Bond behavior of EBR CFRP systems in concrete: influence of surface preparation

The EBR strengthening technique has been used to improve existing reinforced concrete (RC) structures. In many cases CFRP laminates are used as reinforcing material, whereas epoxy adhesives are used as the bonding agent. In the last decades several investigations have been carried out in order to predict the bond strength of EBR CFRP systems in concrete and, as consequence of that, many analytical expressions can be found out in the literature, including in standards. However, these expressions do not account for the influence of the type of surface preparation, which is a mandatory and critical task in the strengthening application. The present work gives contributions for this lake of knowledge. For this purpose an experimental program composed of single shear lap bond tests was carried out. The main parameters studied were the type of surface preparation and the bond length. The instrumentation included sensors to measure the pullout force and the loaded and free end slips. This paper details the experimental program, presents and analyzes the obtained results. As expected, the results revealed that the bond strength depends on the type of surface preparation. Finally, existing expressions in the literature were upgraded in order to account for the type of surface preparation in the estimation of the bond strength.This work was supported by FEDER funds through the Operational Program for Competitiveness Factors – COMPETE and National Funds through FCT (Portuguese Foundation for Science and Technology) under the project FRPLongDur POCI-01-0145-FEDER-016900 (FCT PTDC/ECMEST/1282/2014) and partly financed by the project POCI-01-0145-FEDER-007633. The authors also like to thank the S&P Clever Reinforcement Ibérica Lda. company for providing the materials.info:eu-repo/semantics/publishedVersio

Durability of bond of EBR CFRP laminates to concrete under real-time field exposure and laboratory accelerated ageing

The durability of bond between carbon fibre-reinforced polymer (CFRP) laminates and concrete with the externally bonded reinforcement (EBR) technique was investigated under real-time field exposure (RTFE) and accelerated ageing. The experimental program, over two years, includes four outdoor environments inducing carbonation, freeze–thaw attack, extreme temperatures, and airborne chlorides from the ocean. A laboratory environment (20 ◦C/55% RH) was used as reference environment. Additionally, a water-immersion environment (20 ◦C) was also considered. Relatively low values of bond degradation were observed, where the maximum pullout force varied between − 4 % and +16 % under RTFE, while on water–immersed specimens, the maximum pullout force decreased by ~8 %.This work was carried out in the scope of the project FRPLongDur POCI-01-0145-FEDER-016900 (FCT PTDC/ECM-EST/1282/2014) and DURABLE-FRP (PTDC/ECI-EGC/4609/2020) funded by national funds through the Foundation for Science and Technology (FCT) and co-financed by the European Fund of the Regional Development (FEDER) through the Operational Program for Competitiveness and Internationalization (POCI) and the Lisbon Regional Operational Program and, was partly financed by FCT/MCTES through national funds (PIDDAC) under the R&D Unit Institute for Sustainability and Innovation in Structural Engineering (ISISE), under reference UIDB/04029/2020, and under the Associate Laboratory Advanced Production and Intelligent Systems ARISE under reference LA/P/0112/2020. The first author wishes also to acknowledge the grant SFRH/BD/131259/2017 provided by Fundação para a Ciência e a Tecnologia (FCT)

Seminário de conclusão do projeto FRPLongDur

The FRPLongDur research project (reference no. POCI-01-0145-FEDER-016900) was financed by national funds through FCT and co-financed by the European Regional Development Fund (FEDER) through the Competitiveness and Internationalization Operational Program (POCI), and Lisbon Regional Operational Program. This project had as participating institutions at the University of Minho and the National Civil Engineering Laboratory. It also had the participation of Empa - Swiss Federal Laboratories for Materials Science and Technology. FRPLongDur aimed at contributing to the knowledge on the long-term behavior and durability of reinforced concrete elements strengthened with CFRP (Carbon Fiber Reinforced Polymers) laminates according to the EBR (Externally Bonded Reinforcement) and NSM (Near Surface Mounted) reinforcement techniques, under the effect of aging in real environments. The work involved: (i) an extended experimental program, with the creation of five experimental stations distributed throughout Portugal country, involving different environments (Elvas, Guimarães, Lisbon, Serra da Estrela and Viana do Castelo), where test specimens at three scales (material, connection and structure) were installed to evaluate its performance during the time; (ii) the development of numerical simulations, based on the results obtained in the monitoring carried out; and, (iii) making recommendations for the project. On the last 30th of October 2020, the seminar to conclude the FRPLongDur project took place in a Webinar mode, in which the main results were presented. The present eBook summarizes the presentations carried out

