The study of an energy efficient cool white roof coating based on styrene acrylate copolymer and cement for waterproofing purpose—Part II: Mechanical and water impermeability properties

• The low Tg of the binder endows the cool waterproof coating with good flexibility.
• The coating’s high tensile strength is due to the cross-linked nature of the binder.
• Thermal, alkali, water and UV treatments increase the tensile strength of the coating.
• Thermal, alkali, water and UV treatments reduce the coating’s breaking elongation.
• The cool white waterproof coating has excellent waterproofing efficacy.

The mechanical properties and water impermeability of the developed cool white roof coating based on styrene acrylic copolymer and cement are systematically investigated in the current paper. The coating has good tensile properties, adhesion strength and compliance at low temperature. In particular, the coating possesses excellent water impermeability. The good flexibility and compliance at low temperature result from the low glass transition temperature of the high elastic styrene acrylate copolymer emulsion. Compared with the untreated specimens, after thermal, alkali, water immersion and ultraviolet treatments, the tensile strength of the coating is increased, while its breaking elongation is decreased. In addition, the coating has good artificial accelerated weather resistance in terms of mechanical properties. The excellent water impermeability of the coating stem from the cross-linked nature of the high elastic styrene acrylate copolymer emulsion, the formation of interpenetrating network structures and the Ca2+ bridging effect.