Effect Of Regenerant On Chemical Components And Rheological Properties Of Recycled Asphalt Mortar

As China’s highway development enters a period of equal emphasis on construction and maintenance,a large amount of old asphalt pavement mixture milling material produced by asphalt pavement maintenance urgently needs to be dealt with.The use of asphalt pavement recycling technology is of great significance to reuse old asphalt mixtures and solve problems such as environmental protection and lack of aggregates.At present,the research on the improvement of the performance of aging asphalt by rejuvenator is still not perfect,which restricts the promotion and application of asphalt pavement regeneration technology.Therefore,this paper studies the effects of regenerant on the physical properties,rheological properties and chemical components of recycled asphalt mortar through experiments,in order to provide a certain theoretical basis and technical support for the promotion of asphalt pavement regeneration technology.First,the recycled asphalt mortar was obtained by extracting and recycling the old asphalt pavement milling material,and then the recycled asphalt mortar was added with a regenerant to obtain the regenerated asphalt mortar.Secondly,the recycled asphalt mortars with different amounts of regenerant were tested for the three conventional physical properties of asphalt materials,rotational viscosity test,infrared spectroscopy test,and the anti-aging performance of the regenerated asphalt mortar was analyzed by using the indexes of mass loss percentage,residual penetration and softening point increment.Finally,the dynamic shear rheological test,bending beam rheological test and ductile tensile healing test were carried out on the original and aged regenerated asphalt mortar with different regenerant content,and the effect of regenerant on the rheological properties of recycled asphalt mortar was comprehensively analyzed.The research results of this paper show that:（1）The regenerant has a good improvement effect on the three major indexes of recycled asphalt mortar,and the viscosity and temperature sensitivity of the recycled asphalt mortar are reduced.After the short-term aging of the regenerated asphalt mortar with with different regenerant content,the residual penetration ratio is smaller and the softening point increment is larger.（2）The regenerant can reduce the intensity of the absorption peak of the aging characteristics of the recycled asphalt mortar;quantitative research on the infrared spectrum found that with the increase of the amount of regenerant,the I_B aliphatic functional group index gradually increased,the I_C=O carbonyl index and I_S=O sulfoxide functional group index gradually decreased.（3）The regenerant can reduce the complex shear modulus,rut factor,and fatigue factor of recycled asphalt mortar,increases the phase angle,and the improvement of phase angle behind the complex shear modulus.The slope of the regenerated asphalt mortar Han graph curve indicates that the regenerant can transform the recycled asphalt mortar to a homogeneous phase.Both short-term and long-term aging will increase the complex shear modulus,rutting factor,and fatigue factor of the recycled asphalt mortar,and the phase angle will decrease.（4）Grey correlation entropy mathematical model analysis found that the degree of influence of characteristic functional groups on the complex shear modulus,rut factor,and fatigue factor of regenerated asphalt mortar was ranked as sulfoxide,carbonyl,and aliphatic compounds,and the degree of influence on phase angle is the opposite.（5）The regenerant reduces the creep stiffness of the regenerated asphalt mortar and increases the creep rate.The aging effect has a greater impact on the low-temperature performance of the regenerated asphalt mortar with more regenerator content.The comprehensive compliance index established based on the parameters of the Burgers model shows that the more the content of regenerant,the better the low-temperature performance of the regenerated asphalt mortar.（6）The self-healing rate of regenerated asphalt mortar increases with the extension of heat preservation and healing time,and at the same temperature and healing time,as the amount of regenerant increases,the self-healing rate of regenerated asphalt mortar increases.