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.

Development of High-Tech Self-Compacting Concrete Mixtures Based on Nano-Modifiers of Various Types

“…determination of the characteristics of the initial raw materials by standardized methods for binder and aggregates and research methods of laser granulometry for nanomodifying additives; -determination of the technological characteristics of concrete mixes by standardized methods with verification of the results by the author's method; -determination of the characteristics of the resulting concrete by standardized methods [46][47][48][49][50][51][52][53][54][55][56].…”

Microfiller Influence on the Modified Cement Granulometric Composition

“…According to the literature data [6], the specific surface area measured by the nitrogen adsorption method varies within 18 ... 25 m 2 /g due to the high cost of silica dust, which, as a rule, exceeds the cost of cement in various European countries -by 2-3 times. In this regard, it is advisable to combine microsilica with other mineral additives -ash, slag, which ensures the production of concretes with the required quality indicators both in the early and late periods of hardening [8][9][10][11][12][13].…”