| Polymer modified emulsified asphalt has received widespread attention due to its ability to overcome problems such as surface water seepage,high wear,and poor resistance to rutting deformation on asphalt roads.At present,the most effective modifier in polymer modified emulsified asphalt is styrene butadiene styrene block copolymer(SBS).At present,the preparation method of SBS modified emulsified asphalt is to first modify the asphalt with SBS particles and then emulsify it to obtain modified emulsified asphalt.However,the cumbersome process steps and high requirements for emulsification equipment limit the large-scale production of SBS modified emulsified asphalt.If SBS is made into latex,it can effectively solve this problem.Therefore,the development of SBS latex is the future development trend.Based on this,this article prepared excellent performance SBS latex(I)and SBS latex(II)through two emulsification systems,and applied the SBS latex to asphalt modification and compared its performance with SBS particle modified emulsified asphalt.SBS latex(I)was prepared by using surfactant as emulsifier.The effects of emulsifier type,emulsifier concentration,water oil volume ratio,stabilizer type,stabilizer concentration and process parameters on the performance of SBS latex(I)were analyzed through evaluation indicators such as gel amount,mechanical stability,storage stability and viscosity,and the formula and process parameters were optimized.When the mass ratio of SBS solution,water,sulfonated OP-10 and PVA1788 is 100:30:4:0.3,the dispersion speed is 3000 rpm,the dispersion time is 20 min,and the emulsification temperature is 50 ℃,the amount of SBS latex(I)gel is less,and the storage stability and mechanical stability are higher.Through scanning electron microscopy(SEM),it was observed that the latex particles in SBS latex were spherical with uniform particle size distribution,with an average particle size of 1.402 μ m,which matched the average particle size of emulsified asphalt.The Zeta potential is 57.31 m V,indicating that the latex system is stable.The gel content of SBS latex(I)is 200 ppm,and the residual solvent content is 100 ppm.Based on the stability mechanism of atypical Pickering lotion,SBS latex(Ⅱ)was prepared by using modified silica sol and surfactant as emulsifier.The influence of surfactant concentration,silica sol concentration and Na Cl concentration on the performance of SBS latex(II)was analyzed through the evaluation indexes such as gel amount,mechanical stability,storage stability and viscosity.The optimal formula of SBS latex(II)was determined as follows:SBS solution: water: modified silica sol: sulfonated OP-10: Na Cl=100:30:1:0.5:0.5.The physical parameters of SBS latex(Ⅱ)were characterized by scanning electron microscope and Zeta potentiometer.The results showed that compared with SBS latex(Ⅰ),the Zeta potential of SBS latex(Ⅱ)was increased by 1.83 m V,the gel content was reduced by 100 ppm,the residual solvent content was reduced by 50 ppm,and the storage stability and mechanical stability were improved.It shows that the stability of lotion can be further improved by mixing modified silica sol with surfactant.Finally,the relevant properties of SBS latex modified emulsified asphalt prepared by using two types of SBS latex as modifiers were studied.The results showed that the ductility and softening point of the modified emulsified asphalt gradually increased with the increase of the amount of modifier added.When the amount of modifier added is 8 wt%,compared to traditional SBS particle modified emulsified asphalt,the softening point of SBS latex(I)modified emulsified asphalt increases by 19 ℃ and the ductility increases by 31 cm;The softening point of SBS latex(II)modified emulsified asphalt increased by 21 ℃ and the ductility increased by 34 cm.This indicates that the high and low temperature performance of the two types of SBS latex modified asphalt has been significantly improved compared to SBS particle modified emulsified asphalt. |
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