INFLUENCE OF ANTIFOAMING ADDITIVES ON THE STRUCTURE AND PROPERTIES OF MODIFIED CONCRETE BASED ON A GYPSUM-CEMENT-POZZOLAN BINDER

It is known that the introduction of air-entraining additives (SAA) improves both the technological properties of the concrete mix - workability, and increases the operational characteristics of concrete - frost resistance. At the same time, it is also possible to improve the operational characteristics by controlling the nature of the pore structure of concrete. One of the known methods for controlling the pore structure is the use of antifoaming additives. The paper shows the effect of antifoams in concretes based on gypsum-cement - pozzolanic binder (GCPB). The choice of concrete for the study based on gypsum-cement - pozzolanic binder is due to the development of additive technologies. The effect of three types of antifoaming additives on the properties of concrete mix from gypsum-cement-pozzolanic binder was studied: mobility, air entrainment and density, as well as the properties of gypsum-cement concrete - this is strength and its softening coefficient. To determine the pore structure, a method based on the analysis of images of the pore structure of gypsum-cement concrete was used. A direct dependence of the influence of the size and number of pores on the strength characteristics of concrete with antifoaming additives has been established. An optimal composition of the GCPB mixture with an antifoaming additive based on polyester-modified silicone has been obtained, which allows increasing: mobility by 13.5%, density by 2%, compressive strength by 15% and bending strength by 34% relative to the control composition.