Experimental study for flexural behavior of high strength rc beams with hybrid fibers

An experimental program is achieved in this study to show the enhancement gained from addition of steel, basalt, and glass fibers to the concrete mix on the flexural performance of reinforced concrete beams. Ten different reinforced concrete beams are tested and results are compared. First one is a control beam, group A consist of three beams strengthened with different volumetric ratios (0.5, 1.0, and 1.5 %) of steel fibers. Group B consist of three beams (0.25-0.75, 0.5-0.5, and 0.75-0.25) % of steel and basalt hybrid fibers, and group C consist of three beams (0.25-0.75, 0.5-0.5, and 0.75-0.25) % of steel and glass hybrid fibers. Moreover, 30 standard concrete cubes are tested to show the effect of the fibers on concrete compressive strength, and 30 standard concrete cylinders are tested to show the difference in split strength. Test and comparison results show that group A beams give enhancement in first crack load values, which means enhancement in tension zone characteristic with maximum values of 60 % increase in cracking load for the beam with 1.0 % addition of steel fibers. Yield load is also, enhanced by (9.0 %, 0.4 %, and 5.0 %) increase for beam 1.0 % and 1.5 % volumetric ratios of steel fibers, and (0.5-0.5) % volumetric ratios of steel-glass hybrid fibers, respectively. Ultimate loads are enhanced by 0.6 %, and 2 % for beams with volumetric ratios of 1 % steel fibers and (0.5-0.5) % steel-glass hybrid fibers additives, respectively. Extending this experimental program to study different beam cross sections, deep beams, hybrid beams and creep-shrinkage effect are suggested as future work.