Experimental and Theoretical Investigation on Flexural Behavior of LWSCC Beams Strengthened with an ULW-ECC-FRP Mesh Layer

The structural performance of lightweight self-consolidating concrete (LWSCC) structures is susceptible to degradation due to its inherent brittleness. To address this challenge, the ultra-lightweight engineered cementitious composite (ULW-ECC) emerges as a promising strengthening material owing to its strain-hardening behavior and high strength-to-weight ratio. This study experimentally and theoretically investigates the flexural performance of LWSCC beams strengthened with a ULW-ECC layer reinforced with fiber-reinforced polymer (FRP) meshes. The test results indicated that the flexural capacities of strengthened beams were significantly enhanced by the strengthening layer, ranging from 19.5% to 39% with different FRP meshes. Glass FRP (GFRP) and basalt FRP (BFRP) meshes marginally affected the failure mode and crack pattern of the ULW-ECC layer. In contrast, the carbon FRP (CFRP) mesh had adverse effects. Compared with ULW-ECC with the externally bonded FRP sheet technique, the ULW-ECC-FRP mesh layer enhanced the ductility and energy absorption of the beam. Subsequently, a new design method was developed to predict the flexural capacity of LWSCC beams strengthened with an ULW-ECC-FRP mesh layer. Finally, a systematic parametric study on the effects of comprehensive factors on flexural strength was conducted.