Design Method Of Aspalt Mixture Gradation Based On Penetration Test

As an important component of asphalt pavement structure,asphalt mixture directly affects the pavement performance.Gradation design which is an important part of the asphalt mixture design process has always been the focus of scholars at home and abroad.In view of the comnon rutting diseases on the road surface,An asphalt mixture grading design method based on penetration test was attemped,which has positive significance for guiding asphalt pavement design,improving vehicle travel environment and road service life.The single-variable method was used to study the influence of the parameters of the coarse aggregate penetration test on the results.Finally,the test criteria for the coarse aggregate penetration test were as follows:the forming method is selected from dry compact molding,the capacity cylinder was selected to be 15L,and the penetration head shape is selected to be a 100mm cylindrical indenter,with the penetration speed is selected to be 5mm/min.A fitting penetration curve slope index was proposed to evaluate the coarse aggregate penetration test process,which was compared with the penetration load index.The results showed that the penetration load index at the depth of penetration is difficult to reflect the characteristics of the whole penetration curve,and balance the discrimination and stability of the test results.The slope of the fitting penetration curve is not only highly discriminative,but also used to evaluate the coarseness.The stability of the aggregate parallel penetration test results is also better.Through the crushing screening test,the compaction screening test and the coarse aggregate penetration test the standard of coarse and fine aggregates in the mixture was studied,it showed that the nominal and maximum particle size mixture thickness of the aggregate not greater than 13.2mm and not less than 16mm is 2.36mm,4.75mm;based on the rough aggregate penetration test,the rough aggregate grading design method suitable for actual engineering was proposed.In the project,the two coarse aggregates can be determined by changing the proportion of coarse aggregate and conducting the penetration test.Gradation,three or more coarse aggregates can be changed by the orthogonal test design method,and then the coarse aggregate gradation was optimized according to the penetration test results;the influence of the fine aggregate blending ratio on the penetration test results was analyzed.Trying to determine the fine aggregate grading design method based on the penetration test,it was found that the logarithmic function can fit the fine aggregate penetration curve well,and the regression parameters were used to evaluate the fine aggregate penetration test results.Leifa carried out the grading and grading synthesis,and deduced its design steps.Comparing the evaluation parameters of different gradings with the grading characteristics,it was found that the grading shape evaluation method and the key sieve method can achieve good fitting effect.Briefly explaining and comparing the current common grading design methods in China,a representative 19mm nominal maximum particle size gradation in the surface layer of asphalt pavement was formulated.The best oil-stone ratio was determined and the asphalt mixture performance was evaluated by referring to the Superpave mixture design method.A high-temperature performance prediction model of asphalt mixture based on grading evaluation parameters was establed,the results showed that the 19mm nominal maximun particle size mixture determined by the penetration test method has better performance and coarse aggregate.The slope index of the fitting penetration curve has certain correlation with the dynamic stability of the mixture and the uniaxial penetration load index.The coarse aggregate penetration test is used to guide the coarse aggregate grading design with good feasibility and application effect.The uniaxial penetration load of the mixture has a good correlation with the dynamic stability index.The uniaxial penetration test of the mixture can effectively evaluate the high temperature performance of the mixture.The power function regression method can predict the high temperature performance of the mixture to some extent.