Permittivity is a widespread property used to estimate the water content in concrete. To improve the reverse conversion from permittivity measurements to moisture content, we suggest the building of an electromagnetic model of concrete. In this paper, such a model is developed for the case of cement pastes. It relies on electromagnetic homogenization schemes which require an information about the permittivity of the predominant species in the material. Estimating those properties over the frequency range [200 MHz; 1 GHz] was achieved by synthesizing model cementitious binders (C-S-H and portlandite mixtures), by characterizing their macroscopic permittivity with an open-ended coaxial probe and by identifying their intrinsic permittivity with a specific homogenization procedure combining effective medium equations. The identified values are used as inputs for a homogenization procedure estimating the water content in cement pastes. For a wide range of water content, the simulated and measured real parts of permittivity show a good agreement.

介电常数是用于估计混凝土中水含量的广泛特性。为了提高从介电常数测量值到水分含量的反向转换，我们建议建立混凝土的电磁模型。在本文中，针对水泥浆情况开发了这种模型。它依赖于电磁均质化方案，该方案需要有关材料中主要物质的介电常数的信息。在[200 MHz]频率范围内估算这些特性 通过合成模型胶结粘合剂（CSH和波特兰石混合物），使用开放式同轴探针表征其宏观介电常数以及通过结合有效介质方程式的特定均化程序来识别其固有介电常数，可以实现1 GHz]。所识别的值用作均化程序的输入，以估计水泥浆中的水含量。对于广泛的水含量，介电常数的模拟和实测值显示出良好的一致性。