Engineered cementitious composites reinforced by CFRP textile grid: Laboratory tests

To further enhance the application of Engineered Cementitious Composites (ECC) in underground spaces, particularly in underground mining environments, this study utilized metal mine tailings as aggregates to develop a novel cementitious composite. By incorporating carbon fiber reinforced polymer (CFRP) and basalt fiber reinforced polymer (BFRP) grids as reinforcement, a high-strength, high-ductility support material for underground mining was successfully developed. Three experimental series were designed: six specimens reinforced with 1–3 layers of CFRP, six specimens reinforced with BFRP, and six unreinforced ECC control specimens. All specimens were produced using the same mix proportions and underwent uniaxial tensile tests and three-point bending tests. The results indicated a significant improvement in the mechanical properties of the CFRP-reinforced specimens. Tensile strength increased progressively with the number of CFRP layers, showing a 232.4% enhancement with one layer compared to the unreinforced ECC. Flexural load-bearing capacity also increased incrementally with additional CFRP layers; the ultimate load-bearing capacity of beams with one CFRP layer increased by 9.9%, although the deflection decreased by 41.8% compared to the ECC control group. Using digital image correlation (DIC), the strain evolution throughout deformation was analyzed, providing a systematic examination of stress-strain behavior, crack propagation, and failure mechanisms. DIC further elucidated the full-field strain development during tensile and bending tests, enabling an in-depth investigation into the reinforcing effects and underlying mechanisms of CFRP across all stages of deformation.