Best Practices for Maintenance of Concrete Bridge Elements Against Mold and Mildew Growth

Biodeterioration of concrete surfaces on vertical elements of bridges represents a serious challenge to the highway infrastructure in the state of Louisiana, not only for its poor aesthetic appeal but also because of the accelerated deterioration that biofilm causes on concrete. This paper investigates the causes of biofilm proliferation on concrete, the consequences that these living organisms have on concrete, and the best methods used to control and eliminate biofilm growth on concrete. A literature review was conducted, and a survey was developed and distributed among different states' DOTs to determine current biofilm preventing and cleaning practices and their effectiveness. The survey results show that not all the states have biofilm growth, and that those that do are located in warm and humid geographical locations. Results also suggest that the main cause of biodeterioration of concrete surfaces is caused by micro-organisms' activity present at the surface. Furthermore, current practices used to prevent and clean biofilms growth are pressure washing, biocides, and addition of self-cleaning photocatalytic nano titanium dioxide (TiO₂) coatings to concrete surfaces. Results also suggest that the use of self-cleaning photocatalytic nano TiO₂ coatings appears to be the most effective method in preventing microbial growth on concrete surfaces.