Evaluation of mechanical properties of concrete containing a combination of steel and polypropylene fibers

Today improvement the behavior of fiber-reinforced concrete in concrete technology is one of the most common methods. Adding fiber to concrete causes strength growth, improve the stress - strain and will increase ductility. Steel fibers, polypropylene and glass fibers used are most commonly. In this study, concrete water-cement ratio of 0.45 and 400kg/ cement content and percentages of steel fiber and polypropylene were built both separately and in combination as well. The results of compressive and tensile strength and stress-strain tests has showed that by adding different percentages of fiber at the age of seven days there has not been much change but the sample compressive and tensile strength of 28 days old has been increased. The greatest strength growth was related to the samples containing 1 percentage of steel fibers. According to stress-strain curves, the strength of thoughness has been significantly improved and have gotten formed the behavior of samples. Then for better comparison of results and improve short-term strength by adding Silica fume two examples were built. The results have showed that adding Silica fume causes the strength parameters improved.