Analytical approaches for flexural analysis of RC slabs strengthened with prestressed or non-prestressed CFRP laminates

The 15th International Conference on Fibre-Reinforced Polymers for Reinforced Concrete Structures (FRPRCS-15) & The 8th Asia-Pacific Conference on FRP in Structures (APFIS-2022), 10-14 December 2022, Shenzhen, China.Analytical approaches are developed for predicting the flexural behaviour of reinforced concrete slabs strengthened with carbon fibre reinforced polymer (CFRP) laminates applied according to (i) near-surface mounted (NSM) and (ii) externally bonded reinforcement (EBR) as non-prestressed strengthening techniques, as well as according to the EBR with (iii) mechanical anchorage (MA) and with (iii) gradient anchorage (GA) systems as prestressed strengthening techniques. The approaches are based on a trilinear relationship of force-deflection curve, in which the formulations depend on the type of failure mode, strengthening type, and initial concrete and CFRP strains. In order to predict the ultimate load, different formulations existing in the literature for the calculation of the CFRP failure strain are applied and compared. Experimental results previously published by the authors are compared with the results from the developed analytical approaches and a good agreement is found.This work was carried out in scope of the project FRPLongDur POCI-01-0145-FEDER-016900 (FCT PTDC/ECM-EST/1282/2014) and Durable-FRP (PTDC/ECI-EGC/4609/2020) funded by national funds through the Foundation for Science and Technology (FCT) and co-financed by the European Fund of the Regional Development (FEDER) through the Operational Program for Competitiveness and Internationalization (POCI) and the Lisbon Regional Operational Program. This work was partly financed by FCT / MCTES through national funds (PIDDAC) under the R&D Unit Institute for Sustainability and Innovation in Structural Engineering (ISISE), under reference UIDB/04029/2020. This work is financed by national funds through FCT under grant agreement [DFA/BD/08403/2021] attributed to the first author

Durability of epoxy adhesives and carbon fibre reinforced polymer laminates used in strengthening systems: accelerated ageing versus natural ageing

This work addresses the durability of structural epoxy adhesives and carbon fibre reinforced polymer (CFRP) laminates typically used in strengthening of existing reinforced concrete structures exposed to natural ageing. The experimental program included four natural (real) outdoor environments inducing ageing mainly caused by carbonation, freeze-thaw attack, elevated temperatures, and airborne chlorides from seawater. Moreover, a control (reference) environment (20 °C of temperature and 55% of relative humidity) and an environment involving water immersion of the materials under controlled temperature (20 °C of temperature) were also included in this investigation. The characterization involved the assessment of the physical, chemical and mechanical properties along a study period of up to two years. Furthermore, comparisons between the natural ageing tests developed in the scope of the present work and accelerated ageing tests existing in the literature were performed. Regarding to the epoxy adhesives, an increase in the glass transition temperature with the time was observed, while the tensile properties decreased, regardless of the outdoor environment. The CFRP laminates were marginally affected by the studied environments. Despite the remarkable dispersion of the results observed in the accelerated ageing tests for the period investigated, this testing protocol yielded higher mechanical degradation than under natural ageing.This work was carried out in scope of the project FRPLongDur POCI-01-0145-FEDER016900 (FCT PTDC/ECM-EST/1282/2014) funded by national funds through the Foundation for Science and Technology (FCT) and co-financed by the European Fund of the Regional Development (FEDER) through the Operational Program for Competitiveness and Internationalization (POCI) and the Lisbon Regional Operational Program and, partially financed by the project POCI-01-0145-FEDER007633, and partly financed by FCT/MCTES through national funds (PIDDAC) under the R&D Unit Institute for Sustainability and Innovation in Structural Engineering (ISISE), under reference UIDB/04029/2020. This work is financed by national funds through. Foundation for Science and Technology, under grant agreement (SFRH/BD/131259/2017) attributed to the first author

