固废原位矿化二氧化碳的离子析出机制和矿相界面特性研究

Given the urgent and wide demand of carbon emission and solid waste reduction, this project presents an in-situ CO2 mineralization route based on solid waste conversion, to produce low-carbon and high performance building materials. In light of the low conversion efficiency and unclear microscope reaction mechanism in CO2 mineralization, the ion leaching mechanism and mineral interface evolution process of cementitious materials with multiple minerals are the key scientific issues in this project. The specific leaching and carbonation properties of different silicate minerals would be systematically investigated under mild temperature and pore water environment. The carbonation reaction path would be depicted and the interactional of minerals would be studied, as well as thermodynamics of CO2 mineralization. Based on the multi-scale analysis, the structural characteristics and evolution mechanism of mineral interface during the reaction would also be studied through advanced characterization technologies. The microscale properties of carbonation interface would be linked to the physical properties of concrete. The effect of different mineral interfaces (from different minerals, reaction condition and solid wastes) on mechanical and thermal properties would be investigated to get the regulation method of material performance. Based on the systematical investigation on reaction, interface and physical properties of in-situ CO2 mineralization, this project would contribute fundamental knowledge for optimizations of formula (solid waste cementitious material) and mineralization process.

面向二氧化碳、固废大规模减排的国家或区域重大需求，本项目提出基于固废的原位矿化CO2技术，并副产高性能的绿色建材产品。针对矿化过程中转化效率低、微观反应机制不清等问题，本项目将围绕复杂矿相聚合体系在CO2原位矿化过程中的离子析出机制和界面演变两个关键科学问题展开研究：系统考察胶凝材料体系中多种硅酸盐矿物在常温、孔隙水等环境下的独特离子析出机制及碳酸化特性，刻画碳酸化路径并探究不同矿物交互影响机制，建立反应热力学体系。通过微观-宏观多尺度分析，采用先进测试手段对特定矿相界面的结构特性及矿化中演变规律进行细致刻画；将界面微尺度特性投射到宏观物性，系统探索不同矿物种类、反应工况及固废原料矿化形成的矿相界面对力学和热物性的影响规律，获得材料物性定向调控方法。本项目通过矿化反应过程-微观界面-宏观物性的系统研究，有望为后续工艺层面的固废基胶凝材料配方和矿化反应过程优化提供重要理论指导。

面向二氧化碳、固废大规模减排的国家或区域重大需求，本项目提出基于固废的直接矿化CO2技术，并副产高性能的绿色建材产品。针对矿化过程中转化效率低、微观反应机制不清等问题，本项目解决了以下两个关键科学问题：复杂矿相体系在CO2矿化过程中的离子析出机制和界面特性。首先系统研究了胶凝材料体系中硅酸三钙（C3S）、硅酸二钙（β-C2S和γ-C2S）、硅酸一钙（CS）等矿物的独特离子析出机制及碳酸化特性，探究了在不同分散状态下的硅酸钙矿物间的交互影响机制。通过精密量热实验，得到了不同复合胶凝材料的反应热。通过对水泥和不同种类工业固废的矿化反应体系热力学进行分析，建立了固碳率与矿物组分的线性关联模型。此外，通过微观-宏观多尺度分析，对矿化转化特性和矿相界面结构特性进行了细致的刻画。基于对不同矿物种类、反应工况对微观界面特性和宏观物性的影响的探究，发现了固碳率和气体扩散通道与抗压强度的关联关系，获得了有效的建材产品的物性调控方法。通过矿化反应-微观界面-宏观物性的系统研究，本项目为矿化固废工业应用中的配方和工艺优化提供了新思路和新方法，并为2020年在河南焦作进行的国内首个万吨级CO2矿化养护制建材工业示范提供了重要的理论指导。