Dispersion method for hydrophobic nano-silica aerogels in cement-based composites based on reversible regulation
Lu Lu, Haodong Wang, Ming Ye, Jian Hu, Shan Yun, Bin Xu, Mingming Wang
Abstract
In the context of carbon neutrality, external wall insulation technology has entered a new developmental phase. Hydrophobicity is an important indicator of the weather resistance of external wall insulation materials. In this study, we successfully developed a method to prepare a hydrophilic silica aerogel paste by mixing hydrophobic nano-silica aerogel powder with an ethanol–water solution, thereby addressing the dispersion challenge in cement-based composites. Upon drying, the aerogel reverts to its hydrophobic state while maintaining its nanoporous structure, representing a mechanism of reversible regulation. The dispersion characteristics of the silica aerogel paste in water were investigated through experiments and numerical simulations. Based on these finding, a preparation method was proposed for silica aerogel cement-based composites. Optical microscopy tests revealed that silica aerogel participated in the cement hydration process and became embedded in the cement material, significantly reducing its thermal conductivity. Energy-dispersive spectroscopy point scanning for carbon element analysis confirmed the effective restoration of methyl groups, confirming the uniform dispersion of the nano-silica aerogel in the cement-based material. This study is of great significance for promoting the application of hydrophobic nano-silica aerogels in the modification of cement-based composite insulation materials. It also provides new insights and methods for technological advancements in relevant fields.