Durability of short carbon fiber reinforced cement-based materials during exposure to chemical attack

摘要--短碳纤维增强水泥基材料在化学侵蚀下的耐久性。桑切斯混凝土的退化是美国经济的一大负担。复合材料一直被认为是打破老化基础设施恶化循环的一种手段，其基础是表现出的耐腐蚀性、对裂纹扩展的控制和提高的强度/重量比。在这些复合材料中，短碳纤维混凝土还表现出额外的性能增强，包括增加电磁干扰屏蔽、传感内部应变、自我监测机械损伤、传感温度变化和热激励。由于这些多功能材料的吸引人的特性，以及它们在改善基础设施健康和功能方面所起的关键作用，更好地了解它们的长期耐久性是很重要的。本研究的目的是研究(I)化学侵蚀对碳纤维混凝土微观结构和形态的影响，以及(Ii)碳纤维和胶凝材料界面的微观结构和形态的变化如何反过来影响材料的宏观力学和物理性能，包括强度、导电性和耐久性。将使用最先进的物理(表面积、微孔率、孔结构三维成像和先进的热分析)和化学(元素组成、固相矿物学和形态)技术和传统耐久性测试来(I)表征不同条件下(“原始”、表面处理后和水化反应期间)碳纤维的表面，(Ii)量化碳纤维-水泥界面和散装水泥浆体在脱钙过程中的物理和化学变化，并将其与观察到的宏观性能相关联。这项拟议的研究将标志着朝着了解如何进一步提高碳纤维增强水泥基材料的性能迈出了关键的一步。教育外展将通过与当地教育工作者和教育专家的伙伴关系，向小学教师和学生提供对土木工程学习和研究及其对社会的好处的更多了解，并将涉及为市中心、初中生和高中生开发适合年龄的教学模块。

Abstract - Durability of short carbon fiber reinforced cement-based materials during exposure to chemical attackF. SanchezConcrete degradation is a large burden on the US economy. Composite materials have been advocated as a means to break this cycle of deterioration in aging infrastructure based on demonstrated corrosion resistance, control of crack propagation, and increased strength-to-weight ratios. Among these composite materials, short carbon fiber reinforced concrete has shown additional property enhancements including increased electromagnetic interference shielding, capability of sensing internal strain, self-monitoring of mechanical damage, sensing of temperature changes, and thermal actuation. Due to the appealing properties of these multifunctional materials and the critical role that they can play in improving infrastructural health and function, it is important to gain a better understanding of their long-term durability. The goal of this research is to investigate (i) the effect of exposure to chemical attack on the microstructure and morphology of carbon fiber reinforced concrete and (ii) how microstructural and morphological changes at the interface between the carbon fibers and the cementitious material in turn affect the macro scale mechanical and physical properties of the material, including strength, electrical conductivity, and durability. State-of-the-art physical (surface area, microporosity, 3-D imaging of pore structure, and advanced thermal analysis) and chemical (elemental composition and solid phase mineralogy and morphology) techniques and traditional durability testing will be used to (i) characterize the surface of the carbon fibers under different conditions ("as-received," after surface treatment, and during hydration reaction), (ii) quantify and relate the physical and chemical changes of the carbon fiber-cement interface and of the bulk cement paste during decalcification to observed macro scale properties. The proposed research will mark a critical step towards understanding how to further enhance the performance of carbon fiber reinforced cement-based materials. Educational outreach will provide an increased appreciation of civil engineering study and research and its benefits to society to primary education teachers and students through partnership with local educators and education experts and will involve development of age-appropriate teaching modules for inner-city, middle and high school students.