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[EN] The present work presents the results obtained with a stainless steel (SS) voltammetric sensor to detect variations in humidity (H2O) and oxygen (O2) availability in concretes. First, studies in solution were run by preparing several solutions to represent the different conditions that can be found in concrete pores. Second, the sensor's response was studied by varying O2 availability by argon or synthetic air bubbling. Then concrete conditions with different degrees of carbonation were simulated using solutions with a pH between 13 and 8.45. After characterization in solution, a study by means of concrete samples with several water/cement ratios (0.6, 0.5 and 0.4) was performed, in which sensors were embedded and studied under different O2 and H2O saturation conditions. The obtained results revealed that with the voltagram, it is possible to evaluate O2 availability variation from the slopes of the lines identified logarithmically in the voltagram for the obtained cathodic sweeping. All the results obtained with the sensor were correlated/validated by standard assays to characterize porosity in hardened concretes.

[EN] The main objective of this study was to analyze the influence that the addition of finely ground hydrated lime has on chloride-induced reinforcement corrosion in eco-efficient concrete made with 50% cement replacement by fly ash. Six tests were carried out: mercury intrusion porosimetry, chloride migration, accelerated chloride penetration, electrical resistivity, and corrosion rate. The results show that the addition of 10¿20% of lime to fly ash concrete did not affect its resistance to chloride penetration. However, the cementitious matrix density is increased by the pozzolanic reaction between the fly ash and added lime. As a result, the porosity and the electrical resistivity improved (of the order of 10% and 40%, respectively), giving rise to a lower corrosion rate (iCORR) of the rebars and, therefore, an increase in durability. In fact, after subjecting specimens to wetting¿drying cycles in a 0.5 M sodium chloride solution for 630 days, corrosion is considered negligible in fly ash concrete with 10% or 20% lime (iCORR less than 0.2 µA/cm2), while in fly ash concrete without lime, corrosion was low (iCORR of the order of 0.3 µA/cm2) and in the reference concrete made with Portland cement, only the corrosion was high (iCORR between 2 and 3 µA/cm2).

[EN] Reinforced concrete elements frequently suffer small cracks that are not relevant from the mechanical point of view, but they can be an entrance point for aggressive agents, such as oxygen, which could initiate the degradation processes. Fiber-Reinforced Concrete and especially Ultra High Performance Concrete increase the multi-cracking behavior, reducing the crack width and spacing. In this work, the oxygen availability of three types of concrete was compared at similar strain levels to evaluate the benefit of multi-cracking in the transport of oxygen. The types of concrete studied include traditional, High-Performance, and Ultra-High-Performance Fiber-Reinforced Concrete with and without nanofibers. To this purpose, reinforced concrete beams sized 150 x 100 x 750 mm(3) were prepared with embedded stainless steel sensors that were located at three heights, which have also been validated through this work. These beams were pre-cracked in bending up to fixed strain levels. The results indicate that the sensors used were able to detect oxygen availability due to the presence of cracks and the detected differences between the studied concretes. Ultra High Performance Concrete in the cracked state displayed lower oxygen availability than the uncracked High Performance Concrete, demonstrating its potential higher durability, even when working in cracked state, thanks to the increased multi-cracking response.

[EN] The monitoring of reinforced concrete structures allows us to detect the presence of aggressive agents into of the concrete matrix, on site and in a real time. These aggressive agents can produce the unexpected failure of the structures, thus discovering their presence is a fundamental aspect in the preservation of people safety and the durability of the structure. On the other hand, helps to reduce the cost of maintenance and repair operations, due to allow us to identify the problems faster, minimizing the intervention to be done. The present research paper was focused in the hydronium detection; the reduction of this species generates hydrogen, the hydrogen produces the embrittlement and cracking of the steel, which seriously compromises the right behaviour of the structure. The problem of hydrogen appears in industries such as ammonia processing or petrochemistry industries and nuclear power plants. All of them are industries in which a failure seriously compromises the welfare of people and the environment. Therefore, the detection of hydrogen penetration in reinforcement concrete structures in these cases are very interesting. In this study, with the purpose to detect the hydronium or hydrogen in the hardened concrete matrices is proposed the use of voltammetric sensor, which is part of a multisensory system called Electronic-Tongue. This is a preliminary study. The objective of these initial steps was to evaluate the detection capability of the sensor. Currently, have been designing a sequential test in order to evaluate the sensor in different partial hydrogen pressures with the purpose to develop mathematical models to the hydronium or hydrogen detection and quantification in hardened concrete matrix.

