Consumption study and energy optimization of a typical Valencian house

[EN] This paper reports on the energy consumption study of a typical Valencian house with the aim of achieving a maximum reduction in HVAC energy demand. With this purpose, an extensive simulation project was done by using TRNsys 17 software. Previously, all necessary data were collected and studied. Then, an energy simulation of the original house was performed, hence obtaining experimental evidence to verify the predictive capability of the developed energy model. Subsequently, the energy optimization strategy was proposed and the measures to improve the energy demand were implemented on the model, in order to reach a zero HVAC demand. Finally, the following conclusions were obtained: energy model adjustment is fundamental for reproducing the specific thermal behavior of the studied building and for the optimization of the energy demand and secondly, enhancing the building envelope is the most effective proposal for achieving the reduction in the HVAC requirements for the building.[ES] El documento describe el estudio energético desarrollado con el objetivo de lograr una máxima reducción de la demanda de energía para finalmente obtener un cero consumo de climatización. Con este objetivo se ha llevado a cabo un trabajo muy extenso de simulación con el uso del software TRNsys 17 con los siguientes pasos consecutivos: Registro previo de todos los datos climáticos y constructivos registran del edificio original es llevado a cabo, obteniendo de esa manera la comparación experimental para comprobar la capacidad predictiva del modelo energético desarrollado. La estrategia de optimización energética se planea cuidadosamente y las propuestas de mejora se aplican en el modelo con el análisis detallado de los resultados. Se obtienen las siguientes conclusiones: En el ajuste del modelo energético es fundamental reproducir el comportamiento térmico específico del edificio estudiado En la optimización de la demanda de energía, el aislamiento de la envolvente del edificio es la propuesta más eficaz para lograr la reducción de los requerimientos energéticos del edificio.Martínez-Ibernón, A.; Royo, R.; Tormo Esteve, S. (2018). Consumption study and energy optimization of a typical Valencian house. CRC Press. 295-300. http://hdl.handle.net/10251/20136129530

Influence of hydrated lime on the chloride-induced reinforcement corrosion in eco-efficient concretes made with high-volume fly ash

