Research On Cracking Behavior Of High-Volume Hot Recycled Asphalt Mixture Based On Digital Speckle Method

The process of road construction in our country has gradually entered the stage of large and medium repair and maintenance.At this stage,a large amount of waste asphalt mixture will be produced.Using these waste materials to the greatest extent can save a lot of resources and has extremely high economic benefits.Therefore,under the premise of ensuring the normal use of the road surface,the use of waste asphalt mixtures as large as possible is the inevitable development trend and direction of my country’s highway asphalt pavement recycling technology research.In this paper,a combination of laboratory tests and digital speckle correlation method meso-analysis methods are used to study the high-volume RAP hot-recycled asphalt mixture.Through indirect tensile test,the tensile performance and tensile deformation performance of high-volume RAP plant-mixed hot-recycled asphalt mixture are studied.Analyzed the principle of indirect tensile test and test influencing factors,determined the influence of gradation,test temperature,and loading rate on the test results,studied the RAP content and split tensile strength,failure tensile strain,failure stiffness modulus The law between the quantity and the influence of the regenerant on the test results.From a macro perspective,conduct laboratory tests on the high-temperature stability,low-temperature stability,and water stability of high-volume recycled asphalt mixtures,and use the test results to obtain the maximum RAP content that can simultaneously meet the above-mentioned road performance indicators,and After adding the regenerant,the maximum RAP content that meets the requirements is explained,combined with the results of the indirect tensile test at room temperature to explain the above maximum content.From a mesoscopic point of view,the digital speckle method is used to study the cracking behavior of asphalt mixtures at room temperature.The three-stage strain field of the indirect tensile test is studied by analyzing the collected digital speckle images,and the strain field under different RAP content is studied.Use processing software to process the gray-scale pixel image,analyze the maximum crack displacement of the crack in the indirect tensile test,and the crack propagation process.Combined with the results of the cracking behavior research,the above-mentioned maximum content value is further explained.