Preparation Of SBS Latex For Asphalt And Its Application In Micro-surfacing

The modified emulsified asphalt is a bonding material at the micro-surfacing,and its quality obviously affects the quality of the micro-surfacing.At present,SBR latex is the most widely used modifier in modified emulsified asphalt,but the application of SBS in modified emulsified asphalt is limited because the preparation of SBS modified emulsified asphalt is mainly obtained by first modification and emulsification,SBS modified asphalt is difficult to emulsify,so there is a limit to industrial production.Based on this consideration,this thesis studies the preparation process of SBS latex,and obtains latex with excellent performance and applies it to the micro-surfacing.Firstly,SBS solution was prepared by swelling SBS with suitable solvent.The fluidity of SBS solution under different conditions was studied to determine the mass ratio of solvent to SBS in SBS solution.Secondly,according to the emulsification process of SBS latex,the raw materials are selected and the emulsification process parameters are determined.At the same time,the orthogonal test design of four factors and four levels was adopted.The effects of various factors on the performance of SBS latex were analyzed by mechanical stability,Zeta potential and viscosity.The optimal formula of SBS latex was determined.The concentrated SBS latex with good stability was obtained by distillation process,and the performance of SBS latex before and after distillation was evaluated.Then,the modified emulsified asphalt was obtained by emulsifying first and then modifying,and the conventional performance indexes were analyzed and studied.Finally,three kinds of modified emulsified asphalts,SBS latex modified emulsified asphalt,SBS modified emulsified asphalt and SBR modified emulsified asphalt,were used to prepare micro-surfacing,and the effects of three modified emulsified asphalt on the pavement performance of Micro-surfacing were compared.The results showed that cationic emulsifiers were used in combination with nonionic emulsifiers.The cationic emulsifier(cetyltrimethylammonium bromide)was determined by investigation of the emulsion properties: nonionic emulsifier(nonylphenol ethoxylate)= 3:1.The SBS latex formulation obtained by orthogonal test was: Water/SBS(0.8),emulsifier(8%),inorganic stabilizer(0.2%)and organic stabilizer(0.1%).The properties of SBS latex beforeand after distillation were evaluated.It was found that the size distribution of SBS latex before and after distillation was uniform and the stability was excellent,and the SBS latex after distillation was more stable than that before distillation.By comparing the properties of SBS latex modified emulsified asphalt,SBS modified emulsified asphalt and SBR latex modified emulsified asphalt,it was found that the evaporative residues of SBS latex modified emulsified asphalt were relatively good in high temperature stability and low temperature crack resistance.The microstructures of SBS latex modified emulsified asphalt were analyzed by fluorescence microscopy.The results show that SBS latex is well dispersed in modified emulsified asphalt and has excellent emulsifying effect.The micro-surface mixture was prepared from modified emulsified asphalt with different modifiers,and the conventional performance comparison analysis was carried out.The abrasion resistant performance,water resistance performance and rutting resistance of the three modified emulsified asphalt micro-surfacing materials are in compliance with the specifications.Among them,SBS modified emulsified asphalt has the best performance,while SBS latex and SBR latex have little difference in performance.The micro-surfacing mixtures under the three modifiers are almost impermeable and have good waterproof function.At the same time,their friction coefficients are not different,but they are larger than the technical requirements.The micro-surfacing mixtures of the three modifiers have good skid resistance.