| Drained asphalt pavement(OGFC)is a kind of asphalt pavement with large voids.It is widely used because of its good drainage and noise reduction.However,due to its large voids,its mixture must use high viscosity modified asphalt as its binder.At present,SBS and rubber powder are widely used as modifiers.SBS and rubber powder are used for compound modification to improve the performance of asphalt.However,there is no clear performance index of high-viscosity modified asphalt that can evaluate the road performance index of drainage asphalt mixture,which is a research hotspot.This subject studied the performance of rubber powder composite modified asphalt and mixture and which performance indexes of asphalt can evaluate the road performance of the mixture.The contents of the research include:(1)Using Shell and Shuanglong 70 #matrix asphalt with 4.5% SBS and 0%,6%,8%,10%,12%,14% content of rubber powder through mechanical shear mixing to prepare rubber powder composite modification asphalt,testing the penetration,softening point,ductility,60℃ dynamic viscosity,zero shear viscosity,135℃ Brinell viscosity,dynamic shear rheology,etc.to study the influence of powder on the performance of composite modified asphalt from the perspective of the amount of rubber powder;(2)The OGFC-13 type is selected for the drainage asphalt mixture for gradation design,and the compound modified asphalt prepared with different amounts of rubber powder is mixed with the drainage asphalt mixture.The mixture was subjected to high-temperature rutting,freeze-thaw splitting,and water immersion scattering test to analyze the impact of the amount of rubber powder on the road performance of the drainage asphalt mixture;(3)Aiming at the question of which index can evaluate the road performance of the high-viscosity modified asphalt,based on the gray correlation analysis method,the road performance of the drainage asphalt mixture is used as the reference factor,and the performance of the composite modified asphalt is the comparison factor,judging and analyzing the relationship between the two factors.The research results are as follows:(1)As the content of rubber powder increases,the penetration of modified asphalt decreases,the softening point increases,the dynamic viscosity at 60℃、Brinell viscosity at 135℃ and anti-rut factor increase.When the content of rubber powder reaches 10%,the penetration of the composite modified asphalt is greater than 4mm,the softening point exceeds 80℃,and the dynamic viscosity value at 60℃ far exceeds 20000 Pa · s,which has met the requirements of high viscosity modified asphalt;(2)Because the viscosity of high-viscosity modified asphalt is prone to "false height",zero shear is a novel method for measuring asphalt viscosity.The Carreau model is used to calculate the zero shear viscosity and the zero-shear viscosity increases with the amount of rubber powder added.When the rubber powder content is 10%-12%,the zero-shear viscosity increases sharply,the asphalt viscosity increases;(3)The application of rubber powder composite modified asphalt to drainage asphalt mixture improves the road performance.When the rubber powder content is 10%,the road performance is optimal.The rutting stability reaches about 4000 times / mm,and the intensity ratio exceeds 80%,and the scattering loss rate is less than 5%;(4)Based on the calculation of gray correlation,the correlation value of asphalt zero shear viscosity and high temperature rutting reaches0.839,the correlation value of softening point and water stability is 0.954,the correlation value of phase angle and scattering is 0.977.The general correlation value is greater than0.6.It means that there is a high degree of correlation between the two factors,so zero shear viscosity can be used as a key indicator of the impact of high temperature performance of the mixture,the softening point as a key indicator of the impact of water stability performance,and the phase angle as a key indicator of the impact of scattering performance. |
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