京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21068号 / 工博第4432号 / 新制||工||1689(附属図書館) / 京都大学大学院工学研究科機械理工学専攻 / (主査)教授 北條 正樹, 教授 琵琶 志朗, 准教授 西川 雅章, 教授 平方 寛之 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

炭素繊維強化樹脂系複合材料(CFRP)の界面あるいは界面層においては、CFの陽極酸化処理条件やサイジング剤の存在により、その化学的、物理的な機能が影響を受け、CFとマトリックス樹脂との接着性やCFRPの機械的特性に影響を及ぼすことを明らかにした。また、界面/界面層の化学的、物理的機能を把握し、その構造制御を行うことにより、CFRPの優れた機械的特性を有効活用できることを示した。 / Chemical and physical functions of interface/interphase of CFRP are affected by the condition of surface treatment of CF and the existence of sizing resin and consequently will make some significant effects on the mechanical properties of CFRP. In order to make the best use of the superior mechanical properties of CFRP, it is important to know the chemical/physical functions of interface/interphase of CFRP and control their strctures. / 博士(工学) / Doctor of Philosophy in Engineering / 同志社大学 / Doshisha University

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This master thesis deals with the performance of existing reinforced concrete bridges strengthened with externally bonded carbon fibre reinforced polymers (CFRP). One of the main aims of this work is to understand the functionality of such an external strengthening method applied to a concave surface in a heavy concrete structure such as a bridge. Another important goal is to investigate the bond behavior of this method. To accomplish the aforementioned aims a case study bridge is chosen to be examined. The Essinge bridge located in the central Stockholm, is the selected bridge in which this report will focus on. Externally strengthening an existing bridge is a method used to both preserve as well as improve the existing structure. Some examples justifying the need to use such a technique are: the degradation of materials or changes in the bearing capacity of the structure which might be the result of increased traffic loads. In the case of Essinge bridge, the structure is strengthened with externally bonded CFRP sheets after the extension of the bridge which led to changes in the statical mode of action of the structure. An additional reason which makes this case interesting to study is the ’’concave’’ surface on which the CFRP sheets are applied to. To study the Essinge bridge in detail, both a numerical analysis and a three-dimensional finite element model is used. All the numerical simulations are performed in the Abaqus software. It is important to mention that for the majority of the simulations a two-axle vehicle load of 300kN (per axle) is applied to the structure. Moreover, a quality assurance of the FE model is carried out to verify the functionality of the model. Some of the results coming from these analyses can be compared with measurements from the monitoring system placed on the bridge. Moreover, other simulation results could be compared with results coming from a test loading performed on the bridge on May 2021. From this comparison, a satisfactory agreement could be found in the peak values of normal strain in concrete and CFRP. Due to time limitations, only linear static analyses are performed. Consequently, in order to capture the non-linearity of the concrete, the Extended Finite Element Method (XFEM) available in Abaqus is used to model a possible crack in the concrete. More specifically, the crack is placed in the concrete part of the deck plate where the maximum value of normal stress is obtained. The bond behavior between the concrete and the CFRP sheets is modelled in two different ways. The first way represents a ’’perfect’’ bond between these two materials meanwhile the second one is based on the so-called Cohesive Zone Method (CZM). The fundamental difference between these two methods is that when using the CZM, a possible failure mode in the bond layer can be captured. Moreover, the input data and parameters defined in the CZM have a detrimental role in the obtained results. It can be noted that the results of the case study bridge cannot be generalized. On the other hand, a better understanding about the external strengthening method implemented on the example of Essinge bridge is obtained. By using the CZM, a