Alireza Sassani

Superhydrophobic Coatings on Asphalt Concrete Surfaces: Toward Smart Solutions for Winter Pavement Maintenance

Millions of dollars are annually spent for ice or snow removal from the roadways and airport paved surfaces in cold regions. The presence of snow or ice on paved areas can cause traffic accidents and financial loss because of flight cancellations or delays. For mitigating winter pavement maintenance issues, the use of superhydrophobic (super-water-repellent) coating techniques is gaining attention as a smart and cost-effective alternative to traditional snow and ice removal practices. This study focuses on creating, characterizing, and evaluating innovative superhydrophobic coatings on asphalt concrete surfaces for ice- and snow-free flexible pavement applications. The layer-by-layer (LBL) method was used to create an asphalt concrete surface coating with polytetrafluoroethylene (PTFE) as a well-known super-ice- and super-water-repellent material. Superhydrophobicity and skid resistance of the coated asphalt concrete surface were characterized by the water contact angle, the work of adhesion, and the coefficient of friction at the microtexture level. These properties were evaluated for test variables including spray times and dosage rates of PTFE under a statistical design–based experimental test program. The measurement results indicate that uses of the LBL method for spray-depositing the PTFE particles and the microtribometer for measuring coefficient of friction at the microtexture level are promising methods for creating and characterizing superhydrophobic coatings on asphalt concrete. The results of statistical analyses indicate that the spray time and dosage of PTFE significantly affect the ability of a coated flexible pavement to be icephobic or superhydrophobic and skid resistant.

Fabrication of Polytetrafluoroethylene-coated Asphalt Concrete Biomimetic Surfaces: A Nanomaterials-based Pavement Winter Maintenance Approach

Application of super ice/water-repellent materials on pavement surfaces has increasingly drawn attention as a smart and cost-effective method for ice and snow removal. This study focused on fabricating and evaluating icephobic coatings on asphalt concrete pavements for obtaining ice- and snow-free biomimetic icephobic surfaces. After a statistical design, the layer by layer (LBL) method was used for spray depositing the polytetrafluoroethylene (PTFE) on the asphalt concrete at variable dosages of PTFE and different spray times. The degree of hydrophobicity/icephobicity of the coated asphalt concrete was characterized through measuring the water contact angles. Statistical analysis proved the significance of design variables. In addition, skid resistance measurements on the PTFE coated surfaces were compared with those from uncoated surfaces to evaluate the effect of PTFE coating on pavement slipperiness of asphalt surface. A slight decrease in skid resistance of the PTFE coated surface was negligible in comparison to the drastic reduction in skid resistance caused by presence of ice/snow.

Influence of Deicing Salts on the Water-Repellency of Portland Cement Concrete Coated with Polytetrafluoroethylene and Polyetheretherketone

Sustainable super water/ice-repellent pavements are gaining attention as a smart solution for mitigating problems associated with winter pavement maintenance of roadways and airfields. Such smart pavements can facilitate surface drainage and prevent or curb ice formation or snow accumulation. While a conventional method for melting ice and snow is the use of deicing chemicals, such materials can transfer to the surface of nanotechnology-based pavements and influence their water/icerepellency by changing the chemistry of water or ice. This study focused on characterizing the degree of hydrophobicity of Portland cement concrete (PCC) nanocoated with polytetrafluoroethylene/polyetheretherketone (PTFE/PEEK). A layer-bylayer (LBL) spray deposition technique was used for spraying the binding agent and water-repellent materials. The liquidrepellency was characterized by measuring the static liquid contact angles (LCAs) and calculating the works of adhesion (WA). The liquid types used included distilled water and two types of deicing chemicals prepared by dissolving salts in distilled water. Data analysis results revealed that salt contamination improves the waterrepellency of nano-coated surfaces.