ФИЗИКО-ХИМИЧЕСКИЕ ОСНОВЫ СТОЙКОСТИ БЕТОНОВ К ВОЗДЕЙСТВИЮ НИЗКИХ ОТРИЦАТЕЛЬНЫХ ТЕМПЕРАТУР (ЧАСТЬ 2)

Abstract

Generalization and analysis of scientific hypotheses and theories of domestic and foreign researchers in the field of the frost action mechanism on concrete has been performed. A critical author's assessment of them from the point of view of the basics of physical chemistry of silicates and solid state physics is presented. The initial prerequisites for the frost resistance of heavy concrete and equal-strength structural light concrete in connection with their structure are formulated, including of this article author's targeted experimental studies on the relationship of the frost resistance of these concretes with their pore structure. Thermodynamic models of freezing-thawing of water, including its adsorption layers in capillaries of cement materials porous structures are used. The data of studies of the critical degree of water saturation of concrete are considered and a reasonable assessment of it is given as an integral characteristic that determines the possibility of formation of micro- and then macro-defects in the concrete structure during its cyclic freezing and thawing. Based on the results of analytical and experimental studies, using the basic principles of physics of the solid state, as well as the physical and physical-chemistry of silicates, has been developed the physical-chemical basis for the resistance of structural lightweight concrete in comparison with equally strong normal weight concrete to the effects of low (up to minus 70 °C) subzero temperatures. The results of this work are considered by the authors as a modern scientific basis for the development of the main provisions of the technology for manufacturing structural lightweight and normal weight concretes with high durability (frost resistance and water resistance), intended for reinforced concrete structures of engineering constructions, operated in severe climatic conditions, including in the conditions of the Arctic coast.