Guidelines for the Selection, Specification, and Application of Chemical Dust Control and Stabilization Treatments on Unpaved Roads

Unacceptable levels of dust, poor riding quality, impassability in wet weather, and unsustainable maintenance and gravel replacement practices are experienced on most unpaved road networks, and although it is acknowledged that unpaved roads are fundamental to local, regional, and national economies, many current management practices used on these roads leave much to be desired. Over the past 100 years a range of chemical treatments has been developed to fill the need for reducing the environmental and social impacts of road dust, improving the performance and safety of unpaved roads, and/or improving the properties of marginal materials to the extent that a road can be given all-weather status or upgraded to a paved standard. Most of these chemical treatments are proprietary and there is often little documented information regarding the chemistry of the treatment, the results of experimental trials to determine under what conditions the chemical treatment will work best, or guidelines on where and how to use the treatment. Most unpaved road chemical treatments carry no formal specification nor do they adhere to formal environmental testing requirements. Consequently, there has been no large-scale effort to establish and/or implement formal unpaved road chemical treatment programs anywhere in the world, other than those used in site-specific industrial applications such as mining operations. This guide introduces a new process for selecting an appropriate chemical treatment category for a specific set of unpaved road conditions using ranked potential performance. The process is based on the practitioner setting an objective for initiating a chemical treatment program and understanding the road in terms of materials, traffic, climate, and geometry. Using the information collected, the most appropriate chemical treatment subcategories for a given situation can be selected from a series of charts and ranked using a simple equation. This process can be completed manually using a paper form, or by using a web-based (www.ucprc.ucdavis.edu) or spreadsheet tool. Matrices for each of the objectives were developed based on documented field experiments and the experience of a panel of practitioners. Guidance on specification language for procuring and applying unpaved road chemical treatments is also provided, along with comprehensive guidance on understanding unpaved road wearing course material performance.