Effect Of LDHs On Properties Of SBS Modified Bitumen

Layered double hydroxides(LDHs) is a kind of unique structure of the layered clay,it has an effect of shielding,blocking,scatering and abosorption for ultraviolet light, effectively reduce the irreversible ageing effect of uv light on the material, has been applied in the ageing resistance of the SBS modified asphalt materials. However there are many factors affecting the properties of LDHs, different kinds of LDHs motherboard layer metal elements has different interlayer anion, which makes the different performance of LDHs;different manufacture process of LDHs in particle size, element composition differences also affect the shield blocking ability of LDHs for ultraviolet light. So the study of different structure and preparation process of LDHs similarities and differences performance to improve the physical properties and aging resistance of SBS modified asphalt is very important.This paper perpares the clean process of Mg-Al-LDHs, traditional craft production of Mg-Al LDHs and Zn-Mg-Al LDHs three different LDHs, using modern test methods such as X-ray fluorescence spectrum analysis, Fourier transform infrared spectrum analysis, scanning electron microscopy(SEM), X-ray diffraction analysis and uv-vis spectrum test to study the different kinds of LDHs composition and structure on the properties of LDHs uv blocking effect, and with different pitch melt blending preparation into LDHs/SBS modified asphalt, discuss the influence of LDHs on the physical properties of SBS modified asphalt, and conduct experiment of LDHs/SBS modified asphalt for the indoor accelerated ultraviolet aging, simulating natural light aging and hot oxygen aging for a long time. to the influence factors of LDHs/SBS modified asphalt aging process and LDHs/SBS modified asphalt resistance to aging performance has made the evaluation. The main research conclusions are as follows:(1)The X-ray fluorescence spectrum analysis results show that the preparation of LDHs in traditional technology and clean production makes small differences in the elements; Fourier transform infrared spectrum analysis and X-ray diffraction analysis results show that when the interlayer anion specie is same-, LDHs of layered structure and the layer spacing is constant; scanning electron microscopy(SEM), X-ray diffraction analysis and uv-vis spectral test results show that the effect of LDHs shield to ultraviolet light relate to the particle size of LDHs and layers of sheet metal elements, the LDHs size close to the wavelength of ultraviolet light the better of uv blocking ability, and the introduction of zinc metal layer board element can obviously increase the LDHs absorption effect of UVC of ultraviolet light.(2) the addition of LDHs slightly increase the resistance performance of SBS modified asphalt to high temperature and low temperature, the types of LDHs have less effect on the physical properties of SBS modified asphalt, the dosage of LDHs have bigger influence on the physical properties of SBS modified asphalt: when the dosage of LDHs is less than 3%, the bigger the dosage, the higher the softening point of SBS modified asphalt; when the dosage increased to 3%, the softening point of SBS modified asphalt does not significantly increase, and LDHs have little impact on the tenderness of the SBS modified asphalt.(3) The improvement effect of LDHs on the SBS modified asphalt resistance ultraviolet aging ability is mainly related to the particle size of LDHs, the closer the diameter and the wavelength of ultraviolet ray of LDHs, the the better ability of the SBS modified asphalt aging resistance to uv light, the resistance to aging asphalt by using LDHs particle size rang from 200 nm to400 nm(i.e., covering the ultraviolet light UVB and UVA wavelengths) is relatively appropriate;theconsequence of plate layer metal elements on SBS modified asphalt ultraviolet aging resistance ability is small, the influence of LDHs plate element zinc layer introduced did not significantly improve the ability of modified asphalt aging resistance to uv light.(4) the LDHs can improve the ability of the SBS modified asphalt hot oxygen aging: lamellar structure can cut off oxygen into the SBS modified asphalt, reduce the reaction of asphalt under the action of heat and oxygen aging. But the resistance to high-temperature aging ability of LDHs to the SBS modified asphalt is not significant different,compared to the to resistance ultraviolet aging.(5) Different asphalt preparation of LDHs/SBS modified asphalt properties makes no difference,there are differences between resistances to ultraviolet aging performance, factors associated with the form of asphalt;the smaller penetration of asphalt is, the better performance of its resistance to ageing.The smaller penetration of asphalt is,contained light component such as saturates,aromatics less, the less content of colloidal asphaltene influenced by factors such as light,thermal and oxygen aging,the better resistance to aging.