自减振多壁碳纳米管超高性能混凝土制备及其阻尼调控机理研究

The damping performance of traditional concrete is poor. It is difficult for building structures to achieve the goal of self-reducing vibration relying on material damping. A huge number of interfaces can be introduced into composites by adding multi-walled carbon nanotubes. The energy dissipation system of deformation-slip-friction with carbon tube can be formed. Those effects can significantly improve the damping capacity as well as the mechanical properties. In this project, the multi-walled carbon nanotubes is composited with cement-based materials. Firstly, the dispersion and stabilization of carbon tube are investigated. The synergy mechanism between the carbon tubes and cement complex gelling system is revealed. The ultra-high performance concrete containing high amount and dispersed uniformly of carbon nanotubes are fabricated. Then, a single carbon nanotubes pull-out test is conducted by using atomic force microscopy, scanning electron microscopy testing technology. Combined with nanoindentation, evolution and intensity gradient variation of the interfacial transition zone is quantitative characterized. The mechanism of energy dissipation of ultra-high performance concrete with carbon nanotubes is revealed. The micro structure of the carbon tube / matrix interface transition region is designed precisely. The interfacial bond strength is controlled by using chemical modification of carbon nanotubes and regulation of multiple nanoparticles. The mechanism of damping energy dissipation based on microstructure is formed. Those measures ensure the maximum energy dissipation of carbon tube and matrix. A new generation of ultra high performance concrete with high strength, high toughness and high damping is successfully produced. This will provide strong scientific bases to achieve the goal of self-reducing vibration.

传统混凝土阻尼性能差，难以依靠材料自身阻尼实现建筑结构自减振目标。多壁碳纳米管能在复合材料中引入数量巨大的界面，形成碳管变形-滑移-摩擦耗能体系，显著提高阻尼能力的同时改善力学性能。本项目将多壁碳纳米管与水泥基材料进行复合，首先研究多种碳管的分散及稳定技术，揭示碳管与水泥复杂胶凝体系的协同效应机制，制备出碳管掺杂量高、分散均匀的超高性能混凝土；然后，采用原子力显微镜、环境扫描电镜等测试技术，对单根碳纳米管进行拉拔试验，结合纳米压痕技术定量表征界面过渡区微结构演变及强度梯度变化规律，揭示碳纳米管超高性能混凝土阻尼耗能机理；通过精确设计碳管/基体界面过渡区微结构，利用碳管表面化学修饰、多元纳米颗粒调控的方法调节界面粘结强度，形成基于微结构的阻尼耗能调控机理，确保碳管/基体耗能体系耗能最大化，成功制备出同时兼具“高强、高韧性、高阻尼”的新一代超高性能混凝土，为实现建筑结构自减振提供理论基础。

传统混凝土阻尼性能差，难以依靠材料自身阻尼实现建筑结构自减振目标。多壁碳纳米管能在复合材料中引入数量巨大的界面，形成碳管变形-滑移-摩擦耗能体系，显著提高阻尼能力的同时改善力学性能。通过项目的开展，获得以下理论成果，发明了适合于极低水胶比超高性能混凝土的多壁碳纳米管稳定分散和改性技术，构建了多壁碳纳米管材料的理化特性测试方法与性能评价系统；探明了多壁碳纳米管材料与超高性能混凝土复杂胶凝材料体系协同作用机制。设计与制备出了具有最紧密堆积状态的超高性能混凝土胶凝体系，揭示了极低水胶比超高性能混凝土粘度的调控机制，提出了多壁碳纳米管超高性能混凝土最佳制备工艺，并建立了基于功能的多壁碳纳米管超高性能混凝土优化设计方法。研究了多壁碳纳米管与水泥基体、碳纳米管与碳纳米管之间的黏-滑(stick-slip)运动机制，探明了碳纳米管与水泥基结合体微结构特征对振动能量耗散效应的影响规律，揭示了多壁碳纳米管超高性能混凝土阻尼耗能机理，建立了超高性能混凝土微结构与宏观力学行为、阻尼行为的关系，并提出基于功能的超高性能混凝土性能调控机制。系统研究了多壁碳纳米管超高性能混凝土的基本力学行为、阻尼性能及框架结构模型耗能减震效果，揭示了多壁碳纳米管对复合材料的强化与韧化效应与阻尼增强机理，并建立 基于多尺度的静态力学本构模型和多相复合阻尼本构模型。制备出的同时具备“高强、高韧性、高阻尼”的新一代超高性能混凝土，解决阻尼与力学性能难以同时兼备的科学难题，实现建筑结构自减振目标，满足高速铁路、高层与超高层建筑、跨海大桥、海上石油平台、核电站等重大基础工程建设的迫切需求，具有重大的理论和现实意义。