vehicle load which could initiate damage in the bond layer could be found. / Detta examensarbete handlar om prestandan för befintliga betongarmerade broar som är externt förstärkta med kolfiberväv. Ett av huvudsyftena med detta arbete är att förstå hur en sådan förstärkningsmetod fungerar när den är applicerad på ett konkavt underlag av en tung betongkonstruktion, såsom en bro. Ett annat viktigt mål är att undersöka beteendet av bindningsskiktet som finns mellan betongen och kolfiberväven. För att uppnå de ovannämnda målen, undersöks en fallstudie bro. Bron över Pampaslänken, som ligger i centrala Stockholm, är den utvalda bron som denna rapport kommer att fokusera på. Att förstärka en befintlig bro externt är en metod som använts för att både bibehålla och förbättra den existerande strukturen. Några exempel som motiverar behovet av att använda en sådan metod är nedbrytning av material eller förändringar i konstruktionens bärförmåga som kan vara ett resultat av ökade trafikbelastningar. När det gäller bron över Pampaslänken, applicerades den externa förstärkningen efter breddningen av bron, vilket ledde till förändringar i strukturens statiska verkningssätt. En ytterligare anledning som gör detta fall intressant att studera är den konkava ytan för vilken förstärkningsmetoden används. För att studera bron över Pampaslänken i detalj, används både en numerisk analys samt en tredimensionell finit elementmodell. Alla numeriska simuleringar är utförda i programvaran Abaqus. Det är viktigt att nämna att för de flesta av simuleringarna appliceras en tvåaxlig fordonslast på 300kN (per axel) på konstruktionen. Dessutom genomförs en kvalitetssäkring av FE-modellen för att verifiera modellens funktionalitet. Några av resultaten från dessa analyser kan jämföras med mätningar från systemet med trådtöjningsgivarna som är placerade på bron. Andra simuleringsresultat kan jämföras med resultat som kommer från en provbelastning som utfördes på bron under maj 2021. Från denna jämförelse kan en överenskommelse hittas i de maximala töjningsvärdena i både betongen och kolfiberväven. På grund av tidsbegränsningar utförs endast linjära elastiska analyser. För att kunna fånga betongens olinjära beteende används den så kallade utvidgade finita elementmetoden (XFEM) som finns i Abaqus, för att modellera in en eventuell spricka i betongen. Mer specifikt placeras sprickan på den delen av farbaneplattan där de maximala normalspänningarna erhålls. Bindningsskiktet som finns mellan betongen och kolfibervävarna modelleras på två olika sätt. I det första sättet skapas ett ’’perfekt’’ band/skikt mellan dessa två material medan i det andra baseras modelleringen på den så kallade Cohesive Zone Method (CZM). Den grundläggande skillnaden mellan dessa två metoder är att när man använder CZM kan ett eventuellt vidhäftningsbrott fångas upp i bindningsskiktet. Dessutom har indata samt olika parametrar som är definierade i CZM, en stor påverkan på de erhållna resultaten. Det kan konstateras att resultaten från fallstudiebron inte kan generaliseras. Däremot har man fått en bättre förståelse för den externa förstärkningsmetoden som implementerats i bron över Pampaslänken. Genom att använda CZM hittas en fordonlast som kan orsaka skador i bindningsskiktet.

Carbon fibre reinforced plastic (CFRP) materials are of interest for the aerospace and aviation industry to master growing economic and ecological challenges. In contrast to conventional metallic materials, they offer both higher specific material properties, such as strengths, stiffnesses, and an increased energy absorption capacity in case of impact loading scenarios. Additionally, the possibility of integrating functional elements, such as actuators and sensors, predestine CFRP for the development of more lightweight structural components. In this study, a generic composite structure is instrumented with embedded piezo ceramic sensor elements. A technology for TEmSAL is presented and applied within an autoclave manufacturing process. Aspects of the designing process, manufacturing and instrumentation as well as experimental impact sensing and self-actuation results are presented and discussed.

