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Abstract

The first part of this chapter focuses on the constituent materials (fibres and polymeric matrices), manufacturing processes, general properties and field of application of fibre reinforced polymer (FRP) composites used in civil engineering applications. Subsequently, detailed information is provided about the following three main types of FRP shapes used in structural applications: (1) glass fibre-reinforced polymer (GFRP) pultruded profiles; (2) FRP rebars and (3) FRP strengthening systems. For each of these three main FRP typologies, the following aspects are discussed: geometries, typical physical and mechanical properties, advantages and difficulties compared to more traditional construction materials, field of application, application process and connection technology, and regulation.

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Article
This paper presents results of experimental investigations on the behaviour of GFRP pultruded profiles exposed to fire, in order to study the viability of their structural use in floors of buildings, taking into account the fulfilment of fire resistance requirements. The feasibility and efficacy of using three different protective coatings/layers, often used to protect structural steel, and a water cooling system to provide fire protection to GFRP pultruded profiles were investigated. The experimental programme included dynamic mechanical analyses (DMA), thermogravimetric and differential scanning calorimetry (TGA/DSC) experiments and fire resistance tests on GFRP tubular loaded beams. The unprotected GFRP beam failed after about 38 min, the three different passive protection systems provided a fire resistance between 65–76 min and the water cooling system provided a fire resistance of at least 120 min. Failure occurred in the upper part of the beams, due to compression and shear stresses. Results of these experiments allowed defining the field of application of each investigated solution, according to building code requirements.
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The technologies for recycling thermoset composite materials are reviewed. Mechanical recycling techniques involve the use of grinding techniques to comminute the scrap material and produce recyclate products in different size ranges suitable for reuse as fillers or partial reinforcement in new composite material. Thermal recycling processes involve the use of heat to break the scrap composite down and a range of processes are described in which there are various degrees of energy and material recovery. The prospects for commercially successful composites recycling operations are considered and a new initiative within the European composites industry to stimulate recycling is described.
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This paper is addressing the current waste management options for composite waste in the UK. It outlines legislation that is having an impact on the composites industry. Covers ways of managing waste from the composite industry through the waste hierarchy. Presents findings of projects examining the potential for using composite recyclate to make new useful construction products.
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The introduction of polymers and advanced polymer composites in the civil infrastructure has been a very rapid process in comparison to other civil engineering materials when they were in their infancy. Advanced polymer composite materials have hitherto been utilised predominately in the aerospace and marine industries, but for the last three decades there has been a growing awareness amongst civil/structural engineers of the importance of the unique mechanical and in-service properties of these materials together with their customised fabrication technologies. These extraordinary properties have enabled the design engineers to have greater confidence in the materials’ potential and consequently to use them in the renewal of civil infrastructure ranging from the strengthening of reinforced concrete, steel and cast iron, and the seismic retrofitting of bridges and columns for the use in replacement bridge decks and in the new bridge and building structures. This paper will outline the developing stages of this exciting material and will indicate future prospects for it.
Article
Durability of glass-fiber/polymer composites is dictated by the durability of the components: glass fiber, matrix, and the interface. Environmental attack by moisture, for example, can degrade the strength of the glass fiber; plasticize, swell, or microcrack the resin; and degrade the fiber/ matrix interface by either chemical or mechanical attack. The relative rates of these degradation processes are a function of the chemistry of the resin, temperature, length of time of exposure, degree of stress (whether cyclic or static), chemistry and morphology of coating of coupling agent on the glass fiber, and type of glass fiber. Several examples illustrate how the chemistry and morphology of the coatings of coupling agents that are on the glass fiber influence the strength and durability of the interfacial region.
Article
In the summer of 2005, after eight years of use as a temporary bridge during the winter, the Pontresina Bridge for pedestrians was transported to the Swiss Federal Institute of Technology Lausanne for a detailed assessment of the structural safety, serviceability, and long-term durability of the bridge. The assessment included a visual inspection, quasistatic testing identical to that performed in 1997, and detailed investigations of material degradation. The visual inspection showed a variety of different local defects and damage such as local crushing caused by impact, local cracks due to inappropriate storage and lifting of the structure, fiber blooming, degradation of cut surfaces, and damage due to vandalism. Comparisons between load tests performed in 1997 and 2005 showed, however, that the structural safety and serviceability of the bridge have not been affected by these local damages. The stiffness of the pultruded shapes remained unchanged, whereas a slight decrease in strength between 13 and 18% was measured, which, however, is not critical when taking into consideration the high effective safety factors. In view of a further service period of 5 years until the next inspection, the visible damages were repaired. This experience showed that the durability is primarily affected by inappropriate constructive detailing and that pultruded glass fiber-reinforced polymer shapes, if correctly manufactured and processed, can offer good long- term performance and durability. © 2007 ASCE.
