| Along with the development of economic construction,the construction of infrastructure such as roads and bridges is also strengthening.During the maintenance and reconstruction of highways,improper handling of RAP materials will cause serious pollution to the environment.In the actual production,the mixing station has added RAP to the hot mix asphalt mixture to form a low RAP content hot mix asphalt mixture,but there is no practical theoretical basis.Because of the complex composition of hot mix asphalt mixture with low RAP content,and the comprehensive effect of climate,traffic and other factors in the process of use.The pavement is prone to fatigue damage,so this paper has done the following research on hot mix asphalt mixture with low RAP content:1.Test of material performanceThe RAP and new aggregates of milling planer were screened by screening test,and the basic properties were tested at the same time.The performance of old asphalt in base asphalt and RAP compound is also tested.The test results show that both of them meet the requirements of the specification.2.Mix ratio Design of Hot mix Asphalt mixture with low RAP contentBecause of the low RAP content hot mix asphalt mixture mixed with a certain proportion of rap,the mix ratio design becomes more complex compared with the ordinary asphalt mixture.The Marshall test determines that the amount of RAP added is 10 and 15,20 AC-10.The gradation of two types of AC-13 low RAP hot mix asphalt mixture and the optimum bitumen ratio.3.Fatigue Test of Hot mix Asphalt mixture with low RAP contentThe fatigue test was carried out by four-point bending trabeculae,and the test was carried out at the temperature of 15 ℃.The loading waveform was sinusoidal and the loading frequency was 10 Hz.The fatigue test of hot mix asphalt mixture with low RAP content was carried out by stress control model,and the results were fitted by exponential fitting and logarithmic fitting:(1)The fatigue performance of AC-13 hot mix asphalt mixture with low RAP content using preheated RAP is better than that of AC-10 hot mix asphalt mixture,and with the increase of RAP content,the fatigue performance of AC-13 hot mix asphalt mixture is better than that of AC-10 hot mix asphalt mixture.The fatigue properties of AC-13 are improved gradually,while the fatigue properties of AC-10 are decreased gradually.(2)For AC-13 low RAP mixed asphalt mixture with pre-heated RAP,the fatigue life of asphalt mixture was significantly changed when the stress ratio was 0.5.When the stress ratio of AC-10 low RAP mixed asphalt mixture was 0.35,it can be seen that the fluctuation of stress ratio in high stress state affected the fatigue life of asphalt mixture with low RAP content.(3)The fatigue performance of AC-10,AC-13 low RAP mixed asphalt mixture with non-heated RAP under the same stress ratio is much better than that of asphalt mixture after adding heated RAP.(4)Under the same stress ratio,the fatigue performance of AC-10 and AC-13 low RAP content hot mix asphalt mixture mixed with unheated RAP is much better than that of RAP asphalt mixture after heating.4.Pavement structure Analysis and checking calculation of low RAP Hot mix Asphalt mixture Test RoadBased on the investigation of climate and vehicle load in Fushun area,AC-13(20%)low RAP content hot mix asphalt mixture was selected for pavement design,and its permanent deformation,low temperature cracking and fatigue performance were analyzed,which all met the requirements of operation.5.Test road test and economic benefit analysis.According to the structure design of pavement paving test road length is 3.3km in Xinbin County of Fushun City,in the paving completed and opened to traffic after the operation of flatness,and the economic benefit is analyzed.The test results and economic feasibility analysis of low RAP content of hot mix asphalt mixture is verified from economy and technology double,which will later RAP reuse provides certain theoretical support. |
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