Synthesis And Application Of A Slow-cracking And Fast-setting Quaternary Ammonium Asphalt Emulsifier Containing Steric Hindrance

The demand for transportation,especially the maintenance of the road,has increased with the rapid development of economy.Compared with hot asphalt,emulsified asphalt mixtures possess many advantages,such as low energy-consumption,little pollution,easy construction,and so on.Slurry seal is an effective way to repair the road quickly,and it requires the emulsifier to be slow-cracking and fast-setting.Therefore,the preparation of slow-cracking and fast-setting asphalt emulsifier is the key.In this paper,four different quaternary ammonium salts asphalt emulsifiers?A,A₁,C,C1?of slow-cracking and fast-setting and two intermediates?B,B1?were synthesized by using pyrrolidine,epichlorohydrin,1-bromohexadecane,1-bromooctadecane and triethylenetetramine.A and A1 are monocatalin asphalt emulsifiers,and C and C1 are bi-quaternary ammonium asphalt emulsifiers.The products and intermediates were characterized by IR spectroscopy.The experimental route was selected,and the reaction conditions such as the reaction temperature,the reaction time,the feeding amount of the catalyst and the molar ratio of the reactants were optimized.The cationic properties of the two intermediates and four products were tested by bromophenol blue respectively.The color of bromophenol blue solution of the two intermediates did not change,but the color of the bromophenol blue solution of the four products changed from red to blue-violet,which confirmed that the intermediates didn't have cationic properties and the four products were all cationic asphalt emulsifiers.The surface properties of the products were tested according to the surface tension method and the conductivity method,and the HLB value was also confirmed.The results of the surface tension method and the conductivity test method were consistent,and the four products had good surface properties.At the same time,with the increase of the alkyl chain,the emulsifier showed a lower CMC value.The two intermediates and four products were prepared in emulsifing asphalt.B and B₁ had no emulsifying effect,but A,A₁,C and C₁ can emulsify asphalt.Simultaneously,the octadecyl product presented better emulsifying effect than the hexadecyl product.The conditions of emulsified asphalt were studied,and the results showed that the structure of the emulsifier,the amount of the emulsifier and the pH value of the emulsion had certain influence on the emulsifying effect and the stability of the emulsion.The test of demulsification indicated that the products were slow-cracking and fast-setting asphalt emulsifier,which mainly due to the introduction of pyrrole ring in the product.At the same time,the introduction of triethylenetetramine increased the number of hydrophilic groups,which also led to the slow-cracking effect.