Determination of tensile strength and fracture toughness of 3D-printed ultra-lightweight engineered cementitious composites reinforced with fibre-reinforced polymer mesh

This paper investigates the fracture behaviours of three-dimensional (3D)-printed ultra-lightweight engineered cementitious composites reinforced with fibre-reinforced polymer (FRP) mesh (3DP-ULW-ECC-FRP). While prior research has focused on the mechanical properties of 3DP-ECC or ECC-FRP composites, their fracture behaviour has received scant attention. To address this gap, three-point bending tests were conducted on notched prismatic specimens. A fracture model to determine the tensile strength ( f t ’) and fracture toughness ( K IC ) was proposed based on the boundary effect model (BEM). Furthermore, the tensile strength contributions of ULW-ECC and FRP mesh were separated, and the fracture coefficients considering the material discontinuity and heterogeneity were discussed. The predicted f t ’ and K IC followed the normal distribution, which can be easily calculated from the peak load from the fracture test. Comparison with experimental results demonstrates the proposed model exhibits satisfactory accuracy and reliability. This study advances the understanding of fracture cracking behaviour in 3DP-ULW-ECC-FRP mesh composite.