Article
Fiber-reinforced synthetic polymers (FRP) are the building materials that may permit both the improvement of long-term building performance and the simplification of the construction process. Thanks to their high specific strength, low thermal conductivity, good environmental resistance, and their ability to be formed into complex shapes, FRP materials are well-suited to fulfilling many building functions. By integrating traditionally separate building systems and layers into single function-integrated components and industrially fabricating those components, the amount of on-site labor can be greatly reduced and overall quality can be improved. In order to profit from the advantageous qualities of FRP, however, it is essential to address the unique weaknesses and disadvantages of the material. Most notably, the problems of poor fire safety and high material costs must be overcome. In response to these challenges, a new multiple-story building system employing FRP materials is proposed. Within this system, fire safety is ensured through the use of an internal liquid cooling system, which circulates a cooling medium through the load-bearing FRP elements to maintain their temperature within a safe operating range. This system is made cost-effective through the integration of the building's heating and cooling system. By controlling the temperature of the circulating liquid, the building's structural elements can serve as heating or cooling emitters (radiators). Further, the addition of the liquid within the cells of the FRP elements helps maintain a more constant interior climate through the "thermal flywheel" effect, which improves energy efficiency and comfort. Experimental investigations were performed to explore the fire safety aspects of the proposed system. An existing FRP cellular bridge deck material was adapted to incorporate an internal liquid cooling system. After several preliminary investigations, large-scale experiments involving structural and fire loading were conducted on both liquid-cooled and non-liquid cooled specimens. The experiments demonstrated the efficacy of the system in protecting load-bearing FRP elements from the weakening effects of high temperatures, especially those that are stressed in compression. Structural fire endurance times were improved from less than one hour to more than two hours (EC1 Part 1.2) through the implementation of the liquid cooling system. Alongside the experimental program, a series of mathematical models were developed. Numerical thermochemical and thermomechanical models simulate the response of loaded liquid-cooled FRP panels in fire, while analytical models predict the post-fire mechanical behavior of fire-damaged sections. All models provide predictions that are within 10% of experimentally measured values. Glasfaserverstärkte Kunststoffe (GFK), als Baumaterialien eingesetzt, sind in der Lage sowohl die Bauwerksfunktionen dauerhaft zu verbessern als auch den Konstruktionsprozess zu vereinfachen. Dank ihrer hohen spezifischen Festigkeit, geringen Wärmeleitfähigkeit, guten Witterungsbetändigkeit und der Möglichkeit sie in zusammengesetzten Formen auszuführen, eignen sich GFK Materialien, vielfältige Bauwerksfunktionen zu übernehmen. Das Zusammenführen traditionell getrennter Bausysteme und Abschnitte zu funktionsintegrierten, industriell vorgefertigten Bauelementen veringerte die Arbeiten vor Ort erheblich und verbesserte die Qualität insgesamt. Um jedoch aus den vorteilhaften Eigenschaften des GFK Nutzen zu ziehen, ist es unerlässlich sich mit den einzelnen Schwächen und Nachteilen dieses Materials auseinanderzusetzen. Insbesondere die Probleme hinsichtlich des geringen Feuerwiderstands und der hohen Materialkosten müssen überwunden werden. Als Antwort auf diese Herausforderungen schlagen wir ein neues mehrstöckiges Bausystem aus GFK Materialien vor. Als Bestandteil dieses Systems sorgt ein internes Kühlsystem, welches eine Kühlflüssigkeit durch die lasttragenden GFK Elemente strömen läßt um die Temperaturen innerhalb eines sicheren Betriebsbereiches zu halten, für den notwendigen Feuerwiderstand. Durch die Einbindung des Heiz- und Kühlsystems in die Konstruktion kann das System wirtschaftlich hergestellt werden. Durch Temperaturänderung der Kühlflüssigkeit können die tragenden Bauteile zum Heizen bzw. Kühlen eingesetzt werden. Darüber hinaus hilft die Flüssigkeit in den Zellen der GFK Elemente, ein konstanteres inneres Raumklima durch den so genannten "thermal flywheel" Effekt aufrecht zu erhalten