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This paper reviews the evaluation of hydration of cement-based materials by means of electrical methods from the view point of direct and alternative current methods. The merits, demerits and application scenarios of electrical methods for hydration characterization are described. Influencing factors (pore solution conductivity, porosity, pore size distribution and pore connectivity) of electrical methods are briefly commented. Besides, the predictions of setting time and shrinkage, and the determination of hydration stages by electrical methods are presented. The combinations of some mainstream computer simulations and electrical methods are reviewed. [ABSTRACT FROM AUTHOR]

This paper presents a preliminary work to evaluate influences of water to cement ratio, hydration age and content of superplasticizer on porosity, volume and surface fractal dimensions of pore structure in 56 groups of calcium sulfoaluminate cement pastes by nitrogen adsorption/desorption (NAD) tests and low temperature differential scanning calorimetry (LT-DSC). Additionally, a fractal sponge model is developed to analyze intrinsic relations among porosity, volume and surface fractal dimensions by changing the removed number of cells, iterate steps and number of fractal cells. [ABSTRACT FROM AUTHOR]

This paper reviews the evaluation of pore structure in cementitious materials by means of electrical impedance methods from the view point of direct and alternative current tests with or without electrodes. Some main equivalent circuit models in the literatures, which are employed to evaluate the pore structure from experimental results of alternating current impedance spectroscopy (ACIS), are discussed. The latest utilization of non-contact resistivity/impedance measurement for the hydration monitoring, pore structure and transportation investigation is presented in this review. The related merits and demerits of ACIS with electrodes and non-contact methods and their application scenarios are also discussed. [ABSTRACT FROM AUTHOR]

Highlights: [•] The permeability of young cement pastes is evaluated using new impedance system. [•] A fractal permeability model based on this measurement is proposed. [•] The permeability value of cement pastes can be measured continuously. [•] A fractal permeability simulation is conducted. [ABSTRACT FROM AUTHOR]