Study On Rheology Of Chemical Activated Crumb Rubber Modified Rubber Asphalt

With the rapid development of the automobile industry,there have been a large number of used tires.The large amount of waste and accumulation of used tires has caused serious environmental pollution and waste of resources.We can process the tires into crumb crumb rubber and prepare crumb rubber modified binder(CRMB).The CRMB has good performance of high temperature,aging resistance and durability,and exhibits good road performance.However,the poor compatibility of crumb rubber and binder limits the partial performance of CRMB.Because of its excessive viscosity and high mixing temperature of the mixture,which increases the construction difficulty,accelerates the thermal oxygen aging of the asphalt,causes excessive consumption of energy.To solve the above problems,the crumb rubber was activated by three different ratios of hydrogen peroxide solution and sodium hypochlorite solution,and chemically activated rubber asphalt was prepared.The physicochemical properties of activated crumb rubber and the high temperature rheological properties and microscopic mechanism of activated rubber asphalt were studied.The physicochemical properties and microstructure of the activated crumb rubber were investigated by scanning electron microscopy,physical adsorption and X-ray energy spectrum tests.The results showed that the pore structure of the crumb rubber changed significantly after H2O2 and Na Cl O activation.The macropores in the activated crumb rubber contributed the most to the cumulative pore volume,and the mesopores contributed the most to the cumulative pore area.After the crumb rubber is activated by the H2O2 solution,agglomeration occurs between the particles,and the contact surface with the asphalt increases.After activation by the Na Cl O solution,the surface of the crumb rubber is oxidized and eroded by the Na Cl O solution.The content of O element in the activated crumb rubber is significantly increased compared to the unactivated crumb rubber.The pore structure,microscopic morphology and oxygen content of the crumb rubber have an effect on the road performance of the rubber asphalt,showing a certain correlation.The viscoelasticity and road performance of rubber asphalt before and after activation of crumb rubber were compared by Brookfield viscosity and dynamic shear rheological test.The microscopic molecular structure of rubber asphalt before and after activation of crumb rubber was analyzed by gel permeation chromatography and infrared spectroscopy.The results show that the viscosity and high temperature performance of H2O2 activated rubber asphalt decrease with the increase of solution ratio.The viscosity of Na Cl O activated rubber asphalt decreases with the increase of the proportion of solution;when the ratio of Na Cl O solution is the largest,the elasticity is the highest,and the high temperature resistance to rutting is the best.The infrared spectrum shows that the rubber asphalt contains a light component such as an aromatic component,and contains an aliphatic amine group and an aliphatic hydrocarbon-based organic functional group.Both H2O2 and Na Cl O solutions reduce the LMS content in the asphalt,and the H2O2 solution has a more significant effect on the reduction of LMS content.The properties of the activated rubber asphalt after aging were studied by Brookfield viscosity and dynamic shear rheology test.The results show that the viscosity of Na Cl O activated rubber asphalt decreases after short-term aging,while the viscosity of activated rubber asphalt of H2O2 solution increases to different degrees.W0,H1 and H3 are elastically enhanced after short-term aging.N1 and N3 have weaker elasticity and increased viscosity after short-term aging,while H2 and N2 are elastically enhanced under low temperature conditions after short-term aging.After short-term aging,the rutting factor of W0 and Na Cl O activated rubber asphalt has been reduced,but the rutting factor of N3 is still the largest;while the rutting factor of H2O2 activated rubber asphalt has increased.Infrared spectroscopy results show that the original,short-term and long-term aging samples of the seven rubber asphalt samples all show the presence of S=O functional groups.The change of C=O functional groups indicates that the long-term aging has more significant oxidation of rubber asphalt.The results of gel permeation chromatography showed that with the gradual deepening of aging,the LMS content of unactivated rubber asphalt and H2O2 activated rubber asphalt increased gradually.The LMS content of the Na Cl O activated rubber asphalt with the aging effect gradually deepens,first decreased and then increased.