Dans le domaine du renforcement et/ou de la réparation des structures en béton armé par des matériaux composites à l'aide de la méthode du collage extérieur au moyen d'un adhésif époxy, une des préoccupations de la communauté scientifique est l'intégrité structurelle de ce système dans le cas d'incendie dans lequel la haute température est une caractéristique essentielle et peut atteindre jusqu'à 1200°C. Ce travail de recherche est axé sur le comportement thermomécanique à très haute température des matériaux composites [un composite à base de polymère carbone/ époxy (Carbon Fiber Reinforced Polymer- CFRP), un composite textile/ mortier cimentaire (Textile Reinforced Concrete- TRC) et un adhésif à base d'époxy]. L'évolution des propriétés mécaniques et d'autres aspects mécaniques de ces matériaux composites avec la température a été caractérisée. Une nouvelle procédure expérimentale concernant la mesure de la déformation de l'éprouvette à l'aide du capteur laser est développée et validée. Une étude numérique et expérimentale a été réalisée dans le but de déterminer principalement la température à la rupture des joints « composite/ adhésif/ composite » sous les sollicitations mécaniques et thermiques. L'efficacité de la protection thermique de deux isolants [PROMASPRAY®T (produit commercial de la société PROMAT] et Isolant A (produit développé par le LGCIE site Tusset) a aussi été étudiée dans cette thèse. Enfin, une approche numérique, à l'aide du logiciel ANSYS, est utilisée afin de déterminer, de façon préliminaire et approximative, à l'échelle matériau, les propriétés thermiques des matériaux (composite textile/ mortier cimentaire -TRC et Isolant A) / In the area of the strengthening and/or the reparation of reinforced concrete structures with composites by means of the external bonding method using an epoxy adhesive, one of the preoccupation of the scientific community is the structural integrity of this system in the event of fire in which the high temperature is the essential feature et can reach up to 1200°C. This research focuses on the thermo-mechanical behavior of composite materials [carbon/epoxy adhesive composite (or carbon fiber reinforced polymer (CFRP), textile/cementitious mortar composite (or textile reinforced concrete (TRC)] and an epoxy-based adhesive. The evolution of mechanical properties and other mechanical aspects of these materials with the temperature has been characterized. A new experimental procedure concerning the measurement of sample strain by the laser sensor is developed and validated. An experimental and numerical study has been realized in order to mainly determine the temperature at the failure of "composite/adhesive/composite" joints under thermal and mechanical loadings. The effectiveness of the thermal protection of two insulators [PROMASPRAY®T (a commercial product of the PROMAT company and the insulator A (product developed by the LGCIE site Tuset)] has also been investigated in this PhD thesis. Finally, a numerical approach, using ANSYS software, is used to determine, in the preliminary and approximate way, at material scale, thermal properties of the materials [the textile reinforced concrete (TRC) and the insulator A]

Die Oberflächenmodifizierung mittels Plasma bei Atmosphärendruck ist eine bekannte und etablierte Technologie. Sie gewinnt aktuell aufgrund der rasant wachsenden Markt- und Entwicklungsnachfrage im Automotive- und Luftfahrttechnikbereich mit deren hohen Anforderungen an Neuentwicklungen auf dem Gebiet der Leichtbau-Komposite immer mehr an Bedeutung. Forderungen, die oftmals an die eingesetzten Plasmaquellen gestellt werden, sind (a) die Behandlungsmöglichkeit großer Oberflächen bei (b) gleichzeitig variierenden Arbeitsabständen von einigen Zentimetern für die Bearbeitung fertiger Bauteilgruppen, (c) die Einsatzmöglichkeit verschiedenster Prozessgase für die Erzeugung einer Vielzahl von spezifischen funktionellen Oberflächengruppen sowie (d) die Integration der Plasmaquelle in die Prozesskette z. B. in Form der Installation an einem Roboterarm. Diese Anforderungen werden derzeit nur durch die LARGE-Plasmaquelle (Long Arc Generator), eine lineare Gleichspannungslichtbogen-Plasmaquelle, erfüllt. Mit ihr sind Flächen auf einer Breite bis zu 350 mm bei Prozessgeschwindigkeiten von bis zu 100 m min-1 bearbeitbar. Ziel der vorliegenden Arbeit war es, die Einsatzgebiete der LARGE-Plasmatechnologie aufzuzeigen und sie zur Industriereife für großflächige Oberflächenmodifizierungen zu