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OCR for page 38
38 Glossary Dynamic Modulus: The absolute value of the complex modulus of a Reduced Frequency: The computed frequency at the reference viscoelastic material calculated by dividing the peak-to-peak stress temperature equivalent to the actual loading frequency at the test by the peak-to-peak strain for a material subjected to a sinusoidal temperature. loading. Reference Temperature: The temperature at which the master curve is Dynamic Modulus Master Curve: A composite curve constructed at a constructed. reference temperature by shifting dynamic modulus data from var- Servo-hydraulic: A closed-loop hydraulic testing machine that responds ious temperatures along the log frequency axis. to minimize the difference between the command signal and the First Article Devices: Prototype equipment produced primarily for feedback signal from a transducer attached to the test specimen. evaluation. Shift Factor: Shift in frequency associated with a shift from a test tem- Flow Number: The number of load cycles corresponding to the mini- perature to the reference temperature. mum rate of change of permanent axial strain during a repeated Simple Performance Tests: Mechanical tests for asphalt concrete mix- load test. tures that are related to pavement performance and can be used Flow Time: The time corresponding to the minimum rate of change of in the mixture design process to evaluate the performance of a axial strain during a creep test. mixture. Extensometer: Self contained device that measures strain or deforma- Simple Performance Test Specimen Fabrication System: An auto- tion over a fixed gauge length. mated device for preparing test specimens for the Simple Perfor- Level 1 Analysis: The Mechanistic-Empirical Pavement Design Guide mance Test System. provides the option to choose between three levels for input data. Simple Performance Test System: Commercial testing equipment Level 1 is the most extensive input data requiring measured mate- developed in National Cooperative Highway Research Program rial properties or traffic data. Project 9-29 to perform the Simple Performance Tests. Linearly Variable Differential Transformer: Electronic device consis- SolverTM: A function included in Microsoft ExcelTM that performs non- tent of a coil and a core that measures displacement. The signal from linear optimization. This function can be used to assemble dy- the device varies linearly with the position of the core in the coil. namic modulus master curves. Mechanistic-Empirical Pavement Design Guide: The mechanistic- Superpave Volumetric Mixture Design: Volumetric design procedure empirical pavement design procedure developed in National for dense-graded hot-mix asphalt that was developed during the Cooperative Highway Research Program Project 1-37A. Strategic Highway Research Program.