Experiments Of Mix Design And Pavement Performance For SBS Modified Semi-Open-Graded Asphalt Mixture

High viscosity asphalt or special asphalt are mostly used when semi-open graded asphalt mixture was used to pave wear layer.In order to enrich the types of semi-open graded asphalt mixture,this paper use SBS modified asphalt and fiber to prepare DK-7S and DK-10S asphalt mixtures which have 9%-13%voids.Then,the material composition design method and properties were studied to select the suitably types of semi-open graded asphalt mixture.The allowable fluctuation range of the key sieve pass rate of its gradation is further studied.The main test and analysis results are as follows:(1)there is no specification for the composition design of semi-open graded asphalt mxture of surface layer.Therefore,this paper determined the gradation design method and test method suitable for semi-open graded asphalt mixture by analyzed and summarized the existing results and conducted indoor test demonstration.The improved CAVF method is used to design the semi-open graded asphalt mixture.It is recommended to test the density of semi-open graded asphalt mixture by CoreLok method.Double-sided compaction 50 times is used to form the semi-open graded asphalt mixture.The reasonable dry mixing time of fiber under different mineral quality is recommended.(2)The semi-open graded asphalt mixtures DK-7S and DK-10S were designed by using SBS modified asphalt,basalt coarse aggregate and domestic granularly lignocellulose in laboratory tests.And the road performance was compared with AC,SMA,OGFC,UTFC and other mixtures under the same maximum particle size.The test results show that the semi-open graded asphalt mixture with 9%-13%voids have good performance under the high content of coarse aggregate,a large amount of asphalt,and an external fiber.(3)Comparing the performance of DK-7S and DK-10S mixture,it is recommended to use 11%voids DK-10S as surface layer of semi-open graded asphalt mixture.For domestic granularly wood fiber and German fiber AD-10,Hamburg wheel-track device and simulated test of the acid rain were carried out.And AD-10 fiber is used in semi-open graded asphalt mixture of surface layer.(4)Considering the fluctuation of mixture material composition caused by the uncertainty in the large-scale construction of real engineering,and based on the raw materials used in practical engineering,the allowable fluctuation range of key sieve pass rate of DK-10S-AD mixture was preset.With three gradations DK-10S-AD mixture were designed based on the upper,middle and lower limits of this range.Laboratory tests were carried out to compare their porosity,oil film thickness,leakage loss,dispersion loss,high and low temperature performance,water stability and skid resistance.The rationality of the allowably fluctuation range of the preset critical sieve pass rate was verified.