Pavement Damage Due to Different Tire and Loading Configurations on Secondary Roads
Due to the large percentage of goods moved by commercial trucks and its ever-growing freight industry, the U.S. needs innovative technologies to improve the efficiency of trucking operations and ensure continuous growth of the economy. One example of such a technology is the introduction of wide-base single tires to replace conventional dual tire systems. After more than two decades of research powered mainly by the tire industry, a new generation of wide-base tire was recently introduced. Compared to the first generation of wide-base tires, these new tires offer safety and cost-savings characteristics. Despite the significant advancements achieved through previous research projects on the impact of wide-base tires on pavements, past investigations have not evaluated the damage wide-base tires cause to low-volume secondary roads. This pavement class is widely encountered in many trucking applications, although for short distances, but the impact of the new generation of wide-base tires on these pavement structures is unclear. In addition, the static uniform loading assumption used in conventional flexible pavement design methods is inconsistent with realistic tire loading conditions and may result in erroneous pavement response and damage predictions. To address these shortcomings, this research project uses a developed three-dimensional (3-D) finite element model to predict pavement responses to loading applied by various tire configurations on secondary road pavements. This model incorporates the measured 3-D tire-pavement contact stresses, hot-mix asphalt (HMA) linear viscoelasticity, continuous moving load, and utilizes implicit dynamic analysis. The impact of wide-base tires on secondary road pavement damage was analyzed using available damage models, and the results were compared to the damage from conventional dual-tire assemblies. Findings of the study suggest that due to the different contact stress distributions at tire-pavement interface, the impact of the new generation of wide-base tire (455/55R22.5) on secondary road pavements varies when compared to the impact of the conventional dual-tire assembly.
Impact of Wide-Base Tires on Pavements: Results from Instrumentation Measurements and Modeling Analysis
Wide-base tire technology can reduce vehicle fuel consumption and greenhouse gas emissions because there is less rolling resistance at the tire–pavement interface. This study investigated the impact of wide-base tires on two typical flexible pavement structures—full-depth and thin asphalt pavements—through accelerated pavement testing and advanced finite element modeling. Three tire configurations (dual, the first-generation 425, and the new generation 455 wide-base tires) and various pavement sections with different asphalt layer and granular base layer thicknesses were considered. In particular, the advanced modeling simulated realistic tire–pavement interaction and considered appropriate material properties for each pavement layer. It was evident from this study that, of the three possibilities, the wide-base 425 tire configuration caused the greatest pavement damage. The wide-base 455 tire was found to cause greater bottom-up fatigue cracking and increased potential for subgrade rutting than the dual-tire assembly on most tested sections except the thin pavement section with the thickest granular base layer. However, the impact of wide-base tires on fatigue cracking and subgrade rutting potential became less significant with a stronger pavement structure. The finite element modeling results indicated that, compared with the dual-tire assembly, the wide-base 455 tire resulted in similar or less primary rutting potential in thin asphalt pavements and less near-surface cracking potential in thick asphalt pavements.
Full-Depth Flexible Pavement Response to Different Truck Tire Loadings
The objective of this paper is to investigate the potential indication of distress in medium-volume, full-depth flexible pavement when exposed to loading conditions under accelerated pavement testing at various speeds, inflation pressures, and loads, under three different tire configurations: dual-tire (11R22.5), and old and new generations of wide-base tires (425/65R22.5 and 455/55R22.5), respectively. In addition to longitudinal strain measurements at the bottom of hot-mix asphalt, a three-dimensional finite element model was developed in order to evaluate pavement response to loading at various critical locations in the pavement after being calibrated with field-measured data. Field measurements showed that the new generation of wide-base tires, 455/55R22.5, yields 7% more longitudinal strain than a dual-tire assembly at the same tire pressure. The dual-tire assembly shows differential longitudinal strains of 13 to 66% if the very common difference in inflation pressure between the two tires in the dual-tire assembly ranged from 140 and 555kPa, respectively. Using calculated parameters indicative of pavement distresses, the study found that for medium-volume, full-depth flexible pavement under the same loading and environmental conditions, the 455 wide-base tire has the potential to cause similar secondary rutting and fatigue cracking as the dual-tire assembly. In addition, less potential for primary rutting and significantly less potential for top-down cracking are expected when a wide-base tire is used.