[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).This research was funded by MINISTERIO DE ECONOMIA Y COMPETITIVIDAD, grant number MAT2012-38429-C04-04.Valcuende Payá, MO.; Calabuig Pastor, R.; Martínez-Ibernón, A.; Soto Camino, J. (2020). Influence of hydrated lime on the chloride-induced reinforcement corrosion in eco-efficient concretes made with high-volume fly ash. Materials. 13(22):1-16. https://doi.org/10.3390/ma13225135S1161322Isaia, G. C., & Gastaldini, A. L. G. (2009). Concrete sustainability with very high amount of fly ash and slag. Revista IBRACON de Estruturas e Materiais, 2(3), 244-253. doi:10.1590/s1983-41952009000300003Golewski, G. L. (2018). Green concrete composite incorporating fly ash with high strength and fracture toughness. Journal of Cleaner Production, 172, 218-226. doi:10.1016/j.jclepro.2017.10.065Hanehara, S., Tomosawa, F., Kobayakawa, M., & Hwang, K. (2001). Effects of water/powder ratio, mixing ratio of fly ash, and curing temperature on pozzolanic reaction of fly ash in cement paste. Cement and Concrete Research, 31(1), 31-39. doi:10.1016/s0008-8846(00)00441-5Deschner, F., Winnefeld, F., Lothenbach, B., Seufert, S., Schwesig, P., Dittrich, S., … Neubauer, J. (2012). Hydration of Portland cement with high replacement by siliceous fly ash. Cement and Concrete Research, 42(10), 1389-1400. doi:10.1016/j.cemconres.2012.06.009Isaia, G. ., Gastaldini, A. L. ., & Moraes, R. (2003). Physical and pozzolanic action of mineral additions on the mechanical strength of high-performance concrete. Cement and Concrete Composites, 25(1), 69-76. doi:10.1016/s0958-9465(01)00057-9Simčič, T., Pejovnik, S., De Schutter, G., & Bosiljkov, V. B. (2015). Chloride ion penetration into fly ash modified concrete during wetting–drying cycles. Construction and Building Materials, 93, 1216-1223. doi:10.1016/j.conbuildmat.2015.04.033Thomas, M. D. A., Hooton, R. D., Scott, A., & Zibara, H. (2012). The effect of supplementary cementitious materials on chloride binding in hardened cement paste. Cement and Concrete Research, 42(1), 1-7. doi:10.1016/j.cemconres.2011.01.001Delagrave, A., Marchand, J., Ollivier, J.-P., Julien, S., & Hazrati, K. (1997). Chloride binding capacity of various hydrated cement paste systems. Advanced Cement Based Materials, 6(1), 28-35. doi:10.1016/s1065-7355(97)90003-1Chalee, W., Ausapanit, P., & Jaturapitakkul, C. (2010). Utilization of fly ash concrete in marine environment for long term design life analysis. Materials & Design, 31(3), 1242-1249. doi:10.1016/j.matdes.2009.09.024Lollini, F., Redaelli, E., & Bertolini, L. (2015). Investigation on the effect of supplementary cementitious materials on the critical chloride threshold of steel in concrete. Materials and Structures, 49(10), 4147-4165. doi:10.1617/s11527-015-0778-0Baroghel-Bouny, V., Kinomura, K., Thiery, M., & Moscardelli, S. (2011). Easy assessment of durability indicators for service life prediction or quality control of concretes with high volumes of supplementary cementitious materials. Cement and Concrete Composites, 33(8), 832-847. doi:10.1016/j.cemconcomp.2011.04.007Wongkeo, W., Thongsanitgarn, P., & Chaipanich, A. (2012). Compressive strength and drying shrinkage of fly ash-bottom ash-silica fume multi-blended cement mortars. Materials & Design (1980-2015), 36, 655-662. doi:10.1016/j.matdes.2011.11.043Poon, C. S., Lam, L., & Wong, Y. L. (2000). A study on high strength concrete prepared with large volumes of low calcium fly ash. Cement and Concrete Research, 30(3), 447-455. doi:10.1016/s0008-8846(99)00271-9Garcés, P., Andión, L. G., Zornoza, E., Bonilla, M., & Payá, J. (2010). The effect of processed fly ashes on the durability and the corrosion of steel rebars embedded in cement–modified fly ash mortars. Cement and Concrete Composites, 32(3), 204-210. doi:10.1016/j.cemconcomp.2009.11.006Ghafoori, N., Najimi, M., Diawara, H., & Islam, M. S. (2015). Effects of class F fly ash on sulfate resistance of Type V Portland cement concretes under continuous and interrupted sulfate exposures. Construction and Building Materials, 78, 85-91. doi:10.1016/j.conbuildmat.2015.01.004Han, C., Shen, W., Ji, X., Wang, Z., Ding, Q., Xu, G., … Tang, X. (2018). Behavior of high performance concrete pastes with different mineral admixtures in simulated seawater environment. Construction and Building Materials, 187, 426-438. doi:10.1016/j.conbuildmat.2018.07.196Zuquan, J., Xia, Z., Tiejun, Z., & Jianqing, L. (2018). Chloride ions transportation behavior and binding capacity of concrete exposed to different marine corrosion zones. Construction and Building Materials, 177, 170-183. doi:10.1016/j.conbuildmat.2018.05.120Cheewaket, T., Jaturapitakkul, C., & Chalee, W. (2010). Long term performance of chloride binding capacity in fly ash concrete in a marine environment. Construction and Building Materials, 24(8), 1352-1357. doi:10.1016/j.conbuildmat.2009.12.039Fanghui, H., Qiang, W., & Jingjing, F. (2015). The differences among the roles of ground fly ash in the paste, mortar and concrete. Construction and Building Materials, 93, 172-179. doi:10.1016/j.conbuildmat.2015.05.117Alaka, H. A., & Oyedele, L. O. (2016). High volume fly ash concrete: The practical impact of using superabundant dose of high range water reducer. Journal of Building Engineering, 8, 81-90. doi:10.1016/j.jobe.2016.09.008Huang, Q., Zhu, X., Liu, D., Zhao, L., & Zhao, M. (2021). Modification of water absorption and pore structure of high-volume fly ash cement pastes by incorporating nanosilica. Journal of Building Engineering, 33, 101638. doi:10.1016/j.jobe.2020.101638Anjos, M. A. S., Camões, A., Campos, P., Azeredo, G. A., & Ferreira, R. L. S. (2020). Effect of high volume fly ash and metakaolin with and without