Aggregate-surfaced roads are a viable component of the transportation network; they provide significant increases in road stability over earthen-surfaced roads while avoiding the high placement and maintenance costs of pavements. The use of higher-quality, more stable aggregates will significantly reduce both the cost of maintaining gravel roads and the environmental concerns related to road runoff. This paper aims to provide a better understanding of wearing course aggregates by describing a comparative analysis experiment done as part of Pennsylvania's Dirt and Gravel Road Maintenance Program. Three aggregates commonly used in Pennsylvania were placed side by side under two different placement methods for each type of aggregate as part of a 3-year study to compare their long-term durability and cost-effectiveness. The two methods tested were the "dump and spread" method known as tailgating and the application of aggregate by a motor paver. Cross-sectional surveys were done on each aggregate section for 3 years following placement to determine elevation changes in the road surfaces. No significant difference in performance was found between aggregate sections placed with a paver and the same aggregate placed by tailgating. Driving surface aggregate was the only aggregate of the three tested that did not show a statistically significant change in road elevation during the 3-year course of study. Results illustrate the importance of selecting a properly graded aggregate containing minimal clay and soil material for use as surface aggregate on low-volume roads.
Samenvatting