INFLUENCE OF MINERAL AND ORGANIC MODIFIERS ON THE FORMATION OF THE STRUCTURE OF SELF-COMPACING CONCRETE

The article presents the analysis of modern techniques for the development of self-compacting concrete mixtures, which have become widespread in recent decades. The role of finely dispersed active and inert mineral additives of natural and artificial origin used to increase flowability and reduce bleeding of self-compacting concrete mixtures is shown. It has been established that the use of mineral additives makes it possible to fill the intergranular space of Portland cement clinker, increase the density of concrete and the degree of hydration of the binder. The mechanism of action of a complex chemical additive based on polycarboxylate esters, defoamers and an air-entraining component is given. It is shown that the introduction of plasticizing additives into the composition of any concrete mixtures leads to significant air entrain-ment, which is especially evident in the presence of polycarboxylate esters. The reduction of air entrainment is achieved by the introduction of defoamers, which contribute not only to the removal of entrained air, but also lead to an increase in the flowability of the concrete mixture and a decrease in plasticizer consumption. The presence of air-entraining additives leads not only to the formation of a significant amount of emulsified air in the system, preventing the destruction of air bubbles and being a source of formation of conditionally closed pores that act as a "reserve" in concrete, but also stabilizes the properties of concrete mixtures, which is manifested in reducing segregation and maintaining their coherent structure.