Structural Formation of the Cement Pastes Based on the Concrete Modified Dispersed Mineral Components

Abstract

With the increase in the number of finely dispersed mineral additives in concrete, their water demand increases and the effect of micro-filling weakens. To solve this problem, various methods of dry surface modification are proposed. As a result of the finely dispersed mineral powders’ surface modification, an improvement in their rheological characteristics, a decrease in wettability, a change in granulometry and other properties are achieved. This article discusses the surface modification effect’s laws in a high-voltage electric field on the autogenous properties of mineral dispersed concrete components, structure formation processes, mechanical properties, and cement stone hydration products. According to the results of the study, it was found that the surface modification of bulk materials - concrete components - in a high-voltage electric field changes autohesion properties in comparison with control samples. The data indicate lower values ​​of bulk density and angle of repose. This is due to a change in the balance of forces that arise during the mutual contact of particles after surface modification. With a certain balance of these forces, autohesion will contribute to the dense packing of particles and thereby affect the structure formation processes. The results of changes in the plastic strength of cement pastes confirm that there is an intensification of the structure formation process. Moreover, a more intense increase in plastic strength is observed during bipolar charging of particles in comparison with unipolar charging. This is due to an increase in the number of heterogeneous charges in the system and, as a consequence, an increase in the strength of adhesive contacts, as evidenced by the data of X-ray phase analysis.