hydrated lime on the properties of self-compacting concrete. Journal of Building Engineering, 27, 100985. doi:10.1016/j.jobe.2019.100985Herath, C., Gunasekara, C., Law, D. W., & Setunge, S. (2020). Performance of high volume fly ash concrete incorporating additives: A systematic literature review. Construction and Building Materials, 258, 120606. doi:10.1016/j.conbuildmat.2020.120606Lorca, P., Calabuig, R., Benlloch, J., Soriano, L., & Payá, J. (2014). Microconcrete with partial replacement of Portland cement by fly ash and hydrated lime addition. Materials & Design, 64, 535-541. doi:10.1016/j.matdes.2014.08.022Panesar, D. K., & Zhang, R. (2020). Performance comparison of cement replacing materials in concrete: Limestone fillers and supplementary cementing materials – A review. Construction and Building Materials, 251, 118866. doi:10.1016/j.conbuildmat.2020.118866Baert, G., Poppe, A.-M., & De Belie, N. (2008). Strength and durability of high-volume fly ash concrete. Structural Concrete, 9(2), 101-108. doi:10.1680/stco.2008.9.2.101Lammertijn, S., & De Belie, N. (2008). Porosity, gas permeability, carbonation and their interaction in high-volume fly ash concrete. Magazine of Concrete Research, 60(7), 535-545. doi:10.1680/macr.2008.60.7.535Bouzoubaâ, N., Bilodeau, A., Tamtsia, B., & Foo, S. (2010). Carbonation of fly ash concrete: laboratory and field data. Canadian Journal of Civil Engineering, 37(12), 1535-1549. doi:10.1139/l10-081Zhang, Y. M., Sun, W., & Yan, H. D. (2000). Hydration of high-volume fly ash cement pastes. Cement and Concrete Composites, 22(6), 445-452. doi:10.1016/s0958-9465(00)00044-5Zhao, Q., He, X., Zhang, J., & Jiang, J. (2016). Long-age wet curing effect on performance of carbonation resistance of fly ash concrete. Construction and Building Materials, 127, 577-587. doi:10.1016/j.conbuildmat.2016.10.065Barbhuiya, S. A., Gbagbo, J. K., Russell, M. I., & Basheer, P. A. M. (2009). Properties of fly ash concrete modified with hydrated lime and silica fume. Construction and Building Materials, 23(10), 3233-3239. doi:10.1016/j.conbuildmat.2009.06.001Filho, J. H., Medeiros, M. H. F., Pereira, E., Helene, P., & Isaia, G. C. (2013). High-Volume Fly Ash Concrete with and without Hydrated Lime: Chloride Diffusion Coefficient from Accelerated Test. Journal of Materials in Civil Engineering, 25(3), 411-418. doi:10.1061/(asce)mt.1943-5533.0000596Kumar, M., Singh, S. K., & Singh, N. P. (2012). Heat evolution during the hydration of Portland cement in the presence of fly ash, calcium hydroxide and super plasticizer. Thermochimica Acta, 548, 27-32. doi:10.1016/j.tca.2012.08.028Gunasekara, C., Sandanayake, M., Zhou, Z., Law, D. W., & Setunge, S. (2020). Effect of nano-silica addition into high volume fly ash–hydrated lime blended concrete. Construction and Building Materials, 253, 119205. doi:10.1016/j.conbuildmat.2020.119205Mohammed, M. E., Al-Shathr, B. S., & al-Attar, T. S. (2020). Effect of incorporating hydrated lime on strength gain of high-volume fly ash lightweight concrete. IOP Conference Series: Materials Science and Engineering, 737, 012058. doi:10.1088/1757-899x/737/1/012058Bentz, D. P. (2014). Activation energies of high-volume fly ash ternary blends: Hydration and setting. Cement and Concrete Composites, 53, 214-223. doi:10.1016/j.cemconcomp.2014.06.018Gandía-Romero, J. M., Ramón, J. E., Bataller, R., Palací, D. G., Valcuende, M., & Soto, J. (2016). Influence of the area and distance between electrodes on resistivity measurements of concrete. Materials and Structures, 50(1). doi:10.1617/s11527-016-0925-2Ahmad, S. (2003). Reinforcement corrosion in concrete structures, its monitoring and service life prediction––a review. Cement and Concrete Composites, 25(4-5), 459-471. doi:10.1016/s0958-9465(02)00086-0Matos, P. R. de, Sakata, R. D., & Prudêncio, L. R. (2019). Eco-efficient low binder high-performance self-compacting concretes. Construction and Building Materials, 225, 941-955. doi:10.1016/j.conbuildmat.2019.07.254Hornbostel, K., Larsen, C. K., & Geiker, M. R. (2013). Relationship between concrete resistivity and corrosion rate – A literature review. Cement and Concrete Composites, 39, 60-72. doi:10.1016/j.cemconcomp.2013.03.019Shi, C. (2004). Effect of mixing proportions of concrete on its electrical conductivity and the rapid chloride permeability test (ASTM C1202 or ASSHTO T277) results. Cement and Concrete Research, 34(3), 537-545. doi:10.1016/j.cemconres.2003.09.007Li, S., & Roy, D. M. (1986). Investigation of relations between porosity, pore structure, and C1− diffusion of fly ash and blended cement pastes. Cement and Concrete Research, 16(5), 749-759. doi:10.1016/0008-8846(86)90049-9Ngala, V., Page, C., Parrott, L., & Yu, S. (1995). Diffusion in cementitious materials: II, further investigations of chloride and oxygen diffusion in well-cured OPC and OPC/30%PFA pastes. Cement and Concrete Research, 25(4), 819-826. doi:10.1016/0008-8846(95)00072-kZhang, T., & Gjørv, O. E. (1996). Diffusion behavior of chloride ions in concrete. Cement and Concrete Research, 26(6), 907-917. doi:10.1016/0008-8846(96)00069-5Amiri, O., Aı̈t-Mokhtar, A., Dumargue, P., & Touchard, G. (2001). Electrochemical modelling of chloride migration in cement based materials. Electrochimica Acta, 46(9), 1267-1275. doi:10.1016/s0013-4686(00)00717-9Shehata, M. H., Thomas, M. D. A., & Bleszynski, R. F. (1999). The effects of fly ash composition on the chemistry of pore solution in hydrated cement pastes. Cement and Concrete Research, 29(12), 1915-1920. doi:10.1016/s0008-8846(99)00190-8Alonso, M. C., & Sanchez, M. (2009). Analysis of the variability of chloride threshold values in the literature. Materials and Corrosion, 60(8), 631-637. doi:10.1002/maco.20090529

