عنوان مقاله [English]
To improve the strength of concrete, recently the use of different types of fiber is very common particularly in for civil engineering constructions. Most of the researches show that using the fibers will improve the compressive, tension and flexural strengths of concrete. The present work attempts to clarify the effect of different types of fiber on the mechanical strength of concrete. To achieve this aim, low amount of steel and glass fibers in mixes designed with two different rates of water to cement (W/C) ratios including 0.35 and 0.45 have been investigated. The steel and glass fibers have been used in concrete for 0, 0.30, 0.60 and 0.90 volume percent of concrete. For each ratio of water to cement: 21 cubic samples (10×10×10 cm) for compressive strength tests, 14 cylindrical samples (15×30 cm) for tensional tests and 14 prismatic samples (10×10×50 cm) for three-point flexural tests have been prepared. The laboratory results show that adding 0.30 to 0.90 percent steel fibers for concrete will increase the compressive, tension and flexural strengths in compare with normal concrete. Using the glass fibers between 0.30 to 0.60 percent by increasing the compressive strengths and by adding more fibers (more than 0.60 present), the compressive strengths will be decreased. In compare with normal concrete samples, by adding the glass fibers in the range of 0.30 to 0.90 percent of concrete volume, the tension and flexural strengths of reinforced concrete will be increased.