bluuebunny/crossref_metadata_2025 huggingface dataset:
Durabilidad vs Vulnerabilidad
Authors: Monjo Carrió J
Published: October 2008

Se propone la defi nición de durabilidad de un elemento constructivo a partir de su vulnerabilidad. Para ello, se analizan estos dos conceptos básicos junto con los de función constructiva, acciones externas y calidad. Se parte de unas fórmulas matemáticas empíricas para defi nir la durabilidad a partir de la vulnerabilidad, se describe con precisión la vulnerabilidad en construcción y sus variantes a partir de los posibles procesos patológicos y sus consiguientes lesiones, susceptibles de afectar a los materiales y elementos de un edifi cio, y se describen dichas lesiones, agrupadas por familias. Finalmente, se desarrolla un ejemplo de defi nición de durabilidad a partir de la vulnerabilidad en chapados de piedra.
La construcción del velódromo de Dos Hermanas, Sevilla (España)
Authors: Escrig Félix , Sánchez José
Published: October 2008

El diseño y la construcción de la Cubierta para el velódromo de Dos Hermanas constituyó un reto de primera magnitud por varias razones: grandes dimensiones; no tocar, ni siquiera simbólicamente el edificio existente y hacer una obra sencilla que no pretendiera asombrar por su espectacularidad. Se buscaba hacer un edificio modesto a pesar de su dimensión. De hecho es un edificio que sobrecoge por su espacialidad interior más que por su apariencia externa. Otro reto planteado fue que sólo se sostuviera en cuatro soportes. Sería así una gigantesca mesa. Y, por último, no queríamos ver barras inclinadas, sólo una superficie que fluyera con naturalidad desde las alturas hasta la cabeza de los soportes, llevando las fuerzas de un modo natural y sin artificio. Quedaba por fin el problema del cerramiento. Aunque se había pensado abierto, decisiones funcionales y de oportunidad solicitaron un cerramiento que no alterara el aspecto que tenía cuando estaba abierto. Ello se consiguió mediante un telón tensado que tampoco toca el edificio existente y, por tanto, no resta liviandad al conjunto metálico. El presente artículo pretende describir los aspectos constructivos que hicieron posible estas ambiciones desde el punto de vista de la práctica constructiva.
Un estudio histórico del problema de las piezas prismáticas rectas sometidas a compresión. Parte II
Authors: Ortega Miguel A. , Romero José L. , De la Rosa Emilio
Published: October 2008

Se complementa la primera parte de este trabajo con un breve repaso histórico de algunos de los modelos teóricos y métodos numéricos empleados en la resolución de los problemas planteados en el artículo anterior, cuando no ha sido posible su descripción analítica. En un primer apartado se mencionan algunos de los métodos que se han utilizado para abordar las ecuaciones que rigen los modelos: analíticos con soluciones cerradas, aproximados, matriciales, elementos finitos y splines generalizados. En un segundo apartado se enumeran distintas técnicas numéricas empleadas para la determinación de los aspectos que describen los problemas en relación con las vigas-columna: deformadas, esfuerzos, trayectorias, puntos límite y críticos, etc.
Mezclas de residuos de poliestireno expandido (EPS) conglomerados con yeso o escayola para su uso en la construcción
Authors: González Madariaga Francisco Javier
Published: October 2008

Se ha logrado ofrecer un grupo de 8 propuestas concretas para reciclaje de poliestireno expandido (EPS) que consiste en mezclar yeso o escayola y agua para constituir pastas que contienen residuos de EPS que se moldean como placas y paneles para la construcción. Se ha ensayado con muestras de pastas que van desde aquellas que contienen proporciones extremas de residuos hasta otras donde la presencia de agua para la preparación de las mezclas es inusualmente rica, también se han ensayado mezclas compuestas por proporciones intermedias de sus ingredientes. De las pastas con los mejores comportamientos en ensayos previos se han aplicado sus fórmulas en la fabricación de muestras de placas y paneles similares a los usados en la construcción. Los ensayos que se reportan aquí son para aplicación en placa constructiva: carga máxima a la flexión, resistencia al impacto, absorción de agua por inmersión, reacción al fuego y se determino su masa por unidad de superficie. Para la aplicación de las pastas como paneles aislantes han sido ensayados a la flexión y a la compresión, también se ha determinado su densidad aparente, reacción al fuego y absorción de agua por inmersión total. Las muestras se han caracterizado según las normas correspondientes y después se ha establecido una comparación con elementos similares hoy comunes en la construcción, de esto se permite señalar que con las pastas con residuos de EPS se pueden fabricar placas y paneles con algunas ventajas en relación a los existentes a lo que se le suma el beneficio medioambiental de reciclaje de EPS.
Las soluciones inconclusas de las cubiertas de los templos medievales del Reino de Sevilla, España
Authors: Gómez de Cózar Juan Carlos , Benítez Bodes Rosa Mª
Published: October 2008

