Development of water-repellent cement mortar using silane enriched with nanomaterials

The exposure of reinforced concrete structures to freezing temperatures during winters can create internal stresses and surface microcracks in concrete owing to tiny ice crystal formations in the pores of concrete structures. Thus, in the present study, superhydrophobic surfaces were created on concrete by spraying and admixing superhydrophobic materials, comprising 1H,1H,1H,2H-perfluorodecyltriethoxysilane (PFDTS) with nano TiO2 and SiO2 inclusions, with cement mortar. TiO2 nanomaterials were synthesized using ginger (Zingiber officinale) as a bio-template. The PFDTS enriched with nanomaterials (PFDTS-NM) was admixed with cement mortar during casting and was spray-coated on the cement mortar surface after casting. The spray-coated and admixed cement mortar sample surfaces were characterized by XRD, SEM/EDAX, and UV-vis spectroscopy, and their water-repellent properties were evaluated by measuring the contact angles (CA) and conducting water absorption and freeze-thawing tests. The pore size distributions of the samples before and after freeze-thawing were evaluated by mercury intrusion porosimetry (MIP). The results confirm the presence of PFDTS with inclusions of rod-shaped TiO2 nanoparticles on the concrete surface. Further, the CAs of normal, coated, and admixed cement mortar surfaces were found to be 45.5°, 162.3°, and 162.0°, respectively. The spray-coated and admixed concrete can be used to form superhydrophobic surfaces on concrete structures to reduce water absorption and increase the durability of cement mortar.