Multi-criteria decision analysis to assess the environmental and economic performance of using recycled gypsum cement and recycled aggregate to produce concrete: the case of Catalonia (Spain)

The production of virgin raw materials used in construction and the generation of construction and demolition waste (CDW) are key environmental issues in the construction industry. Portland cement and concrete are used extensively in the construction sector. Processing of CDW to produce recycled gypsum cement and recycled aggregates (RA) and their use in the production of structural and non-structural concrete are one way of slowing natural resource depletion and reducing the amount of CDW landfilled. This study proposes the application of multi-criteria decision analysis (MCDA) to compare the production of “green” concretes made from recycled gypsum cement (RGC) and RA with the production of conventional concrete made from natural aggregate and ordinary Portland cement. The VIKOR MCDA method was employed to determine the best or a set of good alternative(s) for concrete production, considering environmental and economic criteria. The life cycle assessment method was used to select the environmental evaluation criteria, and the reference cost of producing concrete alternatives in Spain was used to determine economic criteria. The results of this study, in which environmental and economic criteria were considered of equal weight, or one of the two criteria was given greater weight, showed that the best option for structural and non-structural concrete was the use of RGC and RA. In both cases, the worst alternative was conventional concrete. In conclusion, we found that the use of RGC and RA in concrete production is positive because it replaces the original raw material, reduces the environmental impact, and lowers the economic costs.Postprint (published version

¿Porqué PERT & GANTT no funciona en proyectos de edificación?

Process engineering applied to building projects has not developed its own methodology for project management, so it has been using generic project management tools, based on PERT and GANTT, under the paradigms Critical Path Method or Critical Chain. Both PERT and GANTT do not consider some variables that are relevant in the specific environment of a construction site, such as: location, repetitive activities, productivity, continuity of work for external crews, material transformation, space clashes, etc. This article analyzes: 1) The theoretical foundations of generic project management tools based on activities management, 2) The significant variables in both production and project management paradigms, 3) The new paradigm and conceptual tools developed over the last 20 years in the Lean Construction community of knowledge. The findings of this research will help construction managers and superintendents, explaining why the standard tools they are using are not enough to manage their regular work, and proposing a more adequate set of tools and systems to plan and control production activities on site.Postprint (published version

Adoption of web databases for document management in SMEs of the construction sector in Spain

This paper presents a web-based tool designed to improve internal and external document management for small and medium-sized enterprises (SMEs) in the architecture, engineering and construction (AEC) sector. For each specific project, the system creates an organisational document structure to be downloaded to the stakeholders’ PCs or servers and also to the web-based project management system (WPMS) that is being used to manage the entire project. A survey was conducted in Spain to define new user requirements in which the need for set rules on how to organise all the information related to a project was identified. The survey revealed that SMEs need to improve document management for large-scale projects. Based on the requirement studies, a concept model of information flow was developed and implemented in a web-based tool designed according to current standards and theories of classification and organisation of information related to construction. This system was evaluated by an independent panel of experts: academics, construction company representatives and software vendors.Peer ReviewedPostprint (author's final draft

Post-handover housing defects: sources and origins

In Spain, the high levels of inexperienced workers and the long chains of subcontracting contribute to the poor quality of dwellings. Althoughthe Ley reguladora de la subcontratación en el Sector de la Construcción (subcontracting law) has established quality measures, the number of customer complaints is still increasing. In this paper, a total of 2,351 posthandover defects derived from four Spanish builders and seven residential developments are classi fi ed according to their source and origin. The research reveals that the most common defects identi fi ed by customers at posthandover were derived from bad workmanship and were related to construction errors and omissions. Typical defects were foundtoincludeincorrectinstallation,appearancedefects,andmissinganitemortaskmainlyrelatedto fi nishingandconsideredtobeminor.No defects were caused by poor design because they are mainly detected and resolved during construction or become apparent after some years of use. This study demonstrates the negative impact of redoing defective work during the fi nal stages of construction and provides knowledge to de fi ne measures to improve the quality of the fi nished buildings, such as understanding customer expectations and preferences, training programs for workers, specialization of subcontractors, and tightening external controls prior to handover.Postprint (author's final draft

Quantitative internal infrared thermography for determining in-situ thermal behaviour of façades

The thermal behaviour of a building is often underestimated or neglected during its construction and operation stages. In recent years, the heat flux meter (HFM) method has been commonly used to determine the U-value, a key parameter for assessing the thermal quality of the building envelope in steady-state conditions. However, this non-invasive test takes at least 72 h to execute, the accuracy is 14–28%, and it is not reliable for non-homogeneous building elements. An alternative technique is based on infrared thermography (IRT). Although it is generally used for qualitative analysis, quantitative internal IRT methods may also be adopted for in-situ measurement of the U-value. This research presents a method for determining in-situ U-values using quantitative internal IRT with a deviation of 1–2% for single-leaf walls and 3–4% for multi-leaf walls. It takes 2–3 h and can be used to provide information about the building envelope for the future refurbishment of existing buildings or to check the thermal behaviour of new building façades according to their design parameters.Peer ReviewedPostprint (author's final draft

The circular economy in the construction and demolition waste sector: a review of initiatives in Spain

