Impact of cross-anisotropy on embedded sensor stress–strain and pavement damage

Abstract

The effects of cross-anisotropy on asphalt pavement responses and damage are investigated in this study. As a part of this investigation, a dynamic Finite Element Model (FEM) of a pavement section at interstate I-40 (Mile Post 141) in New Mexico is developed in ABAQUS. This section has recently been instrumented with strain gauges, moisture probes and pressure cells. The dynamic FEM has been simulated to determine pavement responses under Falling Weight Deflectometer (FWD) and truckload. Pavement response (i.e. stress, strain and deflection) from the instrumented section are then compared to the FEM predicted values. To study the effect, a total of five combinations of cross-anisotropy are considered. The first combination considers cross-anisotropy of modulus in every layers of the pavement. The rest of the combinations considers it in each of the individual layers such as surface (Hot Mix Asphalt (HMA)), base (Granular aggregate), sub-base (PPC) and subgrade (Fine soil), respectively. Time-deflection histories, stress and strain are predicted from the FEM under FWD and truckload. Results show that predicted deflections, stress and strain are highly sensitive to HMA and all layer cross-anisotropy. In these cases, predicted deflections, stress and strain increase with a decrease in n-value, defined by the ratio of horizontal to vertical modulus of elasticity. The effect of cross-anisotropy in base, sub-base and subgrade is not as significant as the former two cases. Pavement damage is also determined using the tensile strain at the bottom of surface (HMA) layer. It is observed that damage increases with decrease in n-value. This effect is pronounced in HMA and all layer cross-anisotropy among the five combinations of cross-anisotropy. Finally, it is recommended to include this effect in the mechanistic analysis to improve the pavement design and evaluation.

Impacts of Material Orthotropy on Mechanical Behaviors of Asphalt Pavements

“…We found that the material anisotropy increased the surface deflection to an extent, which was in good agreement with the results of Tarefder et al [4]. Moreover, it should We found that the material anisotropy increased the surface deflection to an extent, which was in good agreement with the results of Tarefder et al [4].…”

“…An anisotropic material indicates that the material properties (the stiffness, modulus, etc.) vary in three directions, i.e., the vertical, longitudinal, and transverse [4,5]. However, most current asphalt pavement design methods only consider the material properties as isotropic, which can significantly skew the mechanical behaviors of asphalt pavements [6,7].…”

“…Without considering the transverse isotropy of pavement materials, an error prediction in pavement fatigue cracking and potential rutting would occur [17,18]. In addition, previous studies showed that the damage of asphalt pavement increased with the growing transverse isotropy [4]. The mechanical behaviors of asphalt pavement between transverse isotropic and isotropic materials were compared [19].…”

“…In addition, the transverse isotropy effects of the separated layer on the pavement mechanical behaviors were discussed in several studies, and detailed information for these layers can be found in the literature, such as surface layer [22,23], semi-rigid base layer [24][25][26], sub-base layer [27,28], and subgrade layer [29][30][31]. Tarefder et al [4] investigated the transverse isotropy effects of the combined layers, including hot-mix asphalt (HMA), base, sub-base, and subgrade, on the pavement mechanical behaviors. They argued that the transverse isotropy effects on the HMA and all-layer combination structures were significant in the pavement response.…”

“…In general, the transverse isotropy is a simplified case, since the material properties are identical in the transverse and longitudinal directions [35,36]. This case does not conform to the actual anisotropic properties of asphalt pavement materials [4]. Recently, the orthotropy (i.e., different material properties in the transverse and longitudinal directions) of pavement materials was proposed and considered in the HMA layer to increase the prediction accuracy [33].…”