wodurch die Energie effizienter genutzt und die Behaglichkeit gesteigert wird. Um die einzelnen Aspekte des Feuerwiderstands zu erforschen wurden versuchsgestützte Untersuchungen durchgeführt. Zu diesem Zweck wurde ein bereits bestehendes zellenförmiges Brückendeckelement so umgebaut, dass ein internes Füssigkeitskühlsystem installiert werden konnte. Nach mehreren Voruntersuchungen wurde ein Großversuch unter jeweils flüssigkeitsgekühlten und trockenen Bedingungen durchgeführt, der sowohl statische als auch Brandlasten einschloss. Die Versuche zeigten die Wirksamkeit des Systems, lasttragende GFK Elemente vor dem sie schwächenden Einfluss hoher Temperaturen, besonders im Druckbereich, zu schützen. Die Feuerwiderstandszeiten des Tragwerks konnten so durch den Einsatz des Flüssigkeitskühlsystems von weniger als einer auf bis zu zwei Stunden erhöht werden (EC1, Teil 1.2). Neben dem Versuchsprogramm wurde eine Reihe mathematischer Modelle entwickelt. Numerische thermochemische und thermomechanische Modelle simulieren die Antwort belasteter flüssigkeitsgekühlter GFK Profile unter hohen Temperaturen während analytische Modelle das mechanische Verhalten abgebrannter Teilprofile abschätzen. Die Abweichungen der von den Modellen gelieferten Prognosen lagen innerhalb 10% der versuchstechnisch ermittelten Werte. Les matériaux composites en polymères renforcés par des fibres (FRP) permettent d'améliorer les performances à long terme des bâtiments et de simplifier le processus de fabrication. Grâce à leur haute résistance spécifique, faible conductivité thermique, bonne résistance aux actions environnementales et à leur capacité à être produits sous des formes complexes, les matériaux en FRP sont adaptés pour une utilisation multifonctionnelle dans le bâtiment. L'intégration de systèmes et de couches du bâtiment traditionnellement séparés en un composant unique à fonctions intégrées ainsi que la fabrication industriellement de ce composant, permet de réduire de manière considérable le temps de travail in-situ et d'améliorer la qualité de l'intégralité des travaux. Afin d'exploiter les nombreux avantages des matériaux en FRP, il est cependant essentiel d'adresser les faiblesses et les inconvénients propres au matériau. Notamment, les problèmes liés à la faible sécurité à l'incendie et le coût élevé du matériau doivent être surmontés. En réponse à ces défis, un nouveau système en FRP de bâtiment à plusieurs étages est proposé. Dans ce système, la sécurité au feu est assurée par l'utilisation d'un système de liquide de refroidissement interne qui circule par les éléments porteurs en FRP afin de maintenir leur température dans une plage de fonctionnement sûre. Ce système devient rentable en intégrant le système de chauffage et de refroidissement du bâtiment. En commandant la température du liquide de circulation, les éléments structuraux du bâtiment peuvent fonctionner en tant que chauffage ou émetteurs de refroidissement (radiateurs). De plus, la présence du liquide dans les cellules des éléments en FRP permet d'entretenir un climat intérieur plus constant par l'effet de "volant thermique", ce qui améliore l'efficacité énergétique et le confort. Des études expérimentales ont été conduites afin d'examiner le comportement au feu du système proposé. Un matériau cellulaire existant en FRP, utilisé pour les tabliers de pont, a été adapté afin d'y incorporer un système de liquide de refroidissement interne. Suite aux études préliminaires, des expériences structurales et d'incendie à grande échelle ont été conduites sur des éprouvettes sans et avec liquide de refroidissement. Les expériences ont démontré l'efficacité du système de protection des éléments porteurs en FRP sur leur dégradation sous hautes températures, particulièrement ceux sollicités en compression. Les durées caractérisant la résistance au feu exigée ont été améliorées en augmentant de moins d'une heure à plus de deux heures (EC1 partie 1.2) par l'introduction du système de liquide de refroidissement. Simultanément au programme expérimental, plusieurs modèles mathématiques ont été développés. Les modèles numériques thermochimiques et thermomécaniques permettent de simuler la réponse des panneaux en FRP réfrigérés par un liquide et chargés pendant l'incendie, alors que les modèles analytiques permettent de prévoir le comportement mécanique des sections brûlées après l'incendie. Les différents modèles fournissent des prévisions entre 10% des résultats expérimentaux.
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