CAREER: SusChEM: Controlling Carbonation Degradation in Sustainable Cements by Stabilizing Amorphous Calcium Carbonate

非技术描述：波特兰水泥生产占全球人为二氧化碳排放量的5-8%，随着混凝土利用率在未来几十年翻一番，迫切需要可持续的混凝土替代品。其中一种替代品是碱活化材料（AAMs），这是一种水泥，其制造过程中排放的二氧化碳比波特兰水泥少。然而，在建筑行业就业之前，必须了解和优化新型胶凝材料的长期耐久性。该项目研究了由于暴露于大气中的二氧化碳而导致的AAMs降解过程中发生的化学反应，这是一种困扰波特兰水泥和新型胶凝材料的降解形式。通过利用镁对碳酸盐基反应产物（无定形碳酸钙）的稳定作用，正在探索阻止降解反应的能力。耐用和可持续胶凝材料的发展将导致可持续产品在住宅和商业建筑行业的实施，这将大大减少相关的二氧化碳排放。该项目通过以新泽西州高中正在制定的新的应用科学/工程课程为中心的外展内容，促进和鼓励代表性不足的少数民族和女性在科学、技术、工程和数学（STEM）领域的发展。技术细节：该项目将提供一个复杂的相形成过程的深刻理解，发生在炭化诱导的渣基AAM浆料的降解。主要目标包括(i)对镁在稳定沉淀的无定形碳酸盐相中的作用有一个基本的了解，（ii）确定无序相的短期和长期稳定性，包括钙（钠）铝硅酸盐水合物凝胶和无定形碳酸盐。通过这项研究，高抗碳化渣基aam正在开发中，它有可能取代现有的水泥技术。为了获得这种理解，正在使用一套最先进的实验技术，包括在前沿研究中培训下一代科学家（本科生和研究生）。技术包括：利用x射线对分布函数分析结合微层析成像获得微米级的原子结构信息，利用纳米荧光、x射线衍射、红外光谱、热分析和同步加速器x射线吸收精细结构进行纳米级元素制图。

NON-TECHNICAL DESCRIPTION: Portland cement manufacturing accounts for 5-8% of global anthropogenic carbon dioxide emissions, and with concrete utilization set to double over the next few decades there is a pressing need for sustainable concrete alternatives. One such alternative is alkali-activated materials (AAMs), a class of cement whose manufacture emits less carbon dioxide than Portland cement. However, the long term durability of new cementitious materials must be understood and optimized prior to employment in the construction industry. This project investigates the chemical reactions that occur during degradation of AAMs due to exposure to atmospheric carbon dioxide, a form of degradation that plagues both Portland cement and new cementitious materials. The ability to arrest the degradation reaction(s) is being explored by exploiting the stabilizing effect of magnesium on the carbonate-based reaction products (amorphous calcium carbonate). The development of durable and sustainable cementitious materials will lead to the implementation of sustainable products in residential and commercial construction industry, which will significantly reduce the associated carbon dioxide emissions. The project promotes and encourages underrepresented minorities and women in science, technology, engineering and mathematics (STEM) through outreach components centered on the new applied science/engineering curriculum that is being instituted in high schools in New Jersey.TECHNICAL DETAILS: This project will provide a deep understanding of the complex phase formation processes that occur during carbonation-induced degradation of slag-based AAM pastes. Key objectives include (i) obtaining a fundamental understanding of the role of magnesium in stabilizing the precipitated amorphous carbonate phase and (ii) determining the short and long-term stability of the disordered phases, including calcium-(sodium)-alumino-silicate-hydrate gel and amorphous carbonates. Highly carbonation-resistant slag-based AAMs are being developed through this research, which have the potential to supplant existing cement technologies. To obtain this understanding a suite of state-of-the-art experimental techniques are being used, including training the next generation of scientists (undergraduate and graduate students) in cutting-edge research. Techniques include: micron-resolved atomic structural information obtained using X-ray pair distribution function analysis combined with micro-tomography, nanoscale elemental mapping using nano-fluorescence, X-ray diffraction, infrared spectroscopy, thermal analysis and synchrotron X-ray absorption fine structure.