En ocasiones, cuando se visita un templo medieval y se observa el despliegue de formas de crucería que se desarrolla sobre nuestras cabezas, cuesta cierto esfuerzo suponer que una disposición tan compleja sólo resulte ser un elaborado falso techo de piedra, ya que sobre ellos hay dispuesta una cubierta (normalmente de madera) que resuelve el contacto con el ambiente exterior. La mayor parte de la bibliografía existente, trata el tema así. Por lo tanto, cuando se realizan predicciones sobre el comportamiento mecánico, la carga fundamental es el peso propio de la bóveda. Sin embargo, hay lugares en donde la situación es distinta. El intradós de las bóvedas se produce con geometrías similares a las ya conocidas, pero sobre su trasdós se localiza un relleno sobre el que se construye una azotea (a veces transitable). Esta inclusión tiene un impacto enorme en el comportamiento de la bóveda (mecánico, estanqueidad, cambios térmicos, etc...). Y, por otro lado, cuando se observan las cubiertas se manifiestan como inconclusas. Contribuir a concluirlas y preservarlas en el tiempo es el objetivo fundamental de este artículo.
La ingeniería en las revistas españolas de arquitectura: 1920-1936
Authors: Sambricio Carlos
Published: October 2008

Tras la Primera Guerra Mundial se produjo en España un singular quiebro en la cultura arquitectónica al hacerse acuciante (debido a la migración que llegará a las grandes capitales) el problema de la falta de vivienda. Para solucionar dicho déficit fueron muchos los que reclamaron tanto normalización en la construcción de casas baratas como la utilización del hormigón. Cuando en torno a 1926 la Dictadura de Primo de Rivera potencia las grandes obras de infraestructura, las revistas de arquitectura apenas prestan atención a los proyectos para presas, aeropuertos, mercados, estaciones… que en esos momentos se construyen. Y sólo cuando, llegada la República (al producirse un retraimiento del capital) desde el nuevo gobierno se fomentan los grandes proyectos de Estado es cuando arquitectura e ingeniería inician una singular colaboración, planteándose cómo el trabajo del arquitecto debe ser “la fantasía que trabaja con exactitud”. Y es entonces cuando como, por vez primera, tanto la publicación del GATEPAC como la que edita el “Centro de Exposición e Información permanente de la Construcción” creado por Mariano García Morales o la publicada desde el “Instituto Técnico de la Construcción y la Edificación” que lidera Torroja proponen la reflexión sobre una nueva forma de entender la construcción.
60 años de revista hasta hoy: ¿y después?
Authors: Pérez Arroyo Salvador
Published: October 2008

En el artículo se analizan las condiciones socioeconómicas de la Revista en su fundación. Su repercusión social y científica y al tiempo se describen las razones de su pérdida de protagonismo en la sociedad actual proponiendo nuevos caminos de investigación e integración social de ésta.
Las revistas técnicas. Luces y sombras
Authors: Monjo Carrió Juan
Published: October 2008

Se plantea el interés de las revistas técnicas para la innovación en la construcción edificatoria, y se llama la atención sobre los riesgos que lleva implícito el intento de adaptación de las mismas en los nuevos proyectos sin el adecuado análisis específico.Para ello, se hace una revisión de las revistas técnicas que se han utilizado en las últimas décadas, estableciendo sus periodos de vigencia, y se describen algunos de los principales problemas constructivos y funcionales que han provocado los errores por incorporación indiscriminada de las novedades técnicas que aparecían en las mismas.Asimismo, se lleva a cabo un análisis de los condicionantes constructivos básicos a tener en cuenta en el diseño constructivo y, por tanto, previo a la incorporación de cualquier producto o sistema novedosos.
Las cubiertas ecológicas de tercera generación: un nuevo material constructivo
Authors: Neila F. J. , Bedoya C. , Acha C. , Olivieri F. , Barbero M.
Published: October 2008

En 1994 se inició una investigación que dio como resultado la construcción de la primera cubierta ecológica en España. Desde ese momento se han realizado modificaciones en su estructura constructiva, en el sustrato empleado y en las plantas empleadas, con la intención de optimizar su comportamiento, adaptándola a las condiciones climáticas que se padecen de España. Todas estas modificaciones han sido ensayadas y se ha evaluado rigurosamente su comportamiento energético. El resultado ha culminado en un modelo de cubierta, ya de una tercera generación, denominada como cubierta ecológica jardín. En este artículo se muestran, tanto los resultados de la investigación previa, como los correspondientes a la fase final que culminó con ese nuevo modelo, considerado como un nuevo material constructivo, plenamente sostenible.
Estudio de la resistencia a compresión simple del adobe elaborado con suelos procedentes de Crescencio Valdés, Villa Clara, Cuba
Authors: Saroza B. , Rodríguez M. A. , Menéndez J. M. , Barroso I. J.
Published: October 2008

En este artículo se estudia la resistencia a compresión simple que presenta el adobe elaborado con diferentes suelos procedentes del pueblo de Crescencio Valdés, situado en el municipio de Camajuaní, Villa Clara, Cuba.
Se valora la idoneidad de la utilización de cada suelo estudiado bajo la premisa de alcanzar con el adobe elaborado una resistencia a compresión simple de 1 MPa (10 kg/cm2), ya que dicho adobe será utilizado posteriormente para edificación en dicho pueblo
La Influencia de la Temperatura Exterior sobre los Sistemas de Ventilación Natural en Grandes Atrios
Authors: Capote J. A. , Alvear D. , Abreu O. V. , Lázaro M. , Espina P.
Published: October 2008

