Analysis of micromechanical response to viscoelastic and plastic behaviors of asphalt mixture using a smart sensing technology

Abstract

The damage evolution of asphalt pavement is intrinsically related to mechanical behaviors of asphalt mixture. Knowing the micromechanical responses of asphalt mixture is of great significance for essentially revealing the pavement damage evolution. This study aims to measure the inter-particle contact force among aggregates in laboratory tests by utilizing a Smart Aggregate, and investigate the micromechanical responses to viscoelastic and plastic behaviors of asphalt mixture in real time. Various uniaxial loading tests, including compression-recovery test, dynamic loading test, penetration test and creep test, were conducted on the asphalt mixture with Smart Aggregate inside. After that, the evolution of inter-particle contact force was comprehensively analyzed for the macroscopic mechanical behaviors in view of particle level. Results indicates that the Smart Aggregate performs well in sensing the evolution of micromechanical behaviors for asphalt mixture under external loads. The measured force along with loading direction (i.e. FSA_Z) follows well with the strain variation of asphalt mixture during the stress-controlled loading tests. The FSA_Z has a significant linear relation to the strain of asphalt mixture, and the correlation coefficients of FSA_Z amplitude with compressive strain and recoverable strain are 0.994 and 0.986, respectively. As the maximum strain amplitude of asphalt mixture is less than 0.006% under dynamic load, the FSA_Z exhibits in lower level even though the stress amplitudes are larger at lower temperature. After the local strain is more than 0.4%, FSA_Z varies with a same trend to the stress evolution of asphalt mixture when it takes a plastic deformation. Strain, which is associated to micro displacements of aggregates and change of their interactions, plays the fundamental role in transmitting the loading stress to the Smart Aggregate.