Study On Performance Of Multi-scale Nanomaterials Modified Asphalt And Its Mixture

Aging is one of the most important factors affecting the service life of asphalt pavements.Studies have found that layered silicates can improve the thermal oxygen aging performance of asphalt materials,while inorganic nanoparticles can improve the resistance of asphalt materials to ultraviolet aging.The two nanomaterials are compounded into multi-scale nanomaterial to improve the anti-aging performance of the asphalt materials and to prolong the service life of asphalt pavement.Multi-scale materials have been used to modify asphalt,but the performance of their mixtures has not been evaluated.Evaluation of multi-scale nanomaterials from the perspective of asphalt mixtures is closer to the actual situation of engineering.1%organic vermiculite（OEVMT）and 3% three kinds of inorganic nanoparticles（nano-Si O₂,nano-Ti O₂and nano-Zn O）were used to modify 70#asphalt and its mixture.In order to evaluate the impact of multi-scale nanomaterials on the performance of asphalt binder,long and short-term,ultraviolet light and natural aging simulations were performed on the asphalt,and the physical,rheological and micro properties of the asphalt before and after aging were evaluated.The asphalt mixture before and after modification is subjected to short-term,loose,and compacted long-term and ultraviolet light aging,natural aging simulations,respectively.The high-temperature,low-temperature,water stability,and fatigue and aging performance of the asphalt mixture are tested and evaluated through laboratory tests.At the same time,the effects of different aging methods on road performance of asphalt mixture and aging degree are compared and correlated with the asphalt binder aging simulation.The main conclusions are as follows:（1）The physical,rheological and microscopic properties of unmodified and three multi-scale nanomaterial modified asphalts after different aging methods are analyzed.It was found that three kinds of multi-scale nanomaterials can make the combination of asphalt and matrix more stable,and improve the aging performance significantly.The effect of different modifiers on high-temperature performance of asphalt binder is inconsistent.However,multi-scale nanomaterials can improve the low temperature performance of asphalt.Except for OEVMT+Si O₂,the other modifiers can improve the fatigue performance of asphalt.In contrast,OEVMT+Zn O has the best behavior.（2）The road performance test results of asphalt mixtures before and after modification prove that in addition to OEVMT+Si O₂,the other modifiers have a slight adverse effect on high-temperature performance.All three multi-scale nanomaterials can improve the low temperature performance and fatigue performance of asphalt mixtures.The addition of multi-scale nanomaterials enhanced the moisture sensitivity of the mixtures.The results of Marshall test and rutting test before and after aging were compared,and it was found that multi-scale nanomaterials improved the aging resistance of asphalt mixtures significantly.Low temperature,water stability and fatigue performance tested with unaged mixtures will affect test accuracy.（3）The mixtures aging degrees of mixed aging,short-term aging,long-term aging and UV aging are compared.The aging methods all can show the improvement effect of multi-scale nanomaterials on the aging performance of asphalt mixture,and the loose UV aging has the most obvious improvement effect.It was found that the rank of aging degree was mixed aging<STOA<LTOA<compacted UV aging<loose long-term aging<loose UV aging.The aging degree of compacted mixture is much lower than that of the loose.The aging effect of ultraviolet light on asphalt mixture is more serious than that of thermal oxygen aging.（4）The aging index results of natural aging asphalt and its mixture show that multi-scale nanomaterials have a significant inhibitory effect on aging,and for binders,the longer the aging time,the more significant the effect.The aging degree of natural aging asphalt binder for 4 months is higher than that of asphalt TFOT,and the aging time of 8 months is slightly lower than that of PAV.