Entre las diferentes estrategias de Control y Evacuación de los Humos del Incendio, los sistemas de ventilación natural presentan numerosas ventajas frente a la ventilación mecánica – fundamentalmente una menor inversión tanto en equipos como en gastos de mantenimiento –. Sin embargo, su eficacia depende de la influencia ejercida por numerosos factores – características arquitectónicas del edificio, dirección y velocidad del viento, proximidad de edificios de gran altura, temperatura de los humos, temperatura ambiental interior, temperatura en el exterior del recinto, existencia de nieve o hielo en cubierta, etc. –. La influencia de la temperatura exterior al recinto, en especial, ejerce un papel decisivo.
El objeto del Estudio fue evaluar la influencia de la temperatura ambiental exterior en el movimiento de los humos y el posible descenso de la capa de gases calientes en relación a la eficiencia de los dispositivos de ventilación natural instalados en la cubierta de Grandes Atrios para el control de los humos, mediante herramientas avanzadas de Modelado y Simulación Computacional. Para los trabajos de investigación se empleó el modelo de simulación computacional de incendios ‘Fire Dynamics Simulator (FDS)’ (1), modelo de dinámica de fluidos computacional (CFD) para reproducir el fenómeno del incendio.
Los resultados demostraron que un diseño que no contemple este factor puede resultar inadecuado, al ejercer una influencia decisiva para la consecución de la Seguridad de las personas durante la evacuación. Se mostraron diferencias significativas en los resultados en relación a diferentes parámetros vinculados al movimiento de humos en un atrio.
Carbonation process in lime pastes with different water/binder ratio
Authors: Arandigoyen M. , Álvarez J. I.
Published: October 2008

Most research on binder carbonation is based on the analysis of depth changes in the carbonation front. Moreover, previous studies have dealt with mortars, where aggregates play a role in the variations in carbonation patterns. In the approach adopted in the present study, carbonation was determined in terms of the variation in weight resulting from CO2 absorption, and a new parameter (independent of the drying process), denominated A, was established. This parameter was assessed in several lime pastes with different W/B (water/binder) ratios and its variations were correlated to paste microstructure. Due to the type of porosity prevailing in lime pastes, diffusion took place according to Fick's law; water was retained not by capillarity but by surface adsorption. Drying did not retard carbonation in lime pastes
Use of copper slag in the manufacture of Portland cement
Authors: García Medina L. E. , Orrantia Borunda E. , Aquilar Elguézabal A.
Published: October 2008

Given its chemical and mineralogical characteristics, copper slag, a solid industrial by-product, may serve as a partial substitute for silica and hematite in raw mixes used to manufacture Portland cement clinker. The benefits of such substitution include lower production costs and energy savings. The effect of slag-containing raw mixes on the reactivity of the CaO-Si02-Al203-Fe203 system was studied at three temperatures (1,350, 1,400 and 1,450ºC). Four mixes were used: M-1 and M-2 prepared with conventional prime materials and M-3 and M-4, in which ignimbrite and hematite were substituted for slag. In M-3 the slag replaced 45.54% of the ignimbrite and 100% of the hematite, and in M-4 100% of the mineral iron. The samples were clinkerized at 1,350, 1,400 and 1,450ºC. At 1,400ºC, clinker M-3 was found to have 10.7% less free lime than M-1, while the level in M-4 it was 15.93% lower than in M-2. The presence of the main clinker phases was confirmed by X-ray diffraction, which also showed that adding slag during c/inker manufacture slightly improves raw mix burnability without generating new unwanted phases. Consequently, recovery in cement kilns would appear to be an economically and environmentally feasible alternative to coprocessing such waste, although the industrial use of slag depends on its heavy metal content.
Alkali activated fly ash binders. A comparative study between sodium and potassium activators
Authors: Fernández-Jiménez A. , Palomo A. , Criado M.
Published: October 2008

This paper shows the effect of the nature of some alkaline activators in the microstructural development of thermal-alkali activated f/y ash systems. The alkaline compounds employed in this investigation were: NaOH, KOH, Na2C03, K2C03, sodium silicate and potassium silicate. Results confirm that the main reaction product of the activation process (throughout the studied systems) is the amorphous alkaline aluminosilicate gel with a three-dimensional structure already observed in earlier research. It has been proved that the type of anion and cation involved in the activation reaction of the ashes not only affects the microstructural development of the systems but the Si/Al ratio of that prezeolitic gel too. For example, in the presence of soluble silicate ions the content of Si in the final structure is notably increased (Si/Al =2.7-3.0), however carbonate ions play a different role since the formation of Sodium or Potassium carbonate/bicarbonate acidifies the system and consequently the reaction rate is considerably slowed. Finally it is evident that; when all experimental conditions are equal, sodium has a greater capacity than potassium to accelerate the setting and hardening reactions of fly ash and also to stimulate the growth of certain zeolitic crystals (reaction by-products). In general it can be affirmed that OH- ion acts as a reaction catalyst; and the alkaline metal (M+) acts as a structure-forming element.
Encapsulation and re-use of wood industry waste: varnish powder
Authors: Oteiza I. , Hernández-Olivares F. , Acosta A.
Published: October 2008

