Research And Application Of Composite Modified Emulsified Asphalt Micro-surfacing

At present,the emphasis of highway in China has been gradually shifted from newly built to maintenance.Preventive maintenance,represented by the micro-surfacing,widely used in domestic,but also gradually revealed two major problems: one is the modified emulsified asphalt is difficult to get the balance between the excellent high temperature and perfect low temperature performance,the other one is the micro-surfacing mixture is easy to appear egregation,loose,the lack of cohesive force,poor durability during the construction.In order to get modified emulsified asphalt with balanced high and low temperature performance,this paper attempts to make composite modification of emulsified asphalt with excellent high temperature performance of gilsonite and excellent low temperature performance of SBR.First study is the formula research of matrix emulsified asphalt,which is a good foundation for the research of compound modified emulsified asphalt,and then compares the difference among the emulsification and modification,modification after emulsification,emulsificatio after modified,determines that the best preparation method to get Gilsonite-SBR modified emulsified asphalt.On this basis,studies the influence of gilsonite content on the performance of modified emulsified asphalt.on the of range from 3% to 4%,gilsonite can infulence effectively the performance of modified emulsified asphalt.Then,the optimal solution is determined through orthogonal design and material optimization:3% of gilsonite,5% of SBR latex,3.7% emulsifier and 35 min emulsification time.Through the selection of gilsonite and matrix asphalt,it is found that the modification effect of qingchuan gilsonite is better than that of zhongdong gilsonite,qingchuan gilsonite is suitable for SK-70 matrix asphalt.Aimed to solve the segregation and loose in the construction of micro-surfacing,grade A is selected by adjusting the key sieve hole pass rate,and combined with wet wheel abrasion value and structural depth,and compared with the median grade B,analyzes the oil-stone ratio on the performance of two graded mixture,finds the grade A is superior to B in wear resistance,resistance to water damage performance,but in the mixing time,rutting resistance,slip resistance,grade A is slightly lower than B,but still meet the requirement of the guide.The effect of cement content on the performance of mixed materials in mixture is studied,the optimum content of cement is determined by 1.5%,and the optimum oil stone ratio of grade A mixture is 7%.The performance compare is completed among the Gilsonite-SBR modified emulsified asphalt,SBR modified emulsified asphalt,SBS modified emulsified asphalt and the mixtures.The study finds that the Gilsonite-SBR modified emulsified asphalt with the high temperature performance which is better than SBR modified emulsified asphalt,and the low temperature performance which is better than SBS modified emulsified asphalt.The content of 3% gilsonite has no obvious improvement on the wear-resisting property of the mixture,but it improves the water stability of the mixture and improves the anti-deformation ability.Finally,combining with the chongqing zhongxian preventive maintenance has carried on the real engineering application,the construction and open the traffic no segregation occurred,the problem such as peeling,engineering effect is good,the social benefit is remarkable.