Preparation And Properties Of Orgnanic LDHs/SBS Modified Bitumen

SBS modified bitumen was widely applied in the field of pavement construction due to its excellent high and low temperature properties.However bitumen is apt to aging under the effect of natural environment factors such as ultraviolet(UV)radiation,oxygen and heat.As a consequence,leading to great damage to its road performance and service of life.Layered double hydroxides(LDHs)have been used to improve the aging performance of bitumen due to their excellent UV shielding properties.However the compatibility of LDHs and bitumen is too poor to obtain homogeneous and stable dispersion of asphalt/LDHs composite,and LDHs particles are easily prone to reunite and segregate during the process of storage and transportation,so the UV shielding properties of LDHs are not effectively carried out.Therefore,it is of great significant to get good stability and ultraviolet aging resistance of LDHs/SBS modified asphalt mixture system by adopting organic interacted LDHs.In this paper,three organic anionic surfactants,Sodium dodecyl benzenesulphonate(SDBS),sodium dodecyl sulfate(SDSO)and sodium dodecyl sulfonte(SDS),and a UV absorber,2-hydroxy-4-methoxy benzophen-5-sulphonic acid(UV 284)were used to prepare the organic intercalated LDHs by anion exchange method.And then,organic intercalated LDHs were added into the SBS modified bitumen to prepare organic intercalated LDHs/SBS modified bitumen.And the effect of organic intercalated LDHs on properties of SBS modified bitumen were investigated by compatibility test,conventional physical properties test,dynamic shear rheometer test,aging procedure and Fourier transform infrared spectroscopy(FTIR)analysis.And the main conclusions are as follows:(1)X-ray diffraction(XRD)and UV-vis spectroscopy analysis shows that organic anions are successfully intercalated into LDHs and expand the LDHs layer spacing,and enhance the ultraviolet absorption capacity of LDHs.However,the interlayer spacing and ultraviolet absorption ability of organic intercalated LDHs are associated with anionic categories;the capability of ultraviolet absorption of UV absorbent interlaced LDHs is significantly improved.(2)The compatibility of LDHs and SBS modified asphalt was improved significantly,and the aggregation and settlement of LDHs is reduced.The compatibility between different organic anion intercalated LDHs and SBS modified bitumen are associated with anionic categories: the higher the molecular weight anion intercalated agent,and the stronger the force of asphalt molecular and the larger LDHs layer spacing,the greater compatibility between organic anion intercalated LDHs and SBS modified bitumen.(3)The stable dispersion of organic LDHs in SBS modified asphalt not only reduces the adverse effects on the penetration and ductility,but also improves the low-temperature cracking resistance of LDHs/SBS modified asphalt.(4)Compared to LDHs,SDBS-LDHs and SDS-LDHs and UV 284-LDHs can further improve short-term thermal oxygen aging properties of bitumen,and the increase of the effect depending on the compatibility between organic LDHs and bitumen and the plate number of organic LDHs effectively inhibit the infiltration of oxygen and light group volatile: the better compatibility Organic LDHs and bitumen,the larger plate number of organic LDHs which can be effectively inhibit the infiltration of oxygen and light group volatile,the better modified asphalt thermal oxygen aging resistance.(5)After ultraviolet aging(UV),the changes in softening point,ductility and viscosity of SDBS-LDHs,SDS-LDHs and UV 284-LDHs LDHs/SBS modified asphalt is less than that of LDHs.Since the ultraviolet light is a major cause of bitumen aging and UV 284-LDHs have good shielding and absorption to UV light,as a result,the improvement of UV 284-LDHs on ultraviolet aging of bitumen is better than that of anionic surfactant intercalated LDHs.(6)FTIR results show that the oxygenic functional groups(C=O,S=O)of bitumen after aging are increased and the characteristic peak(C=C)of SBS is decreased.However,the increment in the content of C=O,S=O and decrement in the content of C=C of bitumen are decreased with the addition of LDHs and anionic intercalated LDHs.After short-term thermal-oxidative aging,for different LDHs/SBS modified bitumen,the differences in the degree of changes in functional group is small,but after ultraviolet aging,the degree of changes in functional group of UV 284-LDHs/SBS modified asphalt are significantly lower than of anion intercalated LDHs/SBS modified bitumen.