| Road traffic safety is still a common problem faced by all countries in the world.In the traffic safety impact system composed of people-vehicles-roads-environment-management,the role of "roads" is very important.An important factor that causes frequent traffic accidents is the lack of sufficient friction between tires and roads.At the same time,the greater capacity and wheel load(especially heavy-duty vehicles)accelerate the polishing and abrasion of road surface aggregates,which quickly decays the anti-skid ability of the road surface,and the problem of traffic safety is becoming increasingly prominent.Pavement skid resistance is one of the key technical issues to achieve high-grade,heavy-traffic road safety,comfort,and highspeed driving,and the long-term anti-wear properties of aggregates and the gradation composition of the asphalt mixture have an extremely important impact on the service durability of the anti-skid surface of the pavement.This article introduces a new type of anti-skid and wear-resistant aggregate-calcined bauxite.Mechanical properties attenuation law,resistance to salt erosion and morphology characteristics of five kinds of aggregates of different grades of calcined bauxite(75#,85# and88#),steel slag and limestone was explored by increasing the pressure,abrasion times and polishing times,as well as salt solution immersion and.etc.Based on multi-point support skeleton theory,progressive filling theory and n method,aggregate compaction density and skeleton clearance ratio(VCA)as evaluation indicators was used to design the coarse and fine aggregate gradation of small particle size SMA-7 asphalt mixture And through Marshall test to determine the ratio of coarse and fine aggregates,so as to obtain the composition of SMA-7asphalt mixture.Based on the volume method,mixed to form an SMA-7 asphalt mixture with significant difference in polishing characteristics.Adopt rutting test,trabecular low temperature bending test,water immersion Marshall test,freeze-thaw splitting test,and anti-skid test,etc.The influence of different aggregate was analyzed of SMA-7 asphalt mixture.On this basis,the gray decision theory is used to determine the optimal blending plan of SMA-7 material composition.Finally,relying on the test section of a secondary road reconstruction and expansion project of Yunnan National Highway G219,its field service effect and conduct a life cycle cost-benefit analysis was evaluated.The study found that,Among the five types of aggregates,calcined bauxite aggregates have the best anti-wear and anti-wear properties(and the higher the label,the better the performance),followed by steel slag and limestone aggregates.Salt corrosion conditions have no effect on the properties of calcined bauxite and limestone aggregates.For the morphological characteristics of the aggregate,the calcined bauxite and steel slag are not much different,but both are better than limestone.Determine the ratio of coarse and fine aggregate to 75:25,and recommend the gradation range of small particle size SMA-7 asphalt mixture.After being mixed with calcined bauxite,the high temperature stability,low temperature crack resistance and skid resistance of the small particle size SMA-7 asphalt mixture are improved to varying degrees,but its water stability is slightly reduced.The performance of asphalt mixture is greatly affected by the content of calcined bauxite and less affected by its particle size.When blended with 100% calcined bauxite aggregate with a particle size of 4.75-6.35 mm,the road performance of SMA-7 is optimally balanced.The long-term anti-skid performance of the mixed asphalt mixture is significantly better than that of the single-mixed limestone asphalt mixture.The test project verifies that the upper layer of SMA-7 exhibits excellent anti-skid durability and economic and social benefits. |
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