Study On Storage Stability Of Low Asphaltene SBS Modified Asphalt

In recent years,the rapid growth of traffic volume and the complex and changeable climate environment in China have put forward a severe test to the performance of asphalt pavement.Through a large number of experimental research and engineering practice,it is found that the road performance of SBS modified asphalt has outstanding advantages,but the compatibility of polymer SBS and asphalt is not good because of the difference in composition,structure,and chemical properties.SBS modified asphalt is easy to segregate in the process of transportation and storage,which seriously affects the road performance of modified asphalt.From the domestic point of view,the asphaltene content of matrix asphalt produced in China is low.Asphaltene,as the most polar component in asphalt,has strong adsorption.The asphalt with low asphaltene content has fewer polar groups,poor adsorption and unstable system,which leads to poor storage stability of modified asphalt.Therefore,how to efficiently apply the homemade matrix asphalt and put forward reasonable modification methods is of positive significance to alleviate the pressure of domestic asphalt demand.In this thesis,the content of each component of asphalt is determined through the four-component experiment of asphalt chemistry,and the effect of asphalt components on the performance of asphalt is analyzed.The asphalt with asphaltene content less than 5%is defined as low asphaltene asphalt.Low asphaltene asphalt was modified by a self-developed stabilizer and an accelerator together with SBS modifier to prepare low asphaltene SBS modified asphalt.The effects of stabilizers and accelerators were studied by the index changes of penetration classification and PG classification.The results show that the addition of stabilizer can greatly improve the segregation of SBS modified asphalt and obtain stable modified asphalt.It has better anti-aging performance when the content is0.18%,but the stabilizer is unable to hange the softness of low asphaltene SBS modified asphalt.At this time,an accelerator is introduced to observe the performance change of the modified asphalt.The addition of accelerator effectively improves the high-temperature performance of low asphaltene SBS modified asphalt,strengthens the internal space structure of modified asphalt,increases viscosity,reduces temperature sensitivity,and has better construction and workability and anti-aging performance,but it is disadvantageous to low-temperature performance.According to the SBS modified asphalt I-C technical standard to regulate low asphaltene SBS modified asphalt,the content range of accelerator is 1.2%to 1.8%and has excellent road performance when the content is 1.8%.The stabilizer has no effect on the PG grade of low asphaltene SBS modified asphalt,but the accelerator improves the high-temperature grade while keeping the low-temperature grade of modified asphalt unchanged.Taking the complex shear modulus difference between the upper and lower parts of the segregation tube after hot storage as an index to evaluate the storage stability of SBS modified asphalt,it is found that the closer to zero the absolute value of the complex shear modulus difference of segregation,the better the storage stability of SBS modified asphalt.The microscopic analysis of low asphaltene SBS modified asphalt was carried out by fluorescence microscope and infrared spectrometer,and the stabilization mechanism of SBS modified asphalt was studied.The results show that the network structure of SBS modified asphalt can be formed by the addition of stabilizer,and the accelerator will help the spatial structure of SBS modified asphalt will become more compact and stable.At this time,low asphaltene SBS modified asphalt has a stable system.The infrared spectrum of low asphaltene SBS modified asphalt was quantitatively analyzed.The area ratio of characteristic absorption peak(S₉₆₆/S₁₃₇₇)was used to characterize the SBS content.The changes of characteristic peak area ratio under different SBS content,stabilizer content and accelerator content were discussed.The change law of the S₉₆₆/S₁₃₇₇ difference between the upper and lower parts of the segregation tube after heat storage was observed,which is the same as that of the segregation complex shear modulus difference.The feasibility of using the segregation complex shear modulus difference as the segregation evaluation index is demonstrated from the microscopic point of view.