Results are described from asphalt strain gage measurements made during pavement response tests on the flexible pavement test items at the National Airport Pavement Test Facility (NAPTF). Tests were run at speeds of 0.08, 0.15, 0.23, 0.3, 0.6, 1.5, and 2.2 m/sec (0.25, 0.5, 0.75, 1.0, 2.0, 5.0, and 7.33 feet/sec) with dual-wheel configurations at wheel loads of 106.8, 133.5, and 160.2 kN (24,000, 30,000, and 36,000 pounds) and tire pressures of 1378 kPa (200 psi). The strain gages were located at the bottom of the 125-mm-(5-inch)-thick surface asphalt layer of the conventional and stabilized-base test items and additionally at the bottom of the 125-mm-(5-inch)-thick stabilized-base asphalt layer of the stabilized-base test items. Gages were oriented along the travel direction and transverse to the travel direction. Measurements were made at asphalt temperatures of 11.1°C (52°F) and 22.2°C (72°F). Significant permanent deformations were found in the measurements, particularly in the transverse direction. The measured strains were found to vary strongly with temperature and test speed, spanning the range of 300 to 2,000 microstrains. The upper range of these values is much larger than was anticipated, and the strains are 2 to 3 times higher than layered elastic computer program predictions of asphalt strain responses for the structural and load conditions existing during the tests. Longer duration of loading results in reduced asphalt stiffness. However, the longer duration of loading at slow speeds increases the amount of viscous flow and leads to significant increases in the total strain within the asphalt mix as speed decreases.
Tire and pavement interaction is a critical focus for studying pavement functional performance and safety. For airplane landing or take-off, pavement grooving is increasingly used to prevent hydroplaning during wet weather. Federal Aviation Administration (FAA) Advisory Circular (AC) No. 150/5320-12C has specific requirements for pavement grooving dimensions and performance. Typically, the depth, width, and spacing of pavement surface grooves are a set of parameters to estimate the potential safety risks in the pavement and tire interaction. The groove geometric dimensions would vary over time due to traffic loading. Therefore, the evaluation of groove performance becomes a critical process for pavement safety study. Traditionally point laser ranger based profiling system is used to measure pavement grooves. The groove identification and evaluation are conducted on one line-of-sight profile with this technique; however, this method cannot reflect the entire runway groove information due to the limited quantity of profiles that can be analyzed. This study presents the application of the newly developed 3D laser imaging system called PaveVision3D at the National Airport Pavement Test Facility (NAPTF) of the FAA Tech Center in Atlantic City, New Jersey. In this research, a new groove identification methodology is proposed based on the 3D texture measured at 1mm resolution. Any or all profiles on a runway can be used as input data to identify and evaluate grooves. A comparison study is made between the recommended groove configuration and the estimated groove dimensions from field data.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.