Research On The Gradation Of Hot Central Plant Recycling Asphalt Mixture Based On Fractal Theory

The hot central plant recycling technology of asphalt pavement can efficiently recycle and utilize reclaimed asphalt pavement materials(RAP),and the recycled mixture has good performance,which has significant environmental and economic benefits over other regeneration methods,milling and resurfacing in the life cycle,which has significant economic and environmental benefits,and make it an important measure for sustainable development of highway transportation,and has become an important measure for sustainable development of highway transportation.How to ensure the performance of the hot-recycled mixture is a key issue of the hot central plant recycling technology,and gradation is a prerequisite for the performance of the mixture.At present,effective evaluation methods and systems for the gradation of hot-recycled mixtures have not been formed,and there are extensive experience in key aspects such as determination of RAP content and gradation design.Focusing on the analysis of grading fractal characteristics and research on the grading method of hot-recycled mixture in the hot central plant recycling process.First,the applicability of fractal theory to hot-recycled mixture was discussed,and the gradation fractal expression and fractal dimension calculation method were derived the relationship between fractal theory and traditional gradation theory is analyzed.Secondly,the fractal characteristics of RAP mineral grading at different milling speeds and milling depths are compared,and the influence of the acquisition parameters on the RAP grading is analyzed based on the fractal evaluation.By simulating the production process of the hot central plant recycling,an evaluation index of the degree of RAP dispersion was proposed,the law of RAP dispersion and mineral migration during the process was obtained.Thirdly,using the Menger sponge model to simulate the internal void structure of the hot-recycled mixture,the density function of the void distribution of the hot-recycled mixture was derived,and a fractal model of the void parameters of the mixture was established.Finally,the synthetic gradation of the recycled asphalt mixture is designed by using the model ore gap ratio and the grading fractal dimension as control indicators,and through Marshall and road performance test,the influence of gradation parameters on the volume index and performance index is analyzed,and the prediction model of volume parameter and performance parameter of hot-recycled mixture is presented,and the applicability of gradation design method is analyzed through the application of solid engineering.In this paper,the second-degree fractal dimension is applied to the gradation expression of dense-graded asphalt mixture,and a test method for determining the dispersion characteristics of RAP during thermal regeneration is provided.Based on the fractal model of hot recycled asphalt mixture,a gradation design method is proposed,which can provide the corresponding theory and model basis for the gradation design and application of hot recycled asphalt mixture.