| Asphalt pavement has the advantages of good smoothness,low noise,small vibration,no joint,convenient maintenance and so on,so it is widely used in recent years.By the end of 2022,the total mileage of China ’s expressways reached 169,100 kilometers.The increasing highway traffic volume and heavy-duty vehicles put forward higher requirements for the rutting resistance,low temperature crack resistance and service life of the pavement.At present,emulsified asphalt pavement can no longer meet the requirements of use,and it is easy to cause pavement diseases,thus increasing the number of maintenance times and costs.Therefore,there is an increasing demand for high-performance modified emulsified asphalt.At present,SBR latex is widely used as a modifier for the preparation of modified emulsified asphalt,while SBS(thermoplastic butadiene-styrene rubber),the most widely used modifier in modified asphalt,is limited due to the difficulty in the development of its latex and the high process requirements for modification and emulsification.Firstly,SBS latex was prepared.Four different types of SBS were selected for the preparation of SBS latex,which were star SBS-4303,star SBS-4303-2,linear SBS-1301 and linear SBS-1401.By comparing the swelling effects of cyclohexane,n-hexane,ethyl acetate and acetone on SBS,cyclohexane was finally selected as the solvent for swelling.Then the addition method of emulsifier and emulsification process parameters(shear speed,shear time,emulsification temperature)were investigated in detail.The results showed that the emulsifier was first dissolved in water to prepare a soap solution and then emulsified the SBS solution.The emulsification process parameters were first low speed: 800 r/min,3 min;followed by medium speed: 1500 r/min,6 min;finally,high speed: 4700 r/min,4 min;emulsification temperature was 50 °C;three different types of SBS latex were prepared,and the best emulsification formula was obtained by orthogonal experiment.The first SBS latex prepared by non-ionic emulsifier: the mass ratio of water to SBS is 1.2,7 % emulsifier I,3 % emulsifier II,1.2 % stabilizer;the second is SBS latex prepared by cationic emulsifier: the mass ratio of water to SBS is 1,3 % emulsifier III,7 % emulsifier IV,0.8 % stabilizer;the third is SBS latex prepared by zwitterionic emulsifier: the mass ratio of water to SBS is 1,3 % emulsifier V,2 % emulsifier VI,0.8 % stabilizer.Secondly,emulsified asphalt was modified by self-made SBS latex,and the modification effect was investigated.Through the conventional performance test of emulsified asphalt evaporation residue,the storage stability of asphalt emulsion and the remaining amount on the sieve,the amount of emulsifier and the type of stabilizer were explored,and the best formula for preparing emulsified asphalt was obtained:the amount of emulsifier was 2 %,and the amount of stabilizer was 0.3 %.Then,emulsified asphalt was modified with different types of SBS latex,and the conventional properties such as 25 °C penetration,softening point and 5 °C ductility of the evaporation residue of modified emulsified asphalt were tested.The results show that the type of SBS is the main reason affecting the conventional performance of modified emulsified asphalt.The effect of star SBS latex modified emulsified asphalt is better than that of linear SBS latex modified emulsified asphalt.The effect of SBS latex modified emulsified asphalt prepared by star SBS-4303 is the best.By testing the 5d storage stability performance of different SBS latex modified emulsified asphalt,it is found that the emulsification system has a great influence on the storage stability of modified emulsified asphalt,and the storage stability of SBS latex modified emulsified asphalt prepared by non-ionic emulsifier emulsification system is the best.In short,SBS latex prepared with SBS-4303 as raw material and non-ionic emulsifier as emulsifying system has the best effect on modified emulsified asphalt. |
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