Influence of mechanochemical activation on the cement hydration features

 Nowadays along with the usage of various additives to the concrete mix, the activation of the binder is a promising method to enhance the physical and mechanical properties of the cement concrete. The given paper presents the results of the influence of a mechanochemical activation of cement slurry on the technological properties of the concrete mix and physico-mechanical properties of heavy concrete. The figures of a pore structure of heavy concrete, frost resistance and the coefficient of sulphate cement compositions have been obtained. It is shown that the severe frost resistance of concrete prepared by means of a mechanochemical activation of the binder increases by three times (to the mark F600). This is due to a decrease in the total porosity of 39%, a decrease in capillary porosity of 74.8% and the proportion of closed pores increase by 53% in comparison with the control composition. X-ray diffraction and differential scanning calorimetry investigations have shown that the phase composition of cement paste at the age of 1 day, normal-humidity hardening, obtained by means of a mechanochemical activation of the binder is characterized by a high content of calcium hydroxide (Ca(OH)2) (12 %), high content of ettringite (Ca6Al2(SO4)3(OH)12*26H2O) – 13 %, and the lowest content of the initial phases of Portland cement clinker (16%), which causes high physical and mechanical properties of the resulting composite. The production of cement concrete with a high rate of hardening will reduce the holding time of the concrete in the formwork, to reduce or eliminate the heat treatment, which is relevant in terms of efficient use of energy and resources.