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)

Novel enzymes for the agro-food industries

Dissertação de mestrado em Bioquímica Aplicada (especialização em Biomedicina)Enzymes are biological catalysts that accelerate the rate of chemical reactions in cells and are commonly used in a range of industries. They can improve the efficiency, cost-effectiveness and environmental impact of many processes and enhance the characteristics and quality of products. New enzymes with novel backbone sequences and novel functions and characteristics are constantly called for. In the present project, 116 yeasts from mainly acidic pH biowastes, 11 aquatic filamentous fungi from cold environments in Portugal and Iceland, 3 bacterial isolates and 3 metagenomic clones from Irish soil samples were screened for the production of glycoside hydrolase enzymes of industrial interest, namely xylanases, cellulases, pectinases and chitinases. Methods were investigated and developed for a simplified screening of the various isolates at 16 ºC, pHs 4, 7 and 9, with, in particular, the development of a novel xylanase substrate. The substrate was shown to be suitable for measurement of xylanase activity with the commonly used DNS assay but further tests with other xylanases are recommended to confirm this. Furthermore, the substrate was successfully coupled with remazol brilliant blue (RBB) dye, obtaining a chromogenic substrate and enabling a highly sensitive and efficient plate based screening of xylanases. Screening of the CBMA culture collection isolates allowed for identification of a large number of glycoside hydrolase positive isolates, with 31 isolates showing desired activities exclusively at acidic pH. These enzymes may be of interest for use in various applications and, in particular, in food and beverages applications. In addition, 5 isolates were found to display all 4 activities screened for at pH 4, and these isolates may have potential for use in biomass treatment applications. A cellulase positive metagenomic clone with metagenomic DNA from Irish soil was selected for further analysis. The gene for this cellulase was successfully amplified and digested with restriction enzymes but attempts at ligation in an expression vector and transformation to an E. coli expression host proved unsuccessful within the time scope of the project. Further studies should be focused on overexpressing and characterising this novel enzyme.As enzimas são catalisadores biológicos que aceleram reações químicas, sendo usadas diariamente numa ampla gama de indústrias, promovendo a melhoria da eficiência de processos, da relação custo eficiência, assim como o impacto ambiental, para além de melhorar as características e a qualidade do produto. Há uma constante demanda por novas enzimas, de sequências, funções e características inovadoras. Neste projeto, 116 leveduras, maioritariamente provenientes de bio-resíduos acídicos, 11 fungos filamentosos de ambientes frios em Portugal e Islândia, 3 isolados bacteriais e 3 clones metagenómicos de amostras de solo Irlandês foram usados num rastreio por enzimas glicosil hidrolases de interesse industrial, nomeadamente, xilanases, celulases, pectinases e quitinases. Métodos para um rastreio simplificado dos vários isolados a 16 ºC, a pH 4, 7 e 9, foram investigados e desenvolvidos, tendo-se em particular, desenvolvido um novo substrato de xilanase. Este substrato demonstrou, através do ensaio DNS, ser apropriado para a medição de atividade xilanolítica, mas testes com outras xilanases são necessários para obter confirmação. Adicionalmente, este substrato foi ligado com sucesso ao corante remazol brilliant blue (RBB), obtendo-se um substrato cromogénico, possibilitando um rastreio de xilanases, em placas, altamente sensível e eficiente. O rastreio dos isolados da coleção de culturas do CBMA permitiu a identificação de um grande número de isolados positivos para a presença de glicosil hidrolases, em que 31 demonstraram atividade exclusivamente a pH acídico. Estas enzimas podem ser de interesse para uso em várias aplicações, particularmente na indústria alimentar. Adicionalmente, 5 isolados mostraram ter atividade para todas as enzimas rastreadas a pH 4, podendo ter um potencial uso no tratamento de biomassa. Um clone metagenómico, com ADN metagenómico de solo Irlandês, positivo para atividade celulolítica, foi selecionado para análise adicional. O gene desta celulase foi amplificado com sucesso por PCR e digerido com enzimas de restrição apropriadas, mas tentativas de ligação num vetor de expressão e transformação para hospedeiro de expressão E.coli não foram bem sucedidas dentro do tempo limite do projeto. Estudos futuros deverão concentrar-se em expressar e caracterizar esta nova enzima

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

ABS4GD: a multi-agent system that simulates group decision processes considering emotional and argumentative aspects

