Influence of mixing of various fibers on fresh and mechanical properties of ultra high strength concrete and consideration of its evaluation method

200 MPa class ultra high strength concrete is easy about brittle fracture and explodes on fire. As their countermeasures, the steel fibers are used to suppress brittle fracture and polypropylene short fibers are used to suppress the explosion in fire. However, the previous studies have reported that the strength of concrete is affected by steel fibers. And the fluidity of concrete is reduced by polypropylene short fibers. In this report, the influence of steel fibers, polypropylene short fibers and their combination on the fresh and mechanical properties of 200 MPa class concrete is introduced. © 2021 Architectural Institute of Japan. All rights reserved.