The present article describes the findings of the first stageof the analysis of xiloarcilla, a material made of clayand a wood industry by-product, namely the wood andpolyurethane varnish powder pump-suctioned off woodcomponents during sanding and polishing. This powderwas added to the clay in proportions of from 1% to 5%by weight. The prime materials as well as the xiloarcillacompound were characterized, in the latter case primarilyto determine its physical-mechanical properties andchemical and environmental feasibility as a constructionmaterial.
Influence of the average stress in a unidirectional glass-epoxi composite material subjected to off-axis cyclic loads
Authors: Revuelta D.
Published: October 2008

A fatigue theoretical model for continuous glass-fibrereinforced epoxy composite material under general loadconditions was developed in previous works based onthe principal fatigue failure modes and on local failurecriteria. It was demonstrated that fatigue life dependedon the cyclic shear stress and the maximum stress transverseto the crack growth direction. Following the previousmodel, this work analyzes the influence of the averageapplied stress on the fatigue life of the material.
Alkali-activated slag mortars reinforced with ar glassfibre. Performance and properties
Authors: Puertas F. , Gil-Maroto A. , Palacios M. , Amat T.
Published: October 2008

In light of the practical problem posed by the high drying shrinkage rate exhibited by alkali-activated slag (AAS),due to these materials exhibited a high drying shrinkage the present study analyzes the behaviour of alkali-activated slag mortars reinforced with alkali-resistant (AR) glass fiber especially designed to reduce drying shrink aging cementitious systems. To this end, both alkali-activated slag and reference Portland cement mortars were prepared, with and without AR fiber (in dosages ranging from 0 to 1.1% by weight of the binder). These mortars were subjected to the following tests: drying shrinkage,mechanical strength after 2, 7 and 28 days, toughness,and high temperature. The microstructure of the materials was also studied by SEM/EDX techniques. At a percentage of 0.22%, AR fiber was found to induce a significant reduction (over 20%) in drying shrinkage, without detracting from the fine resistance strength, of alkali activated slag mortar. Moreover, plain activated slag mortars recovered 20% of their initial mechanical strength after exposure to high temperatures, and ins specimens reinforced with glass fiber at a rate of 0.22%,recovery climbed to 50%.
Characteristic compression strength of a brickwork masonry starting from the strength of its components. Experimental verification of analitycal equations of european codes
Authors: Rolando A.
Published: October 2008

In this paper the compression strength of a clay brickwork masonry bound with cement mortar is analyzed. The target is to obtain the characteristic compression strength of unreinforced brickwork masonry. This research try to test the validity of the analytical equations in European codes, comparing the experimental strength with the analytically obtained from the strength of its components (clay brick and cement mortar).
Hydraulic activity of belite cement from class C coal fly ash. Effect of curing and admixtures
Authors: Goñi S. , Guerrero A.
Published: October 2008

The effect of curing method and a water-reducing additive on the hydraulic activity of high lime content (ASTM type C) fly ash belite cement (FABC-2-W) is reported. A class C fly ash was subjected to hydrothermal treatment and subsequent calcination to synthesize FABC. Hydraulic activity was evaluated in the cement paste over 180 days from the physically bound water content as determined by thermogravimetric analysis and the degree of hydration, in turn found with X-ray diffraction (XRD) analysis. Mechanical strength, porosity and pore size distribution were also studied in equivalent mortar samples.
Electrochemical extraction of chlorides from reinforced concrete: variables affecting treatment efficiency
Authors: Sánchez M. J. , Garcés P. , Climent M. A.
Published: October 2008

This paper reports the results of applying electrochemical chloride extraction (ECE) to a series of chloride-contaminated concrete specimens. Experimental conditions were varied to study the efficiency of this technique under different circumstances. The survey covered the possible relationship between efficiency and the location of the sampling point, current density, type of concrete and treatment intermittence. Experiments were also conducted with different reinforcement configurations used in standard structural members such as columns and beams to ascertain the impact of rebar geometry.
Transfer and anchorage bond behaviour in self-compacting concrete
Authors: Martí-Vargas J. R. , Serna-Ros P. , Arbeláez C. A. , Rigueira-Víctor J. W.
Published: October 2008

Self-compacting concretes (SCC) provide solutions to the problems facing precast concrete construction, enhancing competitiveness, reducing turnaround times and improving final product quality. SCC is fast becoming a key product for the future development of the precast pre-stressed concrete industry.The present paper compares the bond performance of SCC and traditional concrete (TC). The bond performance results confirm the viability of SCC in precast pre-stressed concrete manufacture, despite a slightly higher loss of pre-stressing force and slightly greater anchorage lengths in SCC with a low water/cement ratio. No differences in transfer or anchorage length were detected,however, when high strength TC and SCC were compared. The ECADA test method proved to be well suited to detecting the differences between the concretes analyzed.
Cohesion in crumb rubber modified bitumen
Authors: Pérez-Jiménez F. , Miró Recasens R. , Martínez A. , Martínez Laínez C. , Páez Dueñas A.
Published: October 2008