entwickeln. Dazu erfolgte eine Optimierung und Weiterentwicklung der Plasmaquelle, konkret dem Elektroden- und Gasverteilerdesign sowie der Stromversorgung. So wurde dem Stromgenerator erstmalig ein PPS-Modul (Puls-Power-Supply-Modul) zur Reglung des Stromes zugeschaltet. Mit diesem wird der Lichtbogenstrom in eine hochfrequente 20 kHz-Schwingung versetzt. Der Strom schwankt dadurch um eine Amplitude von ± 5 – 20 A. Das verhindert ein Festbrennen des Lichtbogenfußpunktes auf der Elektrode und führt so zur Stabilisierung des Lichtbogens. Durch die Plasmaquellenoptimierung und –weiterentwicklung konnte der Argonanteil vollständig reduziert und erstmals 100 % Druckluft als Plasmagas verwendet werden. Um das Potenzial der LARGE-Plasmaquelle für die großflächige Oberflächenmodifizierung zu demonstrieren, wurden vier konkrete Anwendungen aus der Industrie ausgewählt. So wurden zum einen zwei Beispiele aus der Luftfahrttechnik zum strukturellen Kleben mit epoxidharzbasiertem Klebstoffsystem betrachtet und systematisch untersucht: die SiO2-Schichtabscheidung zur Verbesserung der Haftung der Titanlegierungen Ti-6Al-4V und Ti-15V-3Cr-3Sn-3Al und die Plasmabehandlung von CFK zur Umwandlung von silikonbasierten Trennmittelrückständen zur Verbesserung der Adhäsion beim Kleben. Es konnte gezeigt werden, dass mit der LARGE-Plasmatechnologie zwei Materialgruppen erfolgreich plasmabehandelt werden können. Damit ist sie derzeit das einzige Plasmaverfahren bei Atmosphärendruck, mit dem SiO2-Haftvermittlerschichten auf Titanlegierungen sowie eine Trennmittelmodifizierung auf CFK-Oberflächen mit einem variablen Arbeitsbereich von 2 - 6 cm erfolgreich abgeschieden bzw. umgewandelt werden können. Zum anderen wurden zwei Beispiele aus dem Automotivbereich untersucht und der erfolgreiche Einsatz der LARGE-Plasmatechnologie demonstriert: die Plasmafunktionalisierung von Polypropylen zur Verbesserung der Adhäsion von wasserbasierten Lacken sowie die Plasmafeinreinigung und Entfettung von Aluminium. Auf der Grundlage der Ergebnisse dieser Arbeit zur großflächigen Atmosphärendruck-Oberflächenmodifizierung wurde ein Mobiler LARGE für den Einsatz vor Ort aufgebaut. Mit ihm wird die Marktreife und Konkurrenzfähigkeit dieser Plasmaquelle demonstriert.

External post-tensioning is an attractive technique for strengthening reinforced concrete structures because of its ability to actively control stresses and deflections, speed of installation, minimum interruption for the existing structure, and ease of inspection under service conditions. However, external prestressing implies exposing the tendons to the environment outside the concrete section, which may lead to corrosion in steel tendons. Therefore, the interest in using fiber reinforced polymer (FRP) tendons, which are corrosion resistant, has increased. The present work investigated, experimentally and analytically, the flexural performance of reinforced concrete beams strengthened with externally post-tensioned Carbon FRP (CFRP) tendons, under monotonic and fatigue loadings. Initially, tensile fatigue tests were carried out on CFRP tendon-anchor assemblies to assess their response under repeated cyclic loads, before implementing them in the beam tests. New wedge-type anchors (Waterloo anchors) were used in gripping the CFRP specimens. The assemblies exhibited excellent fatigue performance with no premature failure occurring at the anchorage zone. The fatigue tests suggested a fatigue limit of a stress range of 10% of the tendon ultimate capacity (approximately 216 MPa). Monotonic and fatigue experiments on twenty-eight beams (152x254x3500 mm) were then undertaken. Test parameters included the tendon profile (straight and double draped), the initial loading condition of the beam prior to post-tensioning (in-service and overloading), the partial prestressing ratio (0.36 and 0.46), and the load ranges applied to the beam during the fatigue life (39% to 76% of the yield load). The CFRP tendons were post-tensioned at 40% of their ultimate capacity. The monotonic tests of the post-tensioned beams suggested that overloading the beam prior to post-tensioning increased the beam deflections and the strains developed in the steel reinforcing bars at any stage of loading. However, overloading had no significant effect on the yield load of the strengthened beam and the mode of failure at ultimate. It also had no discernable effect on the increase in the tendon stress at yielding. The maximum increase in the CFRP stress at yield