Study On Performance Of PE Pyrolysis Wax Assisted Foam With Warm Mix Asphalt And Its Mixture

In recent years,foam asphalt is widely used in asphalt pavement because of its excellent characteristics such as energy saving and emission reduction.Compared with traditional hot mix asphalt mixture,foam asphalt mixture can reduce the construction temperature,reduce the emission of harmful gases,improve the construction and ease,reduce the damage to the health of construction personnel,in line with China’s green lowcarbon environmental protection requirements.However,the foam warm mix technology has a limited reduction in the mixing and construction temperature of asphalt.In addition,waste plastic waste has caused serious harm to the environment,China produces a large amount of plastic waste every year,how to make efficient resource utilization of waste plastic waste has become a hot topic today.By catalytic cracking,waste plastics can be made into relatively low molecular weight paraffin wax,which can be used as asphalt warm mixer to improve the compatibility of asphalt in construction.Based on this,this thesis uses PE cracking wax as a modifier to assist asphalt foaming,in order to further reduce the construction temperature and achieve the composite warm mix effect on the basis of foam asphalt warm mix technology.The main research and findings of this thesis are as follows:(1)Firstly,the optimal foaming temperature and optimal water consumption were determined based on the two major evaluation indexes of foam asphalt,expansion rate(ER)and half-life(HF),and the factors affecting asphalt foaming were analyzed for significance.This thesis determines that the optimal foaming temperature of foam asphalt is 120℃,the optimal water consumption is 4%,the expansion rate is 2.03 times,and the half-life is 19.6s.Second,then add different amounts of PE cracking wax to modify the asphalt after foaming,to produce PE cracking wax modified foam asphalt.Finally,the produced PE cracked wax modified foam asphalt was subjected to three major index and Brinell rotational viscosity test.The results showed that the addition of PE cracking wax made the softening point of foam asphalt increased,the ductility and needle penetration decreased,and further reduced the viscosity of asphalt on the basis of foam asphalt,and the mixing and construction temperature range of its asphalt was further reduced.In PE cracking wax dosing of 5%,its temperature reduction range is 5.6～7.6 times of foam asphalt.Considering all the performance indexes,the best admixture of PE cracking wax is recommended to be 5%.(2)High temperature performance,low temperature performance,fatigue performance and adhesion performance of PE cracked wax modified foam asphalt are analyzed based on temperature scanning,differential scanning calorimetry(DSC),linear amplitude scanning(LAS),frequency scanning test and contact angle test.The results showed that the addition of PE cracking wax improved the high temperature performance and fatigue performance of foam asphalt,and had some effect on the low temperature performance and adhesion performance,but the effect was small.(3)The asphalt samples were subjected to short-term aging with three major indexes and multiple stress creep recovery tests to study the changes of the basic performance indexes and the effects of aging on the high temperature performance of asphalt,and microscopic analysis of asphalt by fluorescence microscopy and Fourier infrared spectroscopy tests.It was found that the softening point of PE cracked wax modified foam asphalt increased,needle penetration and ductility decreased,and high temperature performance improved after aging;PE cracked wax and asphalt were well compatible and uniformly dispersed in asphalt;PE cracked wax was physically modified in asphalt.(4)The AC-13 gradation was selected for asphalt mixture ratio design,and the optimum asphalt dosage and optimum mixing and compaction temperatures were determined.The high temperature performance,low temperature performance and water stability of the asphalt mixture were evaluated by rutting test,small beam bending test,water immersion Marshall test and freeze-thaw splitting test.The results show that the optimum oil to stone ratio of PE cracked wax modified foam asphalt mixture is 4.7% and the optimum compaction temperature is 127°C,which is 23°C lower than that of 70#matrix asphalt mixture and further 4°C lower than that of foam asphalt mixture.The high temperature performance was improved,and the low temperature performance and water stability performance had a certain negative impact,but still meet the construction specification requirements.