Flexural strengthening of reinforced concrete beams using engineered cementitious composite (ECC/SHCC): A state-of-the-art review

Engineered Cementitious Composite (ECC) or Strain-Hardening Cementitious Composite (SHCC) are high-performance composites that stand out for their exceptional ductility and distinctive multiple-cracking behavior. Despite extensive studies on both materials, the studies on assessing their combined or comparative efficacy in flexural strengthening of reinforced concrete (RC) structures are sparse. The flexural response of RC members strengthened with SHCC/ECC systems is reviewed in detail in this paper. The bond behavior between these composites and concrete substrates under bending stresses, as well as their interactions with FRP materials and steel reinforcement, was specifically examined. The improved strain capacity and fracture-width control of SHCC/ECC are demonstrated to greatly improve flexural ductility, postpone crack start, and increase post-cracking stiffness, therefore minimizing the brittleness generally observed in conventional RC members. A comprehensive analysis was also conducted for several strengthening setups, and flexural capacity prediction models were developed. Lastly, research limitations and prospects for improving the application of SHCC/ECC in advanced flexural strengthening and retrofitting are noted.