| With the economic development and the intensification of heavy-duty traffic,a single modified asphalt has gradually been unable to meet the requirements of pavement performance.SBS and polyurethane as modifiers have their own advantages and disadvantages for asphalt modification.SBS modified asphalt has excellent performance but high price and poor storage stability.Polyurethane modified asphalt is environmentally friendly and low cost,and can be chemically modified with asphalt,to form a stable cross-linking system structure.Therefore,in order to take advantage of the advantages of different modifiers,this article proposes to prepare composite modified asphalt with SBS and polyurethane as a compound.At the same time,in the design of the dosage,part of the SBS modifier is reduced,and an appropriate amount of polyurethane is added,and compare the performance with higher SBS content.On the basis of summarizing relevant researches at home and abroad,the performance,microstructure and road performance of SBS/polyurethane composite modified asphalt were systematically studied.First of all,through preliminary research on the three major indicators of SBS/poly urethane composite modified asphalt with different content,it is found that SBS/polyurethane composite modified asphalt can better reduce the penetration of asphalt,increase the softening point of asphalt,and make the asphalt more stable.The high temperature performance is improved,while the ductility of the asphalt is improved,and the low temperature performance is also better modified.It can be preliminarily concluded that the addition of polyurethane can replace part of the SBS modifier to achieve the same modification effect.Secondly,the rheological characteristics of SBS/polyurethane composite modified asphalt are studied.The test results show that SBS and polyurethane can increase the apparent viscosity of asphalt,and the effect is better when composite modification is used;the dynamic shear rheological test results show that,The high-temperature deformation resistance and fatigue resistance of the composite modified asphalt have been greatly enhanced;the low-temperature bending rheological test results show that the low-temperature performance of the composite modified asphalt has also been significantly improved.A comparative analysis of the composite modification of polyurethane and SBS with a lower content and a higher content of SBS alone showed that polyurethane can replace part of the SBS modifier and improve the high and lowtemperature performance of asphalt by equivalent or even better changes.Sexual effects.From the consideration of modification effect and economy,it is recommended that the best combination of SBS/polyurethane composite modified asphalt is 4%SBS+6%PU.At the same time,the microstructure of the SBS/polyurethane composite modified asphalt was analyzed.The study showed that the two modifiers can be evenly dispersed in the asphalt system to form a stable cross-linked network structure;there are physical modification and Chemical modification also has excellent storage stability.Finally,the AC-13 gradation was used to verify the road performance of the asphalt mixture,and compared the road performance of base asphalt,polyurethane modified asphalt and SBS modified asphalt.The study found that the high temperature of SBS/polyurethane composite modified asphalt Stability,low temperature crack resistance,and water stability have all been improved. |