Hydronium Detection in Hardened Concrete

[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.The authors would like to express their gratitude to the Spanish Ministry of Science and Innovation for the pre-doctoral scholarship granted to Ana Martínez Ibernón (FPU 16/00723). Also, to the Universitat Politècnica de València for the financial support in the project ¿Ayudas a Primeros Proyectos de Investigación (PAID-06-18)Martínez-Ibernón, A.; Gandía-Romero, JM.; Gasch, I.; Valcuende Payá, MO. (2020). Hydronium Detection in Hardened Concrete. International Center for Numerical Methods in Engineering (CIMNE). 843-850. https://doi.org/10.23967/dbmc.2020.151S84385

Impact of climate change on heating and cooling energy demand in a residential building in a Mediterranean climate

[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.Pérez-Andreu, V.; Aparicio Fernandez, CS.; Martínez-Ibernón, A.; Vivancos, J. (2018). Impact of climate change on heating and cooling energy demand in a residential building in a Mediterranean climate. Energy. 165:63-74. https://doi.org/10.1016/j.energy.2018.09.015S637416

Methodology and key didactic resources used in teachinglearning process in the subjects of Construction II and III on Bachelor's Degree in Technical Architecture

[EN] Construction II (Flat roofs and sloped roofs) and Construction III (Facades, partitions and claddings) are two mandatoy subjects of second-year courses. The new European Higher Education Area and the competence-based learning approach required a global and integrated approach. This paper describes key methodological aspects used in both subjects and exposes those didactic resources considered essential to achieve the learning outcomes and the competences defined in the teaching guide. In addition, promoting the acquisition of transversal competences has been a key factor in the design of activities and for the selection of teaching resources. At the end of the work, the student's perception of the usefulness of the resources used is analyzed.[ES] Las asignaturas de Construcción II (Cubiertas planas y cubiertas inclinadas) y de Construcción III (Fachadas, particiones y revestimientos) son dos asignaturas obligatorias de segundo curso. El nuevo espacio europeo para la educación superior y el aprendizaje basado en competencias requirieron de un enfoque global e integrado. En el presente trabajo se describen aspectos metodológicos y se exponen aquellos recursos didácticos considerados imprescindibles para alcanzar los resultados de aprendizaje y las competencias definidas en la guía docente. El enfoque de la asignatura hacia la adquisición de competencias ha sido clave en el diseño de actividades y en la selección de los recursos. Al final del trabajo se analiza la percepción del alumno sobre la utilidad de los recursos empleados.Gandía Romero, J.; Iborra Lucas, M.; Martínez Ibernón, A. (2021). Metodología y recursos didácticos claves en el proceso de enseñanza-aprendizaje de las asignaturas de Construcción II y III del Grado de Arquitectura Técnica. En EDIFICATE. I Congreso de Escuelas de Edificación y Arquitectura Técnica de España. Editorial Universitat Politècnica de València. 147-162. https://doi.org/10.4995/EDIFICATE2021.2021.13537OCS14716

