Mixing Flow Characteristics Of Different Types Of Asphalt Mixtures

Mixing workability of asphalt mixture refers to the degree of difficulty in mixing the mixture,which has an important impact on the mixing and paving of asphalt mixture,which is related to the road performance.At present,the quantitative evaluation of asphalt mixture mixability is less,and the definition of the workability index is narrowly defined.This paper studied the mixing flow characteristics of different types of asphalt mixture.Based on the rheological model of mixing,the factors such as the mixing temperature,the amount of asphalt,the nature of the asphalt and the type of grading were investigated,and the index of the mixability of the asphalt mixture was comprehensively evaluated.The paper selected five common grading types,such as AC-13,AC-20,SMA-13,OGFC-13,and ATB-25,which are common in the project.The variable speed mixing power testing device developed by the research group was used to change the speed of the mixture.Mixing tests to analyze the effect of grading types on the mixing characteristics of asphalt mixtures.Based on the components of the asphalt,such as the amount of asphalt,the nature of the asphalt,and the grading type,the mixing flow characteristics of the asphalt mixture are analyzed at different mixing temperatures,and the workability index is defined.The results show that the mixing flow characteristics of the asphalt mixture obey the linear visco-plastic Bingham model,the constitutive equation is P=F+??V,the intercept F is the internal plastic limit?F>0?,and the slope?is generalized Viscosity.The mixing power of the asphalt mixture shows a positive correlation with the increase of the mixing rate,and it shows a negative correlation with the increase of the temperature and a significant change with the different gradation types.The?value of different grades of dry mix aggregates is very small,not affected by temperature and size of aggregates,showing inviscidity,but there is a big difference in the internal plastic limit F value,the greater the maximum nominal particle size,the internal plastic The larger the limit,the larger the coarse aggregate ratio?Cr?for the same maximum nominal particle size and the greater the internal plastic limit.The greater the internal plastic limit F of the gradation corresponding to the largest nominal particle size,the worse the workability.Considering the asphalt mixture's generalized viscosity?,the internal plastic limit F,and the mixing rate V,a trapezoid is constructed by mixing the P-V rheogram axis,the flow deformation straight line,and V=50r·min^-1 to the trapezoidal area(=₂¹(1?++?1?=25?2+50??The inverse centimeter rate is used as the workability index,and the best mixing temperature and the workability index-temperature curve of the asphalt mixture?The I-T curve?determines the best mixability index for different asphalt mixtures.Through the study of the workability index,the mixing flow characteristics of the asphalt mixture are analyzed to provide a theoretical basis and method for the asphalt paving.