Study on application of carbon fibers laminates for strengthening of concrete samples
Jan Piekarczyk, Beata Macherzyńska, Stanisłąw Błażewicz Akademia Górniczo-Hutnicza, Wydział Inżynierii Materiałowej i Ceramiki, al. Mickiewicza 30, 30-059
Quarterly No. 2, 2005 pages 33-39
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abstract The aim of this work was the manufacture of high-modulus carbon fibers - based epoxy resin laminates and application them for strengthening of samples made of concrete and cement mortar. Four types of carbon fibres were used in this work, varying in Young modulus from 230 GPa (T-230) to 960 GPa (K-950) (Tab. 1, Fig. 1). The elastic properties of fibres, epoxy resin and laminates were calculated by using ultrasonic method (Fig. 2, Tables 2 and 3). Figures 4-6 demonstrate the shapes of samples for studying the mechanical properties. The carbon fibers - based laminates were obtained by impregnation of carbon fibres tows with epoxy resin solution. Subsequently, unidirectional fibre composite tapes were formed under compression (30 atm) to reduce an excess of resin followed by the curing of the laminates at room temperature. Figure 7 shows photomicrograph of cross section area of the composite. Composite laminates having different values of Young modulus were prepared, depending upon the type of carbon fibres reinforcement and its volume fraction (Tab. 3). Mechanical tests results from the various unidirectional composite laminates showed that the values of Young’s modulus ranged from 90 to 595 GPa. Adhesion assessment of laminates to the concrete samples surfaces indicated that the interlaminar shear strength is 5.8+/−0.78 MPa. An increase of flexural strength of cement mortar and concrete samples strengthened with laminates from 7 to 14-times was obtained, as compared to the as-received cement samples. The effect of water exposure of cement samples with glued laminates on mechanical properties revealed that no loss in flexural strength occurred within the time of two months. Key words: polymer laminate, carbon fibers, concrete strengthening, mechanical properties