Effectiveness of the two chemical treatments (CaCl2 and MgCl2) as dust suppressants on gravel roads.

This study evaluates the effectiveness of dust treatments on gravel roads. Two dust suppressant types: CaCl2 and MgCl2 were used in this study on 26 gravel roadway segments. Two dust measuring devices: HAZ-DUST EPAM-5000 and Colorado State University (CSU) Dustometer were used to measure the fugitive dust emissions. The variables that might have an impact on the effectiveness of dust treatments were also collected. The data collection included traffic counts, 85th percentile speed, soil properties (moisture content, liquid limit, plastic limit and per cent passing through #200 sieve) and most importantly, dust emission. Statistical analyses indicated that dust emission was reduced by 87% after applying treatment compared to before treatment. HAZ-DUST EPAM-5000 (mean: 1.47 mg/m3, standard deviation: 0.93 mg/m3) was performed better than CSU Dustometer (mean: 1.48 mg/m3, standard deviation: 1.37 mg/m3). The dust reduction by applying two chemical treatments, CaCl2 and MgCl2, was very close to each other. Also, before applying treatment, traffic counts, % fines passing #200 sieve and annual rainfall were found to be significant. After applying treatment per cent, no variable was found to be significant. [ABSTRACT FROM AUTHOR]