Wide-Base Single-Tire and Dual-Tire Assemblies

Abstract

Past studies suggest that wide-base single tires [WBSTs (455/55R22.5)] induce pavement strains that can be either more or less severe than those caused by dual tires of similar sizing, as strain depends on both the spatial direction of the strain and where the strain is located in the pavement. An experimental assessment of strain basins occurring at various positions within the hot-mix asphalt (HMA) layer, as well as within pavement unbound layers, was undertaken to further this understanding. The method and the results of this assessment, along with the pavement damage predicted by using available models are presented. Four failure mechanisms were considered: HMA rutting, both bottom-up and top-down fatigue cracking, and structural rutting. Testing was conducted at two sites on four roads over a range of loads, pressures, and temperatures by using WBSTs and different sizes of dual tires. Data analysis showed several critical strain zones near the tire edges and at the tire center. Optic-fiber sensors were used to analyze these phenomena. HMA rutting was calculated by considering vertical shear strain near the surface under the edge of the tires. Other failure mechanisms were calculated by using maximum strain. The results predicted that the WBSTs tested may induce less damage in the upper part of the HMA layer and more damage when fatigue cracking and rutting of soils and unbound materials are considered. Data collected were from specific tires, and all tests were conducted only under smooth, steady-state rolling conditions. Thus, results should neither be generalized to all tires nor extrapolated to the prediction of actual field performance.