The fatigue properties of the asphalt pavement layer are influenced significantly by different strain levels and temperatures. This research investigated the critical fatigue position within the asphalt pavement layer considering the couple effects of strain levels and temperatures. Firstly, field tests were conducted to measure the typical temperature distribution of the asphalt pavement layer. Secondly, laboratory four-point beam fatigue test and dynamic modulus test were applied to evaluate the fatigue life and the dynamic modulus of the asphalt mixture, respectively. Based on the results of field and laboratory tests, the distributions of strain and fatigue damage within the asphalt layer at different temperature conditions were calculated. It was found that the fatigue life of asphalt mixture decreased with the rising strain level but increased with the rising temperature. The critical fatigue position in the flexible pavement changed from 5 to 20 cm when the pavement temperature condition varied from high to medium/low. In terms of the semi-rigid pavement, this position varied between 6 and 12 cm at different temperature conditions. In addition, the fatigue damage within the semi-rigid pavement at high temperature was found to be as noticeable as that at medium/low temperatures. Thus, the fatigue properties of the asphalt layer at higher temperatures need to be carefully evaluated as well.

Reducing greenhouse gas emissions has turned into a pillar of climate change mitigation. Truck platooning is proposed as a strategy to lower emissions from vehicles on roads. However, the potential interactive impacts of this technology on road infrastructure emissions remain unclear. Here, we evaluate the decarbonization effects of truck platooning on the integrated vehicle-road system at a large-scale road network level, spanning 1457 road sections across North America. We show that truck platooning decreases emissions induced by truck operations, but it degrades faster the durability of road infrastructure and leads to a 27.9% rise in road emissions due to more frequent maintenance work. Overall, truck platooning results in a 5.1% emission reduction of the integrated vehicle-road system. In contrast to the benefits of emission reduction, truck platooning leads to additional financial burdens on car users and transportation agencies, calling for the consideration of tradeoffs between emissions and costs and between agencies and users. Our research provides insights into the potential applications of truck platooning to mitigate climate change.

An asphalt mixture has different tensile properties as compared with compressive ones due to the combined effect of aggregate interlock, binder stiffness, and aggregate-binder interactions. This study aims to investigate the dynamic tensile and compressive moduli of asphalt mixture through indirect tensile and four-point bending modulus tests. Firstly, methods for determining the tensile moduli of the mixtures in the preceding two tests are developed based on the bimodular theory. Then, the compressive and tensile moduli of one asphalt mixture are determined using the developed methods. It was found that the compressive moduli of the asphalt mixture exceed the tensile ones over the entire frequency domain in both types of test. In general, tensile moduli obtained from indirect tensile and four-point bending tests are in good agreement, especially at the intermediate- to high-frequency domain. The ratios between the compressive moduli and tensile moduli obtained from the two tests are also similar, regardless of test temperature and air-void content. The ratios are about 2.5 at low and intermediate temperatures and increase to approximately 4.0 at high temperatures. The conventional solution for the indirect tensile test based on a single-modulus assumption mainly reflects the compressive properties of the mixture but provides an unrealistic estimation for its Poisson’s ratio. Conversely, in the four-point bending test, the solution based on a single modulus well represents both the tensile and compressive properties of the mixture.