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

非技术描述：波特兰水泥制造业占全球人为二氧化碳排放量的5%-8%，随着混凝土使用量在未来几十年翻一番，对可持续混凝土替代品的迫切需求。碱激活材料(AAM)就是这样一种替代材料，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，在建筑行业使用之前，必须了解和优化新型胶凝材料的长期耐久性。该项目调查了由于暴露在大气二氧化碳中而导致的AAM降解过程中发生的化学反应，这种降解形式困扰着波特兰水泥和新型胶凝材料。通过利用镁对碳酸盐反应产物(无定形碳酸钙)的稳定作用，正在探索阻止降解反应的能力(S)。耐久和可持续胶凝材料的发展将导致住宅和商业建筑行业实施可持续产品，从而显著减少与之相关的二氧化碳排放。该项目通过以新泽西州高中正在实施的新的应用科学/工程课程为中心的外展部分，促进和鼓励科学、技术、工程和数学(STEM)领域中代表性不足的少数民族和女性。技术细节：该项目将提供对碳化导致矿渣基AAM浆料降解过程中发生的复杂相态形成过程的深刻理解。主要目标包括：(1)从根本上了解镁在稳定无定形碳酸盐沉淀相中的作用；(2)确定无序相，包括钙(钠)铝硅酸盐水合物和无定形碳酸盐的短期和长期稳定性。通过这项研究，正在开发高度抗碳化的矿渣AAM，它们有可能取代现有的水泥技术。为了获得这一理解，正在使用一套最先进的实验技术，包括培训下一代科学家(本科生和研究生)进行尖端研究。技术包括：利用X射线对分布函数分析结合显微断层成像获得微米分辨的原子结构信息，利用纳米荧光、X射线衍射、红外光谱、热分析和同步辐射X射线吸收精细结构获得纳米级元素图谱。

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.