Durability of bond in NSM CFRP-concrete systems under different environmental conditions

This paper addresses the durability of bond between concrete and carbon fibre reinforced polymer (CFRP) strips installed according to the near-surface mounted (NSM) technique (NSM CFRP-concrete systems) under the effects of two main groups of environmental conditions: (i) laboratory-based ageing conditions; (ii) real outdoor ageing conditions. The bond degradation was evaluated by carrying out direct pullout tests on aged specimens that were previously subjected to distinct environmental conditions for different periods of exposure. Moreover, the degradation of the mechanical properties of the involved materials was investigated. The digital image correlation (DIC) method was used to document the evolution of the deformation fields at the surface over the whole region of interest consisting of concrete and epoxy adhesive at the ligament region. This information supported the discussion about the evolution of the bond resistant mechanism developed in NSM CFRP-concrete specimens during testing, as well as the assessment of the bond quality of the system. In general, the results obtained from the durability tests conducted have shown that the different exposure environments, which may be considered as quite severe, did not result in significant damage on NSM CFRP-concrete system. The maximum decrease of about 12% on bond strength was obtained for real outdoor environments. Conversely, a maximum increase of 8% on bond strength was obtained on the specimens exposed to the temperature cycles between –15 °C and +60 °C. DIC allowed to document the stress transfer mechanisms established between the CFRP and the concrete substrate, revealing the crack patterns and the influence widths of the CFRP reinforcement strips, which were shown to be important for avoiding group effect when using multiple parallel strengthening CFRP strips.FEDER funds through the Operational Program for Competitiveness Factors - COMPETE and National Funds through FCT - Portuguese Foundation for Science and Technology under the projects CutInDur FCOMP-01-0124-FEDER-014811 (PTDC/ECM/112396/2009), FRPLongDur POCI-01-0145-FEDER-016900 (PTDC/ECM-EST/1282/2014) and partly financed by the project POCI-01-0145-FEDER-007633. The authors also like to thank all the companies that have been involved supporting and contributing for the development of this study, mainly: S&P Clever Reinforcement Ibérica Lda., Artecanter - Indústria de Transformação de Granitos, Lda., Vialam – Indústrias Metalúrgicas e Metalomecânicas, Lda.info:eu-repo/semantics/publishedVersio

Durability of CFRP-concrete bond and corresponding involved materials under different natural environmental exposures for a period of four years

Ageing of interfaces between Carbon Fibre Reinforced Polymer (CFRP) laminates and concrete, applied according to externally bonded reinforcement (EBR) and near-surface mounted (NSM) techniques, and their constitutive materials was investigated. That is, experimental tests on the ageing of concrete, epoxy adhesive, CFRP laminate, and the CFRP-concrete interface were performed for specimens after being exposed to different natural outdoor environments to promote degradation due to carbonation, chlorides, freeze-thaw attacks, and high temperatures. Besides, tests of the reference specimens, kept under a control environment of 20 °C and 55% RH, and of specimens continuously immersed in water with a controlled temperature of 20 °C were also included for comparison purposes. The characterization of physical and mechanical properties of the involved materials, and the degradation of CFRP-concrete interface for the specimens strengthened according to EBR and NSM techniques were assessed for a study period of up to four years. The results generally showed significant variations in the properties of the concrete and adhesive while the ageing of CFRP was found insignificant in all the studied environments. Besides, slight variations of the bond strength were observed, probably as a result of changes in the constitutive materials’ mechanical properties with time and environmental exposure

