Research On Rheological Behavior And Fatigue Characteristics Of Low-heat Generation Composite Modified Asphalt

Rutting is one of the main diseases of asphalt pavement,which is mainly because the viscous components in asphalt materials produce irreversible permanent deformation under high temperature conditions.The energy generated by this permanent deformation is mainly dissipated in heat at the microscopic level.In fact,as a typical viscoelastic material,the viscosity ratio of asphalt materials is usually characterized by the phase angle,and the tangent of the phase angle is closely related to the heat generation characteristics of the asphalt material.In addition,the structure of asphalt pavement is fatigue-failure under the long-term effect of vehicle load.The fatigue and rheological properties of asphalt materials are the key to evaluating the durability of asphalt materials.So in this paper,the fatigue properties and rheological properties of low-heat-generation composite modified asphalt are studied.In this paper,three low-heat-generation modifiers HPT,HPT-E,HPT-R are selected to prepare low-heat-generation composite modified asphalt with SBS modifier by the blending process.The fatigue properties and rheological properties of the composite modified asphalt with the optimal dosage are studied to discuss the comprehensive performance and lay the foundation for engineering applications.For the preparation process of low-heat-generation composite modified asphalt,the low heat generation composite modified asphalt was prepared by the blending process.The influence of the modifiers' content on the technical properties of the composite modified asphalt was obtained,and the best content is 1.5%.HPT and HPT-E can improve the high-temperature performance of SBS modified asphalt and reduce its loss factor,but HPT-R has little effect on the asphalt penetration classification and PG classification index.For the rheological properties of low-heat-generation composite modified asphalt,the rotational viscosity test,multi-stress repeated creep recovery test(MSCR),temperature scanning test,low-temperature bending beam rheological test(BBR)are used to study the low-heat-generation composite modified asphalt's high and low temperature performance.By drawing the main curve,the rheological performance in a wider time temperature range are studied.The results show that: HPT,HPT-E can better improve the high temperature performance of SBS modified asphalt,and HPT-R has little effect on the high temperature performance of SBS modified asphalt.The three low-heat-generation modifiers have no significant effect on the low temperature performance of SBS modified asphalt;from the main curve study,we can see that HPT and HPT-E make the elastic modulus of SBS modifiedasphalt increase,thus improve the high temperature performance.For the fatigue performance of low-heat-generation composite modified asphalt,through fatigue tests under different stress loads and different loading modes,based on the fatigue life corresponding to the parameters such as complex modulus,dissipated energy,cumulative dissipated energy,rate of change of dissipated energy and cumulative dissipated energy ratio,the fatigue properties and self-healing properties of low-heat-generation composite modified asphalt is studied.The results show that: HPT has the most obvious improvement in the fatigue performance of SBS modified asphalt,followed by HPT-E.After adding HPT-R,the fatigue life of SBS modified asphalt becomes smaller or unchanged.The fatigue life corresponding to the complex modulus and phase angle is used as the evaluation index.By calculating the self-healing coefficient,it can be known the effect of HPT-R and HPT-E on the self-healing improvement of SBS modified asphalt is better,and the effect of HPT is less.For the micro-mechanism of low-heat-generating composite modified asphalt,through atomic force microscope observation,differential scanning calorimeter method and infrared spectroscopy test,the modification mechanism of low-heat-generating composite modified asphalt was explained from a microscopic point of view.The results showed that:,The addition of HPT and HPT-E makes the internal structure of SBS modified asphalt more dense and stable by enhancing its elasticity.And the high temperature performance and fatigue performance are improved because of the production of its unique nitrogen-containing bonds and functional groups.After adding HPT-R,the structural change is very small,and the types of bonds and functional groups have small change.So it has little effect on the rheological properties and fatigue properties,but the self-healing enhancement of SBS modified asphalt is more obvious.