[ES] Disponer de un modelo energético de un edificio en el que se posibilite verificar su capacidad predictiva para que a su vez permita establecer medidas preventivas que hagan que la demanda energética en una situación climatológicamente distinta a futuro no se incremente y se comporte de la manera esperada es determinante a la hora de tomar decisiones por parte del usuario. Este trabajo realiza el estudio energético de una vivienda típica valenciana (alquería) que tras su rehabilitación se desarrolla un modelo energético que conlleva su calibración y ajuste a través del contraste de medidas experimentales tomadas en el interior de la vivienda (monitorizadas a través de cinco sensores) y las obtenidas tras la simulación del modelo, resultado de usar un archivo climatológico en concreto. En el modelo se ajusta las características constructivas finales, las cargas (según datos de consumos reales y ocupantes de la vivienda), el flujo de aire en las zonas térmicas al implementar un sistema de ventilación natural y mecánica, además de introducir las infiltraciones de manera real en el edificio. El alcance de este trabajo pretende realizar una verificación de la mejora energética que se ha implementado en el estado actual de la vivienda al comparar el efecto que tiene un archivo climatológico como EnergyPlus, Meteonorm o uno propio construido con datos recogidos de la estación meteorológica de la UPV. El resultado del estudio indica que siempre que se quiera que los modelos energéticos reproduzcan la realidad, se tiene que hacer un estudio exhaustivo del comportamiento, por tal será muy importante cómo esté funcionando el edificio a nivel térmico, así como los hábitos de uso de las personas, y sin dar menor importancia es el uso de un archivo climatológico cercano a la zona de estudio como el caso de la UPV, que aunque no posea peso estadístico como los dos mencionados anteriormente que usan datos recogidos a lo largo de varios años, pero sin embargo tiene datos actuale, [EN] To have an energy model of a building in which it is possible to verify its predictive capacity so that in turn it allows to establish preventive measures that make the energy demand in a climatologically different situation in the future does not increase and behaves in the expected way is determinant at the time of taking decisions on the part of the user. This work carries out the energy study of a typical Valencian house (alquería) that after its rehabilitation develops an energy model that involves its calibration and adjustment through the contrast of experimental measures taken inside the house (monitored through five sensors) and those obtained after the simulation of the model, the result of using a specific weather file. The model adjusts the final constructive characteristics, the loads (according to real consumption data and occupants of the dwelling), the air flow in the thermal zones by implementing a natural and mechanical ventilation system, as well as introducing the infiltrations in a real way in the building. The scope of this work aims to perform a verification of the energy improvement that has been implemented in the current state of the house by comparing the effect of a weather file such as EnergyPlus, Meteonorm or an own built with data collected from the UPV weather station. The result of the study indicates that whenever it wants the energy models to reproduce reality, an exhaustive study has to be made of the behavior, so it will be very important how the building is working at a thermal level, as well as people¿s habits of use, and without giving less importance is the use of a weather file close to the study area as the case of the UPV, which although it does not have statistical weight as the two previously mentioned that use data collected over several years, but nevertheless it has current and measured data in the area, which will serve to make different predictions for the future.

