Best Practices for Dust Control on Aggregate Roads

This study evaluated the performance and cost of commonly used dust palliatives using a mobile air sampling technique. Treatments of calcium chloride, magnesium chloride, and organic polymer-plus-binder were evaluated at standard application rates during the first year and at variable rates during the second year. The treatments were applied to a variety of subject roads that were located throughout Minnesota. Average daily traffic levels varied from 25 to 700 vehicles per day. The overall data trend showed that treatments reduced dust levels and measurements showed that aggregate surface moisture content was the best predictor of dust control efficiency. Positive relationships were measured between dust control efficiency and other variables in the study, generally reinforcing the concept that higher application rates may be more successful on gravels containing greater amounts of material passing the #200 sieve. A negative relationship was measured between dust control efficiency and sand equivalency, showing that treatments on gravels containing more sand material were less effective. In addition to dust control, study participants observed a secondary benefit of surface stabilization, which lasted for a period of time. Treated sections that developed surface stabilization were able to reduce maintenance activities to intersection areas only.