REDUCTION OF ROAD FRICTION COEFFICIENT CAUSED BY THE APPLICATION OF CALCIUM CHLORIDE SOLUTION

Abstract

 We conducted laboratory and field experiments on dense-graded asphalt concrete and porous asphalt concrete in order to clarify the decrease in road friction coefficient μ caused by calcium chloride solution sprayed as an antifreezing agent. In the laboratory experiment, the skid resistance of road specimens sprayed with calcium chloride solution and that of road specimens sprinkled with water after the calcium chloride precipitated were measured. The values of μ immediately after the application of calcium chloride solution, even a high-concentration solution, were found to be at least 0.4, which is not much different from the values for the wet road surface. When calcium chloride precipitated on the road surface, the values of μ for dense-graded asphalt concrete and porous asphalt concrete were about 0.2 lower than those for the wet road surface. Furthermore, field experiments showed that the precipitation of calcium chloride and decreases in μ associated with that precipitation could occur on actual roads.