Using Wavy Steel Fibers to Study the Rheological Properties, Mechanical and Fracture Parameters of Self-Compacting Concretes with Different Coarse Aggregate Volumes

Considering the low concrete resistance to cracking and high volume of aggregate used in it, this study has addressed the effects of increasing the volume of wavy steel fibers (0.15, 0.3 and 0.45%) and volume of coarse aggregates (30, 40, 50 and 60%) in relation to the total volume of aggregates on the properties of fresh, hardened self-compacting concrete as well as on the fracture mechanics. To this end, different tests were performed on: 1) fresh concrete (slump-flow, T-50, J-Ring, Sieve analysis and L-BOX tests), 2) hardened concrete (compressive strength, tensile strength and modulus of elasticity tests) and 3) fracture mechanics (Mode I fracture toughness test on ENDB specimens) using 108 cylindrical specimens. Results showed that increasing the coarse aggregate volume improves the rheological properties and increasing the wavy steel fiber volume reduces the efficiency and flowability of the self-compacting concrete, but improves the compressive strength in concretes containing 50 and 60% coarse aggregate volume. Increasing this volume, will slightly reduce the tensile strength of only the fiber reinforced self-compacting concretes containing 60% coarse aggregates. Increasing the coarse aggregate volume by 30 to 60% improves the modulus of elasticity of specimens containing a fixed fiber percent and increasing the volume of wavy steel fibers, at 30 and 40% coarse aggregate volumes, increases the fracture toughness (Mode I) of the self-compacting concrete specimens containing wavy steel fibers.