Proposed Equation of Elastic Modulus of Hybrid Fibers Reinforced Concrete Cylinders.

To control the cracks and to increase the serviceability of concrete members, different types of fibers are used. The present research is conducted to study the behavior of hybrid-fiber reinforced concrete (HFRC) to enhance the load carrying capacity of concrete in compression and tension. Two different types of fibers are studied in this research; one is steel fibers (SF), and the other is polypropylene fibers (PPF). By using a different volumetric combination of SF and PPF, 42 concrete cylinders are cast in order to study the compressive and tensile behavior of concrete. The results exhibited the physical changes in the concrete due to the addition of different low-volume fractions of SF and PPF. The maximum compressive strength was achieved using 0.7% SF along with 0.3% PPF and the maximum tensile strength was achieved at 0.8% SF and 0.9% PPF by the total volume of the sample. A comparative study was also made for the previously proposed equations of the elastic modulus of concrete in order to obtain an equation which predicts the elastic modulus of HFRC accurately. [ABSTRACT FROM AUTHOR]