Abstract
The strain responses of asphalt pavement layer under vehicular loading are different from those under falling weight deflectometer (FWD) loading, due to the discrepancies between the two types of loadings. This research aims to evaluate and compare the asphalt layer responses under vehicular loading and FWD loadings. Two full-scale asphalt pavement structures, namely, flexible pavement and semirigid pavement, were constructed and instrumented with strain gauges. The strain responses of asphalt layers under vehicular and FWD loadings were measured and analyzed. Except for field measurements, the finite element (FE) models of the experimental pavements were established to simulate the pavement responses under a wide range of loading conditions. Field strain measurements indicate that the asphalt layer strain under vehicular loading increases with the rising temperature roughly in an exponential mode, while it decreases with the rising vehicular speed approximately linearly. The strain pulses in the asphalt layer generated by FWD loading are different from those induced by vehicular loading. The asphalt layer strains generated by FWD loading are close to those induced by low vehicular speed (35 km/h). The results from the FE model imply that the asphalt layer strains under FWD loading and vehicular loading are distributed similarly in the depth profile. For flexible pavement, the position of critical strain shifts gradually from the bottom of the asphalt layer to the mid-depth of the layer, as the temperature increases. For semirigid pavement, the position of critical strain is always located at the intermediate depth of the asphalt layer, regardless of temperatures.
Highlights
Asphalt pavement constitutes one of the most common pavement structures for highways or steel bridge roadways
In pavement overlay design or rehabilitation design, the falling weight deflectometer (FWD) test results are applied to obtain the in situ moduli of existing pavement layers [6]. e obtained in situ moduli are used to predict the responses and the remaining fatigue life of the in situ pavement under repeated vehicular loadings [6]. erefore, it is assumed that the properties of the asphalt layer measured based on FWD test reflect what asphalt layer exhibits under actual vehicular loading
The effects of temperature, vehicular speed, and axle load on asphalt layer strains were analyzed. e equivalent vehicular speed of FWD loading was determined using the criterion that the maximum tensile strains in the asphalt layer induced by FWD and vehicular loadings were equal
Summary
Asphalt pavement constitutes one of the most common pavement structures for highways or steel bridge roadways. Considering that vehicular loading is the most common loading on the pavement, the strain responses of the asphalt layer under this type of loading are utilized in the design method. 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. Wang and Li [27] calculated the theoretical pavement responses under FWD loading and vehicular loading via the finite element method and found that the FWD loading corresponds to vehicular speeds ranging between 24 and 80 km/h. E equivalent vehicular speed of FWD loading was determined using the criterion that the maximum tensile strains in the asphalt layer induced by FWD and vehicular loadings were equal. Except for field measurements, the finite element (FE) models of the experimental pavements were established to simulate the pavement responses under a wider range of loading conditions. e calculation results from FE model were used to analyze the position of critical strains in the flexible and semirigid pavement
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