Material Characterization And Mechanism Of Low Rolling Resistance Modified Asphalt

When vehicles travel on the road,tire tread and road surface will produce rolling resistance,which will affect energy consumption.Reducing energy consumption will have a positive impact on building an environment-friendly society.At present,the research on rolling resistance mainly focuses on tires.Based on the theory of viscoelastic mechanics,low dynamic heat-generating rubber was obtained to produce low rolling resistance tire by modifying the molecular structure and reducing the strain lag of rubber.Asphalt pavement is the most widely used road surface,but the research on rolling resistance of pavement is still blank.Therefore,this study independently developed a low rolling resistance asphalt modifier HPT,and systematically investigated the influence of HPT on the physical properties of modified asphalt;studied the rheological properties by dynamic mechanical analysis;and characterized the micro-structure of low rolling resistance modified asphalt,and discussed the modification mechanism.Firstly,the influence of HPT content on the conventional index of low rolling resistance modified asphalt was studied.The results show that with the increase of HPT content,the softening point increases,penetration decreases,ductility decreases and viscosity increases,and the segregation characteristics are effectively changed.The non-uniformity of dispersion caused by SBS at high temperature is alleviated.It can promote the formation of network structure and enhance the performance of SBS.In order to standardize low rolling resistance modified asphalt according to SBS modified asphalt I-D standard,the segregation characteristics of SBS are improved.The content of low rolling resistance modifier HPT ranges from 0.25% to 1.62%.Secondly,the effect of HPT content on rheological properties of low rolling resistance modified asphalt was studied by dynamic shear rheological test and low temperature bending beam rheological test.The results show that the phase angle of SBS modified asphalt is obviously different from that of SBS modified asphalt.The phase angle of low rolling resistance modified asphalt decreases continuously with the increase of temperature,which is the thought source of "low rolling resistance".In the aspect of High Temperature Rheological properties,the linear viscoelastic range is determined by stress scanning,and the stress applied in the linear viscoelastic range of low rolling resistance modified asphalt is determined in the stress range of 1000 Pa.Frequency scanning experiment shows that the zero shear viscosity of low rolling resistance modified asphalt is obviously higher than that of SBS modified asphalt.It has high viscosity and strong resistance to deformation.It provides a reference for the determination of construction temperature.MSCR experiment shows that low rolling resistance modified asphalt has the strongest high temperature performance with HPT1.4% and 1.6% content.The low temperature and fatigue properties of resistance modified asphalt are poor,and the harm of low temperature cracking and fatigue cracking needs to be improved later.Compared with several common modified asphalts,low rolling resistance modified asphalt has lower temperature sensitivity,less influence with temperature change and stronger construction and workability.It is determined that low rolling resistance modified asphalt can greatly improve traditional SBS modified asphalt from macrorheological point of view to make it higher.Temperature performance is excellent.By comparing different low rolling resistance modifier HPT dosage,the optimum performance is determined in the range of 1.4%-1.6%.It can be used as a reference for future road construction dosage.Thirdly,fluorescence microscopy,infrared spectroscopy and differential scanning calorimeter are used to study the mechanism.HPT can play a dual role.Firstly,HPT can improve the thermal storage stability of SBS modified asphalt and solve the segregation problem.With the increase of HPT content,the performance of modified asphalt is gradually improved.The addition of PT promotes the bonding between SBS and asphalt,and makes the network structure more stable at the junction of SBS and asphalt.Compared with SBS modified asphalt,HPT is a new additive with a new melting point,and the melting point is higher than SBS.Under high temperature load,the change of viscous flow transition temperature is small,the energy loss is low,and the rolling resistance is excellent.Finally,the rolling resistance test and evaluation method of low rolling resistance modified asphalt was established by referring to the tire industry tire rolling resistance test method.The performance differences between low rolling resistance modified asphalt and SBS modified asphalt were compared and investigated.According to the standard of "compression and flexion test of vulcanized rubber",the endothermal performance was evaluated.Compared with SBS modified asphalt,the heat generation rate of low rolling resistance modified asphalt is reduced by 14.4%,while the heat generation rate of low rolling resistance modified asphalt mortar is reduced by 15.5% compared with SBS modified asphalt mortar,which can effectively reduce energy loss.The rolling resistance performance is evaluated according to the "Test Method for Rolling Resistance of Automobile Tires".Compared with SBS modified asphalt,the heat generation and power loss of the rolling resistance model made of low rolling resistance modified asphalt and carbon black rubber are 3.7% and 5% lower,which proves its low rolling resistance characteristics.Based on the above research,the addition of low rolling resistance modifier HPT promotes the combination of SBS and asphalt,reduces the phase angle,improves the high temperature performance of asphalt,effectively reduces rolling resistance and energy loss.