Hydration Of Cementitious Systems Research Articles

Preparation of nano cement particles by wet-grinding and its effect on hydration of cementitious system

In this study, nano cement particles (Nano-C) were prepared via wet grinding cement. Nano-C was characterized by laser particle size distribution, X-ray diffraction (XRD), Thermogravimetric analysis (TGA), Scanning electron microscope (SEM), Transmission electron microscope (TEM) and 29Si magic-angle spinning nuclear magnetic resonance (29Si MAS NMR). The particle size of Nano-C was D50 = 53.1 nm. In order to disperse the nano particles, polycarboxylate superplasticizer was used in the process of grinding. The results show that 0.5%, 1.0%, 2.0%, and 4.0% Nano-C could increase the 12-h compressive strength by 49%, 109%, 194% and 197%, in comparison with the reference. The influence of Nano-C on the hydration, hydration products, microstructure was tested by means of hydration heat, chemical shrinkage, XRD, Thermogravimetric analysis (TGA), SEM, 29Si MAS NMR, and Mercury injection porosimetry (MIP). The results revealed that Nano-C not only used as distinguished nucleus seed to enhance the PC system hydration but also exhibited high hydration activity to produce C-S-H gel to further raise the PC hydration up. These findings provided a novel way to prepare nanomaterials, which was expected to provide a way to improve the early strength of precast concrete.

Hydration of Synthetized Clinker Phases C<sub>3</sub>S and C<sub>3</sub>A with Metakaolin in Isothermal Conditions

Heat flow development during initial hydration of fresh pastes based on mixtures of pure clinker phases C3S and C3A with metakaolin was investigated by means of isothermal calorimetry. Phase composition development was examined by "in situ" X-ray diffraction technique. Obtained results from calorimetric measurements and X-ray diffraction were correlated with recent studies in field of hydration of cementitious systems. The effect of co-sintering of clinker phases on early hydration was characterized by isothermal calorimetry.

Initial hydration of cementitious systems using a simple isothermal calorimeter and dynamic correction

A simple isothermal calorimeter ideal to study hydration of cementitious systems is described together with an ampoule design to allow addition of water and mixing with the ampoule inside the calorimeter. An overview of dynamic corrections is given, and the utilisation of the different dynamic corrections on the calorimeter output is discussed. Correction of data on b-hemihydrate hydration to form gypsum has shown good kinetic agreement with data from synchrotron X-ray diffraction.