This article reports on a study of crumb rubber-mediated improvement in bitumen cohesion, analyzed with the UCL method. UCL, a procedure developed to characterize bituminous binders, evaluates the cohesion obtained by adding a certain amount of bitumen or bituminous mastic to a standard mix aggregate. This method was chosen because it can be used to assess bitumen containing crumb rubber added by either the wet or the dry mix process. In the dry mix process crumb rubber is combined with the mix as if it were a fine aggregate; i.e., crumb rubber and binder are blended during mix manufacture, laying and compaction. In the wet mix process, the binder is blended with the crumb rubber prior to mixing with the aggregate; i.e., when added to the mix, it has already been modified. The effect of digesting this dry mixed material prior to use was also analyzed in the present study. A comparison of the dry (with and without digestion) and wet mix processes showed the latter to be more effective, particularly when the crumb rubber was blended with the binder via microscopic dispersion.
Effect of mortar joint thickness on deformability in medieval stone walls
Authors: Cassinello M. J.
Published: October 2008

An analysis of the stone walls in Gothic cathedrals revealed that Medieval master builders varied mortar joint thicknesses from one structural member to another. This fact, which has gone largely unnoticed to date, has a considerable impact on the structural behavior of cathedrals,due to its direct effect on two fundamental parameters,deformability and strength. In the absence offield data, an experimental test program was conducted at the INTEMAC Central Laboratory to determine the possible variations in deformability of Medieval masonry with changes in joint mortar thickness in the range found in the structural members of Spanish Gothic cathedrals. The results obtained show —further to an observation by Eduardo Torroja— that mortar joints are a determinant in the structural behavior of masonry. The modulus of deformation varied from 169.7 to 5,632.7 N/mm2at joint thicknesses ranging from 17.00 to 5.50 mm. Structural models should be adapted to accommodate this behavior pattern via parametric sensitivity analysis to obtain a clearer understanding of structural behaviour in Gothic cathedrals.
Ternary blend cements concrete. Part II: Transport mechanism
Authors: Menéndez G. , Bonavetti V. L. , Irassar E. F.
Published: October 2008

With today’s extensive use of cements containing two or more additions (blended cements), predicting concrete durability on the grounds of its strength alone leads to errors that may affect the service life of the resulting structures. Indeed, concrete of a given strength class can be made from different materials and proportions of widely varying durability. The present study evaluated water absorption, sorptivity and initial surface absorption in concrete made with unadditioned Portland, binary (limestone) and ternary (limestone and granulated slag) blend cement.
The effects of steel fibre reinforced concrete on system ductility
Authors: Kaltakci M. Y. , Arslan M. H. , Yilmaz U. S.
Published: October 2008

Steel fibre-reinforced concrete is being used extensively today in both field applications and experimental studies on concrete strength and ductility. The state of passive confinement generated by the fibre delays cracking and enhances ductility. The present paper reports on both experimental and analytical studies. In the former, a series of 16 steel-fibre reinforced concrete prismatic specimens were subjected to axial loads and the respective axial load-unit strain diagrams were subsequently plotted to determine the effect of steel fibres on reinforced concrete column ductility. Secondly, an analytical study was run to determine the additional ductility accruing to a frame system when steel fibres are included in the concrete. Analytical models were generated for 16 two-storey, single-span reinforced concrete frames. The columns in these frames were designed to the same characteristics as the specimens used in the experimental tests. Non-linear static (pushover) analyses were performed for each frame to obtain load-displacement curves and determine the effect of steel fibres on reinforced concrete column ductility.
Ductility of reinforcing steel with different degrees of corrosion and the ‘equivalent steel’ criterion
Authors: Moreno Fernández E. , Cobo Escamilla A. , Fernández Cánovas M.
Published: October 2008

One of the most significant effects of reinforcing steel corrosion on reinforced concrete structures is the decline in the ductility-related properties of the steel. Such properties condition the behaviour of reinforced concrete structures and must be taken into account when re-engineering corroded members, for even the analytical approach itself may be determined on these grounds. The present experimental study addresses the variation in the ductility of concrete-embedded steel bars when exposed to accelerated corrosion; the results serve as a basis for a discussion of the most suitable methodology for structural analysis.
Concretes with ternary composite cements. Part III: multicriteria optimization
Authors: Menéndez G. , Bonavetti V. L. , Irassar E. F.
Published: October 2008

Optimization methods are tools of vital importance in composite material design, where large numbers of components and design criteria must be taken into account. The formulation of today’s separately milled custommade cements is a clear example of just such a case, for the components must be proportioned to yield mortars and concretes with the proper balance of durability, strength, financial and environmental features. Multicriteria optimization has been used to develop many materials, although its application in cement formulation has yet to be explored. The present paper discusses the use of an objective function to jointly optimize sorptivity and compressive strength in limestone- (up to 20%) and/or granulated blast furnace slag- (up to 20%) additioned Portland cement concrete.
Obtaining cementitious material from municipal solid waste
Authors: Goñi S. , Guerrero A. , Macías A.
Published: October 2008

The primary purpose of the present study was to determine the viability of using incinerator ash and slag from municipal solid waste as a secondary source of cementitious materials. The combustion products used were taken from two types of Spanish MSW incinerators, one located at Valdemingómez, in Madrid, and the other in Melilla, with different incineration systems: one with fluidised bed combustion and other with mass burn waterwall. The effect of temperature (from 800 to 1,200 ºC) on washed and unwashed incinerator residue was studied, in particular with regard to phase formation in washed products with a high NaCl and KCl content. The solid phases obtained were characterized by X-ray diffraction and BET-N2 specific surface procedures.
Characterization of concrete made with recycled aggregate from concrete demolition waste
Authors: Rolón Aguilar J. C. , Nieves Mendoza D. , Huete Fuertes R. , Blandón González B. , Terán Gilmore A.
Published: October 2008

