| In the face of poor road conditions and continuously low natural rubber prices,the countries of origin of natural rubber in south-east Asia have a strong desire to use natural rubber in road asphalt modification,aiming to improve the domestic road conditions and expand the consumption of natural rubber to achieve income.China also intends to expand the application of natural rubber in the road field,but at present,there are few researches on the use of natural rubber modified asphalt in China,and the technology is not mature and the modification effect is not good,which seriously hinders its popularization and application.In view of this,ordinary natural rubber modified asphalt(NRMA)was prepared,and a kind of high-performance vulcanized natural rubber modified asphalt(VNRMA)was prepared based on the principle that natural rubber can react with vulcanizing agent to produce crosslinking.The preparation technology,modifier content,asphalt properties,rheological properties and microcosmic properties of these two kinds of modified asphalt were systematically studied by laboratory test.In this paper,the preparation process of modified asphalt was studied by three major indexes and rotational viscosity test.The blending process of natural rubber and asphalt was determined at 160? with rotation shear of 4000 rpm for 1h,and the development time of vulcanization reaction of natural rubber in asphalt was 1.5h.The properties of NRMA with different natural rubber content were studied.The results showed that natural rubber can significantly improve the high temperature performance of NRMA,but it will have a negative impact on its low temperature performance.The optimal content of natural rubber in NRMA was determined to be 2.5%(denoted as 2.5NRMA).The properties of VNRMA with different natural rubber content and vulcanization formula(different sulfur content)were studied.The results show that the high and low temperature performance of VNRMA is significantly better than that of the base asphalt and NRMA.Performance test determined that VNRMA(denoted as 2.5/10 VNRMA)prepared by adding various vulcanization additives into 2.5% rubber asphalt according to the vulcanization formula NR 100 phr,ZnO 5phr,SA 2phr,TMTD 2phr and S 10 phr has the best performance.In order to further verify the performance of the modified asphalt,the elastic recovery,temperature sensitivity,storage stability and rheological properties of 2.5NRMA and 2.5/10 VNRMA were studied by elastic recovery test,rotational viscosity test,segregation test and rheological test.The results show that: 2.5NRMA and 2.5/10 VNRMA have lower temperature sensitivity and better storage stability;The high temperature deformation resistance and low temperature cracking resistance of 2.5/10 VNRMA are significantly better than that of 2.5NRMA and base asphalt;2.5NRMA has slight elastic recovery performance,while 2.5/10 VNRMA has excellent elastic recovery performance.Vulcanization crosslinking of rubber can significantly enhance the elasticity of modified asphalt.Finally,the micro characteristics of modified asphalt were studied by fluorescence microscope and infrared spectrum.The results show that: in NRMA,the natural rubber with large particles is cut into fine particles and evenly dispersed in asphalt,the compatibility between rubber and asphalt is good,and no new chemical bond is generated in the modification process,which belongs to physical modification;in VNRMA,the addition of sulfur can make the natural rubber cross-linked in asphalt to form a three-dimensional network structure,at the same time,it can further disperse the natural rubber.The above research shows that the new vulcanized natural rubber modified asphalt prepared in this paper has excellent performance,which can provide reference for the application of natural rubber in the field of asphalt modification. |
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