[EN] This study was carried out to compare the results obtained using potential step voltammetry and linear sweep voltammetry with a rotating gold disc electrode (RDE), when models based on equivalent circuits (EC) were used. The results lead to an equivalent circuit model that allows us to interpret the electrochemical behavior of aqueous solutions containing Fe(CN)(6)(-4) and Fe(CN)(6)(-3). With this model, we determined the values of the electrical resistance of the medium (R-s) as well as its polarization resistance (R-p), and established correlations between these values and the kinetic parameters of the system. The proposal highlights the need to introduce a new component for modeling using EC, which we have called the electrochemical diode. (C) 2019 Elsevier Ltd. All rights reserved.

[EN] Potential step voltammetry is used to characterize the resistive and capacitive properties of electrochemical systems. Within those systems, electrochemical processes are modeled by means of equivalent circuits (ECs). In this study, we established and experimentally validated algebraic expressions describing the electrical response of those ECs. We then analyzed the features that allow significant differentiation between the ECs. Finally, we have proposed a method to graphically visualize and analyze the electrical response of the circuit to a potential step sequence. The application of this method to real electrochemical systems will allow us to not only identify the electrochemical processes taking place in an experiment but to also assess parameters such as the double layer capacitance, the solution resistance, and the polarization resistance of the redox process.

[EN] The corrosion rate in metals is usually studied by means of the application a potential signal with the purpose of leading the system to unbalance conditions, due to an electric current response is produced. This response is recorded and processed through the electric circuit analogy. Doing the fitting of the response to the properly model is getting the corrosion current. The application of voltammetric potential pattern to the analysis of corrosion, it is very useful, because does not produce polarization of the system. There fore, with this technique is possible to perform tests in sequence without the results being affected. Furthermore, through the integration over time of the electric current response, the accumulated electric charge curve is got which is very useful to the quickly identification of the system behaviour (faradic or non-faradic behaviour). In this paper, it is showed the capability of characterization a system through the accumulated electric charge; it allows identifying at a glance if the system has a faradic behaviour or a non-faradic behaviour. This will be very effective in the monitoring of the metal elements that are out of sight, such as: buried metal conduits or the reinforcement bars in the reinforcement concrete structures.

The developed Integrated Sensor Network (ISN) allows a non-destructive monitoring of the rebar condition at different parts of the structure. The corrosion sensor allows the accurate determination of the corrosion rate (µm/year). Moreover, additional sensors are integrated in order to detect relevant changes in the concrete electrochemical condition. The ISN has been published as an international invention patent (reference number WO 2016/177929 A1). The system is based on an economic, simple, reliable and durable technology, which makes its implementation viable on new and repaired reinforced concrete structures (RCS). Therefore, it is also possible monitoring non-accessible parts such as deep foundations or submerged and buried zones. In any case, no technical personnel are needed because the acquisition, storage and transmission of data is autonomous. In this way, it is possible a remote corrosion assessment of several RCS. In addition, the system needs minimum maintenance works and shows low failure rates. The ISN has been installed for corrosion monitoring of a marine prestressed structure built with Formex®, an Ultra High Performance Fibre Reinforced Concrete (UHPFRC). Five zones of the structure are being monitored. After seven months of monitoring, the corrosion rate (CRATE) stands around 0.2 µm/year, lower than the corrosion rate of the conventional concrete specimens installed (0.5 µm/year). In any case, CRATE is under 1.16 µm/year, the threshold above which the corrosion begins to be considered significant.

[EN] A range of energy improvement measures applied to a typical Mediterranean residential building are modelled under various climate-change scenarios. Global Circulation Models (CNRM-CM5 and MPI-ESMLR), under two emission scenarios (RCP4.5 and RCP8.5), downscaled by the Spanish Meteorological Agency, are used to generate four temperature projections. Energy simulations are obtained with TRNSYS tools in a Mediterranean climate based on temperature projections in two periods: 2048-2052 and 2096-2100, with the same time span. Various energy measures apply thermal improvements to a conventional residential building model that complies with current regulations for this analysis of best practice in passive construction solutions. Sequential implementation of eight different energy improvements measures are applied to the initial building model: six passives (infiltration, insulation thickness, glazing and frame type, window area, shading devices and natural cross ventilation) and two active (mechanical ventilation and a heat recovery system) measures. The climatic trends that are predicted show a local scenario with a warming climate and the thermal behaviour of the building is shown to differ in each scenario. The demand for indoor heating decreases significantly when the outdoor temperature increases, while the demand for cooling and the risk of overheating increase considerably in all the scenarios. The data for the building conditions that are projected in this study predict that natural and forced ventilation strategies will have the least impact, while increased thermal insulation and reductions in infiltration will have a greater effect on global energy demand.

