MODEL OF A CONCRETE SYSTEM WITH INTERNAL HYDROPHOBIC FUNCTIONALIZATION AND SUPERHYDROPHOBIC COATINGS WITH LONG-TERM STABILITY

Cement and concrete are indispensable basic materials for national economic construction and social development, have a wide application and will continue to play a central role in the production of building materials in the future. However, their durability crisis is becoming increasingly noticeable due to the inherent characteristics of the material and external environmental factors, which poses a serious challenge to the sustainable growth of the construction industry. In particular, the concept of “long-term building service life” is proposed specifically to meet the basic strategic needs of national security and sustainable development. It is relevant to severe operating conditions (carbonation, chloride aggression, freeze-thaw cycle, wet-dry), safe operation and maintenance, where increased requirements are placed on the durability of structural concrete. Researching practical and effective technologies to improve durability is an important task to be solved at this stage. The porous structure of concrete and the metastable properties of hydration products are the cause of deterioration of its performance characteristics at later stages. Structural looseness refers to the presence of loose transition interfaces in concrete. They consist of weak interfaces caused by excessive accumulation of water on the surface of aggregates and steel rods, as well as interface defects arising due to significant orientation of Ca(OH)2 and weak forces of interlayer bonding. Porosity is the formation of pores during the preparation, construction, and hydration of cementitious materials. The density of the microstructure of concrete is primarily affected by the uneven space formed as a result of the consumption or evaporation of water during mixing. Metastability refers to the phenomena of dissolution, carbonation, and transformation occurring in the hydration products of cement, which can cause changes in the volume of concrete and subsequently impact its durability. Harsh environmental conditions can significantly modify the durability of concrete, especially in environments with high concentrations of corrosive ions, such as marine environments, freeze-thaw cycles, and hot and humid wetting-drying cycles. It was noted by the founders of concrete corrosion science that “the permeability or impermeability of concrete is a characteristic directly related to durability.” However, cement-based materials are inherently porous and metastable. This makes traditional engineering approaches, such as compaction, difficult to inhibit water-salt transport over the long term, resulting in reduced durability. In recent years, the application of hydrophobic modification technology for corrosion protection has attracted considerable attention due to its relationship with the theory of “lotus leaf effect”. This approach opens up new prospects for effectively improving the durability of cement concrete.