The Properties Of Recovered Asphalt Binders From Laboratory-weathered Asphalt Mixtures

Asphalt pavement is widely used in highway and airport public infrastructure;Asphalt aging is the main cause of asphalt pavement service life.The current asphalt accelerated aging methods are limited to the single influencing factor for binder which is not able to reflect the real pavement situation.This topic focused on the performance impact of aging time and asphalt mixture types on aging asphalt mixture under the situation of integrated weathering.Two kinds of asphalt mixture gradation of AC-13 and SMA-13 were designed,forming Marshall specimen and rutting specimens respectively.The both specimens were put in the integrated weathering oven,aging time was set to 0h,1000 h,2000h,3000 h.Asphalt mixtures at the ageing time were pulled out of oven and then extracted of the aging asphalt from mixtures after extraction and distillation.According to the aging of asphalt viscosity index and dynamic shear rheological(DSR)performance research,macroscopic properties of asphalt aging was explored.The most advanced technology of atomic force microscope(AFM)was used to explore the aging mechanism of asphalt—topography height,adhesion and Modulus etc.The change of microstructure and mechanical properties was studied.Infrared spectroscopy(IR)technology was used to explorer the factors of aging before and after the change of the characteristic functional groups of the asohalt mixture under the integrated weathering.From the macroscopic aspect,after integrated weathering of 1000 h,2000h,3000 h aging,asphalt viscosity and DSR rut factor gradually increased.Aging asphalt viscosity of AC-13 and SMA-13 mixtures changed with small difference with aging time increased;But with the increase of aging time,under the same aging time,the rutting resistance of aging asphalt in AC-13 mixture is bigger than that of SMA-13 mixture.From the microcosmic aspect,the results showed that: 1)with the increase of aging time,asphalt binders extracted from AC-13 and SMA-13 mixture appeared a certain degree of oxygen reaction,while the asphalt binder from AC-13 asphalt mixture was observed more oxygen than SMA-13 mixture;2)SBS modifier in AC-13 mixture were decomposed more rapidly than the SMA-13 mixture;3)Anti-aging ability of the asphalt binders from AC-13 mixture was weaker than those from SMA-13 mixture.Atomic force microscope results showed that: 1)Morphology roughness of the asphalt binders from AC-13 and SMA-13 mixtures gradually reduced with the increase of aging time.2)Topography height of the asphalt binders from AC-13 and SMA-13 mixtures gradually reduced with the increase of aging time,tend to be "flat",topography height of "bee" structure area was higher than the "non-bee" structure area;3)Micro adhesion force and modulus of the asphalt binders from AC-13 and SMA-13 mixtures were decreased first and then increased with the increase of aging time.Adhesion force and modulus of the 3000 h aging asphalt increased significantly,adhesion force and the modulus the "bee" microstructure is bigger than the "non-bee" structure area.