The ability of palliatives such as hygroscopic salts and synthetic fluids to reduce dust emissions from unpaved roads and other unpaved surfaces is well known. However, the effectiveness of different products used to control the loss of fine aggregate particles has largely been evaluated by observing the intensity of dust plumes produced behind moving vehicles. Currently, no standardized laboratory test exists for predicting dust palliative performance. Presented here is a laboratory methodology capable of predicting the effectiveness of palliatives applied to unpaved aggregate surfaces. The procedure evaluates the ability of palliatives to retain fine particles by measuring the total mass of PM10 (particulate matter less than 10 µm in size) present in material abraded from the treated aggregate surface. Total mass is determined by measuring PM10 concentrations in settling dust resulting from propelling a sample into a column. The test methodology is simple yet provides repeatable results. Moreover, the resolution in the test results is high enough to distinguish the performance between different palliatives applied at different application rates. Minor limitations are inherent in the methodology owing to the natural heterogeneity that exists in compacted aggregates. These limitations can be reduced with careful sample preparation.
