Validation of Flexible Pavement Structural Response Models with Data from the Minnesota Road Research Project

Abstract

A dynamic load test study was performed on instrumented asphalt and concrete pavement test sections at the Minnesota Road Research facility. Test variables included different types of vehicles (featuring various axle groupings, load levels, and tire pressures) operating at various speeds over different structural sections. Four flexible pavement sections were selected for inclusion, and the primary structural response measured was horizontal strain at the bottom of the asphalt layer. The test data suggest that the structural response of the four sections to varying loads was linear when other test parameters were held constant. The pavement sections also exhibited a pronounced viscoelastic behavior in response to changes in vehicle speed and load rate. This behavior was attributed mainly to the asphalt concrete layer. Changes in tire pressure did not significantly affect pavement behavior. The test data were used to validate a multilayer linear elastic pavement structural model. Sub-grade and base moduli inputs were back calculated from falling weight deflectometer data, and the asphalt modulus was determined experimentally from measured strain. This model adequately reproduced the strain distribution observed at the bottom of the asphalt layer under the passage of moving vehicles with certain limitations: the longitudinal strain asymmetry due to viscoelastic effects could not be reproduced, and the modulus of the asphalt layer had to be readjusted for temperature and vehicle speed. Also, it was not possible to calibrate or fit the model to observed longitudinal and transverse strains simultaneously because the pavement behaved more stiffly longitudinally than transversely.

Comparisons between Asphalt Pavement Responses under Vehicular Loading and FWD Loading

“…Equivalent vehicular speed (km/h) Mateos and Snyder [24] 48 Qin [25] 88 Ai et al [26] 26∼48 Wang and Li [27] 24∼80 is research 26-44 10 Advances in Materials Science and Engineering FE models are used to calculate the strain of the asphalt pavement layer under a wide range of loading conditions.…”

“…Several studies have been conducted to correlate asphalt layer responses under FWD and vehicular loadings. Mateos and Snyder [24] compared the strain responses of Minnesota test road under FWD and vehicular loadings and found that the strains of asphalt layer under FWD loading resemble those under vehicular loading with speed at 48 km/h. erefore, they concluded that the FWD loading represents the vehicular speed at 48 km/h.…”

Evaluation of Structural Response of Cracked Pavements at CEDEX Transport Research Center Test Track

“…Anisotropy is present in both asphalt mixtures and soils, as well as discrete (versus continuous) behavior. Nonetheless, several studies have shown that a reasonable degree of accuracy can be achieved with use of linear elasticity for predicting pavement structural response, as soon as appropriate conditions are selected for characterization of pavement materials (2)(3)(4). In particular, an asphalt modulus should be selected for a frequency that is representative of the vehicle load pulse, and a soil modulus should be determined for a load level that adequately represents the stress state developed under the vehicle loads.…”

Mechanistic–Empirical Study of Effects of Truck Tire Pressure on Pavement

“…Pavement responses can be measured directly with in situ instruments buried in pavement structures. During the past two decades, computercontrolled instrumentation technology has improved with cheaper and yet faster microprocessors, and real-time measurements of pavement responses to dynamic traffic loading have become popular (15)(16)(17)(18)(19)(20)(21)(22)(23).…”