Stainless Steel Voltammetric Sensor to Monitor Variations in Oxygen and Humidity Availability in Reinforcement Concrete Structures

[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.The authors would like to express their gratitude to the Spanish Ministry of Science and Innovation for the pre-doctoral scholarship granted to Ana Martinez Ibernon (FPU 16/00723). To the Universitat Politecnica de Valencia for the financial support in the project "Ayudas a Primeros Proyectos de Investigacion (PAID-06-18): Lengua Electronica Voltametrica para el control de durabilidad en hormigones, SP20180245"Martínez-Ibernón, A.; Lliso-Ferrando, JR.; Gandía-Romero, JM.; Soto Camino, J. (2021). Stainless Steel Voltammetric Sensor to Monitor Variations in Oxygen and Humidity Availability in Reinforcement Concrete Structures. Sensors. 21(8):1-21. https://doi.org/10.3390/s21082851S12121

Corrosion Assessment in Reinforced Concrete Structures by Means of Embedded Sensors and Multivariate Analysis-Part 1: Laboratory Validation

[EN] Reinforced Concrete Structures (RCS) are a fundamental part of a country's civil infrastructure. However, RCSs are often affected by rebar corrosion, which poses a major problem because it reduces their service life. The traditionally used inspection and management methods applied to RCSs are poorly operative. Structural Health Monitoring and Management (SHMM) by means of embedded sensors to analyse corrosion in RCSs is an emerging alternative, but one that still involves different challenges. Examples of SHMM include INESSCOM (Integrated Sensor Network for Smart Corrosion Monitoring), a tool that has already been implemented in different real-life cases. Nevertheless, work continues to upgrade it. To do so, the authors of this work consider implementing a new measurement procedure to identify the triggering agent of the corrosion process by analysing the double-layer capacitance of the sensors' responses. This study was carried out on reinforced concrete specimens exposed for 18 months to different atmospheres. The results demonstrate the proposed measurement protocol and the multivariate analysis can differentiate the factor that triggers corrosion (chlorides or carbonation), even when the corrosion kinetics are similar. Data were validated by principal component analysis (PCA) and by the visual inspection of samples and rebars at the end of the study.This research was funded by the Spanish Government, grant number PID2020-119744RB-C21 funded by MCIN/AEI/10.13039/501100011033.Ramón Zamora, JE.; Lliso-Ferrando, JR.; Martínez-Ibernón, A.; Gandía-Romero, JM. (2023). Corrosion Assessment in Reinforced Concrete Structures by Means of Embedded Sensors and Multivariate Analysis-Part 1: Laboratory Validation. Sensors. 23(21):1-19. https://doi.org/10.3390/s23218869119232

Integrated Sensor Network for Monitoring Steel Corrosion in 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

Influence of cracking on oxygen transport in UHPFRC using stainless steel sensors

