Preparation And Properties Of Layered Double Hydroxides/Hindered Phenolic Antioxidant Modified Asphalt

Asphalt pavement has many advantages,such as the high comfort of driving,excellent anti-sliding performance and easy maintenance and repair.These contribute to a reality that asphalt pavement is the primary type of domestic and foreign high-grade highway pavement construction.But in the process of field placement,compaction and long-term service,asphalt binders for pavement are vulnerable to many external factors?such as heat,oxygen and ultraviolet?and occur aging,causing cracking,rutting,pothole and other diseases of road surface,which lead to the deterioration of road performance of asphalt pavement and shorten its service life.Therefore,the preparation of asphalt material with excellent performance to resist both UV and thermal-oxidative aging is of great importance to reduce the maintenance cost of asphalt pavement and prolong its service life.This paper investigated the effect of Mg-Al LDHs,Irganox 1010,and their compound?Mg-Al LDHs/Irganox 1010?on physical,UV and thermo-oxidative aging properties of asphalt.The rheological properties,functional structures,generic fractions as well as colloidal structures of Mg-Al LDHs,Irganox 1010,and their compound modified asphalts before and after aging were characterized by dynamic shear rheometer?DSR?,Fourier transform infrared spectroscopy?FTIR?and thin layer chromatography with flame ionization detection?TLC-FID?,respectively.Based on these,the relationship of chemical components,structures and properties of different anti-aging additives modified asphalts was established.The main conclusions are as follows:?1?Mg-Al LDHs increases slightly the viscosity and softening point,and decreases faintly the penetration and ductility.Mg-Al LDHs improves the ability of SK-70 asphalt to resist UV aging and short-term thermal-oxidative aging,while the effect of Mg-Al LDHs on long-term thermal-oxidative aging properties of asphalt is not obvious.?2?The addition of Irganox 1010 increases faintly the penetration and ductility,while the viscosity and softening point of modified asphalt are decreased.Irganox1010 enhances the ability of SK-70 asphalt to resist thermal-oxidative aging,and it has a certain improvement effect on UV aging properties of asphalt at low dosage.?3?The softening point and viscosity of Mg-Al LDHs/Irganox 1010 modified asphalt slightly increase,and the penetration and ductility faintly decrease.The synergism between LDHs and Irganox 1010 improve the thermo-oxidative and UV aging aging resistance of asphalt,Mg-Al LDHs and Irganox 1010 play a dominating role in the process of photo-oxidative aging and long-term thermo-oxidative aging,respectively.?4?DSR analysis shows that the addition of Irganox 1010 decreases the complex modulus and increases the phase angle of SK-70 asphalt binder,while Mg-Al LDHs shows the opposite effects,and the compound of two additives moderates the influence.Mg-Al LDHs,Irganox 1010 and their compound ameliorate the rheological properties of SK-70 asphalt after aging.The effect of compound is the most obvious and the changes of the complex modulus and phase angle are minimal.?5?FTIR analysis shows that the values of carbonyl(C=O,1700 cm^-1)index and sulphoxide(S=O,1030 cm^-1)index of Mg-Al LDHs,Irganox 1010 and their compound modified asphalts are increased after TFOT and UV aging,but the compound modified asphalt show a smallest increment,which indicates that Mg-Al LDHs/Irganox 1010 can inhibit thermal-oxidative aging and photo-oxidative aging of SK-70 asphalt.Furthermore,the values of phenolic hydroxyl(O-H,3645 cm^-1)index of Irganox 1010 and Mg-Al LDHs/Irganox 1010 modified asphalts are decreased after aging,which indicates that Irganox 1010 is involved in the aging reaction of asphalt by means of capturing the living free radical caused by heat oxygen or ultraviolet.?6?TLC-FID analysis shows Mg-Al LDHs have little effect on the contents of four generic fractions of SK-70 asphalt,while the content of aromatics increases with the addition of Irganox 1010,which leads to the increased colloidal index?Ic?.The colloidal index of Mg-Al LDHs/Irganox 1010 modified asphalt is maximal after thermo-oxidative and UV aging,which shows that the compound of LDHs and Irganox 1010 further improves the aging resistance of asphalt as compared with single Mg-Al LDHs or Irganox 1010.?7?The effect of the compound of Mg-Al LDHs and Irganox 1010 on physical and aging properties of four asphalts from different sources shows that the additive decreases slightly the penetration and ductility,and increases faintly the viscosity and softening point while the degree of influence on four asphalts is different.Anti-aging agent can improve the aging resistance of all kinds of asphalts,especially which are sensitive to heat,oxygen and ultraviolet radiation.