New Plaster Composite with Mineral Wool Fibres from CDW Recycling

Over the last decade the intense activity of the building sector has generated large quantities of construction and demolition waste (CDW). In particular, in Europe around 890 million tons of CDW is generated every year; however, only 50% of them are recycled. In Spain, over the last years 40 millions of tons of construction and demolition waste have been generated. On the other hand, since the implementation of the Technical Building Code regulation the use of mineral wools as building insulation materials has become a widespread solution in both rehabilitation and new construction works, and because of that, this kind of insulation waste is increasing. This research analyzes the potential of a new composite (gypsum and fiber waste) including several mineral wools waste into a plaster matrix. For this purpose, an experimental plan, characterizing the physical and mechanical behaviour as well as the Shore C hardness of the new composite, was elaborated fulfilling UNE Standards

Waste volume estimation tool for optimizing construction and demolition waste management in railway works

The increase of construction and demolition (C&D) waste generation has raised new regulations for C&D waste prevention among the European countries, including the obligation to quantify the C&D waste expected to be generated during construction works. This has led to the development of many research works. However, almost none regarding civil engineering works. Therefore, the aim of this research study is to provide a C&D waste estimation tool for railway works. For this purpose several Spanish railway roads have been analyzed in order to develop an equation to estimate in advance the volume of C&D waste likely to be generated, analyzing the category of C&D waste generated for each of the functional units considered. From the analysis performed it has been proved a relationship between the amount of C&D waste generated and the functional units of railways. In short, the methodology presented can help in assigning an optimal and systematic management of the C&D waste produced and assist the construction agents in developing the waste management plans according to the existing legislation

Influence of recycled aggregate quality from precast rejection on mechanical properties of self-compacting concrete

The use of coarse aggregates from crushing pre-existing concrete in the manufacturing of new concrete needs experimental results to validate its influence in the properties of the new concrete elements. In the present study we assessed the impact of using different proportions of replacement up to 100% of natural aggregates with recycled aggregates in the concrete properties; moreover, the effect of pre-treatments of pre-saturation, washing and the aggregates’ source (from precast concrete rejected pieces and construction and demolition waste) was analysed. The best results were obtained with dry and washed recycled aggregates, the compressive strength increment was between the 8 and 17% compared to conventional concrete. Results also pointed out that recycled aggregate that exclusively comes from precast concrete pieces lead to a better concrete mechanical characteristic than the aggregates which origin is construction and demolition waste. In addition, a clear relationship between the percentage of recycled aggregate substitution and the workability and mechanical performance of self-compacting concrete is observed. The results presented in this paper allow to state that precast concrete factories can recycle their rejected elements into recycled coarse aggregates for manufacturing new products, this will allow to protect the environment by reducing the need of raw material consumption and the C&DW landfill

Crushed Bricks: Demolition Waste as a Sustainable Raw Material for Geopolymers

Demolition activity plays an important role in the total energy consumption of the construction industry in the European Union. The indiscriminate use of non-renewable raw materials, energy consumption, and unsustainable design has led to a redefinition of the criteria to ensure environmental protection. This article introduces an experimental plan that determines the viability of a new type of construction material, obtained from crushed brick waste, to be introduced into the construction market. The potential of crushed brick waste as a raw material in the production of building precast products, obtained by curing a geopolymeric blend at 60 °C for 3 days, has been exploited. Geopolymers represent an important alternative in reducing emissions and energy consumption, whilst, at the same time, achieving a considerable mechanical performance. The results obtained from this study show that the geopolymers produced from crushed brick were characterized by good properties in terms of open porosity, water absorption, mechanical strength, and surface resistance values when compared to building materials produced using traditional technologies

Avances en el uso de metacaolín para la mejora de las propiedades de los morteros de cemento tipo portland

El presente trabajo resume los avances conseguidos hasta el momento en la búsqueda de la mejora de las propiedades de los morteros de cemento tipo portland adicionados con metacaolín, que forman parte de fábricas constituidas por estos morteros y ladrillos cerámicos

Evaluación de los Costes y de la Planificación en Rehabilitaciones de Bloques de Vivienda = Evaluation of the Costs and Planning in Residential Block Renovation Projects

