Repeatability of Testing Procedures for Resilient Modulus and Fatigue

摘要

Extensive use of diametral resilient modulus and fatigue testing is made by the Oregon State Highway Division to evaluate asphaltic concrete materials. Test results on similar materials (e.g., adjacent field cores), however, often indicate a poor level of repeatability. In the study, laboratory fabricated briquettes were tested to evaluate the repeatability of the diametral modulus test at two laboratories, Oregon State Highway Division (OSHD) and Oregon State University (OSU), and the repeatability of the fatigue test at a single laboratory (OSU). Modulus tests at the OSHD laboratory were conducted at one temperature and three strain levels while modulus tests at the OSU laboratory were conducted at two temperatures and the same three strain levels. Fatigue testing at the OSU laboratory was conducted at two temperatures and at one initial strain level. Significant findings include modulus tests are highly repeatable within each laboratory, modulus tests under similar test conditions could not be satisfactorily reproduced (at the 5% significance level) between laboratories; depending on test conditions, fatigue tests had a very low to high level of repeatability.