SBIR Phase I: Economically Viable High-Performance Concrete Nanocomposites

这个小型企业创新研究一期项目将补充使用相对低成本的石墨纳米材料和常规微纤维，以实现高性能混凝土各种工程性能的平衡收益。靶向纳米材料以极低的成本提供了碳纳米管的大部分几何和性能优势；它们还提供了相对较高浓度的表面官能团，这有利于它们在混凝土中的分散和界面相互作用。混凝土结构和施工实践的特殊性对纳米级钢筋的有效使用提出了独特的挑战。这些挑战将通过改善胶凝材料的粒度分布、减小毛细孔大小和含量、降低水泥水合物中微米级结晶产物的存在以及使用聚电解质和高分子表面活性剂对纳米材料表面进行改性来解决。这些措施使用了经济上可行的材料和方法，通常用于高性能混凝土和纳米材料。拟议的项目将：(I)确定具有成本效益的纳米和微米级钢筋的补充选择、表面改性条件和剂量，以及混凝土配合比设计；(Ii)开发一个理论框架，解释纳米材料在混凝土中的增强作用；(Iii)评估高性能混凝土纳米复合材料的商业优点和优先应用。本项目的更广泛的影响/商业潜力得益于使用经济上可行的纳米级和混合加固系统在混凝土基础设施的安全性(在爆炸、火灾和地震下)、结构性能和耐久性(耐候性和耐磨性，以及疲劳寿命)方面取得的重大进展。新的增强系统给混凝土带来的好处远远超过传统(微米级)纤维的改善程度和受影响的性能范围。所选纳米材料的高增强效率、相对较低的成本和工业规模的可获得性使它们相对于传统纤维具有很强的成本竞争力。新的混合增强在广泛的质量和性价比方面提供了显著的改进，超过了每个增强系统单独提供的性能价格比。混杂增强的高性能混凝土材料提供了前所未有的质量平衡，有助于将其市场扩展到传统纤维以外的市场，影响到混凝土外加剂(包括纤维)的更广泛市场。高性能混凝土纳米复合材料的优先应用实例包括关键任务基础设施系统(保护性掩体、危险/核废物遏制系统、核电站)、交通基础设施的关键部件(桥梁、隧道)以及水力和下水道基础设施的关键部件。

This Small Business Innovation Research Phase I project will make complementary use of relatively low-cost graphite nanomaterials and conventional microfibers to realize balanced gains in diverse engineering properties of high-performance concrete. The targeted nanomaterials offer most of the geometric and performance advantages of carbon nanotubes at substantially reduced cost; they also provide a relatively high concentration of surface functional groups, which facilitate their dispersion and interfacial interactions in concrete. The peculiarities of concrete structure and construction practices impose unique challenges for the effective use of nano-scale reinforcement. These challenges will be addressed through refinement of the particle size distribution of cementitious materials, reduction of the capillary pore size and content, lowering the presence of micro-scale crystalline products among cement hydrates, and modification of nanomaterial surfaces using polyelectrolytes and high-molecular-weight surfactants. These measures employ economically viable materials and methods commonly used with high-performance concrete and nanomaterials. The proposed project will: (i) identify complementary selections, surface modification conditions and dosages of nano- and micro-scale reinforcement, and concrete mix designs which are cost-effective; (ii) develop a theoretical framework to explain the reinforcing action of nanomaterials in concrete; and (iii) assess the commercial merits and priority applications of high-performance concrete nanocomposites.The broader impact/commercial potential of this project draws upon major gains in the safety (under explosion, fire and earthquake), structural performance and durability (weathering and abrasion/erosion resistance, and fatigue life) of the concrete-based infrastructure resulting from the use of economically viable nano-scale and hybrid reinforcement systems. The benefits rendered to concrete by the new reinforcement system far surpass those of conventional (micro-scale) fibers in terms of both the extent of improvements and the range of properties impacted. The high reinforcement efficiency and the relatively low cost and industrial-scale availability of the selected nanomaterials make them highly cost-competitive against conventional fibers. The new hybrid reinforcement offers pronounced gains in a wide range of qualities, and performance-to-cost ratios surpassing those rendered by each reinforcement system alone. The unprecedented balance of qualities provided by high-performance concrete materials with hybrid reinforcement helps expand their markets beyond those of conventional fibers, impacting broader markets for concrete admixtures (including fibers). Examples of priority applications for high-performance concrete nanocomposites include mission-critical infrastructure systems (protective shelters, hazardous/nuclear waste containment systems, nuclear power plants), key components of the transportation infrastructure (bridges, tunnels), and critical elements of the hydraulic and sewer infrastructure.