SBIR Phase I: Economically Viable High-Performance Concrete Nanocomposites

这个小企业创新研究第一阶段项目将互补使用相对低成本的石墨纳米材料和传统的微纤维，以实现高性能混凝土各种工程性能的平衡增益。目标纳米材料具有碳纳米管的大部分几何和性能优势，且成本大大降低；它们还提供了相对高浓度的表面官能团，这有助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。这些挑战将通过细化胶凝材料的粒径分布、减小毛细管孔径和含量、降低水泥水合物中微尺度结晶产物的存在，以及使用聚电解质和高分子量表面活性剂对纳米材料表面进行改性来解决。这些措施采用经济可行的材料和方法，通常用于高性能混凝土和纳米材料。拟议的项目将：(i)确定互补选择、表面改性条件和纳米和微观尺度钢筋的剂量，以及具有成本效益的混凝土混合设计；（ii）建立一个理论框架来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价值和优先应用。由于使用经济上可行的纳米级和混合加固系统，该项目在安全性（爆炸、火灾和地震）、结构性能和耐久性（风化、磨损/侵蚀和疲劳寿命）方面取得了重大进展，因此该项目具有更广泛的影响/商业潜力。在改善程度和性能影响范围方面，新增强体系对混凝土的好处远远超过传统（微尺度）纤维。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用性使它们与传统纤维相比具有很强的成本竞争力。新型混合强化材料在广泛的质量范围内提供了显著的收益，性能与成本比超过了单独使用每种强化系统的效果。混合钢筋的高性能混凝土材料提供了前所未有的质量平衡，有助于扩大其市场，超越传统纤维，影响混凝土外加剂（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示例包括关键任务基础设施系统（防护掩体、危险/核废料密封系统、核电站）、交通基础设施的关键组件（桥梁、隧道）以及水利和下水道基础设施的关键元件。

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.