La Economía Circular (EC) es un concepto recientemente desarrollado que ha ganado un importante reconocimiento en el ámbito político, de negocios y academia, debido a que es considerada una alternativa innovadora aplicable a diversos sectores y que permite satisfacer necesidades de producción y consumo de forma más sostenible. En el sector de la construcción y demolición, la implementación de la EC no ha sido investigada ampliamente y está limitada a enfoques parciales de estudio, abordando especialmente alternativas de recuperación. Existe la necesidad de desarrollar investigaciones más extensas que consideren la aplicación de estrategias circulares en el ciclo de vida completo de las actividades de construcción y demolición. El objetivo central de este trabajo es proveer un análisis de las iniciativas de Economía Circular existentes en España, a nivel estatal y regional, y que tienen una influencia directa en el sector de la construcción y demolición. Para entender el funcionamiento de la EC y las principales iniciativas, se realizó una revisión sistemática de la literatura. Las estrategias identificadas están enfocadas particularmente en la gestión de residuos y el uso de materiales recuperados como materiales secundarios.Postprint (published version

Proposta metodològica per afavorir el treball en equip en assignatures semipresencials que comporten la realització de projectes d’enginyeria amb un alt contingut de disseny

Aquest projecte ha tingut com a finalitat principal impulsar un aprenentatge més efectiu dels alumnes en assignatures que, impartides en una modalitat semipresencial, comporten la realització d’un treball de curs amb un alt contingut de disseny. Paral·lelament es contribueix a millorar el rendiment acadèmic de l’ estudiant, en el marc de la millora global de la docència i de l’aprenentatge a la UPC amb un horitzó d’ aproximació als elements que conformen l’ Espai Europeu d’ Educació Superior. En el context de semipresencialitat, es pretén fomentar l’aprenentatge cooperatiu i donar solució als problemes comunicatius existents a nivell d’intercanvi d’opinions, valoracions i formulació de dubtes vinculats amb el disseny, etc. En aquest projecte, doncs, s’ha creat una metodologia de treball que permet intercanviar informació gràfica (per exemple en format Autocad) a partir de les aplicacions ja incloses en la plataforma virtual Atenea (campus virtual de la UPC). Aquest projecte es basa en tres objectius principals: 1. Millorar l'intercanvi d'informació entre alumnes d’un grup i entre els alumnes i el professor mitjançant el desenvolupament de protocols. 2. Fomentar l’aprenentatge cooperatiu mitjançant la integrar d’eines d’interacció instantània per internet. 3. Adaptar l’assignatura de “Complexos Industrials” al procés de convergència a l’EEES.Peer Reviewe

CCL21-loaded 3D hydrogels for T cell expansion and differentiation

Recent achievements in the field of immunotherapy, such as the development of engineered T cells used in adoptive cell therapy, are introducing more efficient strategies to combat cancer. Nevertheless, there are still many limitations. For example, these T cells are challenging to manufacture, manipulate, and control. Specifically, there are limitations in producing the large amounts of therapeutic T cells needed for these therapies in a short period of time and in an economically viable manner. In this study, three-dimensional (3D) poly(ethylene) glycol (PEG) hydrogels covalently combined with low molecular weight heparin are engineered to resemble the lymph nodes, where T cells reproduce. In these hydrogels, PEG provides the needed structural and mechanical properties, whereas heparin is used as an anchor for the cytokine CCL21, which is present in the lymph nodes, and can affect cell migration and proliferation. The 3D structure of the hydrogel in combination with its loading capacity result in an increased primary human CD4+ T cell proliferation compared to the state-of-the-art expansion systems consisting of artificial antigen presenting cells. Thus, we present a new tool for adoptive cell therapy to help achieving the large numbers of cells required for therapy of selected phenotypes targeted against cancer cells, by mimicking the lymph nodes.info:eu-repo/semantics/publishedVersio

Community-acquired pneumonia management in a short-stay unit: analysis of safety and efficacy

Podeu consultar la versió en castellà a: http://hdl.handle.net/2445/119397Background and objective: Community-acquired pneumonia (CAP) is a highly prevalent disease that often requires hospital admission. We aimed to assess the safety and efficacy of treating CAP in a short-stay unit as an alternative to conventional hospitalization. Methods: Retrospective comparison of patients admitted to a tertiary care hospital with a diagnosis of CAP between November 2005 and April 2007. We compared outcomes for cases managed in the 2 locations (short-stay unit vs conventional hospital ward), excluding patients who required intensive care. Variables and outcomes analyzed were age, sex, Charlson index, mean weight in the diagnosis-related group, scores on the CURB-65 criteria and the Pneumonia Severity Index (PSI), findings of microbiology, and readmission and mortality rates. Results: A total of 606 patients were studied; 187 were treated in the short-stay unit and 419 were admitted to the conventional ward. The main significant differences between the 2 groups were mean age (77.3 vs 67.9 years, respectively; P<.0001) and mean stay (3.48 vs 7.89 days; P<.0001). These differences were also reflected in the comparison between severity subgroups (by PSI). Mortality rates did not differ. Conclusions: Our experience with the short-stay unit suggests it offers a safe and effective way to manage CAP and leads to a significantly shorter hospital stay in comparison with conventional hospitalization, without increasing readmission and mortality rates