This study intends to assess the influence of steel fibres (SF) and polypropylene fibres (PPF) on the hardened and fresh state properties of high-strength concrete (HSC).For this purpose, 99 concrete mixes were designed and applied.SF and PPF were used at six-volume replacement contents of 0%, 0.
1%, 0.2%, 0.3%, 0.
4% and 0.5%.Moreover, nano-silica (NS) was used at three contents, 0%, Generator Fan 1% and 2%, and silica fume powder (SP) was also used at three weight ratios (0%, 5% and 10%).
The slump, compressive and tensile strength, elasticity modulus, water absorption and the electric resistivity of concrete specimens were examined.The results showed that using 1% NS and 10% SP together with 0.5% PPF improved the compressive strength of HSC by about 123%; however, the effect of SF on tensile strength is more significant and adding 0.
5% SF with both Novelties 2% NS and 10% SP increased the tensile strength by 104%.Moreover, increasing the SF content reduces the electric resistivity while using PPF improves this property especially when 1% NS was employed, and it was enhanced by about 68% when 0.5% SF and 1% NS were utilized with 10% SP.