| The construction of the highways in our country had been greatly developed in recent years. However, the disease of the roads was always appeared early in the service life along with the rapid increasing of the traffic flow and heavy load vehicles what caused intense surface abrasion of the roads. Therefore, improving the state of roads quality and reducing the road surface disease became the urgent matters to the departments who maintained the roads. Then asphalt turned into the first choice of the materials that constructed and maintaind roads. In this study, the SBR modified emulsified asphalt and nano-SiO2/SBR compound modified emulsified asphalt were prepared, by using SBR and nano SiO2 as modifying agents. Their making technics, modifying mechanism and main properties were also investigated.First, the modified emulsified asphalt with SBR was prepared,using the compound emulsifier mixed by the proportion of 7∶3 between positive emulsifier and nonionic emulsifier. Through the studies of the three main indexes of the evaporation residue influenced by SBR, it was saw that the softening point and the ductility at 4℃were improved, but the penetration at 25℃was decreased. Then the modifying mechanism of SBR modified emulsified asphalt was discussed according to the submicrostructure observed by the micropolariscope.Second, the method of surface chemistry modification to nano SiO2 using self-made silane resin acceptor was investigated. The results of FT-IR and TG indicated that the surface of nano SiO2 was successfully modified by silane resin acceptor. From observing the dispersions of nano SiO2 in aquous before and after modified by TEM, it showed that silane resin acceptor can improve the dispersion of nano SiO2 in aquous, and it reached better in 1%. The results of XRD showed that the crystal properties of nano SiO2 was not changed after modified. And the ultraviolet-visible absorption spectrum also changed little according to the analysis of UV-visible absorption.Third, compound modified emulsified asphalt with nano-SiO2 and SBR was prepared. The properties about evaporated residue and the mechanism of compound modification were investigated. The results showed that the ductility at 4℃of compound modified asphalt was improved prominently. The ductility was above 150cm only using small quantity such as 0.25‰nano-SiO2/1% SBR and 0.5% SBR/0.5‰nano-SiO2. Alang with the addition of nano SiO2, the softening point increased, but the penetration was decreased. The thermal behavior of evaporated residue was studied by DSC. In the match range in this study, nano SiO2 and SBR can both enhanced the temperature stability and resistance to elevated temperatures. The rangeability was elevated obviously by the addition of SBR, and when they were compounded together, the outcoming was more satisfied. Through the RTFOT test, it showed that the compound modification improved the resisitance to aging remarkable.At last, the effects of the modifying agents on different basal asphalts were discussed studied in the same modifying condition. And it indicated that the more excellent properties basal asphalt used, the better combination properties reached after compound modified, by using ESSO70# instead of GaoFu70# in our study. |
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