Experimental Study On Adhesion Between Asphalt And Aggregate And Water Stability Of Asphalt Mixture Under Freeze-thaw Cycle

Asphalt pavement has been rapidly developed and used in China,but the disease problems in the process of use have also appeared.Among them,the water damage caused by insufficient water stability of asphalt mixture is more prominent.The so-called asphalt pavement water damage,that is,under the action of environmental conditions such as driving load,temperature and humidity,the asphalt mixture is gradually eroded and destroyed,which eventually leads to pits,looseness,squeezing and the like on the road surface,which seriously affects the driving comfort and driving safety.Therefore,this paper studies the adhesion of asphalt and aggregate and the water stability of asphalt mixture.The relationship between the adhesion evaluation method and the water stability evaluation method was studied to provide technical guidance for the design,construction and maintenance of asphalt pavement against water damage.First of all,this paper selects 6 kinds of asphalt,which are: SK 90 matrix asphalt,rubber asphalt,SBS modified asphalt,SK 90 asphalt + 3‰I anti-stripping agent(hereinafter referred to as No.1 asphalt),SK 90 asphalt + 3‰I type anti-stripping agent +3‰II type anti-stripping agent(hereinafter referred to as No.2 asphalt),SK 90 asphalt +3‰II type anti-stripping agent(hereinafter referred to as No.3 asphalt),for the continuous dense grading type(AC-13,AC-16)asphalt mixture,the design of the mix ratio of the mineral material and the determination of the optimum asphalt dosage are given.Secondly,four methods of adhesion evaluation,such as boiling,water immersion,contact angle and photoelectric colorimetry,were used to evaluated the adhesion of six kinds of asphalt to diabase in multiple freeze-thaw cycles(0,3,6,9,12,15 and 18),and different evaluation methods were evaluated.Then,using the freeze-thaw split test and the water-immersed Marshall test,the water stability and permeability of the asphalt mixture under multiple freeze-thaw cycles(0,6,12,18 times)were tested and studied with the research group.The results of the self-improved water seepage device are compared.Finally,the grey-entropy correlation analysis was carried out between the adhesion index of asphalt-aggregate and the water stability index of asphalt mixture.The test results show that under the same number of freeze-thaw cycles,the adhesion of the six kinds of asphalt and the water stability of the asphalt mixture are consistent.The order of the advantages and disadvantages is: rubber asphalt,No.3 Asphalt,No.2 asphalt,SBS modified asphalt,No.1 asphalt,matrix asphalt;Through the correlation analysis between the adhesion evaluation indexes,it is suggested to use the photoelectric colorimetry method combined with the water immersion method,or the combination evaluation method of photoelectric colorimetry and contact angle method to evaluate the adhesion of asphalt and aggregate.Through the correlation analysis between the adhesion evaluation indexes,it is suggested to use the photoelectric colorimetry method combined with the water immersion method,or the combination evaluation method of photoelectric colorimetry and contact angle method to evaluate the adhesion of asphalt and aggregate.The TSR and residual stability of the asphalt mixture decrease with the increase of the number of freeze-thaw cycles.The water permeability coefficient increases with the increase of the number of freeze-thaw cycles.Under the same number of freeze-thaw cycles,the water permeability coefficients of the six asphalt mixtures are as follows: matrix asphalt,No.1 asphalt,SBS asphalt,No.2 asphalt,No.3 asphalt,rubber asphalt.The rate of increase of the water permeability coefficient of the AC-16 asphalt mixture is greater than the increase rate of the AC-13 asphalt mixture.The improved water permeability meter can better reflect the water permeability of the asphalt road surface than the standard water permeability meter.Through the gray correlation entropy analysis,the relationship between the four adhesion indexes of each asphalt mixture and the two water stability indexes is obtained,which provides a good theoretical guidance for engineering practice.