The Americans with Disabilities Act (ADA) provides specific guidelines and requirements that must be met in terms of accessibility. However, in the case of unpaved trails, the requirements are less defined. An ADA trail must be firm, stable and slip resistant. Some compacted aggregate material may meet this definition, but degrade over time and can no longer be ADA compliant. The benefits of using unpaved surfaces for ADA trails include fit to the natural environment, cost, sustainability and environmental benefits such as increased permeability. If an unpaved surface can be improved with the use of an additive, more could be used as ADA accessible trails.
A recent study used several different binding materials to improve unpaved ADA accessible trails. However, this study used polymer materials that are costly. Environmentally these materials introduce chemicals that may not be natural to the environment, and unsustainable due to their production. A study currently being conducted with a NITC Small Starts Grant uses naturally occurring, volcanic ash from the eruption of Mt. Mazama as a natural pozzolan. The proposed new study will determine the least amount of portland cement or lime that can be used with this natural pozzolan to create an aggregate binder. This binder will then be applied to existing and newly created compacted aggregate trails in the local community to determine the benefit as a stabilizer and its projected design life. ADA accessibility tools such as the rotational penetrometer will be used to determine if the surface is improved to a firm and stable surface. By determining a low cost, sustainable solution for improvement of ADA accessible trails, more people will have access and connectivity will increase in our community. It is anticipated that this study will provide direct guidance on the composition of a natural pozzolan slurry mix and application methodology to create ADA accessible trails.