Contrastive Analysis Of Asphalt Index System In China And Europe And The Exploration Of New Index

Asphalt as the binder of asphalt pavement,its function is to combine stone and mineral powder to form a complete pavement structure to resist traffic load and temperature load.How to accurately evaluate the performance of asphalt and choose asphalt reasonably have great influence on the pavement performance of asphalt mixture.This paper finds out the asphalt specifications in China and Europe,and compares the differences of classification methods and evaluation indexes of base asphalt and modified asphalt in China and Europe.The results show that for base asphalt,penetration classification is adopted in both standards,and penetration is used as the index to classify asphalt grade,but there are also differences.In China,penetration is the only basis for classifying asphalt grade.In European standards,the penetration of asphalt with different labels overlaps,which shows that European classification of asphalt is not only based on penetration,but also assists other indicators.In classification,the standard classification span of our country is 20,and the European standard responds to the increase of the classification span with the increase of penetration of asphalt.The results show that the classification method in Europe is more reasonable for the classification of low-grade asphalt properties;for the evaluation index of base asphalt,there is no ductility in Europe,and the low-temperature performance of asphalt is evaluated by Fraser brittle point,while in China ductility is emphasized and used to evaluate the low-temperature performance of asphalt.The ductility variability of asphalt from different origins of the same label is large,and the ductility of low label asphalt mostly does not meet the requirements of China's specifications.Conventional test,viscosity test and adhesion test of three kinds of hard asphalt 35/50 from different oil sources in Europe show that the ductility of ERIES and TT asphalts at 15 C is quite different,and the softening point,penetration,viscosity and adhesion index are basically the same,indicating that only 35/50 hard asphalt from different oil sources in Europe has the same ductility.Increasing ductility alone can't do much for the road performance of asphalt,and other conventional indexes should be taken into account.By comparing the evaluation indexes of modified asphalt,it is found that European standards pay more attention to the cohesion of asphalt,and use force ductility,tensile test and pendulum test to evaluate the cohesion of asphalt.Based on the theory of surface energy,this paper evaluates the cohesive work and cohesive work of eight kinds of base asphalt and five kinds of modified asphalt,and studies the correlation between the cohesive work of asphalt and the conventional indexes of asphalt by means of grey correlation analysis method.It is found that the cohesive work of asphalt itself has a great correlation with the adhesion of asphalt.The softening point has a high correlation with the adhesion of asphalt in the three indexes,and the cohesive work of asphalt at 13 Bush viscosity has a low correlation with asphalt adhesion work,which can be controlled by changing the softening point and the cohesive work of asphalt.In this paper,six kinds of asphalt are scanned at the same frequency by means of dynamic mechanical analysis?DMA?.The changes of complex modulus,loss modulus,storage modulus and tangent value of loss angle with temperature are studied.The complex modulus and loss modulus are respectively fitted by Origin software.From the fitting results,Gauss curve can be used to fit loss modulus and Bo curve can be used to fit loss modulus.The complex modulus fitted by ltzmann model is highly correlated,reaching above 0.98.The temperature corresponding to the peak point of Gauss model is taken as the glass transition temperature of asphalt to evaluate the low temperature performance of asphalt.The temperature sensitivity of asphalt is evaluated by the absolute slope value at x₀ of the parameter of Boltzmann model.The two indexes are verified by the rheological experiment of bending beams.The results show that the glass transition temperature of asphalt can be used to evaluate the temperature sensitivity of asphalt.The reliability of evaluating low temperature performance of asphalt by transition temperature is high.There are some rules for evaluating temperature sensitivity of asphalt by absolute slope value at x₀.