Although old houses are found in the housing stock which are affected by infiltration and condensation, resulting in humid walls, software generally consider properly maintained buildings, assuming dry walls. This study aims to simulate the effect of these pathologies under dwelling indoor conditions. The objective is to assess the reliability and accuracy of different solutions through the mass and heat transfer analogy in air and water vapour mixtures. Two different modelling settings are analysed using TRNSYS thermal simulation software, evaluating the condensation and evaporation effect of temperature and humidity in a house. Simulation results are compared with four months worth of monitored data, and a validation procedure is presented. The method proved to be a valid assessment tool to test results reliability in aboveground building modelling. The analogy approach accuracy of the mass and heat transfer in mixtures of air and water vapour was also tested. Results can be used to help designers to optimize the humidity transfer simulation in building energy modelling. © 2016 Elsevier B.V. All rights reserved.

[ES] El presente documento recoge el estudio energético de una vivienda típica valenciana con el objetivo de conseguir una reducción máxima de la demanda energética en consecución de edifico de consumo cero. Para ello se realiza un trabajo ingente de simulación mediante el software TRNSYS 17, en el que:  Previamente se recogen y estudian datos constructivos y climáticos.  Se realiza la simulación energética de la vivienda original obteniendo así contraste experimental para la verificación de la capacidad predictiva del modelo desarrollado.  Se plantea estrategia de optimización energética, se implementan medidas de mejora en el modelo y se analizan los resultados. Obteniendo las siguientes conclusiones:  En el ajuste del modelo será fundamental reproducir los comportamientos térmicos singulares de la vivienda estudiada.  En la optimización de la demanda el aislamiento de la envolvente del edificio es la medida más efectiva para la reducción de los requerimientos de climatización de la vivienda., [CA] El present document recull l’estudi energètic d’una vivenda típica valenciana amb l’objectiu d’aconseguir una reducció màxima de la demanda energètica en consecució d’edifici de consum zero. Per la qual cosa es realitza un treball ingent de simulació per mitjà del software TRNSYS 17 en el que:  Prèviament es recullen i estudien dades constructives i climàtiques.  Es realitza la simulació energètica de la vivenda original obtenint aixi contrast experimental per a la verificació de la capacitat predictiva del model desenvolupat.  Es planteja estratègia d’optimització energètica, s’implementen mesures de millora en el model y s’analitzen els resultats. Obtenint les següents conclusions:  En l’ajust del model esdevendrà fonamental reproduir els comportaments tèrmics singulars de la vivenda estudiada.  En l’optimització de la demanda l’aïllament de l’envolvent de l’edifici es la mesura mes efectiva per a la reducció del requeriments de climatització de la vivenda., [EN] This document reports on the energetic study of a typical valencian house with the aim of achieving a maximum reduction in energy demand and attaining a zero energy building. With that purpose, an extensive simulation work has been done by using the TRNSYS 17 software. in this simulation work:  Construction and climate data have been previously collected and studied.  An energy simulation of the original housing has been performed, hence obtaining experimental evidence to verify the predictive capability of the developed model.  An energy optimization strategy has been proposed, several model improvement steps have been implemented and subsequently, the results have been analyzed. The following conclusions have been drawn from this work:  In the model fitting process, it is essential to reproduce any particularity on the thermal performance of the studied house.  With regards to the optimization of the energy demand, the isolation of the building envelope is the most effective approach to reduce the building cooling and heating requirements.