الفهرس | Only 14 pages are availabe for public view |
Abstract Fiber reinforced concrete is characterized by its high ability to resist fracture by static strains due to dynamic or impact loads. In this research, toughness was determined in terms oftbe area under the load-deflection curve, which changes according to the type of fiber used, and its volume fraction, by means of advanced computerized testing mach ine. It was reviewed previous researches dealing with the determination of toughness parameters, according to distinct standard methods. Also, the effect of several factors affecting toughness parameters was discussed. In this experimental study; Load-deflection curves were drawn simultaneously for different concrete grades (250, 400 and 500 kg/ern’) reinforced with three distinct fiber types, (steel, glass and polypropylene) and various volume fractions of fibers, namely (0.55, 1.0%, 1.5% and 2% for steel and glass fibers and 0.1 %, 0.2% and 0.3% for polypropylene fibers). Toughness parameters were determined by applying three different standard methods; which are: - The American Society for Testing Materials (ASTM C-1 018). - TIle Japanese Standard for Civil Engineering (JSCE - SF4). - The RILEM Method (50-fMC). Parameters obtained according to these standards were used for determining the ideal volume fraction for each type of fiber which improves toughness property for fiber reinforced concrete (FRC). It was introduced a detailed comparison showing” the influence of fiber type, volume fraction of fibers, grade of concrete and presence of notch on the obtained fracture toughness values. Experimental data representing toughness parameters by these three methods were reported and compared.Besides, other properties for FRC were calculated for all concrete mixes with different types of fibers, volume fractions and concrete grades. Compressive and tensile strengths and modulus of rupture were also determined. General observations and conclusions indicate that toughness value for FRC was extensively increased compared to plain concrete. TI,e amount of increment depends main lyon both volume fractions of fiber and fiber type. Steel fiber reinforced concrete (SFRC) showed higher toughness resistance than the other studied types; glass fiber reinforced concrete (GFRC) and polypropylene fiber reinforced concrete (PFRC). Besides, the improvements of toughness parameters for lower concrete grade are better than that for higher grades for SFRC. On the contrary for GFRC and PFRC. Recommended practical volume fractions of fibers as testified in this research in order to moderate FRC ability to resist fracture was suggested. It was found that the Japanese Standard method (JSCE-SF4) is easier in application, than American method (ASTM C 10 18) for measuring toughness parameters, especially for uri-notched specimens. |