Numerical Simulation of Indirect Tensile Test Based on the Microstructure of Asphalt Mixture

Abstract

Indirect tensile (IDT) test is widely adopted to evaluate the anticracking performance of hot-mixture asphalt (HMA) at intermediate and low temperatures. This paper presented an approach to simulate the IDT test based on the microstructure of mixture. The X-ray computed tomography and digital image processing technologies were employed to characterize the microstructure information of the HMA specimen. The viscoelastic numerical simulation results agreed well to the laboratory IDT tests. Two indices, mixture stiffness obtained by numerical simulation and local stress state, were adopted to study the effects on the IDT tests of many factors such as loading orientation, air voids, loading rate, and the aggregate/mastic modulus ratio. Loading orientation will influence the IDT performance of heterogeneous HMA specimens. The multiple IDT tests were suggested to be conducted to reduce the effects of distribution variation of aggregates and mastic in mixture specimens. Loading rate will induce more remarkable influence on the IDT tests at a higher temperature (15°C other than −10°C). The mixture stiffness without air voids can increase about 8% according to the numerical simulation. The aggregate/mastic modulus ratio has significant impact on the strain state of aggregates and mastic. The strain incoordination of aggregate and mastic may induce the distress of mixture under loading.