Study On The Diffusion Behavior Of Asphalt Rejuvenator And Influence Factors

Three different asphalts were chosen to simulate the aging process in lab, and three different rejuvenators were used to recycle the aged asphalts. Turbidimetric titration, dissolution method and research of mixing properties were used to study the influence of adding different rejuvenators on aged asphalts colloidal stability, compatibility of rejuvenators and aged asphalts and the properties of them being compounded, and so on.The experiment of Turbidimetric titration and SARA(Saturants, Aromatic, Resins, Asphaltenes, SARA) analysis were taken on bitumen, aged asphalts and recycled asphalts. The results show that with the bitumen deep aging, its colloidal stability decreases. The changes of SARA influence the colloidal stability of the bitumen, and the asphaltenes is the most important factor. The colloidal stability of old asphalts could be renewed by adding proper rejuvenators. The rejuvenators with high aromatic and low asphaltenes are better.The solvents with Hansen parameters known were used to make sure the parameters of old asphalts and rejuvenators. The MATLAB program can be used to simulate the soluble points in experiments, through which the Hansen parameter were got. The join could be higher than 80% between simulation results and experimental data. Theδp andδh of rejuvenator R3 were higher, so the polarity and H-bond reaction are great. The Hansen parameters difference of rejuvenator R2,R3 A3 and three old asphalts is small, so the compatibility is good. Since the Hansen solvent parameters difference of R1 and three old asphalts is large, so the compatibility is bad. The Flory-Huggins Equation was used to calculate the mixture free energy of aged asphalts and rejuvenators. The results show that the solvent parameters and aromatic carbon ratio is higher than relative new asphalts and with low H/C. The Hansen solvent parameters difference of R1 and three old asphalts is higher than 1.909(J/cm3)0.5,and ?Gm at 25℃of rejuvenator R1 and Cartex aged asphalts is higher than 0.0 (?Gm>0), their process of mixing is not spontaneity. The ?Gm at 25℃of rejuvenator R2,R3 is higher than 0.0(?Gm<0), so they are spontaneous.The aged asphalts recycled by three rejuvenators meet the technical requirements of high way(GB/T15180-2000), however the anti-aging property of aged asphalts recycled by R1 is bad, the weight loss is almost 1.0% after aging. The Penetration Index and Viscosity Temperature Susceptibility were used to evaluate the temperature susceptibility of recycled asphalts. The experiments show that the recycled asphalts are better than new asphalts in low and mid-high temperature area, the asphalts recycled by R3 is better; there is no obvious law of the mid-temperature property, the rejuvenator improve the temperature sensitivity of recycled asphalts, however the rejuvenator R1 lowed the high temperature sensitivity, and the rejuvenators R2 and R3 increase a little. The viscosity of rejuvenator, aged asphalt and recycled asphalt satisfied the complex theory, the viscosity law of rejuvenator and aged asphalts is strong, the quantity of rejuvenator and old asphalts can be gotten by calculating. The SHRP analysis is taken on recycled asphalts, its RTFOT asphalts, PAV asphalts to make sure the performance grade. From experiment results of the DSR and BBR: the adding of rejuvenators low the anti-track property and improve the anti-cracking property of asphalts. The pavement design is the key step course of hot-mix recycling asphalt pavement. Two rejuvenators were used to recycle RAP. The property analysis and recycling experiments were taken on the old asphalts, the DSR experiments were taken on the recycled asphalts. The new aggregates were added to adjust the recycled aggregates, to satisfy the specification. After the design experiments, the parameters all satisfy the demands. At 60℃and 30℃the visco-elasticity can be recovered from the DSR experiments, the anti-track properties of Jinhua Road and Dayong Street recycled asphalts are good. In anti-water damage experiments, only the Marshall stability of Jinhua Road RAP recycled by B is lower than 75%, the remaining stability is 64.8%. The resilience modulus are mostly between 2000 and 4000MPa. The Marshall numbers of RAP recycled by B are all smaller than ones recycled by A. the diffusion of rejuvenators in old asphalts is also be studied.The Fick Equation is used to calculate the coefficients, the temperature, time, molecular size and polarity effects on diffusing are also studied. The results show that temperature has a great effect on diffusing coefficient, the action becomes stronger with higher temperature; the difference of concentrations is smaller, the diffusing coefficient becomes smaller; further the distance from the original level the concentration difference is smaller and so is the coefficient, the coefficients differences of different rejuvenator are great, that's because of the differences of aromatic components and the molecular size. The diffusion of rejuvenators in old asphalts changed the property of old asphalts, so it has a great effect on the rate of diffusing.