Studying On Fatigue Damage Self-healing Performance Of Basalt Fiber Asphalt Mixture

Load cracking is one of the main damage forms of asphalt concrete pavement,which seriously affects the normal operation of the highway.Since Bazin and Saunier used the experiment to prove that asphalt concrete has self-healing ability in 1967,many studies have proved that self healing performance is one of the asphalt mixture'characteristic,and determine the impact of load strain interval,mix structure and different loading and batch ratio factors on self-healing,but there is not much research on basalt fiber asphalt mixture.Basalt fiber has emerged as an important research direction for pavement fiber modifiers due to its obvious improvement in pavement performance,stable chemical properties,natural environmental protection.Therefore,from the perspective of composite materials,this paper uses the anti-cracking characteristics of basalt fiber materials to combine the self-healing properties of asphalt to study the effect of adding basalt fibers on the self-healing ability of asphalt mixtures.First,based on the Marshall test method,the mix ratio design of AC-16 C dense matrix asphalt mixture was carried out to determine the optimum oil/rock ratio of 4.9%,based on which a SBS modified asphalt mixture with a modifier content of 4.5% was prepared,0.03 % mass fraction of basalt fiber asphalt mixture,in this process,the basalt fiber asphalt mixture mixing technology was explored,and a new fiber mixture mixing method was proposed.Secondly,the four-point bending fatigue test was conducted on three asphalt mixtures and it was found that the damage degree had a great influence on the fatigue performance of the asphalt mixture.The greater the damage was,the more obvious the fatigue performance of the modified asphalt mixture was.After adding basalt fiber,the fatigue performance of asphalt mixture increases obviously but it is still less than SBS modified asphalt mixture;the change curve of dissipated energy can better reflect the damage degree of the asphalt mixture.The curve shows that the fatigue damage of the asphalt mixture can be divided into three stages.Corresponding to the accumulation of defects,expansion and stability stage,the degree of damage is 30% is the cumulative stage of defects,30% to 50%is the initiation stage of cracks,and the degree of damage exceeds 50% to 70% is the violent development of internal cracks in the mixture.Thirdly,by orthogonal experiment to analyse the influence of healing time,healing temperature and damage degree on the self healing performance of different asphalt mixtures.Damage rate is chosen as an index for evaluating the healing performance of asphalt mixture.Results are as follows: For the self-healing properties of the three mixtures,the degree of damage has a negative effect,the temperature has a positive effect,the healing time has a positive effect,but the lifting effect is not as obvious as the temperature;The "forging effect" will occur when the SBS modified asphalt mixture and basalt fiber asphalt mixture undergo small fatigue loads,that is,the fatigue resistance will be better than before the healing;when the damage degree exceeds 50%,the healing performance of the base asphalt mixture drops significantly,and the SBS modified asphalt mixture hardly heals,Basalt fiber asphalt mixture has the best healing properties.Finally,this chapter with the help of scanning electron microscope(SEM),analyzed the matrix asphalt,the SBS modified asphalt mixture and basalt fiber asphalt mixture on the micro structure analysis,The effect mechanism of basalt fiber on the performance of asphalt mixture is analyzed by materiao complex theory and fracture mechanics.