可循环水泥混凝土材料设计、制备及其性能调控

The shortage of high-quality raw materials for cement manufacturing and the disposal of huge amounts of waste concrete are two major problems facing by the building industry in China. In this project, the design criteria for multi-objective coupled concrete systems based on recyclability, mechanical properties and durability are studied and established, and ecological concrete for sustainable recycling is designed and prepared. The cement raw material system of the circulatory system is studied to determine the judging index of the cement raw material system. The calcinations mechanism of cement clinker containing multiple complex components was studied, and then reclaimed cement clinker was prepared stably. The hydration characteristics, microstructure formation and development rule of the recyclable cement concrete were studied. The performance evaluation system for cement and concrete was established and methods of recycled cement and concrete systems were revealed. The project relies on the overall planning and design of recyclable cement concrete to achieve the sustainable recycling of cement and concrete. It not only provides a brand-new approach for green sustainable development of building materials, but also lays a solid theoretical foundation for technological innovation in the field of cement and concrete.

水泥生产优质原料日益匮乏和废弃混凝土逐年递增是我国建材工业目前面临的两大突出问题。项目提出可持续循环水泥混凝土材料体系设计理念，设计制备出可持续循环利用混凝土；研究可循环系统水泥生料体系，确定废弃混凝土进入水泥生料体系的评判指标，探索含多元复杂组分水泥熟料的煅烧机理，进而稳定制备再生水泥熟料；分析可循环水泥混凝土再生水泥的水化特性、水泥石微结构形成与发展规律，建立循环再生水泥及混凝土的性能评价体系，揭示循环再生水泥及混凝土的性能调控机制与方法。项目依托可循环水泥混凝土的整体规划设计，实现水泥与混凝土的可持续循环利用，不仅为建筑材料绿色可持续发展提供了全新的途径，也为水泥及混凝土领域的技术革新奠定了坚实的理论基础。

水泥生产优质原料日益匮乏和废弃混凝土逐年递增是我国建材工业目前面临的两大突出问题。项目基于可持续循环水泥混凝土材料体系设计理念，利用机制砂（钙源）替代部分河砂、钢渣（铁源）和粉煤灰（铝源）复掺替代部分水泥，设计制备出类水泥生料组分的C40可循环混凝土并研究其抗压强度、抗渗性能等性能指标。结果表明，虽然可循环混凝土的早期力学性能会有下降，但具有良好的后期强度发展与耐久性。.项目制备的可循环混凝土与水泥生料组成组分类似，在废弃后可以直接或仅需少量校正原料即可制备再生水泥，并且煅烧温度较传统生料降低约50℃。综合考虑可循环混凝土的综合性能与再生水泥的水化硬化特性，研究提出了适应于可持续循环混凝土用于水泥生料配料的率值设计范围；探明了含多元复杂组分的水泥生料体系，特别是硬化水泥石的高温分解特性与掺量，对熟料煅烧过程中易烧性与再生水泥熟料性能的影响机理。结果表明，硬化水泥石替代部分硅酸盐水泥生料会降低液相出现的温度与C3S的表观活化能，但也会稳定C2S的晶型导致C3S形成困难，同时使C3S的晶型由R型向M型转变。分析了可循环水泥混凝土再生水泥的水化特性、水泥石微结构形成与发展规律，低温煅烧得到的水泥虽然早期水化较慢，但在后期表现出了较高的水化能力。.最后研究了“再生水泥-混凝土-再生水泥”多次循环过程中水泥熟料的基本性能演变规律，相较于第一次循环得到的熟料，后三次循环得到的熟料中C3S含量分别减少了11.10%、37.78%和51.99%，导致再生水泥累计水化放热量以及制备的砂浆的力学强度逐步降低。揭示了影响可循环混凝土制备水泥循环次数的关键因素，主要为生料中未水化水泥颗粒的含量。