ADA Accessible Trail Improvement with Volcanic Ash Supplemented Portland Cement

摘要

The Americans with Disabilities Act (ADA) includes specific accessibility guidelines. In the case of unpaved trails however, the requirements are less defined; an ADA accessible trail surface must be firm, stable, and slip-resistant. If an unpaved surface could be improved with the use of an additive, more trails can be ADA accessible. A study has been conducted using a naturally occurring pozzolan from the eruption of Mt. Mazama as a binder applied topically to gravel surfaces. Tests included innovative pour tests to determine depth of penetration of binder in various gradations of aggregate and included a comprehensive study of the unconfined compressive strength of mortar cubes created with Portland cement, lime, volcanic ash, and oyster shells. Bench scale trails were also created in the laboratory to determine the firmness and stability of trail surfaces. In addition to the naturally occurring pozzolans, varying percentages of Portland cement, lime, and crushed oyster shells were used as binding materials. Results indicate that Portland cement must be used in conjunction with naturally occurring pozzolans to create a firm and stable surface. Firmness and stability are measurements provided by the beneficial designs rotational penetrometer that convey how prone a surface is to indentation or material removal due to twisting, downward loads. Through application of a cementitious mix including Portland cement and Mt. Mazama volcanic ash, a surface's firmness and stability can be improved to within acceptable standards.