Study on PVA-siloxane mixed emulsion coatings for hydrophobic cement mortar
Efflorescence is widely regarded as a serious problem in cement-based exterior wall. This phenomenon can affect the appearance and long-term stability of the building. Based on the efflorescence mechanism, one of the causes of efflorescence is the existence of free water to dissolve soluble salts.
Now scientists propose a method for synthesising hydrophobic cement mortar. The main challenge of the super-hydrophobic coating is its robust durability. To synthesize durable hydrophobic cement mortar, PVA was used as an adhesive to enhance the durability of the coating, and siloxane material was used as a hydrophobic agent, through high-speed mixing, to obtain a PVA-coated siloxane material hydrophobic coating.
Excellent water resistance
The measured water contact angles (CA) are between 120° to 140°, and the water absorption after 24 h and 48 h can be reduced by about 10 % and 15 % compared with the reference sample, including the water absorption coefficient is approximately lower than the untreated group 1.7–4 times.
Further results show that the cement mortar treated with hydrophobic emulsion has excellent water resistance and improved efflorescence resistance, and can be widely used in cement-based buildings.
The study has been published in Progress in Organic Coatings, Volume 147, October 2020.