Study On Modification Mechanism And Process Optimization Of Karamay Asphalt

SBS modified asphalt has been widely used because of its excellent performance,but because of its different composition,structure and molecular weight,the modified asphalt has some problems,such as poor compatibility and low softening point.In order to obtain Karamay SBS modified asphalt products in accordance with the technical standards,the modification mechanism and process conditions were studied in this paper.Using Karamay deasphalted oil(DAO)and deoiled asphalt(DOA)as basic raw materials,the 135? rotational viscosity and infrared spectrum analysis were carried out.For DAO-SBS system,DAO-Stabilizer system,DAO-SBS-Stabilizer system,DOA-SBS system,DOAstabilizer and DOA-SBS-Stabilizer system obtained under different process conditions were studied.It was found that when only SBS was added,DAO or DOA did not react with SBS;When only stabilizer was added,DAO did not react with stabilizer,but there was chemical reaction between DOA and stabilizer.When SBS was added to cut and then stabilizer was added to cut and develop,it was found that in DAO,the stabilizer only reacted with SBS,while in DOA,the stabilizer reacted not only with SBS but also with DOA.The appearance of sulfone functional group in infrared spectrum proves this point.he results of 135 C viscosity data show that the 135? viscosity of the modified system obtained by adding SBS and then adding stabilizer is higher than that of the system with SBS or stabilizer alone under the same raw materials and process conditions.According to the ratio of 1:2,1:3.5,1:5,and 1:6 to DAO:DOA,four kinds of base asphalt were prepared.The matrix asphalt-SBS system and matrix asphalt-stabilizer system obtained under different process conditions were studied by using 135? rotational viscosity,25?penetration,5? ductility,soften point,5? ductility,segregation and infrared spectroscopy.Only the matrix asphalt with the right ratio between DAO and DOA is suitable for SBS modification,and the modified asphalt with low or high DOA content can not get qualified modified asphalt with qualified hot storage stability.For the matrix asphalt of DAO/DOA=1:5,when the addition of SBS is 4.5%,the shear rate is 3000 rpm and the shearing time is 30 min,the optimum modification conditions and formula are as follows: the development temperature is 195?,the development time is 3 h,and the content of stabilizer is 0.3%.It is found that under the above optimized process conditions,the soften point of the modified sample is lower.It does not meet the requirements of soften point in I-C of polymer modified asphalt SH/T0740-2003 product specification.Under the above optimized formula and process conditions,the matrix asphalt was modified by adding a certain amount of matrix asphalt modifier(DJ)to the matrix asphalt.Then the asphalt was modified by adding SBS modifier(4.5%)and stabilizer 1 #(0.3%).The samples were studied by rotating viscosity at 135?,penetration at 25?,ductility at 5?,softening point,ductility at 5? after aging and segregation.It is found that the addition of DJ can significantly improve the softening point and viscosity of the modified asphalt,but too much DJ will lead to the deterioration of the hot storage stability of the modified asphalt.Through the optimization of the addition amount of DJ,it is concluded that when the addition amount of DJ is 0.4%,the modified asphalt product obtained under the optimized process conditions meets the technical requirements of I-C SBS modified asphalt product.