The present study aimed: to characterize the physical, chemical and mechanical properties of recycled aggregate from construction and concrete structure demolition waste, processed before and after crushing; to characterize fresh and hardened concrete made with such recycled aggregate; and to design different doses varying the water/cement ratio, the amount of cement and the use of superplasticizing admixtures to offset the effects of absorption. The ultimate objective was to provide a broader perspective of the use of recycled aggregate in the manufacture of new concrete.
The effect of wanes on the bending strength of solid timber beams
Authors: Arriaga Martitegui F. , Esteban Herrero M. , Argüelles Álvarez R. , Bobadilla Maldonado I. , Íñiguez González G.
Published: October 2008

A theoretical analysis is conducted to determine the effect of wanes on the bearing capacity of timber in light of the reduction they entail in cross-sectional area compared to fully rectangular sections. The concomitant loss of bending strength is likewise evaluated. Parallel tests are run on 84 samples —51 with wanes— of large section, Scotch (Pinus sylvestris L.) and Corsican (Pinus pinaster Ait.) pine beams taken from old buildings. The bending strength, modulus of elasticity and density are found in accordance with European standard EN 408. The mechanical properties of the specimens with and without wanes are found to be very similar, and no statistically significant differences are recorded. The effect of the decline in section may be offset by greater continuity of surface fibers and the section shape effect. One practical consequence of this finding is that (within certain limits) wanes may be disregarded when grading large section timber beams in existing structures, where this flaw is very common; this in turn would reduce the high percentage of rejected beams imposed by the present visual grading standards.
Influence of anisotropy on the durability of Madrid-region Cretaceous dolostone exposed to salt crystallization processes
Authors: Fort R. , Fernández-Revuelta B. , Varas M. J. , Alvarez de Buergo M. , Taborda-Duarte M.
Published: October 2008

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.
Sierra Elvira limestone: petrophysical characteristics of an Andalusian heritage stone
Authors: Sebastián Pardo E. , Cultrone G. , Garibaldi V. , Rodríguez Navarro C. , De la Torre M. J. , Valverde I.
Published: October 2008

“Sierra Elvira stone” is one of the ornamental building stones most widely used in the historical monuments of eastern Andalusia. A Liassic age limestone, it appears in the central section of the Baetic Mountains and more specifically in the Middle Subbaetic domain. While the most common variety is a crinoid limestone, a micritic limestone of the same age has also been quarried, albeit in much smaller quantities. These stones form very thick beds, up to nearly 5 m deep, that run in consistently parallel lines and have a dip angle that facilitates quarrying.With petrographic, physical and mechanical properties that ensure stone strength and durability, it is a high quality building material suitable for both structural and ornamental purposes. These properties can be attributed to the minimal open porosity and concomitant excellent water resistance that characterize the stone, as well as to its high mechanical strength and low textural anisotropy, both elastic and mechanical. With such attributes, the stone can be successfully used for any number of purposes, including decorative stonework (portals, fountains, plinths), structural members (column shafts and bases) or urban curbing and paving. Intervention on Sierra de Elvira limestone structures should be limited to cleaning or repair, for consolidating or protective materials are scantly effective.
Fluorinated anti-graffiti coating for natural stone
Authors: Carmona-Quiroga P. M. , Martínez-Ramírez S. , Blanco-Varela M. T.
Published: October 2008

The water- and dirt-repellent properties of fluorinated products have been used primarily in waterproof coatings. The development of new materials or the definition of new functions for existing substances may extend the possible application of these systems to other specific uses, such as new anti-graffiti coatings to guarantee easy clean-up in the event of this kind of vandalism.The present study aimed to assess the anti-graffiti protection afforded by a fluoralkyl siloxane in limestone and granite.The results show that the surface of the substrates darkened and yellowed slightly under the treatment and that the total colour variations (ΔE*) found after the first cleaning were similar in the two substrates. After subsequent graffiti painting-cleaning cycles, ΔE* was greater in the granite, due to its more rugged surface. Water absorption declined, particularly in the low porosity granite, after it was coated. Water repellence was likewise more effective in the granite, whose low initial permeability decreased, but less steeply than in the limestone. The graffiti lowered the water repellence of the treated surfaces. Although the waterproof protection afforded by the coating was not fully recovered after cleaning, the treated specimens were still more water repellent than the uncoated stone. The siloxane polymer penetrated the limestone to a depth of several tenths of a micron, but remained on the surface in the granite.
Magnesium sulfate salts and historic building materials: experimental simulation of limestone flaking by relative humidity cycling and crystallization of salts
Authors: Lopez-Arce P. , Doehne E. , Martin W. , Pinchin S.
Published: October 2008

