Novel Superhydrophobic Cement-based Materials Achieved by Construction of Hierarchical Surface Structure with FAS/SiO2 Hybrid Nanocomposites

Abstract

This work aims at developing novel superhydrophobic cement concrete by applying a tridecafluorooctyltriethoxysilane/nanosilica (FAS/SiO ) hybrid nanocomposite onto surfaces of hardened concrete.The hybrid nanocomposite was synthesized and characterized using 2 TEM, TGA and NMR.The performance of the FAS/SiO treated cement paste/mortar samples were evaluated using a water contact angle 2 (WCA) test, lab-raining detachment test, 3D image analysis, and UV irradiation test.The results indicate that the core-shell spherical structured composite had a particle size of about 200 nm and shell thickness of about 50 nm, displayed high pozzolanic reactivity, and enable to polymerize C-S-H gel of the concrete, thus lowing surface energy and modifying surface structure.The WCA of the FAS/SiO 2 treated-concrete samples was larger than 150, signifying a superhydrophobicity.The FAS/SiO hybrid composite had superior anti-2 detachment performance, proposing that the treated concrete surface would have a long-term high water-proofing performance.A hierarchical structure observed from the 3D image analysis might be primarily responsible for the increase in the hydrophobicity of the hardened cement-based materials.The 800-hour UV irradiation test results suggested a good stability of superhydrophobicity under severe weathering conditions.It is concluded that the FAS/SiO hybrid nanocomposite has a great potential for improving durability of existing 2 concrete structures.2 2along the diamerer of the FAS/SiO hybrid material.