Study On The Influence Of Salt Spray Environment On The Performance Of Asphalt Mixture

With the development of China's economy,a large number of roads and sea-crossing bridges have been built in the coastal areas,and asphalt mixtures have been widely used in road surface and bridge deck pavement.There is a wide range of salt mist environment in littoral area,and the North has the characteristics of salt mist-freeze-thaw cycling coupling.According to the survey,the coastal area of asphalt pavement in the use of a period of time,often did not reach the design life of the cracks,pits,loose and other road diseases,resulting in greater economic losses and social negative impact.In this study,asphalt mixtures commonly used in engineering(modified asphalt SMA-13,modified asphalt AC-13,Matrix asphalt AC-13)as the object of study,using neutral salt spray test method to simulate the coastal salt fog environment,study different temperature(15 ?,25 ?,35 ?,45 ?),and Salt Mist action Time(5d,lOd,15d,20d,25d),the water stability of asphalt mixture,the variation of low-temperature crack resistance,and the effect of salt mist-freeze-thaw cycling coupling on the durability of asphalt mixture.Through theoretical analysis,the paper explores the erosion mechanism of the salt-mist environment on the asphalt mixture,and gives the suggestions for the maintenance of the asphalt pavement in the coastal area.The conclusions are as follows.(1)With the improvement of action temperature and the increase of action time in the salt mist environment,the low-temperature anti-cracking,water stability and durability of three kinds of asphalt mixtures were decreased in different degrees.Compared with three kinds of asphalt mixtures,the residual strength of modified asphalt SMA-13 is the lowest,and the later performance is more stable.The initial flexural tensile strength and splitting strength of modified asphalt AC-13 are better,and the decrease is obvious with the increase of action temperature and the time of action.The AC-13 of the matrix asphalt is weaker than that of the bending and splitting resistance.The results show that the modified asphalt SMA-13 structure has better adaptability to salt mist environment.(2)Analysis of the erosion mechanism of the salt spray environment on the asphalt mixture:the icing expansion pressure and the crystallization pressure of salt solution,and the aggregate and pitch stripping caused by the adsorption of ions and bitumen in salt solution are the main reasons for the effect of salt mist on asphalt mixture performance.It is suggested that the SMA structure should be selected in the coastal area with modified asphalt mixture,which is suitable for high temperature difference or high-grade pavement.In the course of use should be regularly sprinkling to reduce the salt content of the road,in the summer high temperature should also take the limit,speed limit,load and watering to reduce the impact of temperature on the asphalt pavement.