Experimental Study on the Preparation and Bouncing Performance of UHPC Hollow Spheres

Ultra-high performance concrete (UHPC), as the most innovative cement-based engineering material in the past three decades, has achieved a leapfrog improvement in mechanical properties and has gradually been recognized and widely applied in the engineering community. However, the current simple evaluation methods for its mechanical properties are still limited to steel ball impact tests, which are relatively complex and inconvenient to operate. Therefore, this paper proposes the UHPC hollow ball bounce test as a simple evaluation method for its mechanical properties, especially impact resistance, and systematically expounds the significance and process of hollow ball preparation. To investigate the influencing factors and action laws of the bounce performance of UHPC hollow balls, a batch of UHPC hollow balls was prepared. By testing their compressive strength, tensile strength, elastic modulus, and wall thickness uniformity, the study explored the influence of these parameters on bounce performance and analyzed the bounce mechanism. The results showed that the higher the elastic modulus of UHPC, the better the bounce performance of the hollow ball; there is a significant positive correlation between strength and elastic modulus, and strength is the key factor determining bounce performance; improving wall thickness uniformity, adding steel fibers, and using a highly rigid internal mold can significantly improve bounce performance. This paper believes that the research results can not only promote the engineering application of the UHPC hollow ball bounce test as a simple evaluation method but also provide theoretical basis and practical reference for improving the preparation level of UHPC products.