Search

This work analyzes the influence of added plastic polycarbonate waste from recycled compact discs (CDs) and digital optical disc (DVDs) on the mechanical and environmental properties of composites with a gypsum matrix. Fifteen mixtures were produced including different percentages by weight of plastic aggregate with two different granulometries. In each case, the strength properties (flexural and compressive) and density of the new composites were tested. In addition, scanning electron microscopy (SEM) and X-ray computed tomography (XCT) were performed in order to know the internal structure and porosity of the new composites. Finally, a simplified environmental study was conducted using the Life Cycle Assessment (LCA) method. The results show that lighter and more eco-efficient materials can be obtained that have, in some cases, better mechanical properties than the reference material (gypsum). A density reduction of a 9.89% was achieved for mixtures with 60% of plastic waste, having also an environmental improvement of 35% compared to the reference sample. In all the cases, the minimum values for mechanical properties required by the standard were obtained. These properties make the composites suitable for use in new products and in construction works.

This study analyses a procedure to manufacture mortars with different percentages of ceramic waste as partial replacement for aggregates. The study also examines the physical, chemical and mechanical properties of the new mortars, analysing substitution ratios that range from 10% to 50%. Prior to this, all the materials used in the production of the mortar were characterised using X-ray diffraction (XRD) and fluorescence (XRF). The objective was to determine the similarity between different types of ceramic waste, as well as the differences in the minerology and chemical composition with the aggregate. The results of the study show that it is possible to obtain mortars with lower densities compared to the same product with no recycled content. The product’s characteristics make it ideal for the manufacture of prefabricated components for structural floors for rehabilitation works. Finally, the pieces are used in a real rehabilitation case study, highlightining the structural advantages. Caracterización de morteros con cerámica reciclada y su uso en piezas prefabicadas para entrevigado de forjados. Este trabajo analiza morteros con diferentes porcentajes de cerámica reciclada como sustituto parcial de la arena. Además el estudio examina las propiedades físicas, químicas y mecánicas de los nuevos morteros, empleando diferentes porcentajes de sustitución (10% - 50%). Con anterioridad, se caracterizaron todos los materiales empleados en este trabajo mediante difracción y fluorescencia de rayos-X. El objetivo fue determinar las diferencias y similitudes en la composición química y mineralógica de los distintos tipos de residuos cerámicos y del resto de áridos utilizados. Los resultados muestran que es posible obtener morteros con menor densidad frente a las muestras sin contenido reciclado. Sus características los hacen idóneos para la creación de piezas prefabricadas de entrevigado para rehabilitación de forjados. Finalmente. Las piezas se usaron en un caso de estudio real, destacando las ventajas estructurales que conlleva su uso.

The research carried out studies how the addition of plastic polypropylene fibers from recycled non-degradable wet wipes can influence on the physical and mechanical behavior of composites with a gypsum binder matrix. Four different plaster blends were studied, corresponding to percentages of 2, 2.5, 3 and 3.5% by weight of recycled plastic fibers. To characterize the different test specimens, properties such as density and strength (flexural and compressive) were determined. Also, in order to find out about the internal structure of the different composites developed at a microscopic level, a Scanning Electron Microscopy (SEM) test was performed. The results show that more efficient materials can be obtained with a little decrease in their density compared to the reference material (gypsum). However, the improvement in the novel composites’ mechanical properties represents one of the most notable achievement of the study. A flexural strength rise of a 19% was achieved for mixtures with 2,5% of recycled PP fibers compared to the reference specimen. These results confirm the feasibility of using the gypsum composites produced for the design of new construction products and its application in building systems as wall and ceiling lining.

The construction sector consumes 95% of the total production of gypsum due to its multiple applications. Gypsum plaster is one of the most common indoor coating material (pastes and mortars), but it can also be used in prefabricated products like plasterboards, blocks and decorative elements. Gypsum waste recycling provides a solution to an important environmental problem from the use of gypsum plaster, which is the generation of large amounts of wastes at different phases (production, construction, rehabilitation and demolition). This paper studies two different replacement alternatives of natural gypsum: Flue Gas Desulphurization (FGD) gypsum and gypsum waste obtained from industrial plasterboard production. The influence of the previous types, amounts of waste (25, 50, 75 and 100 wt%) and different heating temperatures (100 °C, 150 °C and 180 °C) and processes on the workability of gypsum plasters is evaluated and discussed, based on a microstructure analysis using XRD and SEM techniques. This research highlights the feasibility, in terms of workability, of using Gypsum Plasterboard Waste (GPW), without any heating process, as a replacement gypsum in plasters. Despite the fact that a higher amount of water was necessary in the production of the mixes, a good workability was achieved. On the other hand, the unfeasibility of using unheated FGD as a constituent of plasters was demonstrated. However, a good performance, in terms of workability, of the FGD was obtained when the powder was subjected to a heating process at 180 °C during 6 h.

