纳米-微米多级结构复合纤维改性混凝土材料

The performance of fiber reinforced concrete is directly influenced by the gradual degradation of the fibers and poor bonding between fiber and concrete. Effective enhancement can be achieved on the interface connection as well as the performance of fiber reinforced concrete by means of fiber modification. As a result, the proposed project herein aims to develop nano-micro hierarchically structured hybrid fiber with three dimensional coupling feature to modify concrete material. Based on the physical and chemical surface properties, 1D-arrayed and 3D-branched nanostructure will be designed and in-situ established on micro carbon fiber and micro glass fiber respectively by selecting synthesis route and controlling growing conditions. With such nanostructure successfully built up, nano-micro hybrid fiber will be attained with good self-protecting properties under utilization to be possessed. When as-prepared fibers are mixed with concrete, the physical and chemical interacting manners will be investigated to figure out the bond connecting properties between hybrid fiber and concrete. Also, the interface structure and properties will be studied along with the curing time to illuminate the effect of hybrid fiber on cement hydration. Then, hybrid fiber reinforced concrete will be developed with fresh and hardened properties evaluated by varying aspect ratio and volume percentage of hybrid fiber and w/c ratio of the concrete. For fresh concrete the workability as well as fiber distribution will be more focused on while for hardened concrete the mechanical properties and durability will be tested and analyzed to reveal the modification effect of nano-micro hybrid fiber to concrete materials. It is expected that such contents proposed in this project may provide theoretical basis and novel techniques on property improvement of the fibers as well as bonding enhancement between fiber and concrete, bringing new ideas to high performance concrete development with good toughness and durability to be possessed.

纤维的自身低抗劣性及与基体的低粘结作用限制着纤维混凝土的性能提升，基于纤维改性对纤维混凝土的界面融合增强作用，本项目拟利用多样化纳米材料，以三维密集式铺面耦合纳米-微米多级结构复合纤维改性混凝土材料。基于纤维表面物理化学特性，调控纳米材料生长方式及影响因素，以微米纤维表面原位生长方式构建碳纤维及玻璃纤维表面一维阵列式及三维树枝式纳米结构，研发抗劣性良好的纳米-微米多级结构复合纤维；研究复合纤维与混凝土的结合作用，揭示二者物理化学耦合作用方式，建立连接界面的微环境描述；调整纳米-微米多级结构复合纤维混凝土制备方式，通过力学性能测试及耐久性评价，阐明纳米-微米多级复合碳纤维及玻璃纤维对混凝土的宏观改性效果影响规律。项目研究成果将为提升纤维抗劣性、改善纤维混凝土的界面结合、及设计及研发高韧性及高耐久性纤维增强混凝土提供理论指引与技术支持。

水泥及混凝土的抗拉强度低、延性差、脆性破坏等缺陷限制了其进一步发展。纤维的引入可有效改善水泥基材料力学性能与耐久性表现。但纤维在水泥基体中存在自身性能劣化及与水泥材料粘结作用低等问题，制约着纤维增韧、增强及阻裂作用有效发挥。基于此，本项目利用多样化纳米材料与技术，以三维密集式铺面耦合纳米-微米多级结构复合纤维改性水泥基材料。基于纤维表面物理化学特性，调控纳米材料生长方式及影响因素，以微米纤维表面原位生长方式构建纤维表面一维密集式及三维耦合式纳米结构，研发了抗劣性良好的纳米氧化锰修饰及多巴胺聚合修饰复合纤维；研究了复合纤维与水泥材料的结合作用，确定了复合纤维与水泥材料的结合强度，实现了二者间的界面结合提升；制备了纳米-微米多级结构复合纤维增强水泥基材料，确定了复合纤维对水泥基材料抗弯、抗拉、抗冲击等性能作用影响，获得了纳米原位修饰纤维增强水泥基胶凝材料的抗收缩、早期抗裂及抗冻等性能影响规律。项目研发的纳米-微米多级结构复合纤维制备条件温和、方法简单稳定，可有效提升纤维抗劣性，改善其与水泥基材料的界面结合，为设计及研发高韧性及高耐久性纤维增强水泥基材料提供了理论指引与技术支持。