Legal Aspects which Implement Good Practice Measures in the Management of Construction and Demolition Waste

The construction industry, one of the most important ones in the development of a country, generates unavoidable impacts on the environment. The social demand towards greater respect for the environment is a high and general outcry. Therefore, the construction industry needs to reduce the impact it produces. Proper waste management is not enough; we must take a further step in environmental management, where new measures need to be introduced for the prevention at source, such as good practices to promote recycling. Following the amendment of the legal frame applicable to Construction and Demolition Waste (C&D waste), important developments have been incorporated in European and International laws, aiming to promote the culture of reusing and recycling. This change of mindset, that is progressively taking place in society, is allowing for the consideration of C&D waste no longer as an unusable waste, but as a reusable material. The main objective of the work presented in this paper is to enhance C&D waste management systems through the development of preventive measures during the construction process. These measures concern all the agents intervening in the construction process as only the personal implication of all of them can ensure an efficient management of the C&D waste generated. Finally, a model based on preventive measures achieves organizational cohesion between the different stages of the construction process, as well as promoting the conservation of raw materials through the use and waste minimization. All of these in order to achieve a C&D waste management system, whose primary goal is zero waste generation

Biomaterials from beer manufacture waste for bone growth scaffolds

Agricultural wastes are a source of renewable raw materials (RRM), with structures that can be tailored for the use envisaged. Here, they have proved to be good replacement candidates for use as biomaterials for the growth of osteoblasts in bone replacement therapies. Their preparation is more cost effective than that of materials presently in use with the added bonus of converting a low-cost waste into a value-added product. Due to their origin these solids are ecomaterials. In this study, several techniques, including X-ray diffraction (XRD), chemical analysis, mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM), and bioassays, were used to compare the biocompatibility and cell growth of scaffolds produced from beer bagasse, a waste material from beer production, with a control sample used in bone and dental regenerative processes.

Análisis del comportamiento a corrosión de armaduras embebidas en probetas de mortero, con sustitución parcial de áridos y cemento por escorias blancas de horno cuchara

El hormigón armado es el material estructural más empleado en construcción, lo que exige un exhaustivo control tanto de los materiales que lo componen como de su ejecución, con el fin de garantizar la vida útil para la que ha sido proyectado. Uno de los principales problemas de la durabilidad del hormigón armado, es la corrosión de sus armaduras. Existen en la actualidad diferentes métodos que intentan detener el proceso de corrosión, entre ellos, los inhibidores superficiales de corrosión. El continuo incremento en la producción de acero desde el siglo XIX, ha producido un desequilibrio entre los productos fabricados en las industrias siderúrgicas y los residuos generados. Como consecuencia, toneladas de residuos son depositados en vertederos, provocando graves daños medioambientales con el paso del tiempo. El volumen de escorias producidas en la industria siderúrgica en España asciende a 2,55Mt al año, de ahí la importancia del reciclaje de estos productos y de su integración como materia prima en el proceso de fabricación de otros materiales. Partiendo de estas premisas, en el presente trabajo de investigación se ha estudiado el comportamiento a corrosión, de barras de acero de armar embebidas en probetas de mortero, en las que se ha sustituido parcialmente el árido y el cemento por escorias blancas de horno cuchara (LFS), mediante técnicas electroquímicas y gravimétricas. Para ello, se han fabricado probetas prismáticas de 6 x 8 x 2 cm3 con diferentes porcentajes de ión cloruro, introducidos en el momento del amasado, tanto en probetas patrón como en probetas con escorias LFS. El análisis de los resultados obtenidos permite concluir que las probetas patrón y las probetas con escorias LFS tienen comportamientos similares en presencia de cloruros por encima del 0,4% en peso de cemento y por tanto que la sustitución de escorias LFS por arena (25%) y cemento (30%) no afecta negativamente a la corrosión de las armaduras. Por tanto, el uso de escorias LFS en el proceso de fabricación de hormigón armado es una práctica que presenta ventajas competitivas respecto a las técnicas de construcción tradicionales, desde el punto de vista económico y medioambiental. En cuanto a los inhibidores superficiales de corrosión, no han resultado eficaces en probetas con escorias LFS, independientemente del porcentaje de ión cloruro, mientras que en probetas patrón han sido eficaces para porcentajes de ión cloruro igual o inferior al 0,8% en peso de cemento. ABSTRACT Reinforced concrete is the most widely used structural material. This implies that rigorous control must be applied in order to guarantee the life-span and performance of structures made using this composite material. One of the main problems regarding concrete durability is bar corrosion. At present, there are different methods adopted to stop the corrosion process, among them, surface corrosion inhibitors. The continuous growth in steel production since the 19th century has led to an imbalance between waste products generated in steel production processes and their subsequent use. As a consequence, mass dumping at waste disposal sites has been causing a significant environmental problem over the years. The amount of slag produced by the steel industry each year in Spain amounts to 2.55Mt, hence the importance of recycling by-products from steel production so they can be used as primary material in the manufacturing process of other materials. Starting from this working hypothesis, and using electrochemical and gravimetric techniques, this research work aims to analyse and study the corrosion behaviour of steel rebars embedded in mortar specimens, containing ladle furnace slag in partial substitution for aggregate and cement. Prisms were manufactured from 6 x 8 x 2 cm3 with different percentages of chloride ion introduced at the time of mixing, in standard specimens and specimens with LFS slag. Results from the analysis show that the standard specimens and those containing LFS slag display a similar behaviour in the presence of chlorides. Furthermore, when LFS slag is replaced by sand (25%) and cement (30%) corrosion of rebars is not negatively affected. Additionally, the use of LFS slag in the manufacture of reinforced structures is a practice that represents a competitive advantage over traditional construction techniques, from both an economic and environmental point of view Finally, as for surface corrosion inhibitors, they have not proved effective in specimens containing LFS slag, regardless of the percentage of the chloride ion, whereas in standard specimens they have been effective in chloride ion percentages not exceeding 0.8% (as to the cement amount).

