Currently in France, the cold asphalt concrete market is growing, with microsurfacing increasingly replacing and giving better results than chip seal surface dressing. As part of the promotion of coldasphalt concrete in France, one contractor recently developed the first gap-graded cold mix. The use of polymer-modified asphalt emulsions and synthetic fibers made this practical. The binder is a cationic, ethylene vinyl acetate modified asphalt emulsion specially formulated to have controlled slow-setting characteristics. Both long- and short-term benefits are derived from the addition of fibers. The fibers initially increase the viscosity of the emulsion, so that gap-graded formulations can be placed without segregation. After curing, the fiber network reinforces the cold gap-graded asphalt concrete, increasing the shear strength and wear resistance. To date more than500, 000 sq m of gap-graded fibrated asphalt concrete have been successfully laid. (A)
Abstract