[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.The authors would like to express their gratitude to the Spanish Ministry of Science and Innovation for the pre-doctoral scholarship granted to Ana Martinez Ibernon (FPU 16/00723), to the Universitat Politecnica de Valencia for the pre-doctoral scholarship granted to Josep Ramon Lliso Ferrando (FPI-UPV-2018), and the European Union's Horizon 2020 ReSHEALience project (Grant Agreement No. 760824).Martínez-Ibernón, A.; Roig-Flores, M.; Lliso-Ferrando, JR.; Mezquida-Alcaraz, EJ.; Valcuende Payá, MO.; Serna Ros, P. (2020). Influence of cracking on oxygen transport in UHPFRC using stainless steel sensors. Applied Sciences. 10(1):1-17. https://doi.org/10.3390/app10010239S117101Front Matter. (2013). fib Model Code for Concrete Structures 2010, I-XXXIII. doi:10.1002/9783433604090.fmatterYoo, D.-Y., & Banthia, N. (2016). Mechanical properties of ultra-high-performance fiber-reinforced concrete: A review. Cement and Concrete Composites, 73, 267-280. doi:10.1016/j.cemconcomp.2016.08.001Wittmann, F., & Van Zijl, G. (Eds.). (2011). Durability of Strain-Hardening Fibre-Reinforced Cement-Based Composites (SHCC). doi:10.1007/978-94-007-0338-4Li, V. C. (2003). On Engineered Cementitious Composites (ECC). Journal of Advanced Concrete Technology, 1(3), 215-230. doi:10.3151/jact.1.215Asgari, M. A., Mastali, M., Dalvand, A., & Abdollahnejad, Z. (2017). Development of deflection hardening cementitious composites using glass fibres for flexural repairing/strengthening concrete beams: experimental and numerical studies. European Journal of Environmental and Civil Engineering, 23(8), 916-944. doi:10.1080/19648189.2017.1327888Ravindrarajah, R. S., & Swamy, R. N. (1989). Load effects on fracture of concrete. Materials and Structures, 22(1), 15-22. doi:10.1007/bf02472690Bascoul, A. (1996). State of the art report—Part 2: Mechanical micro-cracking of concrete. Materials and Structures, 29(2), 67-78. doi:10.1007/bf02486196Damgaard Jensen, A., & Chatterji, S. (1996). State of the art report on micro-cracking and lifetime of concrete—Part 1. Materials and Structures, 29(1), 3-8. doi:10.1007/bf02486001Berrocal, C. G., Löfgren, I., Lundgren, K., Görander, N., & Halldén, C. (2016). Characterisation of bending cracks in R/FRC using image analysis. Cement and Concrete Research, 90, 104-116. doi:10.1016/j.cemconres.2016.09.016Correia, M. J., Pereira, E. V., Salta, M. M., & Fonseca, I. T. E. (2006). Sensor for oxygen evaluation in concrete. Cement and Concrete Composites, 28(3), 226-232. doi:10.1016/j.cemconcomp.2006.01.006Yoon, I.-S. (2018). Comprehensive Approach to Calculate Oxygen Diffusivity of Cementitious Materials Considering Carbonation. International Journal of Concrete Structures and Materials, 12(1). doi:10.1186/s40069-018-0242-yBanthia, N., Zanotti, C., & Sappakittipakorn, M. (2014). Sustainable fiber reinforced concrete for repair applications. Construction and Building Materials, 67, 405-412. doi:10.1016/j.conbuildmat.2013.12.073Berrocal, C. G., Löfgren, I., & Lundgren, K. (2018). The effect of fibres on steel bar corrosion and flexural behaviour of corroded RC beams. Engineering Structures, 163, 409-425. doi:10.1016/j.engstruct.2018.02.068Sisomphon, K., Copuroglu, O., & Koenders, E. A. B. (2012). Self-healing of surface cracks in mortars with expansive additive and crystalline additive. Cement and Concrete Composites, 34(4), 566-574. doi:10.1016/j.cemconcomp.2012.01.005Ferrara, L., Krelani, V., & Carsana, M. (2014). A «fracture testing» based approach to assess crack healing of concrete with and without crystalline admixtures. Construction and Building Materials, 68, 535-551. doi:10.1016/j.conbuildmat.2014.07.008Roig-Flores, M., Pirritano, F., Serna, P., & Ferrara, L. (2016). Effect of crystalline admixtures on the self-healing capability of early-age concrete studied by means of permeability and crack closing tests. Construction and Building Materials, 114, 447-457. doi:10.1016/j.conbuildmat.2016.03.196López, J. Á., Serna, P., Navarro-Gregori, J., & Camacho, E. (2014). An inverse analysis method based on deflection to curvature transformation to determine the tensile properties of UHPFRC. Materials and Structures, 48(11), 3703-3718. doi:10.1617/s11527-014-0434-0Lopez, J. A., Serna, P., Camacho, E., Coll, H., & Navarro-Gregori, J. (2014). First Ultra-High-Performance Fibre-Reinforced Concrete Footbridge in Spain: Design and Construction. Structural Engineering International, 24(1), 101-104. doi:10.2749/101686614x13830788505793Negrini, A., Roig-Flores, M., Mezquida-Alcaraz, E. J., Ferrara, L., & Serna, P. (2019). Effect of crack pattern on the self-healing capability in traditional, HPC and UHPFRC concretes measured by water and chloride permeability. MATEC Web of Conferences, 289, 01006. doi:10.1051/matecconf/20192890100

Lenguas electrónicas para la evaluación de la durabilidad de estructuras de hormigón armado y el seguimiento de la corrosión

