The Failure Evaluation And Self-healing Investigation Of Crack Sealant

It is the most effective,simple and extensive maintenance method to treat pavement cracks at present by using crack sealant to repair cracks in pavement.Through field investigation,it is found that some failure forms in the course of service can be self-healing to a certain extent.Based on quantitative evaluation of crack sealant failure in the actual service process and the consideration of influence factors of self-healing,this study establishes failure criteria for crack sealant,which provides a necessary scientific definition of failure for the part hard to be self-healing,a basis of decision-making for pavement maintainer and a reasonable turnover time of crack sealant.The contents and results of the research are as follows:In the first place,based on the field investigatio n of crack sealant on 2 test road sections in Suiman Highway and Hunwu Highway,the classical failure form of crack sealant is obtained.Besides,the investigation index and method of crack sealant failure are established.Combined with image and data,the development tendency of failure and changing pattern of failure index are analyzed.Considering the impacts of failure index,the evaluation model of crack sealant failure under different pouring technology is developed.Secondly,the causes of all types of failure forms and their influence on the pavement performance and the properties of the crack sealant are analyzed.As the results show,the effect of natural aging and pavement temperature stress is the main cause of net cracks on the surface of crack sealant.Natural aging will cause the decomposition of SBS and other modifiers in the crack sealant.Moreover,natural aging will reduce the penetration of the gel,increase the softening point,increase the glass transition temperature,and decrease the tensile properties at low temperature.The aforementioned factors cause early crack of sealant and damage of waterproof property,leading the pavement performance get influenced.Next,the evaluation index of mechanical self-healing and functional self-healing are decided,the influential factors of self-healing are analyzed.The results show that,the sealant with good low-temperature performance has stronger bearing capacity,while that with good high-temperature performance has better mechanical self-healing ability.The adhesion cracks can heal after a certain time when self-healing occur for different crack sealant under a certain temperature.Also,the tensile properties at low temperature recover to varying degrees.Moreover,the self-healing extent will be higher if the crack width is smaller,the self-healing temperature is higher,the self-healing time is longer and the binding environment is cleaner.Because of these reasons,the waterproof property can completely recover after self-healing.Finally,combined with indoor self-healing experiments and real service condition of crack sealant,the failure evaluation index and criteria are established.The failure evaluation method is proposed and the failure evaluation process is comprehensively introduced.