load was approximately 20% of the initial post-tensioning stress, for the in-service and overloaded beams. A very good performance of the strengthened beams was observed under fatigue loading. The fatigue life of the beams was mainly governed by the fatigue fracture of the internal steel reinforcing bars at a flexural crack location. Fracture of the bars occurred at the root of a rib where high stress concentration was likely to occur. No evidence of wear or stress concentration were observed at the deviated points of the CFRP tendons due to fatigue. The enhancement in the fatigue life of the strengthened beams was noticeable at all load ranges applied. Post-tensioning considerably decreased the stresses in the steel reinforcing bars and, consequently, increased the fatigue life of the beams. The increase in the fatigue life was slightly affected by the loading history of the beams. At the same load range applied to the beam, increasing the amount of the steel reinforcing bars for the same post-tensioning level decreased the stress range in the bars and significantly increased the fatigue life of the strengthened beams. In the analytical study, a monotonic model that predicts the non-linear flexural response of the CFRP post-tensioned beams was developed and implemented into a computer program. The model takes into account the loading history of the strengthened beams prior to post-tensioning (in-service and overloading). Good agreement was obtained between the measured and the predicted monotonic results. A strain-life based fatigue model was proposed to predict the fatigue life of the CFRP post-tensioned beams. The model takes into consideration the stress-strain history at the stress raisers in the steel bars. It accounts for the inelastic deformation occurring at the ribs during cycling and the resulting changes in the local mean stresses induced. Good agreement between the experimental and predicted fatigue results was observed. A step-by-step fatigue design approach is proposed for the CFRP externally post-tensioned beams. General conclusions of the study and recommendations of future work are given.

At launching the shell body, especially the backplane of the shell body, will be exposed to very high stresses due to acceleration, pressure and increased temperature from the propellant combustion. Defects in the shell body could in worst case for example result in high temperature gas leakage into the warhead and thereby ignite the explosives before exiting the launcher. This kind of explosion results in serious damages and can seriously injure both the gunner and other people in the surroundings. According to earlier study, carbon fibre reinforced epoxy with filament winding manufacturing method was the primary focus. The purpose of this master thesis was to investigate requirements and testing methods on a shell body manufactured in composite that will guarantee the safety of the gunner and surroundings in the launch phase. The pre-study conducted in this project showed that matrix cracks and fibre breakages are most common defects in the shell body that occur during launching affected by burst pressure. Matrix crack is the less dangerous defect among the impact damage types. Discussion with composite manufacturing companies showed that fibre breakage is a very serious type of defect since more breakage of fibres leads to the shell body have reduced stresses and cannot built-up the fully potential burst pressure during launching.   Two requirement specifications were carried out, one for the shell body and another for the detection methods. These were created by own research and ideas according to found information, telephone- and e-mail contact with experts in areas and with personnel at Saab Dynamics AB. Some requirements for the shell body were that it should be fully usable after drop tests from different heights, vibration and transportation tests yield no cyclic damage after a long transport. Furthermore, the shell body should always use a fully isolated driving band to not have hot explosive gases penetrated into critical sections which results in detonation already in the launcher barrel. The most important requirements for the detection methods were to have depth analysis, high reliability and in-field inspection.   