Tras la crisis económica del año 2008, con gran impacto en el sector inmobiliario, la rehabilitación de viviendas se potenció como modelo urbanístico frente a la ciudad expansiva y de salida de la crisis. Por ello, este trabajo tiene por objetivo analizar la viabilidad económica del proceso de rehabilitación en España, en concreto a través de casos seleccionados de bloques de viviendas rehabilitados en la Comunidad Autónoma de Aragón. La metodología de estudio analiza los diferentes costes que incurren en el proyecto, las ayudas públicas recibidas para la rehabilitación y los flujos de caja que se originan, contrastándolo con los plazos de ejecución de todo el proceso. Este estudio establece estimaciones económicas y temporales para futuros análisis de viabilidad. Además, para poder optar a otras vías complementarias de financiación, mediante la incorporación del sector privado, el estudio fija las necesidades económicas y márgenes de beneficio o perdida.AbstractAfter the 2008 economic crisis, which had a great impact on the real estate sector, housing renovation was promoted as an urban development model in contrast to the urban sprawl and as a means of overcoming the crisis. As such, this paper seeks to analyze the economic feasibility of the renovation process in selected examples of renovated residential blocks in Spain, specifically in the region of Aragon. The study methodology analyzes the different costs incurred in the project, the government grants received for renovation and the cash flows that are generated, contrasting them with the completion times for the whole process. This study establishes economic and time estimates for future feasibility analyses. In addition, in order to be eligible for additional financing routes, by including the private sector, the study sets out the financial needs and profit or loss margins

Algoritmos de Random Forest como alerta temprana para la predicción de insolvencias en empresas constructoras = Random Forest algorithms as early warning tools for the prediction of insolvencies in construction companies

La preocupación de la Unión Europea por evitar que las empresas lleguen a un procedimiento de insolvencia motivó la promulgación de la Directiva (UE) 2019/1023 del Parlamento Europeo y del Consejo, y su transposición obligatoria a las regulaciones de los Estados miembros antes del 17 de julio de 2021. Esta Directiva establece que los deudores deben tener acceso a herramientas de alerta temprana para detectar situaciones de insolvencia inminente. Esta investigación tiene como objetivo contribuir al desarrollo de este tipo de herramientas de alerta temprana para un sector muy específico: la construcción residencial y no residencial. La metodología se ha dividido en dos fases, cada una con su propio objetivo específico: (1) seleccionar las variables predictoras que mejor puedan explicar el modelo (para ello se han utilizado técnicas estadísticas tradicionales); y (2) seleccionar los algoritmos que proporcionen la mayor precisión para el modelo de herramienta de alerta temprana entre cinco algoritmos Random Forest. El objetivo principal de esto es obtener señales de alerta con la suficiente antelación para poder detectar situaciones de insolvencia. El objetivo fundamental es lograr un modelo sin utilizar las cuentas de pérdidas y ganancias de las constructoras investigadas. Esto es así para evitar la falta de objetividad que pueden tener los ingresos y, por tanto, los resultados contables en este sector. Se obtuvieron porcentajes de precisión superiores al 85% tres años antes de que ocurriera la insolvencia utilizando únicamente ratios de balance. El principal valor es poder aplicar la herramienta de alerta temprana de forma sencilla, utilizando pequeñas cantidades de datos, especialmente para el deudor, que puede reaccionar con la suficiente antelación para evitar una situación financiera potencialmente irreversible.AbstractThe European Union's concern with preventing companies from reaching insolvency proceedings motivated the enactment of Directive (EU) 2019/1023 of the European Parliament and of the Council, and its mandatory transposition into Member States' regulations by July 17, 2021. This Directive states that debtors must have access to early warning tools to detect situations of imminent insolvency. This research aims to contribute to the development of such early warning tools for a very specific sector: residential and non-residential construction. The methodology has been divided into two phases, each with its own specific objective: (1) to select the predictor variables that can best explain the model (traditional statistical techniques have been used for this purpose); and (2) to select the algorithms that provide the greatest precision for the early warning tool model from among five Random Forest algorithms. The main objective of this is to obtain warning signs sufficiently enough in advance that insolvency situations can be detected. The fundamental aim is to achieve a model without using the profit and loss accounts from the construction companies under investigation. This is so to avoid the lack of objectivity that income, and therefore accounting results, may have in this sector. Accuracy percentages of over 85% were obtained three years before insolvency occurred using only balance sheet ratios. The main value is to be able to apply the early warning tool in a simple way, using little amounts of data, especially for the debtor, who can react early enough to avoid a potentially irreversible financial situation

Plaster added with plastic cable waste as a new traditional sustainable material

There is no doubt that plastics are present in all areas of our life. Its characteristics such as durability, slow degradation, lightness, thermal, electrical and acoustic insulation capacity or, impermeability, make it an essential material in construction. But, in this culture of using and throwing, in which we generate millions of tons of this waste, we face its real problem: recycling