Pavement Performance Of Oil-modified Asphalt

Low temperature cracking is one of the main problems when asphalt pavement is in service in cold areas.After low-temperature cracks appear on the pavement,rainwater can freely enter the pavement structure.Combined with the effects of freeze-thaw cycles and traffic loads,it will greatly test the riding quality and service life of the pavement.Considering that petroleum asphalt is a non-renewable resource and the cost of polymer modified asphalt is high,oil is added to the petroleum asphalt as a regenerant or modifier.However,there are many types of oils that can be added to asphalt.Current research has not confirmed which oils are suitable for the use of asphalt in cold regions.There is a lack of a systematic and comprehensive evaluation of the performance of oil-modified asphalt.The evaluation system and evaluation indicators also need to be further improved.In view of the above problems,the following researches are carried out in this thesis.Based on the continuous classification temperature of high temperature PG,the blending amounts of six oil content modifiers were determined.Through the rutting factor,fatigue factor,creep stiffness and rate of change proposed in the SHRP,the high,medium and low temperature rheological properties of the oil-modified asphalt were preliminarily evaluated.The MSCR test,LAS test,k index and J index are used to further predict the high,medium and low temperature rheological properties of oil-modified asphalt.The results show that the MSCR test and LAS test considering the damage effect can more effectively reflect the high-temperature damage characteristics and fatigue damage characteristics of the asphalt;k index and J index,which take into account the low temperature deformation ability and stress relaxation ability of asphalt simultaneously,can be used to predict the rheological properties of asphalt at low temperature more accurately.The rheological data obtained from the BBR test were used to estimate the thermal stress,and the low-temperature critical cracking temperature of the oil-modified asphalt was calculated based on the SAP theory.The DENT test was used to estimate the ductile fracture performance of oil-modified asphalt under large strain and nonlinear viscoelastic conditions.The addition of most of the oil components used in this thesis resulted in the reduction of thermal stress and low temperature critical cracking temperature of asphalt.Statistical analysis confirmed this conclusion.The calculation result of CTOD value further verified the improvement effect of oil content on the low temperature crack resistance of asphalt.The complex modulus curve and relaxation modulus curve of the oil-modified asphalt were obtained through frequency scanning tests and BBR tests at different temperatures.Based on the time-temperature equivalence principle,the master curve of the modulus of the binder is obtained.The CAM model and the generalized Maxwell model were used to fit the complex modulus master curve and the relaxation modulus master curve,respectively,to further determine the rheological properties of the oil-modified asphalt in the extreme frequency domain and a wider time domain.Based on the complex modulus rheological data,the glass transition temperature was calculated using the WLF equation to estimate the low-temperature crack resistance of the oil-modified asphalt.The addition of the oil modifier makes the master curve of the modulus of the asphalt move down.The fitting results of the rheological model show that the oil content increases the viscous components in the asphalt and improves the low temperature crack resistance of the asphalt.The calculation results of glass transition temperature further compare the low temperature crack resistance of modified asphalt with different oil content.The rotational viscosities of oil-modified asphalt and Sasobit warm mix asphalt at different temperatures were measured by the Braun rotational viscosity test,and their viscosity reduction effects were compared.Using the viscosity-temperature curve,the mixing temperature and compaction temperature of the oil-modified asphalt and Sasobit warm-mixed asphalt were calculated,and the effects of reducing the mixing and compaction temperature of the matrix asphalt were further compared.The test results show that the ability of petroleum-based oil components to reduce the construction temperature is stronger than that of bio-based oil components,and the reducing effect of all oil components is stronger than that of the warming agent Sasobit.Fourier transform infrared spectroscopy was used to study the anti-aging characteristics and modification mechanism of oil-modified asphalt.The calculation results of hydroxyl index(CI)and sulfoxide index(SI)show that the addition of oil has no significant effect on the anti-aging performance of asphalt.The chemical reaction of the bio-based oil component has occurred,and new functional groups have been generated;the addition of petroleum based oil basically has no chemical reaction,which is a physical reaction.However,the FTIR test can only be used to detect whether there is a chemical reaction in the modification process,and further chemical and microscopic tests are needed to explain the mechanism for improving the performance of the oil-modified asphalt.