Manufacturing And Properties Investigation Of Ultra-thin SMA Wearing Course Made Of Rubber Modified Asphalt

As a preventive maintenance technology,the ultra-thin asphalt mastic aggregate(SMA)wearing layer has attracted increasing attention of domestic and foreign scholars because of its favorable resistance of rutting,wearing and skidding.However,ultra-thin SMA wearing layer currently used in practice generally has problems such as poor bonding to the substrate,high construction cost,and insufficient low-temperature crack resistance.These problems seriously restrict its application.To mitigate the above problems in ultra-thin SMA wearing layer,the anti-rutting agent,waste tire rubber powder and SBS were used to modify the asphalt.Consquently,high-quality rubber modified asphalt was produced in the laborotary.The mix proportion designing method of ultra-thin SMA-5 and SMA-10 wearing layer was investigated.The road performance,construction technology and economy were explored.The main research contents and conclusions include:(1)The dynamic viscosity taking as the main index,through the single factor test of each additional component and the orthogonal test of the composite modifier,and carrying out a series of macroscopic and microscopic tests,the optimum mix of the rubber modified asphalt was determined(original asphalt:waste tire rubber powder(CRM):SBS:the anti-rutting agent(RA)=100:20:2:5).The produced high-viscositic rubber modified asphalt was characterized by softening point of up to 82.6℃,5℃ ductility of 20.9 cm,elastic recovery of 87.2%,dynamic viscosity of 162614 Pa-s at 60℃,and PG grade of PG94-28.(2)Through the Marshall test results and calculating its various volume parameters,the best grading for SMA-5 and SMA-10 was determined,featured with high stability and favorable volume parameters.And comprehensive consideration of Marshall technical indicators high temperature stability and water resistance,the optimum rubber modified asphalt content of SMA-5 and SMA-10 was determined which was 6.3%and 6.4%,respecitvely;(3)The resulted SMA-5 and SMA-10 showed excellent road performance,and the SMA-5 asphalt mixture has the advantages of thinner paving thickness,higher temperature stability,water resistance and impermeability.SMA-10 showed better performance in low temperature crack resistance and interlayer shearing resistance;(4)The cost of ultra-thin SMA-5 and SMA-10 wearing layer was 14.58 RMB/m2 and 22.76 RMB/m2 respectively.And according to the equivalent annual cost method(EAC),the EAC of ultra-thin SMA-5 and SMA-10 wearing layer were 2.43 RMB/(m2 X year)and 3.25 RMB/(m2/year).