Damage and life cycle assessment of new-generation wide-base tires in New Brunswick, Canada. (c2017)

Abstract

Wide-base tires (WBT) provide environmental benefits compared with conventional dual-tire assemblies (DTA), but research has consistently showed higher pavement responses and potential damage due to the use of WBT. Even though improvements were made with the introduction of new-generation wide-base tires (NGWBT) in 2000, NGWBT are still reported to be causing more damage to road infrastructure. However, a comprehensive evaluation of NGWBT and DTA considering the pavement damage and environmental benefits caused by each is not usually performed. This study implements finite element method (FEM) analysis and life-cycle assessment (LCA) to perform a fair evaluation of the impact of NGWBT and DTA on the roads of New Brunswick. On one hand, the FEM analysis incorporates features usually omitted in conventional analysis of flexible pavements regarding material behavior (e.g., asphalt concrete viscoelasticity and granular material nonlinearity) and loading (e.g., moving load, three-dimensional nonuniform tire–pavement contact stresses). Critical pavement responses from the FEM model were input in a transfer function to calculate pavement damage. Two variables, combined DTA-to-NGWBT ratio and combined damage ratio, were utilized to assess both tire technologies from the impact on the pavement structure. On the other hand, LCA provided global warming potential (GWP) and energy consumption considering variables such as NGWBT market penetration, traffic level, and seasonal effect. The highest impact difference between NGWBT and DTA on pavement structure was found near the surface, which could be related to near-surface fatigue cracking, while there was no difference on the subgrade rutting. After combining the distresses considered, pavement damage increased as NGWBT market penetration became greater; for a case study with market penetration of 20%, damage increment due to NGWBT increased by 8%. It has to be noted that the impact of steering wheel was not considered in this study, which usually causes the highest impact on pavements. An analysis tool was developed to ease the evaluation of the pavement and calculate pavement damage under any traffic, as well as base and subbase material. Three scenarios were considered in the LCA analysis: i) Scenario 1: NGWBT and DTA resulted in the same bottom-up fatigue cracking and rutting potential; ii) Scenario 2: tires resulted in different cracking but the same rutting potential; and iii) Scenario 3: the tires resulted in the same cracking but different rutting potential. In general, the higher the NGWBT market penetration, the higher the environmental benefits due to the reduction in fuel consumption. Hence, a holistic assessment should be considered in the analysis of wide-base tire impact.