Preparation And Rheological Behavior Of High Viscosity Asphalt Modified By SBS/Viscosity Enhancing Resin Composite

Composite modified high viscosity asphalt(MHVA)is a kind of high viscosity modified asphalt with specific multi-modifiers and additives in asphalt to improve its viscosity,hardness,adhesion and durability,commonly used in drainage pavement and ultra-thin overlay maintenance technology,which can play a good role in anti-spalling and anti-flaking.At present,domestic and foreign research on composite modified high viscous asphalt is mainly focused on direct injection high viscous modified asphalt and wet high viscous modified asphalt,where the wet high viscous modified asphalt in the modifier type,dosing and rheological behavior,modification mechanism and other aspects of less research.This paper investigates the relevant research at home and abroad on the basis of the proposed use of SBS,tackifying resin preparation of composite modified high viscous asphalt,and the modifier dosing,modified asphalt rheological behavior and modification mechanism of the theoretical analysis,indoor tests,and finally carried out the asphalt mixture road performance verification,the main findings of the study are as follows:(1)SBS modifier,stabilizer and tackifying resin were selected as modifiers for the composite modified high viscous asphalt.The single-factor controlled variable method was used to study the effect of modifier admixture on the performance indexes of composite modified high viscous asphalt conventional properties,dynamic viscosity at60°C,rotational viscosity at 135°C and elastic recovery,and to determine the optimal formulation of composite modified high viscous asphalt.The optimum formulation was7.5%SBS modifier,0.19%stabilizer,3%tackifier A and 1%tackifier B.Based on grey correlation theory,the grey entropy correlation between different amounts of SBS modified bitumen,tackifier A(A)and tackifier A/tackifier B(A/B)was analysed and proved to be good.(2)The shear rheology of the asphalt was determined by dynamic shear rheology.(2)The effects of SBS,tackifier A and tackifier B on the rheological properties of the composite modified high viscous asphalt were investigated by dynamic shear rheometry(DSR)tests.It was found that viscosifier A and viscosifier B were effective in improving the viscosity and elasticity of the high viscosity modified asphalt,and the homogeneous degree of A/B modified high viscosity asphalt was the largest.The high temperature performance and rutting resistance of the high-doped SBS modified asphalt,A composite modified high viscous asphalt and A/B composite modified high viscous asphalt were better,and the fatigue resistance of the asphalt was A/B2~#>A3~#>SBS3~#>substrate.The fitted values of zero shear viscosity of A and A/B composite modified high viscous asphalt were all above 40,000 Pa-s by fitting the Carreau model,with significant viscosity enhancement effect.The addition of appropriate amount of viscosity enhancer A and B to SBS modified asphalt can effectively improve the deformation recovery ability,and the composite modified high viscosity asphalt can meet the super heavy traffic volume and above grade load.(3)The structural morphology,changes in chemical reaction functional groups and microscopic morphological characteristics of the high viscosity modified asphalt were analysed by fluorescence microscopy,Fourier transform infrared spectroscopy and atomic force microscopy(AFM).It was found that after the addition of tackifier A and tackifier B,the fluorescence particles in the fluorescence images were evenly distributed and well dispersed,indicating that the tackifier and the bitumen had good compatibility.During the modification process,the weak absorption peaks of sulfoxide group S=O were found in the range of 1300～1000 cm-1 for the matrix asphalt,high-doped SBS modified asphalt,A composite modified high viscous asphalt and A/B composite modified high viscous asphalt,indicating that oxidative ageing reaction occurred in each asphalt.After the addition of viscosity builder A,the C-H aromatic stretching vibration peak at 3044 cm-1 disappears in the spectra of A and A/B composite modified high viscosity bitumen,and the composite modification process is chemically modified;there is no disappearance of the characteristic peaks or appearance of new characteristic peaks in the spectra of high-doped SBS modified bitumen,so the modification process is physically modified.In the A,A/B composite modified high viscosity asphalt system there is a small number of small and evenly distributed"bee-like structure",the roughness and peak-to-valley height difference is low,which means that the asphalt system within the network structure is more stable,viscosity enhancer B to promote the compatibility of other modifiers and asphalt.(4)A semi-open graded STC-10 asphalt mixture was selected for road performance tests.The results showed that the A/B2~#composite modified high viscosity asphalt mixture prepared by adding viscosifier A and viscosifier B had better high temperature rutting resistance and water stability than 1#high viscosity modified asphalt.