Literacia em saúde mental de adolescentes e jovens: Conceitos e desafios

A literacia em saúde entendida enquanto constelação de competências cognitivas, sociais e capacidades que permitem aos indivíduos aceder, compreender e usar informação no domínio da saúde, tem ao longo da última década sido perspetivada como dimensão fundamental para os programas de promoção da saúde e prevenção das doenças mentais. Neste artigo é apresentado e analisado criticamente o conceito de literacia em saúde e literacia em saúde mental, discutindo a sua abrangência e aplicabilidade, de acordo com os desafios emergentes e que se colocam aos programas de educação e sensibilização para a saúde mental de adolescentes e jovens. Porque a literacia tem tanto de relevância quanto de complexidade (Nutbeam, 2009), apresenta-se também um modelo de literacia em saúde, bem como os principais conceitos com este relacionado, nomeadamente: educação para a saúde, promoção da saúde e comunicação em saúde. Debate-se ainda a extensibilidade desta temática no âmbito das novas ferramentas ao serviço da promoção da saúde como é o caso da web e do seu potencial e utilidade no incremento da literacia em saúde mental de adolescentes e jovens.ABSTRACT: Health literacy, understood as a constellation of cognitive and social skills and competences that allow individuals to access, understand and use information in the health domain, has been, during the last decade, viewed as a fundamental dimension of health promotion and mental illness prevention programmes. In this article, the health literacy concept and mental health literacy are presented and critically analyzed, discussing their scope and applicability, in terms of the emerging challenges that are placed on mental health education and sensitization programs for teenagers and young people. Because literacy is as relevant as it is complex (Nutbeam, 2009), a health literacy model is also presented, as well as the principal concepts related to it, namely: health education, health promotion and health communication. The extension of this theme to the area of new tools at the service of health promotion is also debated, as in the case of the Web and its potential and utility in increasing the mental health literacy of teenagers and young people.RESUMEN: La literacía de la salud se entiende como siendo el conjunto de habilidades cognitivas, sociales y capacitaciones que les permiten a las personas acceder, comprender y utilizar la información en el área de la salud. Esta ha sido enfocada en la última como siendo una dimensión fundamental en los programas de promoción de la salud y de prevención de enfermedades mentales. Este artículo presenta y analiza críticamente el concepto de literacía de la salud y de la salud mental, y razona su alcance y su aplicabilidad, en consonancia con los desafíos emergentes y aquellos que se les colocan a los programas de educación y sensibilización sobre la salud mental de adolescentes y jóvenes. Ya que la literacía tiene tanta importante como complejidad (Nutbeem, 2009), se presenta también un modelo de literacía de la salud, así como aquellos conceptos clave relacionados con ella, es decir: la educación para la salud, la promoción y la comunicación de la salud. Se cuestiona, asimismo, la capacidad de ampliación de esta cuestión en el contexto de las nuevas herramientas para la promoción de la salud, tales como Internet, y su potencial y utilidad en la mejora de los conocimientos sobre la salud mental de los adolecentes y jóvenes

Impact of operatoŕs experience on peri-procedural outcomes with Watchman FLX: Insights from the FLX-SPA registry

Background: The Watchman FLX is a device upgrade of the Watchman 2.5 that incorporates several design enhancements intended to simplify left atrial appendage occlusion (LAAO) and improve procedural outcomes. This study compares peri-procedural results of LAAO with Watchman FLX (Boston Scientific, Marlborough, Massachusetts) in centers with varying degrees of experience with the Watchman 2.5 and Watchman FLX. Methods: Prospective, multicenter, 'real-world' registry including consecutive patients undergoing LAAO with the Watchman FLX at 26 Spanish sites (FLX-SPA registry). Implanting centers were classified according to the center's prior experience with the Watchman 2.5. A further division of centers according to whether or not they had performed ≤ 10 or > 10Watchman FLX implants was prespecified at the beginning of the study. Procedural outcomes of institutions stratified according to their experience with the Watchman 2.5 and FLX devices were compared. Results: 359 patients [mean age 75.5 (SD8.1), CHA2DS2-VASc 4.4 (SD1.4), HAS-BLED 3.8(SD0.9)] were included. Global success rate was 98.6%, successful LAAO with the first selected device size was achieved in 95.5% patients and the device was implanted at first attempt in 78.6% cases. There were only 9(2.5%) major peri-procedural complications. No differences in efficacy or safety results according to the centeŕs previous experience with Watchman 2.5 and procedural volume with Watchman FLX existed. Conclusions: The Watchman FLX attains high procedural success rates with complete LAA sealing in unselected, real-world patients, along with a low incidence of peri-procedural complications, regardless of operatoŕs experience with its previous device iteration or the number of Watchman FLX devices implanted