Research On The Change Characteristics Of Asphalt Mixture Performance Under Old Aging Effect

With the rapid advancement of science and technology,roads are the arteries of the development of modern society.Old aging is an issue that cannot be avoided during road use,it also has a major impact on road life.Asphalt pavements are subjected to many external environmental factors during the service phase to make the performance of asphalt mixtures worse,the ability of anti-aging is the ability of asphalt mixtures to resist these factors to maintain their road performance.The aging process is long and complicated.The short-term aging process takes place during the mixing,rolling and paving of asphalt mixture.After the pavement is cooled to room temperature and put into service,it begins to age.The research in this paper is to test and analyze the performance of asphalt mixture after old aging.Combining domestic and foreign experimental research and actual conditions,this paper selects 70# matrix asphalt and stable rubber asphalt as the two types of asphalt,and using AC-20 grading to simulate the upper and lower layers of the pavement.The SMA-13 grading is selected to simulate the mid-plane.Layers,according to the specifications of the screening,mixing ratio design and calculation of the best ratio of oil and stone,using the data obtained for asphalt mixture test.In order to make the indoor simulated asphalt mixture aging as precise as possible to the aging state of the actual road surface,this paper selects the oven heating method for short-term aging test,and the long-term aging chooses the time-delay oven aging method.Asphalt mixture is aged to varying degrees,short-term aging is selected for 2 hours,4 hours,and 8 hours,long-term aging is selected for 5 days.Besides,the performance of the asphalt mixture after aging with the above conditions is compared with the performance of the asphalt mixture without aging.To evaluate the performance of asphalt mixture from two aspects,road performance and mechanical properties.After referencing a large number of papers,periodicals,and books,this paper evaluates the road performance from four types of performance,High temperature stability,low temperature crack resistance,water stability,and fatigue resistance.High-temperature stability is tested by high-temperature rutting test method,evaluation indicators is the dynamic stability.Low-temperature bending creep test method is selected by the low-temperature crack resistance,the evaluation index is low-temperature bending micro-strain.Water stability is tested by submerged Marshall test and freeze-thaw chapping test,the evaluation indexes are Marshall residual stability ratio and freeze-thaw splitting strength ratio.Four-point bending fatigue test is used to test fatigue performance,and the evaluation index is fatigue life.The mechanical properties are selected through comparison of the applicability and advantages and disadvantages of several test methods for mechanical properties.According to the test procedure,after performing performance tests on the five aging degrees of the two asphalt mixtures,the following conclusions are drawn: the high temperature stability increases with the aging degree,the growing rate after the long-term aging is lower than that after the short-term aging.And the low-temperature crack resistance increases.In the short-term aging period,the decline's speed is faster,and the long-term aging is slower,but the overall low-temperature crack resistance decreases with the aging time.The water stability also decreases with the aging degree,but the long-term aging decline is not as fast as short-term aging.Fatigue performance with ageing,fatigue life decreases sharply.Under the same control variables,dynamic modulus increases with the aging degree of asphalt mixture,the dynamic modulus after long-term aging is the highest,so as the growth rate.Therefore,in order to extend the service life and service life of asphalt pavement,it is necessary to delay the aging of the asphalt mixture by controlling the key factors affecting the aging effect of the asphalt mixture,so as to improve the comfort of asphalt roads and reduce the cost of pavement maintenance.