Differentiation and quantification of interlayer fatigue shear resistance between double-layer composite asphalt mixtures under complex coupled pavement working conditions

Abstract

In order to quantify the interlayer shear fatigue performance between the upper-middle layer composite materials in asphalt pavement structure under complex coupled pavement working conditions (such as temperature, axle weight, vehicle speed, acceleration, road slope, etc), this study proposes a novel fatigue test method (Dynamic Phase-Transition Test Method). Using this method, extensive tests were conducted on the interlayer fatigue shear resistance between double-layer SBS modified asphalt mixtures (SMA-13/AC-16). Differentiation and quantification of interlayer fatigue shear resistance under complex coupled pavement working conditions were carried out. The main conclusions are as follows: compared to traditional fatigue testing methods, the DPT Test method reduces the test workload by 89 % while yielding results with lower variability. The quantitative model for interlayer shear fatigue life N_f, developed from DPT testing results, accurately predicts interlayer fatigue performance under complex coupled road conditions. In comparison to general working conditions (20°C, 0.5 MPa, 45 km/h, 0.0 G, 0 %), the interlayer shear fatigue life N_f decreases by 90 % under high-temperature heavy-load conditions (50°C, 0.7 MPa, 45 km/h), by 96.3 % under high-temperature, heavy-load, low-speed conditions (50°C, 0.7 MPa, 20 km/h), by 99.7 % under extreme conditions of heavy-load vehicle acceleration (50°C, 0.7 MPa, 8 km/h, 0.4 G), and by 99.0 % during extreme conditions of heavy-load vehicle braking downhill at low speed (50°C, 0.7 MPa, 21 km/h, 0.3 G, 9 %). The research findings provide a reference for the specific degree of interlayer fatigue performance decay of upper-middle layer composite materials (SMA-13/AC-16) under complex coupled pavement working conditions.