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

本研究提出了一个多尺度模型的发展早期混凝土的多尺度结构的演变。 该模型可以从混凝土的矿物成分、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，介电和机械性能的影响。 一个专门设计的宽带测量系统集成介电谱和力学谱测量将被用来非破坏性地探测多尺度行为。 多尺度模型是一个由水泥水化动力学决定的演化模型，它包含了纳米、微米、介观和宏观尺度的结构特征。 该模型将从基本的物理化学原理出发来描述纳米尺度的混凝土结构。 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。 利用该模型，可以从混凝土的内部性质（如化学和矿物成分）和外部因素（如与周围环境的热交换和水分交换）预测不同尺度下混凝土的早期性能及其演化，从而加深对新拌混凝土性能机理的理解。 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宏观混凝土性能的潜在机制。 这将有助于对混凝土多尺度结构演化的认识。本研究也将为混凝土水化研究提供一种新的光谱工具和测试方法。该仪器具有成本低、无损、能提供真实的实时数据等优点。 本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.