Dielectric and Mechanical Spectra Assisted Multi-Scale Study of Early Stage Concrete

本研究提出了早期混凝土多尺度结构演化的多尺度模型。该模型可以根据混凝土的矿物组成、化学成分和宏观养护环境来预测混凝土的性能。将进行实验，以研究混凝土成分对其物理、介电和力学性能的影响。利用专门设计的结合介电光谱和机械光谱测量的宽带测量系统，非破坏性地探测多尺度行为。包含纳米、微观、细观和宏观结构特征的多尺度模型将是一个由水泥水化动力学决定其生长速度的演化模型。该模型将从基本的物理化学原理出发来描述纳米混凝土结构。利用化学反应理论和扩散理论建立不同尺度下模型间的传递函数。利用该多尺度模型，可以从混凝土的内在特性(如化学和矿物组成)和外部因素(如与周围环境的温度和湿度交换)来预测早期混凝土在不同尺度上的行为及其演变。如果成功，本研究结果将有助于加深对新拌混凝土行为的机理理解。这将对水化现象的理解和模型描述做出独特的贡献。多尺度方法有助于揭示混凝土宏观性质的潜在机制。这将有助于了解混凝土多尺度结构的演变情况。本研究还将为混凝土水化的研究提供一种新的光谱工具和测试方法。该工具具有价格低廉、无损、提供实时数据等优点。这项研究的成功实施将有助于建设高质量的基础设施，并显着改善目前的设计和施工实践。

This research proposes the development of a multi-scale model for the evolution of multi-scale structure of early stage concrete. This model can predict concrete behaviors from its mineral and chemical constituents and macro curing environment. Experiments will be conducted to investigate the effects of concrete constituents on their physical, dielectric and mechanical behaviors. A special designed broadband measurement system integrating the dielectric spectrum and mechanical spectra measurement will be utilized to non-destructively probe the multi-scale behaviors. The multi-scale model, which embraces nano, micro, meso, and macro scale structural characteristics, will be an evolutional model whose growth rate is decided by cement hydration kinetics. The model will start from fundamental physical-chemical principles to describe the nano-scale concrete structures. The chemical reaction theory and diffusion theory will be utilized to establish the transfer functions between models at different scales. By use of this multi-scale model, the behaviors of early stage concrete at different scales and their evolution can be predicted from the inherent properties (such as the chemical and mineral constituents) and the external factors (such as thermal and moisture exchange with the surrounding environment).If successful, the results of this research will lead to enhanced mechanism understand of fresh concrete behaviors. It will make distinctive contribution to the understanding and model description of hydration phenomena. The multi-scale approach helps to unveil the underlying mechanism for macroscopic concrete properties. It will contribute to the state of knowledge on the evolution of the multi-scale structure of concrete. This research will also provide a new spectra tool and test methodology for study concrete hydrations. The tool features the advantage of being inexpensive, non-destructive and providing real time data. Successful implementation of this research will contribute to the construction of high quality infrastructure and significantly improve the current design and construction practice.