| In order to ensure road performance and prolong the service life of roads,many countries have studied the preventive maintenance of roads.Considering that it is most appropriate to treat the disease at its early stage of germination,the material of self-healing emerge as the times require.The asphalt mixture is a viscoelastic material,it also has self-healing properties.Therefore,based on this performance characteristic,this article aims at the self-healing properties of asphalt concrete,mainly uses 70#base asphalt and 90#base asphalt,and through the SBS modifier and carbon black to prepare asphalt mixture and asphalt mastics.On this basis,the self-healing mechanism,self-healing evaluation indicators,factors that affect self-healing ability and technical measures to enhance self-healing ability were studied.In regard to the self-healing performance,this article elaborates the property from asphalt mastics and asphalt concrete.Based on DSR,fatigue-self-healing test of asphalt mastics was performed,and its self-healing performance was analyzed and characterized by the healing index HI.Based on MTS,the four-point bending fatigue-self-healing-fatigue test was conducted on asphalt concrete,and its self-healing performance was studied by the fatigue life recovery rate.In regard to the self-healing evaluation indicators,this paper selected the splitting strength ratio,healing rate,fatigue life recovery rate and healing index.At the same time,in view of the repeatability analysis method,it used splitting strength test,three-point bending failure test and four-point bending fatigue test to study and analyze.The research showed that the fatigue life recovery rate has the smallest CV value,it meant that the discreteness was the smallest,the result was more accurate,and the self-healing ability of the asphalt mixture can be more accurately characterized.Therefore,it was most appropriate to choose the fatigue life recovery rate as the evaluation indicators.In regard to the impact factors,this paper used the single factor analysis to study its intrinsic factors,and it used the grey relational analysis to study the significant level of each intrinsic factor,the find the most significant factor.At the same time,it used the orthogonal test design to study external factors,and the best combination was analyzed.The study found that:For the intrinsic factors,the asphalt type had the most significant impact on the self-healing ability of asphalt mixture,while that of gradation type is not significant;For external factors,the healing temperature has the greatest effect and the strain is minimal.At the same time,when the combination of healing temperature is 60 ℃,healing time is 6h and strain is 1000με,the self-healing performance was best.In regard to the enhancement measures,this paper verified the he self-healing ability of asphalt concrete with carbon black by microwave heating.And on this basis,by comparing the microwave heating and oven heating modes,determined a better heating mode,and optimized the heating time.Finally,through non-destructive CT scanning technology,it used a new perspective to study the development of fatigue damage of asphalt mixture.The research shows that the self-healing ability of carbon black-SBS modified asphalt concrete is stronger than that of SBS modified asphalt concrete under microwave heating conditions;the microwave heating method also has had stronger effect on the self-healing ability of the asphalt mixture than the oven heating method;On this basis,it determined that the self-healing ability of the asphalt mixture was best when the microwave heating time was 120s.At the same time,the CT scanning technology also verified this result.In summary,the study of asphalt concrete self-healing characteristics and evaluation indicators not only provides technical support for accelerating the construction and development of the green cycle low-carbon transportation system,but also has significant engineering and social benefits. |
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