3D打印功能梯度混凝土断裂性能试验研究OA

3D-printed functionally graded concrete(3D-FGC)presents a potential pathway toward integrated structural-functional design.Owing to its complex heterogeneous nature,elucidating the performance response and underlying mechanisms of 3D-FGC is crucial for its advancement in intelligent construction.To investigate the fracture behavior of 3D-FGC,this study designed three gradient configurations,including two-layer composite(TC),linear gradient(LG),and sandwich gradient(SG),by varying the distribution of recycled sand and polyethylene(PE)fibers.These were compared with conventional homogeneous 3D-printed counterparts(REF),and their fracture behavior was analyzed under bottom,side,and top notches.Three-point bending tests were conducted on notched beams,and the differences in fracture properties were evaluated based on the double-K fracture theory.The results indicate that 3D-FGC is characterized by heterogeneous properties with multiple interfaces and discontinuous component distribution.The gradient configuration and initial notch location significantly affect its fracture performance.Compared with homogeneous specimens,the maximum fracture energy of specimens with gradient construction is increased by 86.67％.Among the three gradient structures,the linear gradient pattern alleviates stress concentration at the interfaces of dissimilar materials via a relatively smooth gradient transition,thereby exhibiting superior energy dissipation capacity and higher material efficiency.Digital image correlation(DIC)observations reveal that cracks undergo deflection and branching as they propagate from the recycled aggregate-dominated gradient layer to the fiber-reinforced gradient layer,which elevates the energy consumption during the crack propagation process.This is a key toughening mechanism underlying the enhanced fracture performance of 3D-FGC.