Study On The Stability Of SBS Modified Asphalt Emulsion Under Strong Stirring For A Long Time

Cement and emulsified asphalt mortar is a mixture of cement, emulsified asphalt, fine aggregate, water and other admixtures. Cement and emulsified asphalt mortar cushion layer which has functions of bracing, adjusting and buffering as the flexible adjustment layer of the slab ballastless track structure. The performances of cement and emulsified asphalt mortar cushion layer will directly affect the durability of track structure and the security of trains. In order to ensure the uniformity of the various components, the SBS modified asphalt emulsion will be stirred strongly with cement, sand and other solid materials for a long period in the mixing process of cement and emulsified asphalt mortar. Therefore, the SBS modified asphalt emulsion, which is applied to the cement and emulsified asphalt mortar, must have high stability under the alkaline conditions and strong mechanical stirring. Until now, few researches has been carried out on this problem in china, consequently, it is quite necessary to study the influence of strong mixing for a long time on the stability of SBS modified asphalt emulsion.This paper mainly studies the effect of the stirring conditions, alkaline environment, the mixing emulsion system on the stability of SBS modified asphalt emulsion and the stirring conditions of SBS modified asphalt emulsion, the mixing process of cement and emulsified asphalt mortar, the temperature on the stability of cement and emulsified asphalt mortar.Results show that:(1) The stirring conditions have a great impact on the stability of the SBS modified asphalt emulsion. When the stirring rate was less than1000r/min, the stability of asphalt emulsion changed little, and the stirring rate would have greatly effect on stability if it was greater than1000r/min, and even beyond the standard requirement. The stability of SBS modified asphalt emulsion getting worse as the stirring time increasing in the same stirring speed. (2) The influence of stirring conditions on the stability of SBS modified asphalt emulsion are not as regular as the natural conditions under alkaline environment. The stability of SBS modified asphalt emulsion got worse as the stirring time increased when the stirring rate was less than1000r/min, and the stability would not be affected by the time if it was greater than1000r/min.(3) The improvement effect of the mixing emulsion system on the stability was not obvious no matter what mixing way we used. Storage stability of SBS modified asphalt emulsion with the increasing of pH, showing a trend first increase and then decreased. The storage stability of emulsion is the best when the pH is4. The pH would influence the emulsifier molecular activity whether it is too large or too small.(4) The suitable stirring speed and time of SBS modified asphalt emulsion can improve the stability of the mortar. The suitable mixing process and the appropriate temperature of cement and emulsified asphalt mortar also have an important role in improving the stability of the mortar.