Coupled Moisture-loading Damage Of Asphalt Mixtures Under Meso-scale

Asphalt pavement is the main form of Expressway in our country.Asphalt mixture is always in contact with various forms of moisture.Under the influence of traffic load,the micro defects in the material gradually produce and expand,resulting in irreversible damage to mechanical properties,which lead to destruction of the pavement structure.On the one hand,road engineering has always regarded asphalt mixtures as isotropic materials,which ignores the influence of meso-scale characteristics,and does not agree with the structural composition of the asphalt mixture itself.On the other hand,people often pay more attention to water damage,ignore the coupled moisture-mechanical effect in long term.Therefore,it is necessary to take into account the meso-scale characteristics of asphalt mixture,and analyze the local damage or failure of asphalt mixture under the presence of moisture.First of all,based on CT scanning and image processing technology,a threedimensional finite element model of asphalt mixture considering real meso-scale characteristics is established.The accuracy of model is verified by volume index such as void fraction.Based on the results of three-dimensional reconstruction of asphalt mixture,the distribution of water is revealed.The important information such as velocity and saturation is obtained.Secondly,the influence of moisture on asphalt mortar was studied by means of dynamic shear rheological test and three-point bend test.The viscoelastic parameters and fracture mechanics parameters needed for simulation are also obtained.The Extended Finite Element Method(XFEM)is used to analyze the mechanical response and local performance decay rules of asphalt mixture under loading action.The presence of moisture will significantly aggravate the material damage of asphalt mixture.Finally,the influence of moisture and the long-term effect of moisture on asphalt mixture are analyzed.Combined with the results of finite element simulation,the moisture damage of asphalt mixture under meso-scale will be discussed.In this paper,the influence of moisture presence on the mechanical performance of asphalt mixture is analyzed.The moisture damage of asphalt mixture under meso-scale is revealed.This research provides a new idea for studying the effect of moisture on asphalt mixture.It also supports the research about failure mechanism of pavement material.