| The layered double hydroxides（LDHs）has a blocking effect on the ultraviolet ligh,which can block the UV light trough to the inner of asphalt.The blocking effect of LDHs is consist of physical shielding and chemical absorption effect on ultraviolet light,the main layer of LDHs is arranged by a certain proportion of metal cations,which can reflect and refract the ultraviolet light,the anions between the main layers have certain chemical absorption effect on ultraviolet light.Therefore,it can obviously improve the anti-aging performance of asphalt.However,because of the differences of physical and chemical properties btween LDHs and asphalt,it is difficult for LDHs to disperse in asphalt uniformly and stably,there is always a agglomeration and segregation phenomenon in the preparation and storage process of LDHs modified asphalt,which decreases the modification effect of LDHs.The sodium stearate（SS）was used to surface organically modify the LDHs for the expectation of improving the compatibility of LDHs with asphalt.The sodium stearate effect on the chemical structure,crystal structure,microstructure and the influence of the light barrier were invested by the FTIR,XRD,SEM and UV-Vis,respectively.In order to study the LDHs dosages effects on the technical performance and anti aging performance of asphalt,the TFOT and indoor ultraviolet aging test were adopted to simulate the short-term hot oxygen aging and ultraviolet aging of asphalt respectively.The chemical structure,physical performance and rheological properties of the LDHs modified asphalt and SS-LDHs modified asphalt were also tested to investigate whether there is a better modification effect for SS-LDHs.In addition,the influence of LDHs on the anti-aging properties of asphalt from asphalt mixture and physical engineering scales.The following conclusions can be concluded.（1）The sodium stearate is successfully adsorbed on the surface of LDHs,and the free hydroxyl group of LDHs disappeared,so that the surface modification of LDHs is realized.After being modified,the sodium stearate does not destroy the crystal structure of LDHs,the free edge,particle roughness and spacing between particles of SS-LDHs all increase.The results of UV-Vis show that the reflectivity of UV light of SS-LDHs was significantly higher than LDHs.（2）When the dosage of LDHs is higher than 4%,with the increase of LDHs dosage,the LDHs effect on physical and rheological properties of SBS modified asphalt increase significantly,but the improvement effect of LDHs on the anti aging performance of the SBS modified asphalt is limited.Therefore,the optimal content is suggested as 4%LDHs.（3）After being mixed with SBS modified asphalt,the layered structure of SS-LDHs is not destroyed,as well as the interlayer and stripping structure are not formed.The storage stability of SS-LDHs modified asphalt is better than LDHs modified asphalt.（4）After TFOT aging and UV aging,the carbonyl index and viscosity aging index of both LDHs modified asphalt and SS-LDHs modified asphalt are smaller than SBS modified asphalt,while SBS index of them are higher than SBS modified asphalt.After TFOT and 28-days UV aging,the ranking order ofcomplex modulus is SS-LDHs modified asphalt<LDHs modified asphalt<SBS modified asphalt.It is shown that both LDHs and SS-LDHs can improve the anti thermo-oxidative aging and anti UV aging performance of SBS modified asphalt,and the modified effect of SS-LDHs is better than LDHs.（5）The results of the chemical structure of recycled asphalt binder before and after aging research show that,under the same aging states,the IC=O and viscosity aging index of both LDHs modified asphalt mixture and SS-LDHs modified asphalt mixture are lower thanthat of SBS modified asphalt mixture,while the ISBS of them are higher than that of SBS modified asphalt mixture;the increment of flexural-tensile strength and the decrement of fatigue life of both LDHs modified asphalt mixture and SS-LDHs modified asphalt mixture are smaller than that of SBS modified asphalt mixture.It is shown that both LDHs and SS-LDHs can improve the anti thermo-oxidative aging and anti UV aging performance of SBS modified asphalt mixture,and the modified effect of SS-LDHs is better than LDHs.（6）The FTIR results of the recycling asphalt binder of the experimental road after one year of opening traffic show that the IC=O of the recycling asphalt binder of the experimental road is smaller than that of the reference road,while the ISBSBS of which is higher than that of reference road.The experimental road with LDHs has a better anti-aging performance. |
