Preparation Of Asphalt Warm Mixing Agent By Modified Fly Ash Catalyzed Waste PE Cracking And Its Warm Mixing Performance

Warm mix asphalt is widely used in road construction because of its lower energy consumption and pollution gas emission,but the cost of common warm mix agent is higher.The waste generated after the use of plastic products increases the pollution of the environment,incineration is a common waste plastic treatment,although in the process of generating a lot of heat energy,but also generated toxic and harmful gases and solid residual substances,how to reduce the environmental problems caused by solid waste at the same time the waste plastic resource utilization for the acquisition of warm mixing agent provides a new idea.In this paper,the residual material after waste incineration fly ash was modified with sulfuric acid as a catalyst,and the polyethylene wax（PEW）was obtained by catalytic cracking of waste linear low density polyethylene（LLDPE）in a pressure reactor.The asphalt was modified with PEW,hoping to reduce the viscosity of asphalt and reduce the construction temperature of asphalt mixture.The following research work has been carried out:（1）The original Fly Ash was washed,washed,dried,calcined and treated with sulfuric acid to prepare two catalysts（FA1 and FA2）.The main components,microscopic morphology and element content of the catalysts were analyzed by X-ray diffraction（XRD）and scanning electron microscope energy dispersive spectrometer（SEM-EDS）.The results show that the main composition of the new substance produced by FA1 is CaCO₃,which is irregularly granular.The main component of the new substance produced by FA2 is CaSO₄,which is in sheet form.Compared with FA,the carbon content of FA1 and FA2 decreased,the oxygen content increased,the calcium content increased significantly,and the content of other metal elements decreased.Pyrolysis wax was prepared by catalytic pyrolysis of waste LLDPE with modified fly ash in a high-pressure reactor.Under the same reaction time of 45min,the pyrolysis temperature was changed,and the optimal pyrolysis temperature range of solid wax was determined to be 250℃～270℃.Within the optimal temperature range,7kinds of PEW were obtained by changing the reaction temperature,time and catalyst type.（2）PEW modified asphalt was prepared by blending PEW with 70#matrix asphalt at the initial dosage of 6%.The influence of PEW on the properties of asphalt matrix was investigated by three indexes,Brinell viscosity,temperature scanning,adhesion test and differential scanning calorimetry test.The test results show that PEW-6 obtained by cracking LLDPE with FA2 at a cracking temperature of 270℃and a cracking time of45min has a good viscosity reduction effect.Compared with matrix asphalt,PEW-6modified asphalt has improved stability and adhesion at high temperature,but its low temperature performance is worse than that of matrix asphalt.（3）Three indexes,Brinell viscosity,temperature scanning and multiple stress creep recovery tests were carried out on PEW-6 warm-mixed asphalt with different dosage to analyze the influence of different dosage of PEW-6 on the properties of matrix asphalt.The test results show that when the content of PEW-6 is 6%,the warm mix asphalt has the best high temperature performance and small viscosity.The results of fluorescence microscopy and Fourier infrared spectroscopy（FTIR）tests on the modified asphalt containing 6%PEW-6 show that the modification of PEW-6 on the matrix asphalt is physical modification without chemical reaction,and the dispersion is uniform in the asphalt.（4）AC-13 mixture grading was used to carry out the mix ratio design,and the optimal asphalt dosage of asphalt mixture was determined according to the volume parameters under each oil stone ratio.According to the principle of equal voidage,the cooling amplitude of the compacting temperature of matrix asphalt mixture specimen with a content of 6%PEW-6 was analyzed.The compaction temperature of PEW-6asphalt mixture decreased by 23℃compared with that of matrix asphalt mixture when the same void ratio was reached.The indoor test of asphalt mixture found that the high temperature rutting resistance of asphalt mixture was improved,but the water stability and low temperature performance were decreased after the addition of 6%homemade warm mixing agent PEW-6.