Experimental and numerical analysis of shear bonding behavior of interface between stone and ultra-high performance concrete made with POM fiber

Ultra-high performance concrete (UHPC) is a promising civil engineering cementitious material characterized by superior mechanical properties, where the compressive strength and elastic modulus are comparable to stone, therefore, UHPC is an ideal potential rehabilitation material for stone architecture. The excellent interfacial bonding property is the premise of UHPC reinforced existing stone structure. In this study, the bonding behavior of interface between stone and UHPC made with polyoxymethylene (POM) fiber was investigated by push-off tests, and the influence of stone surface treatment on shearing performance was analyzed by experiment and numerical simulation. The results showed that the interfacial shearing behavior of composites is associated with the interface roughness, especially the groove treatment, altering the failure mode and improving the shear strength as well as ductility, which is due to the interlocking mechanism and the distribution of fibers in groove. The suitable groove depth is recommended as 20 mm in the UHPC-stone composites using POM fiber with a length of 8 mm. The load-strain relationships of UHPC and stone are similar in the elastic stage due to the comparable elastic modulus, while present nonlinear characteristic in the plastic stage. The numerical simulation with a bilinear stress-displacement model can effectively predict the interfacial bonding behavior of UHPC-stone composites, and analyze the slippage distribution along with the interface. By means of stress contour, it is found that the shearing stress is mainly distributed non-uniformly around the interface, and the stress concentration location is consistent with the experimental failure region. Through the parametric study, it is revealed that the interface shear capacity of UHPC-stone is affected by the groove shapes and depths.