Fabric Reinforced Cementitious matrix (FRCM) materials represent an innovative retrofitting system comprising a fiber textile embedded into an inorganic matrix. The reinforcement could be manufactured of different types of textiles (e.g. aramid, basalt, carbon, glass, PBO, steel) usually in the form of continuous yarns arranged to form grids. The textile can be unidirectional or bi-directional. Composite materials are used both in new structures (e.g. to produce thin walled prefabricated elements) and to retrofit masonry and concrete structures. FRCMs are Textile Reinforced Mortar (TRM) that are specifically used for strengthening. When applied to masonry substrates, they are preferable to Fiber Reinforced Polymer (FRP) strengthening systems due to their major compatibility with the substrate, reversibility, vapor permeability, better resistance to high temperature and durability against detrimental agents [1],[2]. Test set-ups and consequent failure modes are very important parameters because the stress distribution among filaments and yarns is influenced by the matrix cracking [20]. The stress-transfer mechanism in FRCM materials, between the composite and the substrate and between the textile and the matrix, is influenced by different phenomena (e.g. mechanical and adhesion properties, textile geometry, mortar granulometry). The failure modes could be different and influenced by geometrical and mechanical properties of the grid and the matrix. The specimen production, dimension and shapes and load application may largely influence the stress strain behavior. In this thesis the experimental campaign was carried out to study the behavior of glass fiber. The aim is to contribute in deepening the knowledge on this topic; therefore, twenty-eight specimens have been tested in three different configurations: • bare glass • glass coupled with organic matrix (resin) • Glass coupled with inorganic matrix (mortar) The mechanical properties were investigated using two different tensile test set-ups. Direct tensile test and shear bond test were carried out to evaluate the performance of FRCM in terms of composite response under direct tension, failure modes in terms of stress- strain analyzed in the three configurations. Analog LVDTs and digital image correlation (DIC) measurements are employed to study the specimen longitudinal stress-strain behavior.
I materiali a matrice cementizia fibrorinforzati rappresentano un sistema innovativo di retrofit strutturale costituito da un tessuto di fibre incorporato in una matrice inorganica. L’armatura può essere prodotta con vari tipi di tessuto (aramide, basalto, carbonio, vetro, PBO, acciaio), generalmente in filati continui disposti a formare delle reti. Il tessuto può essere unidirezionale o bidirezionale. I materiali compositi sono usati sia per strutture nuove (ad esempio per pareti sottili prefabbricate) sia per il ripristino strutturale di strutture in calcestruzzo o in muratura. Gli FRCM sono malte rinforzate con tessuti, che sono tipicamente usate per consolidamenti. In caso di strutture in muratura, sono più idonee dei sistemi di adeguamento con polimeri fibro-rinforzati (FRP) a causa della maggiore compatibilità con il substrato, reversibilità, permeabilità al vapore, maggior resistenza alle alte temperature e durabilità nei confronti degli agenti nocivi [1] [2]. I test set-up e i conseguenti modi di collasso sono dei parametri significativi poiché la distribuzione delle tensioni lungo i filamenti è influenzata dalla fessurazione della matrice [20]. Il meccanismo di trasferimento delle sollecitazioni negli FRCM, tra il materiale composito e il substrato e tra il tessuto e la matrice, è influenzata da molti fenomeni (proprietà meccaniche e di adesione, geometria dei tessuti, granulometria della malta). Le modalità di collasso possono essere molteplici e dipendono dalle proprietà geometriche e meccaniche della griglia e della matrice. La produzione dei campioni, dimensioni, forma e applicazione del carico, possono influenzare ampiamente il comportamento sforzo-deformazione. In questa tesi, sono state condotte prove sperimentali al fine di studiare il comportamento delle fibre di vetro. Obiettivo di questo lavoro è contribuire all’approfondimento delle conoscenze in questo ambito; difatti, sono stati testati 28 campioni in tre diverse configurazioni: • vetro semplice • vetro combinato con matrice organica (resina) • vetro combinato con matrice inorganica (malta). Le proprietà meccaniche sono state investigate utilizzando due differenti prove di trazione. Sono state condotte prove di tensile test e shear bond tests per valutare le prestazioni degli FRCM in termini di risposta del composito a trazione diretta, modalità di collasso e di sforzo-deformazione, analizzati nelle tre configurazioni. Il comportamento di sforzo-deformazione è studiato impiegando sia misurazioni analog LVDTs e Digital Image Correlation (DIC).
Role of the fiber impregnation in glass FRCM composites
DECANDIA, CATERINA
2017/2018
Abstract
Fabric Reinforced Cementitious matrix (FRCM) materials represent an innovative retrofitting system comprising a fiber textile embedded into an inorganic matrix. The reinforcement could be manufactured of different types of textiles (e.g. aramid, basalt, carbon, glass, PBO, steel) usually in the form of continuous yarns arranged to form grids. The textile can be unidirectional or bi-directional. Composite materials are used both in new structures (e.g. to produce thin walled prefabricated elements) and to retrofit masonry and concrete structures. FRCMs are Textile Reinforced Mortar (TRM) that are specifically used for strengthening. When applied to masonry substrates, they are preferable to Fiber Reinforced Polymer (FRP) strengthening systems due to their major compatibility with the substrate, reversibility, vapor permeability, better resistance to high temperature and durability against detrimental agents [1],[2]. Test set-ups and consequent failure modes are very important parameters because the stress distribution among filaments and yarns is influenced by the matrix cracking [20]. The stress-transfer mechanism in FRCM materials, between the composite and the substrate and between the textile and the matrix, is influenced by different phenomena (e.g. mechanical and adhesion properties, textile geometry, mortar granulometry). The failure modes could be different and influenced by geometrical and mechanical properties of the grid and the matrix. The specimen production, dimension and shapes and load application may largely influence the stress strain behavior. In this thesis the experimental campaign was carried out to study the behavior of glass fiber. The aim is to contribute in deepening the knowledge on this topic; therefore, twenty-eight specimens have been tested in three different configurations: • bare glass • glass coupled with organic matrix (resin) • Glass coupled with inorganic matrix (mortar) The mechanical properties were investigated using two different tensile test set-ups. Direct tensile test and shear bond test were carried out to evaluate the performance of FRCM in terms of composite response under direct tension, failure modes in terms of stress- strain analyzed in the three configurations. Analog LVDTs and digital image correlation (DIC) measurements are employed to study the specimen longitudinal stress-strain behavior.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/144038