Experimental Study On Mechanism Of Vacuum Compacted Asphalt Mixture

As the main form of road traffic,asphalt pavement has many advantages,such as good mechanical performance,high driving comfort,good wear resistance,low noise,short construction period and easy maintenance.The compaction method plays a decisive role in the quality of the pavement compaction.This paper aimed at the present stage of vacuum compaction,a series of tests have been completed by using the multifunctional asphalt mixture vacuum loading test bench.The mechanism of vacuum compaction and the rule of energy propagation are studied in depth.The application value of vacuum compaction and the adaptability to the hard compacted materials are discussed.Firstly,this paper introduces the mechanism of conventional compaction and vacuum compaction,summarizes vacuum compaction research results of the research group and proposes of the problems of vacuum compaction at the present stage;Secondly,it introduces the relevant indexes of evaluating the effect of vacuum compaction,including the two aspects of the vacuum compaction process and the mechanical properties.Finally,through the three different loading methods of static load test,vibration and shock,the principle test,the vibration parameter optimization test and the contrast test are completed.The test results show that compared with non vacuum compaction,in the principle test,the deformation and settlement of the asphalt mixture increases by about 8.17% and 18.22% during the pre compaction process respectively,and the rebound amount reduces by 61.86% to 71.77% in the whole compaction process,energy spread more widely,more complete and efficient compaction.At the same time,under the different compaction energy conditions,the void ratio of the mixture reduces by 8.5% to 15.2%,the splitting strength increases by 27.3% to 47.4%,and the Marshall stability increases by 24.5% to 46.6% with the increase of the vacuum.In the vibration parameter optimization test,the vacuum has a certain influence on the optimization of the vibration parameters,compared with the conventional compaction optimum vibration parameters,the frequency decreases from 37 Hz to 30 Hz,and the excitation force is reduced,the void ratio of the specimens reduces by about 17.6%,the splitting strength and Marshall stability increase s by 45% and 141.1% respectively.In the contrast test,vacuum compaction has good adaptability to hard compacted materials,the void ratio reduces by about 2.2%,the stability and modulus of Marshall increases by about 6.2% and 10.9% respectively,and the stability of high temperature is improved.