| Asphalt aging is an important factor affecting the durability of asphalt pavement.In order to improve the surface service function and long-term service performance of asphalt pavement,without increasing the cost,the factors affecting the aging of asphalt mixture are studied,the evolution law of aging performance of mixture is revealed,and the technical indexes of anti-aging of asphalt mixture are recommended,which can effectively prolong the service life of asphalt pavement.In this paper,starting from the performance analysis of asphalt mortar,five kinds of SBS modified asphalt mortar were prepared for comprehensive evaluation of aging performance.The uniformity of filler distribution in mortar was observed by fluorescence microscope.The short-term aging and long-term aging of SBS modified asphalt mortar were simulated by thin film oven and pressure aging instrument.Temperature scanning test,multiple stress creep recovery test and linear amplitude scanning test were carried out to evaluate the high temperature performance,stress sensitivity and fatigue performance of SBS modified asphalt mortar.The low temperature crack resistance of SBS modified asphalt mortar was evaluated by bending creep test.The water stability evaluation index ER was calculated by contact angle measuring instrument combined with surface energy theory to characterize the adhesion performance of SBS modified asphalt mortar.It is found that the increase of powder-binder ratio can improve the high temperature performance and water stability of the mortar,but the fatigue performance and low temperature performance are reduced.When the powder-binder ratio of asphalt mortar increased from 0.8 to 1.2,the rutting factor increased by 48.3 %(at 64 °C),the water stability evaluation index ER increased by 26.28 %,the fatigue life decreased by30.3 %,and the viscoelastic ratio decreased by 43.0 %.The aging effect further improves the high temperature performance of asphalt mortar,but the low temperature performance and water stability decrease.When the filler-binder ratio increased from0.8 to 1.2,the rutting factor of short-term aged asphalt mortar increased by 80.2 %(at64 °C),the difference of irreversible creep compliance decreased by 37.3 %,and the viscoelastic ratio decreased by 38.7 %.The viscoelastic ratio of long-term aging asphalt mortar decreased by 49.9 %.The ER of short-term aging mortar decreased by 5.7 %,9.8 %,13.7 %,13.6 % and 10.9 % respectively,and the ER of long-term aging mortar decreased by 13.9 %,13.2 %,12.6 %,15.7 % and 15.2 % respectively.In order to study the influence of filler-asphalt ratio,asphalt film thickness and volume index on the aging performance of asphalt mixture,five test schemes of asphalt mixture were designed.The aging of asphalt mixture was simulated by thermal oxygen and ultraviolet coupling oven,and the road performance of asphalt mixture at different aging stages was evaluated.The high temperature performance,low temperature performance and water stability of asphalt mixture were characterized by uniaxial compression dynamic modulus,low temperature bending stiffness modulus and residual stability.Aging makes the dynamic modulus of asphalt mixture increase,the bending stiffness modulus increase,and the residual stability decrease.Therefore,aging improves the high temperature performance of asphalt mixture,and reduces the low temperature performance and water stability.It is recommended that the anti-aging performance of SBS modified asphalt mixture is the best when the powder-binder ratio of SBS modified asphalt mixture is 1.2,the thickness of asphalt film is 9.26 um,the void ratio is 4.6 %,the void ratio of mineral aggregate is 14.8 %,and the asphalt saturation is 68.9 %. |
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