Study On The Preparation Of Super Activated Rubber Powder And Its Modified Asphalt Properties Based On Single Screw Continuous Extrusion

Mixing waste tire rubber powder into asphalt can improve the performance of asphalt to a certain extent,but due to its own three-dimensional mesh structure,resulting in poor compatibility of waste tire rubber powder with asphalt,and its low amount of admixture in asphalt.In view of the defects of waste tire rubber powder,this paper conducted a study on rubber powder activation to improve the compatibility of rubber powder with asphalt and the amount of rubber powder mixed in asphalt to reduce production costs.This work was based on the industrial single screw continuous extrusion production line developed by this research group.Firstly,the optimized design of split barrel of single screw extruder was carried out.Secondly,the super activated rubber powder was prepared by industrial single screw continuous extrusion line.The performance of the super-activated rubber powder was investigated by cross-link density test,Mooney viscosity test,mechanical property test,Fourier infrared spectroscopy test and SEM scanning electron microscopy test.On this basis,the performance of super-activated gum powder modified asphalt was investigated by needle penetration,softening point,ductility and segregation tests.The study was conducted as follows:(1)The barrel structure of single screw extruder was optimized and improved to design a split barrel single screw extruder.The barrel was separated from the screw by a sliding screw structure to solve the problem of barrel clogging due to the high viscosity of the rubber material.(2)Based on the industrial single screw continuous extrusion line developed by our group,the super activated adhesive powder was prepared according to different process formulations.The properties of the super activated rubber powder was investigated by crosslink density test,Mooney viscosity test,mechanical property test,Fourier infrared spectroscopy test and SEM test.The results showed that the decrosslinking of the powder was promoted when the aromatic oil content was low.After the aromatic oil content reached 8 phr,the crosslinking density of the powder remained the same.The more the number of aromatic oils,the lower the Menny viscosity of the super-activated rubber powder,and the mechanical properties showed a trend of first increase and then decrease.At the same number of parts,the aromatic oil improved the performance of super-activated powder better than paraffin oil.The analysis of Fourier infrared spectra and SEM images showed that the C=C bond of super-activated gum powder increased,indicating that the super-activated gum powder recovered part of the linear structure,and the effect of decross-linking was obvious,and the activation effect was better.(3)The super activated rubber powder modified asphalt was studied by needle penetration test,softening point test,elongation test and segregation test.The results showed that the performance indexes of the super-activated mastic powder modified asphalt showed different trends with the increase of mastic powder admixture,the needle penetration and ductility decreased and then increased,the softening point and softening point difference increased and then decreased.The higher the degree of activation of super-activated binder powder,the greater the ductility,softening point and needle penetration of super-activated binder powder modified asphalt prepared by the same binder powder admixture.It showed that the mastic powder modified asphalt prepared by the super activated mastic powder with high activation degree had better high and low temperature performance,but poor storage stability.It showed that the rubber powder was moderately activated to better improve the performance of rubber powder modified asphalt.(4)It was found that the degree of activation of the super activated rubber powder prepared with 0phr aromatic oil was moderate.When its mixture of asphalt reaches47%,the prepared mastic powder modified asphalt has good high and low temperature performance and storage stability.The measured indexes were all in accordance with the specification standards,indicating that the amount of hyperactivated mastic powder in asphalt can reach 47%.(5)It was found by SEM images that the super-activated mastic powder was more compatible with the asphalt and the particle size of the mastic powder was smaller and more uniformly dispersed in the asphalt compared to the waste tire mastic powder.The absorption peaks of S=O bonds present in the matrix asphalt were found to disappear in the super-activated mastic powder modified asphalt by Fourier infrared spectroscopy.The C=C bond absorption peaks in the super-activated mastic powder modified asphalt increased,indicating that the physical swelling and chemical reaction co-exist in the modification process of mastic powder and asphalt.