Elimination- and decision matrices were made to find which detection methods should be the final selections in order to find the defects in a shell body. The detection methods which did not fulfil the criteria from each separate matrix were eliminated and did not proceed further as a concept. Eliminations were performed in concept generation phase (elimination matrix) and concept selection phase (decision matrix). In final selection phase a couple of methods were chosen that together found as many defects as possible.   By using both acoustic emission and shearography all the critical defects and a wide range of other defects can be detected with very high reliability and resolution at an acceptable cost. These two methods “interact” perfectly with each other. Acoustic emission is the best method to find fibre breakage and matrix cracks, which are the most commonly occurring defects during launching. But shearography does not have a good detectability of fibre breakage and matrix cracks. On the other hand, shearography has good detectability of both planar- and volumetric defects. It is concluded that only two inspection methods, i.e. acoustic emission and shearography are needed to detect all of the possible defects in the grenade shell body. This is more economical solution requiring smaller space and fewer operators compared to one separate NDT method for detecting each type of defect. / Vid utskjutning av granathylsan utsätts framförallt bakplanet, för mycket höga påfrestningar genom acceleration, tryck och förhöjd temperatur från krutförbränningen. Vid en genombränning av granatskalet skulle sprängämnet i verkansdelen kunna tändas redan i eldröret och orsaka en vapensprängning. Den här typen av explosion resulterar i allvarliga skador både för skytten samt folk i dess omgivning.   Med hänsyn till tidigare studier har det varit fokus på kolfiberförstärkt epoxi som är tillverkad av fiberlindning. Syftet var att utreda kravställningar och metoder för provning, som garanterar skyttens och omgivningens säkerhet i utskjutningsfasen av en granat tillverkad av kompositmaterial.   Från förstudien i denna rapport visade sig att matrissprickor och fiberbrott är de vanligaste defekter som uppstår i granathylsan under utskjutningsfasen där den största påverkan är ifrån explosionstrycket. Matrissprickor är de mindre farliga defekter av de som uppstår under intryckning. Diskussion med komposittillverkande företag visade att fiberbrott är en väldigt farlig typ av defekt eftersom fibrerna står för styrkan och brott av fibrer leder till att granathylsan klarar av att utsättas för lägre påfrestningar och kan inte hjälpa till att bygga upp det önskvärda trycket som önskas under utskjutningen.   Två kravspecifikationer utfärdades, en för granathylsan och en annan för detekteringsmetoderna. Dessa två skapades genom egen studie och idéer med hänsyn till hittad information, ifrån telefon- samt email kontakt med experter inom områdena samt med hjälp av personal på Saab Dynamics AB. Några krav som valdes för granathylsan var att den ska vara fullt användbar efter fallskärmsprovning från olika höjder, vibration- och transport tester för att inte få cykliska skador efter en lång transportering samt att alltid ha en fullt isolerad gördel så att inte de heta gaserna från explosivorna tänds redan i eldröret vilket orsakar vapensprängning. Några krav för detekteringsmetoder var att de ska kunna göra mätningar/analyser på djupet, ha hög trovärdighet samt vara portabel.   Eliminering- och beslutsmatriser gjordes för att hitta vilka detekteringsmetoder som skulle bli de slutliga valen i jakten på att finna defekterna i granathylsan. De metoder som inte uppfyllde kriterierna från respektive matris blev eliminerade. Elimineringen utfördes i faserna för konceptgenerering och konceptval. I slutliga valet valdes ett par lämpliga metoder som tillsammans hittar så många defekter som möjligt.   Genom att använda akustisk emission samt shearografi hittades samtliga kritiska defekter plus många andra som inte anses vara kritiska med väldigt hög trovärdighet och upplösning till ett mer acceptabelt pris. Metoderna samverkar väldigt bra med varandra eftersom akustisk emission är bästa metoden att hitta fiberbrott och matrissprickor vilket är vanligt förekommande i utskjutningsfasen. Shearografi har inte samma detekterbarhet på dem två defekterna men de har å andra sidan istället väldigt god detekterbarhet på både volymetriska- och plana defekter.   Slutsatsen är att endast två metoder behövdes för att finna alla defekter vilket blir mer ekonomiskt, tar mindre plats och behöver färre certifierade operatörer jämfört med om man ska ha en detekteringsmetod för att finna respektive defekt.

