使用碳纳米管替代微米级纤维可增强超高性能混凝土（ultra-high performance concrete, UHPC）的抗冲击性能，但碳纳米管的弱润湿性和低分散性以及碳纳米管与UHPC之间的弱界面结合限制了其增强效果的充分发挥。因此，本文拟通过官能团化处理提高碳纳米管对UHPC抗冲击性能的增强效果。研究结果表明，通过碳纳米管的官能团化处理可使C‒S‒H 凝胶中的Si‒O‒Ca‒O‒Si 配位键发生断裂，进而在UHPC基体中形成以碳纳米管为中心的增强网络。此外，掺入官能团化碳纳米管（尤其羧基化碳纳米管）可显著降低骨料-基体界面宽度甚至消除界面，提高UHPC 结构整体性。另外，复合官能团化碳纳米管可降低UHPC的孔隙率及孔隙（尤其纳米级孔隙）尺寸，进而诱导UHPC内部C‒S‒H 凝胶收缩，从而增加凝胶内部水化产物的结构致密性。由于上述官能团化碳纳米管对UHPC微观结构的改善作用，复合材料在200~800 s⁻¹应变率冲击压缩荷载作用下的动态抗压强度、动态峰值应变、冲击韧度和冲击耗散能显著提高。在所有复合材料中，羧基化碳纳米管（尤其是羧基化短碳纳米管）复合UHPC的抗冲击性能普遍优于普通及羟基化碳纳米管复合UHPC，甚至超过高掺量的钢纤维复合UHPC。

Replacing micro-reinforcing fibers with carbon nanotubes (CNTs) is beneficial for improving the impact properties of ultra-high performance concrete (UHPC); however, the weak wettability and dispersibility of CNTs and the weakly bonded interface between CNTs and UHPC limit their effectiveness as composites. Therefore, this study aims to enhance the reinforcement effect of CNTs on the impact properties of UHPC via functionalization. Unlike ordinary CNTs, functionalized CNTs with carboxyl or hydroxyl groups can break the Si–O–Ca–O–Si coordination bond in the C–S–H gel and form a new network in the UHPC matrix, effectively inhibiting the dislocation slip inside UHPC matrix. Furthermore, functionalized CNTs, particularly carboxyl-functionalized CNTs, control the crystallization process and microscopic morphology of the hydration products, significantly decreasing and even eliminating the width of the aggregate–matrix interface transition zone of the UHPC. Moreover, the functionalized CNTs further decrease the attraction of the negatively charged silicate tetrahedron to Ca2+ in the C–S–H gel, while modifying the pore structure (particularly the nanoscale pore structure) of UHPC, leading to the expansion of the intermediate C–S–H layer. The changes in the microstructures of UHPC brought about by the functionalized CNTs significantly enhance its dynamic compressive strength, peak strain, impact toughness, and impact dissipation energy at strain rates of 200–800 s⁻¹. Impact performance of UHPC containing a small amount of carboxyl-functionalized CNTs (especially the short ones) is generally better than that of UHPC containing hydroxyl-functionalized and ordinary CNTs; it is even superior to that of UHPC with a high steel fiber content.