Diseño, fabricación, caracterización y aplicaciones constructivas de hormigones de consistencia seca con adiciones de materiales de procedencia orgánica e inorgánica de neumáticos fuera de uso (NFUs)

La siguiente investigación está centrada en establecer las diferencias en la reutilización, en los hormigones de consistencia seca, de dos tipos de caucho obtenidos en el proceso del reciclado del neumático, caucho reciclado del neumático (CRN): los tamaños del granulado (4-8 mm) de caucho reciclado de alta calidad (CR: Caucho Limpio) y el desecho del proceso del reciclado: fibra textil y de acero con trazas de caucho (desecho del caucho reciclado, IR: Caucho de impurezas). Ambos tipos fueron clasificados y añadidos como árido en sustitución del árido grueso (grava) desde el 20 al 100% del volumen. El comportamiento físico y mecánico del IR en los hormigones fue comparado con el hormigón de referencia y las series con el CR para el futuro uso en piezas de hormigón prefabricado. En ambos casos se aprecia una reducción de las resistencias mecánicas en proporción con las cantidades de caucho de sustitución, pero menos en series con IR con una combinación satisfactoria de fibra textil y metálica. El IR muestra mayores pérdidas en propiedades tales como trabajabilidad y densidad, pero también con un incremento de la porosidad. Estos hechos facilitan nuevas opciones para los desechos procedentes del CRN en los hormigones y por lo tanto menores gastos de energía, logrando una tasa de éxito en el proceso de reciclado cercano al 100%. The following research is focused on establishing the differences in the re-use as aggregate in dry consistency concretes of two types of rubber obtained in the process of tyre recycling, recycled rubber from tyres (RRT): granulated sizes (4–8 mm) of high quality recycled rubber (CR: Clean Rubber) and the waste of the recycling process: steel and textile fibers with rubber tracks (waste from recycled rubber, WRR). Both types were classified and added as aggregate in substitution of coarse aggregates from 20 to 100 % by volume. The physical and mechanical behavior of IR in concretes was compared with reference concrete and series with CR for a future use in precast concrete pieces. In both samples a reduction of mechanical resistance occurs in proportion with the amounts of rubber of substitution, but less in serials with IR with a successful combination of steel and textile fiber. IR shows furthermore a reduction in properties such as workability and density, but also an increment in porosity. These facts facilitate new options for waste from CRN in concretes and therefore lower energy costs, achieving a success rate in the recycling process close to 100 %.

