Design Of The Cold Patch Asphalt Mixture

Cold patching asphalt mixture is an effective way to deal with the disease of asphalt concrete pavement under low temperature,it has lots of advantages such as not influenced by environmental factors,simple construction,traffic fast,low maintenance cost,lengthen the service life of the road,energy conservation and emissions reduction,etc.In this paper,a new type of cold patching asphalt mixture was developed based on a large number of laboratory tests and mix proportion design;and a series of performance evaluation of the Cold Patch Asphalt mixture was carried out,including strength,storage property,adhesion property,water stability property,bond performance and so on;Finally,we discussed the storage technology,construction technology and benefits of cold patching asphalt mixture.The main conclusions are as follows:(1)The cold patching asphalt mixture has good water resistance and high initial strength with suspended dense structure.Selecting this structure to design the Cold Patch Asphalt Mixture should pay attention to the amount of fines,The more the amount of mineral powder,the greater the intensity of the cold patching asphalt mixture,the amount of mineral powder should be controlled at about 2% to ensure the workability of the cold patching asphalt mixture.(2)The strength formation of cold patching asphalt mixture can be divided into two stages: At the stage of construction,the cohesion of the asphalt binder is low because of the small volatilization of the thinner,The strength of cold patching asphalt mixture is mainly provided by the interlocking effect of the mineral aggregate,At this time,The strength of cold patching asphalt mixture is called the initial strength.At the stage of use,the cohesion of asphalt binder increases with the large volatilization of the thinner.Under the effect of vehicle load,The internal friction angle between the aggregate increases,The strength of cold patching asphalt mixture increases to the peak value gradually and tends to be stable finally,and the strength is molding strength.(3)Based ob the quantitative tensile strength test of asphalt mixture and Marshall test,overall considering the performances of the cold patching asphalt mixture,the amount of modifier and diluent was determined as follows: SEBS was 5%,the powder was 4%,the diluent was about 29%.(4)In this paper,we put forward the test methods for the storage property,cohesiveness property,water stability,bond strength,initial strength and forming strength of cold patching asphalt mixture.And a method for simulating the process of diluent evaporation in forming strength test is proposed.(5)The main construction procedures of cold patching asphalt mixture include: pit excavation,pit slot cleaning,cold patching asphalt mixture paving,compaction,cleaning.