SBIR Phase II: Low-Cost Glass Fiber Composites Tailored Towards Concrete Reinforcement

这个小型企业创新研究（SBIR）二期项目将用离子交换剂改进玻璃纤维复合材料的聚合物基体，以提高其在混凝土碱性环境中的使用寿命。玻璃纤维复合材料为混凝土中易腐蚀的钢筋的替代提供了性能和成本的理想平衡；然而，它们在混凝土的碱性环境中迅速恶化是一个重大挫折。离子交换剂是携带阳离子（或阴离子）的不溶性固体，可与同符号的离子交换。氢形式的阳离子交换剂用H +取代碱金属阳离子（例如，碱溶液中扩散到聚合物基体中的K +）。这种阳离子交换通过将K + OH -（和Na + OH -等）转化为H2O来中和腐蚀性碱性溶液。通过实验室调查和工业规模的拉挤试验，第一阶段的研究表明，在聚合物基体（或基体的表层）中引入选定的离子交换剂不会干扰拉挤过程，并且可以显著提高玻璃纤维复合材料的耐碱性能。第一阶段的研究还为玻璃纤维复合材料聚合物基质中阳离子交换剂用量的选择建立了理论背景，并验证了我们方法的经济可行性。拟议的第二期项目将：(1)为离子交换剂聚合物基质的配方制定完善的理论原则和设计程序；(2)开发并实验验证含离子交换剂的最佳聚合物基质配方；(3)利用精制聚合物体系对玻璃纤维复合材料的拉挤工艺进行优化，并对最终产品进行充分表征；(4)通过综合实验室研究，结合钢筋混凝土桥面设计、施工和监测的现场调查，评估用精制玻璃纤维复合棒加固的混凝土体系的结构性能和耐久性。二期工程将得到主要复合钢筋制造商（包括该领域的全球领导者休斯兄弟公司）、离子交换剂的主要供应商（陶氏化学公司）、密歇根州交通部和密歇根州经济发展公司的大力支持。密歇根州立大学（复合材料和结构中心）也将参与拟议的研究工作。近三分之一的钢筋混凝土结构，包括桥梁、停车场结构、沿海地区建筑物和近海结构，暴露于腐蚀性环境（除冰盐、海水喷雾等）；用于加固这些混凝土结构的钢材的国内销售额约为每年20亿美元。体现我们技术的玻璃纤维复合材料既能抵抗混凝土的腐蚀作用，又能抵抗混凝土的碱性环境；它们提供了性能和成本的理想平衡，在腐蚀性环境中取代钢筋。在腐蚀环境下的混凝土结构中，通过用耐碱玻璃纤维复合材料代替钢筋，可以在具有竞争力的初始成本下实现生命周期成本的主要节省。用于修复/修复目的的混凝土表面的玻璃纤维复合材料护套和板也容易受到混凝土碱性孔隙溶液的攻击，这代表了我们技术的另一个市场机会。我们已经提交了专利申请，并与陶氏化学（离子交换剂的领先供应商）和休斯兄弟（世界领先的混凝土加固复合棒制造商）达成协议，将技术转移到市场上。

This Small Business Innovation Research (SBIR) Phase II project will refine the polymer matrix of glass fiber composites with ion exchangers in order to enhance their longevity in the alkaline environment of concrete. Glass fiber composites offer a desirable balance of performance and cost for replacement of corrosion-prone steel reinforcement in concrete; their rapid deterioration in the alkaline environment of concrete is, however, a major setback. Ion exchangers are insoluble solids carrying cations (or anions) which can be exchanged with ions of the same sign. Cation exchangers of hydrogen form replace alkali metal cations (e.g., K + in alkaline solutions diffusing into the polymer matrix) with H + . This exchange of cations neutralizes aggressive alkaline solutions by converting K + OH - (and Na + OH - , etc.) into H2O. Through laboratory investigations and industrial-scale pultrusion efforts, the Phase I research demonstrated that introduction of selected ion exchangers into the polymer matrix (or a surface layer of matrix) does not interfere with the pultrusion process, and yields significant gains in alkali resistance of glass fiber composites. The Phase I effort also established a theoretical context for selection of the dosage of cation exchanger in the polymer matrix of glass fiber composites, and verified the economic viability of our approach. The proposed Phase II project will: (1) develop refined theoretical principles and design procedures for formulation of polymer matrices with ion exchangers; (2) develop and experimentally verify optimum polymer matrix formulations incorporating ion exchangers; (3) optimize the pultrusion process of glass fiber composites with the refined polymer system, and fully characterize the end products; and (4) evaluate the structural performance and durability of concrete systems reinforced with refined glass fiber composite bars through comprehensive laboratory studies complemented with a field investigation involving design, construction and monitoring of a reinforced concrete bridge deck. The Phase II effort will receive critical support from major manufacturers of composite rebars (including Hughes Brothers, the world leader in this field), the leading supplier of ion exchangers (Dow Chemical), Michigan Department of Transportation, and Michigan Economic Development Corporation. Michigan State University (Composite Materials & Structures Center) will also take part in the proposed research effort.Close to one-third of reinforced concrete structures, including bridges, parking structures, buildings in coastal areas and offshore structures, are exposed to corrosive environments (deicer salt, seawater spray, etc.); domestic sales of steel for reinforcement of these concrete structures is about $2 billion/yr. Glass fiber composites embodying our technology are resistant to both corrosive effects and the alkaline environment of concrete; they offer a desirable balance of performance and cost to replace steel reinforcement in corrosive environments. Major savings in life-cycle cost can be realized at competitive initial cost through replacement of steel reinforcement with alkali-resistant glass fiber composites in concrete structures exposed to corrosive environments. Glass fiber composite jackets and sheets applied onto concrete surfaces for repair/rehabilitation purposes are also prone to attack by the alkaline pore solution of concrete, representing another market opportunity for our technology. We have filed a patent application, and have reached agreements with Dow Chemical (leading supplier of ion exchangers) and Hughes Brothers (world's leading manufacturer of composite bars for concrete reinforcement) towards transfer of the technology to marketplace.