Spain occupies a very prominent position as a world producer of gypsum. Consequently, the industrial processes are more refined, as the production volumes of the factories are much higher than in other countries. Therefore, the environmental impacts of the production of one ton of gypsum are significantly lower. However, new cleaner alternatives must be studied to promote more sustainable construction. In that sense, this paper aims at studying the environmental assessment of the production of natural and recycled gypsum in the Spanish context. In order to conduct the environmental analysis, a from cradle to gate life cycle assessment (LCA) was carried out, using the Impact 2002 + methodology. All the input data was obtained from a medium-size gypsum manufacturer located in Jaen (Andalusia), one of the best regions in terms of gypsum purity. The results for all the scenarios under study were analyzed separately and compared with previous studies published by other investigators and manufacturers’ reports data. Contrary to most other previous researches, the LCA was performed on the basis of primary data given by the producer, and the regional factors were also taken into account. The results achieved in the LCA showed for the production of recycled gypsum (from plasterboard and powder waste) a significant improvement (more than 40%) in all the impact categories understudy, as compared to the natural gypsum production. Furthermore, the results obtained for the endpoint indicators showed an important reduction (56 and 58%) of the environmental impacts when recycled gypsum production was compared with the natural one. On the other hand, it was reaffirmed that the natural gypsum production process in Spain is less environmentally harmful than in other countries. FPU Program of Spain’sMinistry of Education (FPU15/02939), by the IUACC International-isation Grants of the VI Own Research and Transfer Plan of theUniversity of Seville and by the Czech Science Foundation, underproject No 19-08605S

In this study, wood waste from demolition was used by replacing natural aggregate for developing lightweight mortars. Many domestic buildings in the historical city centers of Spain have wo...

Ultrasonic tests are an effective technique of getting adiagnosis of timber structures in historical buildings. Thistechnique is quite valuable to undertake a restoration job. Anew methodology of analysis and diagnosis of timber roofsthrough this non destructive technique is presented.The aim of this article is to get the state of damage and thebending strenght capacity of the timber roof of the Monasteryof Santa Clara in Carmona (Seville) dining´s room by usingthis technology.From the results obtained about the bending strenghtcapacity of the studied beams, it can be affirmed that thetimber roof is not able to support safely enough the new useproposed.Considering the historic and artistic importance of thistimber roof, we propose as a restoration methodology basedon hanging the roof through bolts from a reinforced concreteplatform built-in the perimeter walls. This solutionguarantees that the timber roof does not work, just adjustingthe distance between the bolts. Los métodos de ultrasonidos son una técnica eficaz para eldiagnóstico de elementos estructurales de madera enedificios antiguos. Esta técnica proporciona una gran ayudaa la hora de acometer una obra de rehabilitación. Sepresenta una metodología de análisis y diagnostico deforjados de madera mediante dicha técnica no destructiva.El objetivo de este artículo es obtener el grado de deterioro yla capacidad resistente de la madera del alfarje delrefectorio del Convento de Santa Clara en Carmona (Sevilla)utilizando la metodología propuesta.Por extrapolación de los resultados obtenidos sobre lacapacidad resistente de las vigas estudiadas se puedeconcluir que el conjunto del forjado no es capaz de soportarcon seguridad suficiente el nuevo uso propuesto.Teniendo en cuenta el valor histórico artístico del alfarje sepropone y aporta como solución de rehabilitación laconsistente en colgar el forjado existente mediante pernos deuna losa de hormigón armado empotrada en los murosperimetrales. Esta solución garantiza, ajustando la distanciaentre pernos, que el forjado prácticamente no trabaja.

A nondestructive technique for inspection and evaluation in place timber structures and components based on ultrasonic pulse velocity, and moisture content is presented herein. By applying this methodology we could obtain the bending strength and elasticity modulus of timber beams, as well as the damage in them. The quantitative determination of the existing strength of timber beams will provide information necessary to take the most suitable decisions in rehabilitation works involving timber structural elements., Este artículo presenta el desarrollo de un método de ensayo, no destructivo, para la inspección y evaluación in situ de elementos estructurales de madera, basado en las medidas de la velocidad de ondas ultrasónicas y determinación de humedad. Mediante la aplicación de este método se podrá obtener una estimación de la resistencia a flexión y del módulo de deformación de la madera estudiada, así como la detección de estados de deterioro de la misma. Esto aportará información suficiente a la hora de tomar decisiones en una obra de rehabilitación con elementos estructurales de este material.