 of the Ministerio de Ciencia y Competitividad. Author MB, owner of the CANNABRIC company, had some role in the design and preparation of mortar samples and in the preparation of this manuscript, but did not have any additional role in data collection and analysis
Thermal characterization of archaeological pot sherds recently excavated in Nedunkur, Tamilnadu, India
Biogeochemistry, grain size and mineralogy of the Central and Southern Adriatic Sea sediments: a review.
Volume 26 Supplement 1, January 2010
Degradation conditions of the materials constituting the lower loggia of the façade of Pavia Cathedral
The "Leaning" tower of Pisa: occurrence and distribution of the masonry decay by-products. Science and Techn. for Cultural Heritage
Lath-shaped particles as incipient transformation stage of smectite/illite lamellae under tectonic stress
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