Seal coats are highly regarded as a pavement maintenance tool because, among other functions, they enhance the friction value of existing road surfaces. Asphalt emulsions are commonly used in seal coat construction for their adaptability to environmental and handling conditions, and the better the bond between emulsion and aggregate, the better the friction value of the seal coat. This study seeks to find out whether antistripping agents enhance the bond between aggregate and emulsion, consequently improving the friction value of the seal coat; to determine the best way of including the antistripping agent in the seal coat; and to establish a mathematical model to predict friction value of a particular seal coat at any time after construction. To those ends, several seal-coat test sections were prepared, subjected to traffic for several months, and then evaluated. The outcome of the research reveals that (a) including the antistripping agent in a seal coat improves the bond between aggregate and asphalt and reduces the tendency of aggregate particles to rotate under horizontal drag forces, both of which led to higher friction values; (b) mixing the antistripping agent with the emulsion instead of applying it to the aggregate surface improved the total bond and led to higher frictional values; and (c) quadratic models were better than exponential models at predicting friction values of seal coats at any time after construction.
Abstract