Emotion although being an important factor in our every day life it is many times forgotten in the development of systems to be used by persons. In this work we present an architecture for a ubiquitous group decision support system able to support persons in group decision processes. The system considers the emotional factors of the intervenient participants, as well as the argumentation between them. Particular attention will be taken to one of components of this system: the multi-agent simulator, modeling the human participants, considering emotional characteristics, and allowing the exchanges of hypothetic arguments among the participants

Personality, emotion and mood simulation in decision making

In this paper is proposed the integration of personality, emotion and mood aspects for a group of participants in a decision-making negotiation process. The aim is to simulate the participant behavior in that scenario. The personality is modeled through the OCEAN five-factor model of personality (Openness, Conscientiousness, Extraversion, Agreeableness and Negative emotionality). The emotion model applied to the participants is the OCC (Ortony, Clore and Collins) that defines several criteria representing the human emotional structure. In order to integrate personality and emotion is used the pleasure-arousal-dominance (PAD) model of mood

Durability of CFRP-concrete bond in EBR and NSM systems under natural ageing for a period of three years

This work aims at assessing the durability of the CFRP-concrete bond exposed to different outdoor ageing environments for a period of three years.Carbon Fibre Reinforced Polymer (CFRP) composites have been shown to possess desirable properties for strengthening of reinforced concrete (RC) structures. The application of CFRP composites is mainly through Externally Bonded Reinforcement (EBR) or Near Surface-Mounted (NSM) techniques. The main objective of the present work was to provide insights on durability of bond between concrete and CFRP strips installed according to EBR and NSM techniques under the effects of ageing induced by outdoor conditions for a period of three years. Specimens were placed in four different outdoor environments (E3-E6) with ageing mainly induced by freeze-thaw attacks, carbonation, airborne chlorides, and elevated temperatures. Besides, the study included a reference environment (E1: ≈20 C / 55% RH) and another environment (E2: ≈20 C / water immersion). The bond test results for the specimens collected from the aforementioned outdoor environments showed a low degradation of the CFRP-concrete bond after three years.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

Bond durability of concrete-cfrp ebr and nsm systems under natural ageing

The use of Carbon Fibre Reinforced Polymer (CFRP) as reinforcement material for strengthening of existing reinforced concrete (RC) structures has been increasing. These materials can be applied mainly by using two strengthening techniques: (i) the Externally Bonded Reinforcement (EBR) by the application of the CFRP on the concrete surface; and, (ii) the Near Surface Mounted (NSM) by the insertion of the CFRP into the grooves on the concrete cover of the RC element to be strengthened. The durability of structures strengthened with CFRP materials is still an open issue. Accelerated ageing protocols under laboratory conditions have been used for the assessment of the durability; however, very few studies have been performed in outdoor environments (natural ageing). Moreover, the relationship between accelerated ageing and real outdoor ageing is not fully understood. The main objective of this paper is to give new insights on the bond durability between concrete and CFRP strips installed according to both EBR and NSM techniques, after a 2-year exposure to natural outdoor conditions. This study includes a reference environment (~20 C / 55% RH) for comparing proposes and four outdoor environments for ageing induced mainly promoting (i) carbonation, (ii) freeze-thaw attack, (iii) elevated temperatures, and (iv) airborne chlorides from seawater. An additional environmental condition, namely continuous immersion in water at ~20 C was also considered. The performance of the bond concrete-adhesive-CFRP was assessed throughout pull-out tests. When compared with the reference environment, small degradation on the bond performance on specimens exposed to outdoor environments has been observed for both strengthening techniques.- (undefined

Decision making based on quality-of-information a clinical guideline for chronic obstructive pulmonary disease scenario

Springer - Series Advances in Intelligent and Soft Computing, vol. 79In this work we intend to advance towards a computational model to hold up a Group Decision Support System for VirtualECare, a system aimed at sustaining online healthcare services, where Extended Logic Programs (ELP) will be used for knowledge re-presentation and reasoning. Under this scenario it is possible to evaluate the ELPs making in terms of the Quality-of-Information (QoI) that is assigned to them, along the several stages of the decision making process, which is given as a truth value in the interval 0…1, i.e., it is possible to provide a measure of the value of the QoI that supports the decision making process, an end in itself. It will be also considered the problem ofQoI evaluation in a multi-criteria decision setting, being the criteria to be fulfilled that of a Clinical Guideline (CG) for Chronic Obstructive Pulmonary Disease

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