[ES] En la presente tesis doctoral se exponen los resultados obtenidos en el desarrollo inicial de un sistema multisensor, tipo lengua electrónica voltamétrica, para el control de la durabilidad de las estructuras de hormigón armado (EHA). Aunque los sistemas multisensores son ampliamente utilizados en diferentes ámbitos, como el del medio ambiente o de la industria alimentaria, su uso en las EHA es novedoso. Igualmente, resulta novedosa la utilización de sensores voltamétricos que, como se demuestra en esta tesis, son de gran eficacia en el análisis de parámetros relacionados con el deterioro del hormigón armado, mejorándose los modelos de durabilidad obtenidos a través de sensores potenciométricos. Todo ello, sin ser aumentada de manera inabordable la complejidad electrónica y computacional del sistema. El prototipo de lengua electrónica diseñado es un sistema de sensores híbridos que consta de cuatro electrodos de trabajo (Au, Ag, Ni e INOX). Se dice que es híbrido porque se usan técnicas tanto voltamétricas (voltametría cíclica) como impedimétricas (espectroscopia de impedancia). Se han utilizado metales nobles (Au y Ag), metales no nobles (Ni) y aleaciones de alta durabilidad (acero inoxidable) con el fin de obtener un comportamiento electroquímico más variado. En la fase previa al desarrollo del sistema se seleccionaron los metales a utilizar en los sensores que formarían parte del sistema multisensor. Para ello se realizó un número ingente de ensayos con distintos metales (Ir, Rh, Pt, Au, Ag, W, Ni y INOX), tanto en disolución (simulando las condiciones de disolución de poro del hormigón), como en hormigón, con el fin de ser seleccionados aquellos metales de cuya respuesta se pudiera extraer una mayor información. Una vez finalizada la fase previa se estudió la respuesta aislada de cada uno de los metales seleccionados (Au, Ag, Ni e INOX), dividiéndose el estudio en 3 fases: ¿ Fase 1. Estudio en disolución: se analizaron los procesos que tienen lugar sobre la superficie del electrodo en disoluciones que simulaban distintas circunstancias que se pueden dar en el hormigón (variación de la disponibilidad de O2, variación del pH y presencia del anión cloro). Los resultados obtenidos se compararon con los encontrados en literatura. ¿ Fase 2. Estudios hechos con el sensor embebido en hormigones convencionales sin adiciones. Se embebieron sensores voltamétricos en hormigones convencionales de distinta relación agua/cemento. Seguidamente, se analizaron las probetas bajo distintas circunstancias que tuvieran influencia en el desencadenamiento y cinética de los procesos de corrosión como son: o Variaciones en la disponibilidad de O2 y H2O. o Carbonatación del hormigón. o Presencia de Cl-. ¿ Fase 3. Se desarrollaron modelos que permitieran identificar variaciones en parámetros relacionados con el deterioro del hormigón armado o estimar y predecir el parámetro de interés. Terminado el estudio de la respuesta aislada de los cuatro sensores, se procedió a evaluar la respuesta cruzada de los sensores siguiendo los protocolos propios de las lenguas electrónicas. Tras analizar y comparar las respuestas aisladas y cruzadas de los sensores, se propuso una rutina de trabajo que en un futuro ayude a optimizar los recursos, tanto operacionales como de fabricación, utilizados en el sistema. Para finalizar, se hizo un estudio inicial para tratar de mejorar la autonomía del sistema, evaluando el efecto producido al simplificar la configuración de celda, reduciendo el número de electrodos de tres a dos.[CA] En la present tesi doctoral s'exposen els resultats obtinguts en el desenvolupament inicial d'un sistema multisensor, tipus llengua electrònica voltamètrica, pel control de la durabilitat de les estructures de formigó armat (EFA). Encara que l'ús d'aquest tipus de sistema està molt expandit en l'àmbit del medi ambient i de la indústria alimentària, el seu ús en les EFAs és molt nou. Igualment, resulta nova la utilització de sensors voltamètrics, que com és demostra en aquesta tesi, són de gran eficàcia en la determinació de les condicions del formigó armat, millorant-se considerablement els models de durabilitat obtinguts mitjançant sensors potenciomètrics. Tot això, sense augmentar la complexitat electrònica i computacional del sistema d'una forma inabordable. El prototip dissenyat de llengua electrònica és un sistema de sensors híbrids compost per quatre elèctrodes de treball (Au, Ag, Ni i acer inoxidable). Es diu que és híbrid perquè en el sistema de sensors s'utilitzen tècniques voltamètriques i impedimètriques. S'han utilitzat metalls nobles (Au i Ag), metalls no nobles (Ni) i aliatges d'alta durabilitat (acer inoxidable). Amb la finalitat d'obtindre un comportament electroquímic més variat. En la fase prèvia al desenvolupament del sistema, es van seleccionar els metalls a utilitzar en els sensors que formarien part del sistema multisensor. Per a això es va realitzar una quantitat ingent d'assajos amb diferents