| With the development of the society, the progress of science and technology, the development of highway construction in our country is rapid. The highway mileage increases year by year, which close to 120000 kilometers. At the same time large traffic flow and heavy traffic accelerated the damage of highway. A large number of studies have shown that the way of the most effective and the most economical maintenance is modification emulsified bitumen slurry seal technology, it save energy/resources, protect the environment, improve the construction conditions, and most important is fast open traffic. Modified emulsified asphalt consist of the matrix asphalt, modifier, and emulsifier, modifier plays a decisive role in improving the performance of the modified emulsified asphalt. However, The most commonly used is MeadWestvac latex in the actual application, it can better improve the high temperature and low temperature performance of asphalt.Through the analysis of modification mechanism, based on styrene and butadiene monomer, we synthesized the high temperature styrene-butadiene latex by the thermal polymerization method; And by controlling the feeding sequence and time interval, got the core-shell structure of styrene-butadiene latex; In order to improve the adhesive properties and mechanical stability of latex, by adding carboxylic monomers (acrylic acid and methyl methacrylate), carboxylic styrene butadiene latex was synthesized, we study the reaction temperature, reaction time, monomer ratio, emulsifier dosage, the amount of carboxylic monomers and other factors that affect the performance of latex. Experimental results show that when the reaction temperature 60 ℃,12 h, St:Bd=25:75, monomer:water= 1:1, used potassium persulfate as initiator, and used 1.5 servings of sodium stearate (quality) and 4.0 servings of disproportionated rosin acid potassium compound solution as emulsifier, the comprehensive performance of latex is good.We prepared the anionic modified emulsified asphalt using anion latex, and determined the preparation technology:asphalt:water is 60:40; anionic emulsifier dosage is 2% of the total; the temperature of latex is 60℃～70℃ and asphalt is 130℃～140℃ at the time of emulsion; first latex be emulsified 1 min in the emulsification machine at 3000 r/min, then joining hot asphalt, be emulsified 5 min at 5000 r/min.In recent years, with the deepening of the research on modified emulsified asphalt, people found that the comprehensive performance of cationic modified emulsified asphalt is better than anionic. We used the two kinds of cationic emulsifier to electrical adjustment of latex in laboratory, the experimental results show that the compatibility of the cationic emulsifier MQK of MeadWestvac and anionic latex is better than 1831. So we preparation the cationic modified emulsified asphalt by MQK emulsifier and tested it, the uniformity and stability of the asphalt emulsion is ok, and the three major indexes of the evaporation residue meet the technical requirements. When the dosage of latex was 3%, all the latex modified data was close to the technical requirements. The parameters of 1227 batches of latex is the closest to MeadWestvac latex, the softening point more than 60℃ when its dosage was 5%, this means that can significantly improved the high temperature performance of asphalt. Through the analysis cross section of evaporation residue of modified emulsified asphalt(by SEM), we knowed that the dispersibility and compatibility of the styrene-butadiene latex and matrix asphalt is good. |
PDF Full Text Request