Reactive powder concrete based on multicomponent cement systems with multilevel optimization of the disperse composition

Abstract

This paper study the process of multilevel optimization of particulate structure of concrete. The improvement of performance characteristics of concrete can be achieved with a minimum binder content. Theoretical and experimental principles for the design of an optimal structure of concrete with an increased concentration of solid phase and operational characteristics, with a complex organo-mineral additive are developed on the basis of a rational proportion of chemical and finely dispersed mineral components. The high density of the structure is achieved by obtaining the dense packages by applying strong particles and grains with high elastic modulus and optimal parameters (dispersion and content) for each structural level. It is shown that it is expedient to use several structural levels of the particles of the clinker phase, and pozzolanization of the matrix must be carried out in accordance with the optimal formulation. Finely-dispersed slag, microsilica and highly dispersed fraction of cement were considered as mineral components, and superplasticizer of polycarboxylate type was used as a chemical additive.

Reactive Powder Concrete Microstructure and Particle Packing

“…The key factor is using different dispersed mineral additives in one concrete mix. Pozzolanic activity and the energy state of mineral additives also significantly affect the solid phase concentration per unit volume of the concrete mixture [ 20 ].…”

“…All of this ensures high homogeneity and non-delamination of self-compacting concrete. The volume of the remaining voids in such a system will be minimal [ 20 , 21 ].…”

Conceptual Framework for Optimizing the Dispersed Composition of Cement Systems

“…The multicomponent composition of the dispersed composition is one of the main methods for producing highly efficient strong concretes with a minimum binder content and high indicators of construction and technical properties (STS). The main principle of obtaining concretes of the highest quality is the creation of a dense, highly filled solid phase of a homogeneous structure by optimizing the particle size distribution at various hierarchical structural levels and possibly low water content of the concrete mixture [1,2,3]. A promising direction in the production of such concretes is the use of self-compacting concrete mixtures (self-compactingconcrete -SCC) [4,5].…”

“…These types of concretes with a high cement content are characterized by an increased heat release, which significantly increases the kinetic energy in the initial period of the cement system. For this reason, the fixation of the formed particles of neoplasms of hydrated phases during structure formation can occur due to molecular selection mainly in the position of further coagulation, thereby determining a significant increase in defectiveness and an increase in its looseness and microporosity, as well as a decrease in the CTC of concrete [2,7,8]. Obtaining concrete mixtures with a high content of cement paste at a lower consumption of clinker cement is possible with its partial replacement with highly dispersed mineral materials (finely ground granulated blast furnace slag, fly ash, microsilica, etc.)…”

“…Therefore, only when a part of the cement is replaced by heterogeneous mineral modifiers and their optimal content at each hierarchical level, a cement paste with a high level of fluidity can be obtained without sedimentation, water separation and delamination, and a concrete mixture with a higher viscosity. The most important factors in terms of the level of significance in this case are the choice of the type, dispersion, content, pozzolanic activity and energy state of MM [2,8,14], which provide a high concentration of a self-organized more ordered solid phase per unit volume and a high binding energy between particles.…”