Magnesium sulfate salts often result from the combination of incompatible construction materials, such as stone or mortar with high magnesium content and sulfates from adjacent mortars or polluted air. When combined with a source of moisture, these materials react to form soluble salts, often leading to significant damage by flaking of the stone, as the magnesium sulfate responds to fluctuating environmental conditions. Several laboratory experiments were performed to reproduce surface flaking on different types of limestone from Spain and the UK to evaluate the effects of humidity cycling on the damage of stone by salt crystallization. The two salt solutions used for the experiments were a single salt of magnesium sulfate and a mixture of magnesium sulfate, calcium sulfate and sodium chloride, a typical salt mixture found in damaged stone at the site of Howden Minster (UK). A climate chamber with precise and programmable temperature and humidity control was used to test the hypothesis that salt damage in the stone can be readily caused by humidity fluctuations. Damage was monitored using Linear Variable Differential Transformer (LVDT), which measure transducers displacement by dimensional change on the order of microns. In addition, Ion Chromatography, Environmental Scanning Electron Microscopy with energy dispersive X-ray spectroscopy (ESEM-EDX) and X-ray Diffraction analyses (XRD) were also carried out to analyze salt behavior. Damage by flaking took place in two types of magnesian limestone cubes impregnated with the salt mixture, from Cadeby quarry and York Minster, apparently by deliquescent salts of low equilibrium relative humidity (RHeq), while the rest of the samples developed a salt crust over the surface, but no damage was observed in the stone. It is important to verify hypotheses developed from field observations with laboratory experiments. By combining both field and laboratory data, a clearer understanding the different mechanisms of decay and associated weathering types under different environmental conditions can be obtained.
Ornamental granite durability: evaluation of damage caused by salt crystallization
Authors: Alonso F. J. , Vázquez P. , Esbert R. M. , Ordaz J.
Published: October 2008

The salt crystallization test is used to evaluate damage caused by soluble salts that penetrate stone and subsequently crystallize in its voids (pores or cracks).The present article discusses the findings for four ornamental granites (gris alba, grissal, rosa porriño and rosavel) tested to European and Spanish standard UNE-EN 12370.Since the rocks studied had an open porosity of less than 5%, their weight loss was practically nil. Nonetheless, certain physical properties such as wave propagation, surface roughness and colour were found to vary after testing.The authors feel that durability in such stones should be based not on weight loss alone, but on the other properties mentioned as well, particularly in the case of granite that is to be used for cladding in exteriors.
Bowing and expansion of natural stone panels: marble and limestone testing and assessment
Authors: Malaga Katarina , Shouernborg Björn , Grelk Bent
Published: October 2008

Natural stone has been used as a building material for centuries. In the past, load bearing members were made of entirely of stone, but in the last 50 years new processing techniques have made the production and use of thin facade cladding a profitable venture. Unfortunately however, marble facades on buildings in Europe and elsewhere have undergone severe deterioration. The EC-financed TEAM project (2000-2005) studied the bowing observed on marble facades in both cold and warm climates. TEAM’s main objectives were to understand and explain the expansion, bowing, and strength loss mechanisms governing the decay of marble- and limestone-clad facades, and to draft new European standards to prevent the use of marble and limestone poorly suited to outdoor cladding. A survey of some 200 buildings afforded a clear picture of the geographical, geological and climatic scope of the problem. Detailed case studies of six buildings resulted in a facade assessment methodology that included a monitoring system and risk assessment. Both laboratory and field research was conducted on almost 100 different types of stone from different countries and in place in different climates. The outcome was the determination of the decay mechanisms and critical factors. Two test methods and respective precision statements, one for bowing and the other for irreversible thermal expansion in high humidity conditions, were prepared for submission to CEN TC 246.
Diagnosing stone decay in built heritage. Facts and perspectives
Authors: Veniale Fernando , Setti Massimo , Lodola Stefania
Published: October 2008

Stone and other materials used for the construction of historic buildings, memorial statues, gravestones and similar are exposed to weathering and polluting agents and, therefore, progressive decay. Such deterioration, whether physical, chemical or biological, involves mineral phases and their interrelationships (structure and texture).A review of the analytical procedures applied in scientific research on stone damage has revealed the need for appropriate tools and tests (each with a specific scope, depending on the extant damage) to identify decay processes and apply the correct “therapy”, i.e. temporary and/or permanent protection (cleaning, protection, reinforcement, repair and/or replacement).
A number of case histories of famous components of the Italian built heritage are discussed in the context of the use of integrated methodologies for researching decay in different kinds of stone.
The mineralogical composition of sandstone and its effect on sulphur dioxide deposition
Authors: Müller Urs
Published: October 2008

Air pollutants often accelerate stone deterioration in historical buildings and monuments in urban areas. The pollutants are themselves the products of fossil fuel combustion and intensive farming. While this trend seems to have been curbed by strict emission laws in the European Union, in most developing and emerging countries air pollution is an ongoing process due to increasing energy needs and vehicle traffic. Many factors condition natural stone behaviour with respect to gaseous pollutants. Two of the more prominent of such factors are the composition of the atmosphere and the type of stone. Due to their porosity, sandstones are particularly vulnerable to air pollutant attack. Many of the reactions between non-carbonaceous sandstones and these gases are not well understood, however. The present study aimed to acquire an understanding of the processes and factors governing sandstone behaviour when exposed to sulphur dioxide. Seven different sandstones from southern and eastern Germany were analyzed for the study. The binder composition of the stones varied significantly. They also exhibited completely different behaviour in connection with SO2 sorption. Interestingly, while the amount of SO2 deposited was unrelated to the specific surface area of the sandstones, this parameter was closely correlated to the iron oxide content. Iron oxide phases are believed to act as a catalyst in the oxidation of SO2 to SO3. The type and amount of clay mineral, in turn, was found to have no significant impact on initial SO2 deposition in sandstones.
Effect of the diameter and colour of colorimeter aperture reducing templates on colour coordinate measurements
Authors: Arroyo F. , Alcalde M. , Villegas R. , Robador M. D.
Published: October 2008

