Aggregate Performance on Forest Roads in the Pacific Northwest

Eleven aggregate quarries from the Pacific Northwest, USA were sampled to measure the variability in rock properties. Additionally, road managers were asked to classify the aggregate source as good or marginal for forest roads with year-round timber hauling as the primary use.  Seven of the eleven quarries were classified as good. A series of materials property tests were performed on the aggregate sampled from each quarry. The test included gradation, LA Abrasion, Micro-Deval, and sand equivalency tests. Three replicates were performed for the LA Abrasion, Micro-Deval, and sand equivalency tests. The results show that only two of the seven rated as good samples met the thresholds established from the literature review. None of the marginally rated aggregates met the thresholds for the material property tests.  The results show that the road managers expectation of rock quality is inconsistent when compared with the results from tests.  It suggests that in order to understand aggregate performance better, testing before placement is a necessity.