metalls (Ir, Rh, Pt, Au, Ag, W, Ni i acer inoxidable), tant en dissolució com en formigó, amb l'objectiu de seleccionar aquells metalls dels quals es poguera aconseguir més informació amb la seua resposta. Una vegada finalitzada aquesta fase prèvia, es va estudiar la resposta aïllada de cadascun dels metalls seleccionats (Au, Ag, Ni i acer inoxidable). L'estudi es va dividir en tres fases: ¿ Fase 1. Estudis en dissolució: es van analitzar els processos duts a terme sobre la superfície de l'elèctrode en dissolucions que simulaven diferents circumstàncies que es poden donar en el formigó (variació de la disponibilitat d' O2, variació de pH i presència de l'anió clor). Els resultats obtinguts es van comparar amb els trobats en la literatura. ¿ Fase 2. Estudis fets amb els sensors embeguts en formigó: es van embeure els sensors voltamètrics en formigons convencionals de diferent relació aigua/ciment i sense adicions. A continuació, es van analitzar les provetes sota diferents circumstàncies que tingueren influència en el desencadenament i cinètica dels processos com són: o Variacions en la disponibilitat d' O2 i H2O. o Carbonatació del formigó. o Presencia de Cl-. ¿ Fase 3. Desenvolupament de models que possibiliten identificar variacions en paràmetres relacionats amb el deteriorament del formigó armat o estimar i predir el paràmetre d'interès. Finalitzat l'estudi de la resposta aïllada dels quatre sensors, es va avaluar la resposta creuada mitjançant protocols propis de les llengües electròniques (PCA i PLS). Després d'analitzar i comparar les respostes aïllades i creuades dels sensors, es va proposar una rutina de treball que un futur ajude a optimitzar els recursos, tant operacionals com de fabricació, utilitzats al sistema. Per acabar, es va fer un estudi inicial per a tractar de millorar l'autonomia del sistema, avaluant l'efecte produït al simplificar la configuració de cel·la, reduint el nombre d'elèctrodes de tres a dos.[EN] In this thesis the results obtained in the development of a multisensor system, known as electronic voltametric tongue, for the reinforcement concrete structures' (RCS) durability control are exposed. Although the use of this multisensor system is widespread in different fields such as: the food industry and environmental control, its use in RCS monitoring is very novel. It is equally novel the use of voltametric sensors, this kind of sensors are very efficient in determining concrete conditions, improving the durability models obtained through potentiometric sensors, all without overly increasing the system's electronic and computational complexity The electronic tongue prototype designed is a hybrid sensor system made up of four working electrodes (Au, Ag, Ni and stainless steel). It has been referred to as hybrid because in the system voltametric and impedimetric electrochemical techniques are used. Noble metals (Au and Ag), non-noble metals (Ni) and high-durability alloys (stainless steel) have also been used with the purpose of achieving a more varied electrochemical behaviour. In the previous development phase of the system, the metals involved in the development of the electronic tongue were selected. In order to do this, a variety of tests with different metals were performed (Ir, Rh, Pt, Au, Ag, W, Ni and SS), in both dissolution (different concrete pore solution conditions were simulated) and hardened concrete. This allowed us to choose the metals which responses contained the most information. The next steps focused on the study of the selected sensors isolated response: ¿ Phase 1: simulation of concrete pore solution in dissolution systems. The results were compared with those already existing in the bibliography. ¿ Phase 2: studies with the sensors embedded in different standard concretes without additions. The samples were tested in different conditions involved in the rebars corrosion kinetics (variations in O2 and humidity availability, concrete carbonation and chlorides presence). ¿ Phase 3: Development of estimation models for the parameters of interest. After finishing the study of the isolated sensors' response, a cross-evaluation of their response was performed using typical protocols used in the electronic tongues (i.e. PCA and PLS). After analysing and comparing the isolated and crossed sensor's response, an optimized multisensory routine work was proposed which could, in the future, help optimize the resources used in the system. Finally, a study was carried out to improve the system's autonomy, in which the repercussion of the cell configuration simplification by means of the removal of the reference electrode was evaluated.La autora quiere expresar su agradecimiento al Ministerio de Educación, Cultura y Deporte por la beca predoctoral FPU 16/00723Martínez Ibernón, A. (2023). Lenguas electrónicas para la evaluación de la durabilidad de estructuras de hormigón armado y el seguimiento de la corrosión [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/19226