Abstract: “Few researches were made in recent decades to explain the relationship between mid-span deflection and crack mouth opening displacement (CMOD). In this study, a concrete mix proportion arrived based on the packing density of concrete incorporated with hybrid combination of different types of fibre with different aspect ratio and dosages. High modulus steel fibre of length 60mm and 35mm and low modulus polypropylene fibre of length 47mm and 23.5mm is used in this study. A yoke set up is used to evaluate load-deflection curve and a specially fabricated C-clamp for evaluation CMOD. The paper mainly focuses on the relationship between the mid-span deflection and CMOD. Manual evaluation of the load-deflection curve and load-CMOD curve is carried out of different hybrid concrete specimen. The experimental results show a linear relationship between mid-span deflection and CMOD.”

Keywords: mid-deflection;CMOD; hybrid; steel fibre; polypropylene fibre; toughness.