Assessing construction and demolition waste on masonry works to avoid future generation

The difficulty of dealing with construction and demolition waste (CDW) on construction sites is not new and continues to be a significant environmental problem. Currently the CDW collection system in Spain is done in a decentralized manner by each sub-contracted company, being necessary to implement effective waste management measures ensuring a correct management and minimization. During the last years several measures have been launched in order to improve and encourage the reuse and recycling of CDW. A widespread solution for CDW recovery is using them as a landscaping aggregate or for road bases and sub-bases. However, measures encouraging onsite prevention still need to be enhanced. This paper studies the major work stage generating CDW and analyses the categories of CDW produced during its execution. For this, several real building sites have been analysed in order to quantify the estimation of CDW generated. Results of this study show that a significant contributor to the CDW generation on building construction sites in Spain are the masonry works. Finally, a Best Practices Manual (BPM) is proposed containing several strategies on masonry works aimed not only at CDW prevention, but also at improving their management and minimization. The use of this BPM together with the Study and Plan of CDW management --required by law--, promotes the environmental management of the company, favouring the cohesion of the construction process organization at all stages giving rise to establishing responsibilities in the field of waste and providing a greater control over the process. Keywords: construction and demolition waste, management, masonry works, good practice measures, prevention.

Estudio de hormigón autocompactante con árido reciclado

La tesis doctoral “Estudio de hormigón autocompactante con árido reciclado” realizada dentro del programa de doctorado de la Universidad Politécnica de Madrid “Máster en técnicas experimentales avanzadas en la ingeniería civil”, investiga la sustitución de áridos gruesos naturales por reciclados en hormigones autocompactantes, para demostrar la posibilidad de utilización de este tipo de árido en la fabricación de hormigones autocompactantes. En cuanto a la línea experimental adoptada, la primera fase corresponde a la caracterización de los cementos y de los áridos naturales y reciclados. En ella se han obtenido las principales características físicas y mecánicas. Una vez validadas las características de todos los materiales y adoptada una dosificación de hormigón autocompactante, se han elaborado cuatro dosificaciones con cuatro grados de incorporación de árido reciclado cada una, y una dosificación con seis grados de incorporación de árido reciclado. Fabricándose un total de 22 tipos de hormigón diferentes, sin contar todas las amasadas iniciales hasta la consecución de un hormigón autocompactante. Las cinco dosificaciones se han dividido en dos grupos para poder analizar con mayor grado de definición las características de cada uno. El primer grupo es aquel que contienen los hormigones con diferentes relaciones a/c, que incluye a la muestra A (a/c=0.55), muestra D (a/c=0.50) y muestra E (a/c=0.45). Por el contrario, el segundo grupo dispone de una relación fija de a/c=0.45 pero diferentes relaciones a/c efectivas, ya que algunas de las muestras disponen de un contenido de agua que permite contrarrestar la mayor absorción del árido reciclado. Estando en este grupo la muestra E (sin agua adicional), la muestra H (con presaturación de los áridos) y la muestra I (con un aporte de agua junto con el agua de amasado. Una vez fabricados los hormigones, se pasa a la segunda fase del estudio correspondiente a la caracterización del hormigón en estado fresco. En esta fase se han llevado a cabo los ensayos de escurrimiento, escurrimiento con anillo japonés, ensayo embudo en V y embudo V a los 5 minutos. Todos estos ensayos permiten evaluar la autocompactabilidad del hormigón según el anejo 17 de la EHE-08. La tercera fase del estudio se centra en la caracterización de los hormigones en estado endurecido, evaluando las características resistentes del hormigón. Para ello, se han realizado los ensayos de resistencia a compresión, a tracción, módulo de elasticidad y coeficiente de Poisson. En la cuarta y última fase, se han analizado la durabilidad de los hormigones, debido que a pesar de ofrecer una adecuada autocompactabilidad y resistencia mecánica, se debe de obtener un hormigón con una correcta durabilidad. Para tal fin, se ha determinado la resistencia a la penetración de agua bajo presión y carbonatación de las probetas. Este último ensayo se ha realizado teniendo en cuenta las condiciones del denominado método natural, con una exposición al ambiente de 90 días y 365 días. Con todos estos resultados se elaboraron las conclusiones derivadas de la investigación, demostrándose la posibilidad de fabricación de hormigones autocompactantes con árido reciclado (HACR) con sustituciones de hasta un 40%, e incluso dependiendo de la relación a/c con