Spray Coating of Nanosilicate‐Based Hydrogel on Concrete

Abstract Hydrogels can be coated on various substrates to add a variety of functions to the substrates. In this study, hydrogel is coated on concrete that widely used as a building material. In general, in order to coat hydrogel on concrete, a prior process such as surface modification or primer layer coating is essential. However, this process is time consuming and requires the use of toxic chemicals. In this study, nanocomposite (NC) hydrogel that can be coated onto concrete in one step is used without any toxic chemicals. The spray‐coating method is adopted for continuous coating over a large area. An experimental device for spray coating is manufactured. Fast and uniform hydrogel coating on concrete is achieved. Various parameters of the spray‐coating process are optimized. Surface analysis on coated NC hydrogel is performed using a scanning electron microscope, atomic force microscope, and contact angle measurement. In order to confirm its applicability to green walls, an experiment is conducted to grow bryophyte on the NC hydrogel‐coated concrete. It is confirmed that bryophyte grows well on the NC hydrogel‐coated concrete. Concrete coated with NC hydrogel is expected to be a promising technology as a hydrogel‐based green wall system.