Laboratory and Field Evaluation of Soybean-Oil-Based Dust Suppressants for Unpaved Roads: Performance and Durability

To assess the performance, durability, and field applicability of soybean-oil-based dust suppressants, controlled laboratory experiments and a 3-week field particulate emissions monitoring program were conducted on unpaved roads. The laboratory program simulated wind erosion, wetting–drying durability, and traffic-induced loading. Soybean-oil treatments exhibited minimal mass loss and maintained surface integrity under all conditions, whereas calcium chloride brine (CCB) experienced substantial erosion. Field experiments were conducted on six sections treated with different materials, dosages, and application methods. Continuous on-vehicle monitoring and blower-induced particulate matter (PM) measurements showed that soybean oil applied at 0.8 L/m² produced the lowest particulate emissions, and sustained strong performance throughout the 3 weeks. In contrast, the CCB-treated section exhibited rapidly increasing emissions. The area under the curve for particulate matter with aerodynamic diameters less than 2.5 µm (PM_2.5) increased by a factor of 11.59, indicating rapid performance degradation and the need for frequent reapplication. Cost analysis showed that soybean oil has a higher unit price than CCB; however the dosage flexibility provides cost advantages. A low-dosage application of 0.12 L/m² costs 1.34 times the price of CCB yet demonstrates superior durability. Overall, soybean-oil-based dust suppressants offer advantages in performance, durability, and environmental profile. They also provide flexibility in balancing cost and treatment effectiveness. Future work incorporating life-cycle assessment and life-cycle cost analysis is needed to evaluate long-term environmental effects, reapplication intervals, and system-level cost effectiveness.