sustituciones del 60% y el 80%. ABSTRACT The doctoral thesis titled Analysis of self-compacting concrete with recycled aggregates, has been developed in accordance with the doctoral program: Master degree in advanced experimental techniques in civil engineering, at UPM. It investigates the possibility of replacing natural coarse aggregates with recycled coarse aggregates, in the field of self-compacting concrete. The aim of this dissertation is to analyze the possibility of using recycled coarse aggregates in the manufacture process of self-compacting concretes. Regarding the experimental part, the first phase refers to mechanical and physical characterization of some materials such as cement, natural aggregates and recycled aggregates. Once the characteristics of all materials have been validated and the mixing proportions have been adopted, four different mixes are elaborated by using four dosage rates of recycled aggregates in each one of the samples. Moreover, an additional sample consisting of six different dosages of recycled aggregates is considered. A total number of 22 concrete specimens have been manufactured, without including all the initial kneading samples used to obtain this type of self-compacting concrete. The aforementioned mixes have been divided in two different groups to be able to analyze with more definition. The first group is the one in which the concrete contains different values of the water - cement ratio. It includes the next samples: A (w/c=0.55), D (w/c=0.50) and E (w/c=0.45). The second group has a fixed water -cement ratio, w/c=0.45, but a different effective water - cement ratio, since some of the samples have a water content that enables to offset the major absorption of the recycled aggregates, being in this group the mixing E (without additional water), the mixing H (with saturated recycled aggregate) and the mixing I (with an additional water content to the existing kneading water). Once the concrete samples have been manufactured, the following section deals with the characterization of the concrete in fresh conditions. To accomplish this, several characterization tests are carried out such as the slump-flow test, test slump flow with Japanese ring, test V-funnel and V-funnel to 5 minutes. These tests are used to assess the self-compacting conditions according to the annex 17 of the EHE-08 The third phase of the study focuses on the mechanical characterization, the assessment of the strength properties of the concrete such as compressive strength, tensile strength, modulus of elasticity and Poisson´s ratio. Within the fourth and last phase, durability of the concrete is evaluated. This fact is motivated by the need to obtain not only good self-compacting and mechanical strength properties, but also adequate durability conditions. To accomplish the aforementioned durability, resistance of the samples under certain conditions such as water penetration pressure and carbonation, has been obtained. The latter test has been carried out taking into account the natural method, with an exhibition period to the environment of 90 days and 365 days. Through the results coming from this research work, it has been possible to obtain the main conclusions. It has been demonstrated the possibility to manufacture self-compacting concrete by using recycled aggregates with replacement rates up to 40% or, depending on the w/c ratio, rates of 60% and 80% might be reached.

Soil aggregate geometry: Measurements and morphology

Aggregates provide physical microenvironments for microorganisms, the vital actors of soil systems, and thus play a major role as both, an arena and a product of soil carbon stabilization and dynamics. The surface of an aggregate is what enables exchange of the materials and air and water fluxes between aggregate exterior and interior regions. We made use of 3D images from X-ray CT of aggregates and mathematical morphology to provide an exhaustive quantitative description of soil aggregate morphology that includes both intra-aggregate pore space structure and aggregate surface features. First, the evolution of Minkowski functionals (i.e. volume, boundary surface, curvature and connectivity) for successive dilations of the solid part of aggregates was investigated to quantify its 3D geometrical features. Second, the inner pore space was considered as the object of interest. We devised procedures (a) to define the ends of the accessible pores that are connected to the aggregate surface and (b) to separate accessible and inaccessible porosity. Geometrical Minkowski functionals of the intra-aggregate pore space provide the exhaustive characterization of the inner structure of the aggregates. Aggregates collected from two different soil treatments were analyzed to explore the utility of these morphological tools in capturing the impact on their morphology of two different soil managements, i.e. conventional tillage management, and native succession vegetation treatment. The quantitative tools of mathematical morphology distinguished differences in patterns of aggregate structure associated to the different soil managements.