Study On Rheological And Anti-aging Properties Of Crumb Rubber Modified Warm Mix Asphalt Materials

With the rapid development of road transportation,the number of automobiles has increased significantly,and more and more waste tires are produced every year,which has become an urgent environmental pollution problem.Waste tires contain many ingredients that are beneficial to improve the performance of asphalt.In this paper,the use of waste crumb rubber（CR）to improve the performance of asphalt has great economic value and social significance in improving the performance of asphalt pavement,saving social resources and protecting the environment.But these crumb rubber modified asphalt（CRMA）has high viscosity,it is difficult to mix during the preparation of various mixtures.In order to reduce its viscosity,improve the construction and workability of asphalt,a wide range of organic viscosity-reducing warm mix agent Sasobit and domestic organic siloxane modified surfactant XP32157 are used to perform warm mix treatment on various CRMA,and to observe the influence on the rheological and anti-aging properties of asphalt,combined with nanotechnology,use nano titanium dioxide and organic nano montmorillonite to study the rheological and anti-aging sensitivity of crumb rubber modified warm mix asphalt（CRWMA）.The main research content of this paper is shown in the following aspects:First,Penetration,Softening Point,Ductility,Rotational Viscosity（RV）,Dynamic Shear Rheometer（DSR）,Bending Beam Rheometer（BBR）,and Multiple Stress Creep Recovery（MSCR）of different types of modified asphalt were tested to analyze the effects of different modifiers on the rheological properties of asphalt.The results showed:CR can significantly improve the rheological properties of asphalt at high temperature and low temperature.The content of CR is the main influencing factor,while the mesh number has little effect on the rheological evaluation indexes of CRMA.Comprehensive evaluation shows that CRMA60-22%has the best rheological properties.The content of warm mix agent Sasobit increased from 1.5%to 3.5%,and the content of surfactant XP increased from 0.1%to 0.3%,the viscosity of the CRMA decreases more,thereby lowering the mix and co MPaction temperature.And Sasobit has a greater influence on the performance indexes of CRMA60-22%than XP.Sasobit improves the workability of CRMA60-22%,while improving its high temperature stability and reducing low temperature plasticity.The best content of improvement effect is 2.5%.XP has no obvious effect on the high temperature anti-deformation ability of CRMA60-22%,but it can improve the low temperature anti-cracking performance to a certain extent.Secondly,Two different aging methods,Rotating Thin Film Oven Test（RTFOT）and pressure aging vessel（PAV）are used to test the anti-aging performance of modified asphalt.The results showed:after aging of RTFOT,the softening point difference of the three different meshes of CR is the smallest at 22%.In the range of 14%-26%content,after aging of PAV,it is found that the viscosity aging index decreases with the increase of the content,and the mesh size has little effect on viscosity aging index.Combining different aging indexes and rheological properties,the optimal mesh number and content is 60 mesh 22%.The warm mix agent Sasobit has a negative i MPact on the long-term anti-aging performance of CRMA,but its temperature sensitivity is improved,while XP will increase its temperature sensitivity,but it has no obvious effect on its anti-aging performance.Then,in order to study the effect of nano materials on the rheological and anti-aging properties of CRWMA,nano titanium dioxide（nano T_iO₂）and organic nano montmorillonite（OMMT）were selected.The test results show that 0.9%nano T_iO₂has limited improvement in the high temperature performance of CRWMA,but it can improve the low temperature anti-cracking performance,while OMMT increases the viscosity of CRMA60-22%-2.5% Sasobit by 42.40%.It has a strong viscosity-increasing effect,but it has a large negative effect on the high temperature anti-rutting ability,and also shows a negative effect on the low temperature anti-cracking performance.In a low temperature environment,nano T_iO₂will reduce the long-term aging resistance of CRWMA60-22%-2.5%,while OMMT has the effect of improving its long-term aging resistance.Finally,it reveals the influence mechanism of different modifiers on the aging process of modified asphalt from a microscopic point of view.The interaction between CR and asphalt is mainly a kind of physical mix,and CRWMA added with OMMT has better anti-aging deformation;the two warm mix agents improve the thermal stability of CRMA to a certain extent,and the effect of Sasobit on the thermal stability of CRMA is better than XP.