Development of Laboratory Procedure for Measuring Friction of HMA Mixtures - Phase I.

摘要

Pavement friction during wet conditions continues to be a major safety concern for pavement design and maintenance. Friction is defined as the relationship between the vertical force and horizontal force developed as a tire slides along the pavement surface. Its magnitude mainly depends on the pavement surface characteristics and vehicle characteristics. Vehicle characteristics, such as speed, braking system and tire condition are not within the control of the highway road engineer. However, the highway engineer should provide pavement surface characteristics with sufficient friction to meet the design criteria. The skid resistance of pavements is commonly measured using ASTM E 274, Skid Resistance of Paved Surfaces Using a Full-Scale Tire. However, there are no standard test procedures for evaluating the friction of an HMA wearing course during the mix design process. There are two tests for evaluating the polishing properties of an aggregate: British portable skid resistance tester (ASTM Test Procedure D 3319-00 and E 303-93 [Re-approved 2003]), and the acid insoluble residue test (ASTM D 3042-03). As a part of the testing on Phase I of the NCAT test track, surface characteristic tests were conducted each month on all sections to evaluate the degradation of the skid resistance with traffic. The testing was conducted by the Alabama DOT using a skid trailer meeting the requirements of ASTM E 274. Figure 1 shows the average results of that testing for like mixtures (above restricted zone (ARZ), below restricted zone (BFZ), through the restricted zone (TRZ), stone matrix asphalt (SMA), and open graded friction course (OGFC).