SBIR Phase I: Microwave Molecular Dynamics of Bound Water in Hydrating Cements

这个小企业创新研究（SBIR）第一阶段项目将展示通过宽带介电常数测量观察到的束缚水介电松弛与波特兰水泥水化程度之间的相关性，并将结果应用于公司正在开发的混凝土养护监测系统的改进。在10 kHz至10 GHz的频率范围内，水泥的复介电常数表现出以下信号成分：1)在10 GHz附近的自由水行为，在固化期间随水化百分比下降，2)在1-1000 MHz之间的结合水行为，在固化初期增加，之后减小并变宽。结合水松弛并不出现在最初的水泥浆中，但在几个小时的固化后确实出现了，反映了它所附着的水化产物的形成。这种行为将通过改变初始化学和确定对信号的影响，量化弛豫频率和振幅随固化时间的变化以及拟合适当的模型来阐明。这个项目的商业潜力在建筑行业。

This Small Business Innovation Research (SBIR) Phase I project will demonstrate the correlation between bound-water dielectric relaxation observed by broadband permittivity measurement and the degree of hydration in Portland cement, and apply the results to the refinement of a concrete cure monitoring system under development at the company. Complex permittivity over the frequency range 10 kHz to 10 GHz in curing cement shows signal components due to 1) free-water behavior near 10 GHz which decreases during cure and follows percent hydration, and 2) bound-water behavior between 1-1000 MHz which increases during early hours of cure and decreases and broadens thereafter. The bound-water relaxation does not appear in the initial cement paste but does appear after several hours of cure, mirroring the formation of hydration products to which it is attaching. This behavior will be elucidated by varying initial chemistry and determining effects on signal, quantifying changes in relaxation frequency and amplitude with cure time and fitting to appropriate models. The commercial potential of this project is in the construction industry.