O reforço de elementos estruturais de concreto armado com uso de polímeros reforçados com fibras de carbono (PRFC) está cada vez mais conhecido, seguro e acessível. Em todo o mundo, a aplicação do PRFC vem sendo estudada sob diversas técnicas. Características como elevada resistência à tração e à corrosão, baixo peso, facilidade e rapidez de aplicação são os principais fatores para essa disseminação. Em particular, a técnica aqui estudada é conhecida como Near Surface Mounted (NSM), que consiste na inserção de laminados de PRFC em entalhes realizados no concreto de cobrimento de elementos de concreto armado. Com dupla área de aderência, ela vem a suprir uma deficiência comum no reforço colado externamente, que é o seu destacamento prematuro. Como nas demais técnicas de reforço à flexão, o material é colado na região do concreto tracionado. Sabe-se que, na prática da intervenção, essa região frequentemente encontra-se danificada por razões diversas, como fissuração causada por ações externas, corrosão da armadura e deterioração do concreto, o que exige a sua prévia reparação. Considerando que a boa qualidade desse reparo é imprescindível à eficiência do reforço, propõe-se uma inovação técnica pela reconstituição da face tracionada da viga com um compósito cimentício de alto desempenho, que sirva como substrato para aplicação do PRFC e elemento de transferência de esforços à estrutura a ser reforçada. Produzido à base de cimento Portland, fibras e microfibras de aço, o compósito tem também potencial para retardar a abertura de fissuras e aumentar a rigidez da viga, melhorando o aproveitamento do reforço. Com apoio da mecânica do fraturamento, foi possível encontrar as taxas de fibras e microfibras de aço a serem adicionadas a uma matriz cimentícia especialmente desenvolvida. Foram realizados ensaios de aderência para estudar o processo de transferência de tensões cisalhantes do laminado para o compósito na zona de ancoragem da viga. Uma vez conhecido o comportamento do sistema, foram ensaiadas vigas de concreto armado de tamanho representativo de estruturas reais, em três diferentes versões de ancoragem do laminado, sendo duas delas com uso do compósito cimentício. Comprovou-se a eficiência da inovação proposta, constatando-se o aumento da rigidez e da capacidade de carga da viga reforçada, com excelente aproveitamento do laminado. Além disso, as fibras e microfibras diminuíram a abertura das fissuras em estágios mais avançados de carregamento, sem que se observasse fissuras horizontais próxima ao reforço, que poderiam indicar destacamento iminente do laminado de PRFC. / Strengthening of reinforced concrete elements with carbon fiber reinforced polymer (CFRP) is increasingly well known, safe and accessible. The application of CFRP has been studied worldwide using various techniques. Features like high tensile strength, corrosion resistance, lightweightness and easy and speedy application are the main factors for dissemination. In particular, the technique here analyzed is known as Near Surface Mounted (NSM), which involves inserting CFRP strips into grooves made on the concrete cover of reinforced concrete elements. With double bonding area, this technique avoids the premature peeling-off that usually takes place in externally bonded CFRP reinforcement. As in others flexural strengthening techniques, the material is bonded in the concrete tension region. It is known in strengthening practice that this region usually requires prior repair. Often it shows up damaged by several reasons such as cracking caused by external actions, reinforcement corrosion and deterioration of the concrete. Whereas the good quality of this repair is essential to strengthening efficiency, an innovative technique is proposed. A high-performance cementitious composite is used as a transition layer for insertion of CFRP strips. The composite is made of Portland cement, steel fibers and microfibers of steel. It also has the potential to delay crack opening and to increase the beam stiffness. Based on fracture mechanics, it was possible to find suitable volume fractions of steel fibers and microfibers to be added to the cementitious matrix. Bonding tests were performed to analyze the shear stress transferring from the CFRP laminate to the beam anchorage zone. Once known the system behavior, real size reinforced concrete beams were tested in three different versions of the anchorage conditions, two of them with use of cementitious composites. The efficiency of the proposed innovation was proved by confirming increased stiffness and load capacity of the strengthened beam. In addition, fibers and microfibers allowed the decrease of the crack opening in later loading steps. No horizontal cracks near to the reinforcement were noticed, which means that CFRP laminate peeling-off was not likely to occur.