Comparative experimental study on flexural strength of concrete beams with cold joints using varying hooked rebar configurations

This study presents a comparative experimental investigation on the flexural behavior of reinforced concrete beams with cold joints using varying hooked rebar configurations. Cold joints are formed when fresh concrete is placed over previously hardened concrete, resulting in a discontinuity that may influence the structural performance of concrete members, particularly under flexural loading. The primary objective of this research is to examine the effect of cold joint location and the role of hooked reinforcement bars on the flexural response of beams. For this purpose, reinforced concrete beams of M25 grade with dimensions 1200 mm × 200 mm × 150 mm are cast with different cold joint conditions, including mid-span and one-third span locations. Selected specimens are provided with 180° hooked reinforcement bars at the joint interface to study their effectiveness in improving bonding and load transfer. All beam specimens are tested under two-point loading conditions, and their performance is evaluated through parameters such as flexural strength, load–deflection behavior, crack pattern, and failure characteristics at different curing periods. In addition, This study aims to provide a systematic understanding of the behavior of cold jointed beams and the influence of hooked reinforcement configurations, contributing to improved construction practices and structural performance of reinforced concrete elements