MODEL OF SPECIAL MATERIAL “MICRO/NANO HYBRID HYDROPHOBIC EMULSION” AND DEVELOPMENT OF PROTECTIVE MATERIALS FOR MARINE CONCRETES BASED ON IT

Developed by modified nanosilica (MNS) and polydimethylsiloxane, the effect of hydrophobic emulsion on the setting time, rheological properties, compressive strength and wettability of cementitious materials. In addition, microanalysis (isometric calorimetry, thermogravimetric analysis, mercury porosimetry, Fourier transform infrared spectroscopy) was used to study the mechanisms of reducing the strength loss and increasing the hydrophobicity of hydrophobic emulsions. Cement-based structures in special environments such as marine engineering, water transport and underground structures are susceptible to corrosion by Cl-, Mg2+, and SO2-These elements promote corrosion of steel rods and destruction of cement-based materials. [1-2]. In addition, in cold regions, cement materials are destroyed by frost and immersion in water, which seriously affects the durability and safety of the structures. [3]. The loose and porous constituents inherent in cementitious materials, as well as the hydrophilic properties of hydration products, directly impact their durability. This poses a problem for traditional methods such as compaction in the long-term inhibition of water and salt transfer due to the porous nature [4]. Recently, advances in hydrophobic modification technology based on the theory of “lotus leaf effect” have made significant progress in corrosion protection. These developments offer new strategies to enhance the durability of cementitious materials [5-8]. The creation of hydrophobic structures on the surface of cementitious materials is the predominant method of hydrophobic modification, including the coating method [9], impregnation method [10], template method [11] and self-assembly [12]. The main drawback of this method is poor hydrophobic stability, which is manifested by the gradual deterioration of the rough structure and interfacial adhesion strength under the influence of environmental factors during the service life. Thick-layer hydrophobic coating is an improved solution to eliminate these problems. Its design idea is to expand the two-dimensional hydrophobic surface to a homogeneous three-dimensional hydrophobic material [13-15]. Although this approach increases the service life of the hydrophobic coating, the comparison with the durability of the substrate remains a challenging task. Moreover, with increasing coating thickness, the issues of interaction between two-layer materials become more pronounced [16].