The colour coordinate values measured with the colorimeters presently on the market are the mean of the readings obtained for the surface area covered by the light projection tube. When the colour of the surface measured is not uniform, such as in the case of stone, the larger the tube aperture the more representative is the colour measurement, for a larger area is involved. While this is often an advantage, when the area studied is smaller than the aperture of the colorimeter used, the values obtained include unwanted information. One possible way to deal with this drawback is by using templates to reduce the measurement area. Templates adapted to a Minolta CR-210 colorimeter were tested in the present study. The conclusion drawn was that in addition to being convenient to use, they ensured that the readings matched the original colour of the surface, i.e., the value that would have been obtained without the templates.
Direct Synthesis of 2,5‐Dihalosiloles
Authors: Morra Nicholas A. , Pagenkopf Brian L.
Published: October 2008

n
‐Butyllithium

Phenyl acetylene

Dichlorodimethylsilane

Dimethyl‐bis‐phenylethynyl silane

Naphthalene

Lithium

Zinc chloride

N
‐Bromosuccinimide

2,5‐Dibromo‐1,1‐dimethyl‐3,4‐diphenylsilole
Palladium‐Catalyzed Dehydrative Allylation of Hypophosphorous Acid with Allylic Alcohols. Preparation of Cinnamyl‐
H
‐Phosphinic Acid
Authors: Bravo‐Altamirano Karla , Montchamp Jean‐Luc
Published: October 2008

Hypophosphorous acid

Cinnamyl alcohol

Palladium(II) acetate

9,9‐Dimethyl‐4,5‐bis(diphenylphosphino)xanthene

Cinnamyl‐
H
‐phosphinic acid
Diphenyldiazomethane
Authors: Javed Muhammad I. , Brewer Matthias
Published: October 2008

Diphenyldiazomethane

Benzophenone hydrazone

Dimethyl sulfoxide

Oxalyl chloride

Triethylamine
High‐Yielding, Large‐Scale Synthesis of

N

‐Protected‐β‐Aminonitriles:
Tert
‐Butyl (1

R

)‐2‐Cyano‐1‐Phenylethylcarbamate
Authors: Mosa Fathia , Thirsk Carl , Vaultier Michel , Maw Graham , Whiting Andrew
Published: October 2008

Sodium borohydride

Iodine

(
S
)‐Phenylglycine

Triethylamine

Di‐
tert
‐butyl dicarbonate

Tert
‐Butyl (1
S
)‐2[(
tert
‐Butoxycarbonyl)amino]‐2‐phenylethyl methanesulfonate

Sodium cyanide

Tert
‐Butyl (1
R
)‐2‐cyano‐1‐phenylethylcarbamate
Efficient Oxidative Synthesis of (‐)‐2‐
Tert
‐Butyl‐(4

S

)‐Benzyl‐(1,3)‐Oxazoline
Authors: Hahn Björn T. , Schwekendiek Kirsten , Glorius Frank
Published: October 2008

(‐)‐2‐
tert
‐Butyl‐(4
S
)‐benzyl‐(1,3)‐oxazoline

(2
S
)‐(‐)‐2‐Amino‐3‐phenyl‐1‐propanol

Trimethylacetaldehyde

N
‐Succinimide
Benzyl Isopropoxymethyl Carbamate – An Aminomethylating Reagent for Mannich Reactions of Titanium Enolates
Authors: Meyer Hartmut , Beck Albert K. , Sebesta Radovan , Seebach Dieter
Published: October 2008

Benzyl hydroxymethyl carbamate

Benzyl carbamate

Aqueous formaldehyde

Potassium carbonate

p
‐Toluenesulfonic acid
Recent international and regulatory decisions about geographical indications
Authors: Marette Stephan , Clemens Roxanne , Babcock Bruce
Published: October 2008

As worldwide consumer demand for high‐quality products and for information about these products increases, labels and geographical indications (GIs) can serve to signal quality traits to consumers; however, GI systems among countries are not homogeneous and can be used as trade barriers against competition. Philosophical differences between the European Union (EU) and the United States about how GIs should be registered and protected led to the formation of a World Trade Organization (WTO) dispute‐settlement panel. In this article, we discuss the issues behind the dispute, the WTO panel decision, and the EU response to the panel decision leading to the new Regulation 510/2006. Given the potential for GI labels to supply consumer information, context is provided for the discussion using recent literature on product labeling. Implications are drawn regarding the importance of the panel decision and the EU response relative to GI issues yet to be negotiated under the Doha Round. [JEL classifications: D8, F1, Q1]. © 2008 Wiley Periodicals, Inc.