Research On The Warm Mixing Mechanism Of Oil-soluble Surface Active Warm Mixing Agent

In recent years,the transportation industry in China has developed rapidly.In order to speed up the construction of an environment-friendly society,reducing energy consumption and pollutant gas emissions has become one of the main issues of concern.Warm mix asphalt technology has been widely concerned because of its outstanding advantages such as emission reduction,good working conditions,energy saving and so on.In the existing warm mixing technology,the surfactant type warm mixing agent is widely used because of its convenient use and excellent properties,but the research on its warm mixing mechanism is relatively few.Therefore,in this paper,four kinds of oil-soluble surface active warm mixing agents were selected to prepare warm mix matrix asphalt and warm mix modified asphalt.The effects of oil-soluble surface active warm mixing agents on the physical properties,rheological properties and surface energy of matrix asphalt and SBS modified asphalt were studied systematically,and the warm mixing mechanism of oil-soluble surface active warm mixing agents was discussed.The effects of oil-soluble surface active warm mixing agent on the conventional properties of matrix asphalt and SBS modified asphalt were studied by means of three indexes and 60 ? dynamic viscosity.The results show that with the addition of warm mixing agent,the softening point,penetration and ductility of matrix asphalt and SBS modified asphalt increase,while the dynamic viscosity at 60 ? decreases greatly.The results show that the warm mixing agent of oil-soluble surface active agent reduces the high temperature performance of matrix asphalt and SBS modified asphalt,weakens the rutting resistance of pavement at high temperature in summer,and enhances the crack resistance at low temperature.The effect of oil-soluble surface active warm mixing agent on the viscosity-temperature relationship of matrix asphalt and SBS modified asphalt was studied by Brinell viscosity test.The results show that the addition of warm mixing agent reduces the Brinell viscosity of matrix asphalt and SBS modified asphalt,but the decrease is very small and can be ignored.The results show that the oil-soluble surface active warm mixing agent does not show obvious viscosity reduction,and the warm mixing effect is not achieved by reducing the viscosity of asphalt.The effect of oil-soluble surface active warm mixing agent on the rheological properties of SBS modified asphalt was studied by dynamic shear rheological test and bending beam rheological test.The results show that the addition of warm mixing agent has little effect on the frequency dependence of the master curve,storage modulus G 'and loss modulus G "of SBS modified asphalt,and does not significantly increase the rutting factor G*/sin ?,so that the cumulative strain increases,the creep stiffness S decreases,and the creep rate m increases.The results show that the oil-soluble surface active warm mixing agent has little effect on the viscoelasticity of SBS modified asphalt and weakens the performance of rutting resistance at high temperature.in engineering application,special attention should be paid to the occurrence of rutting in summer and high temperature weather,strengthening road maintenance,enhancing low temperature crack resistance and reducing the risk of cracks in asphalt pavement caused by sudden drop in air temperature in winter.The effect of oil-soluble surface active warm mixing agent on the surface energy of asphalt and the change of contact angle between asphalt and aggregate surface at different temperatures were investigated by means of surface energy theory.The results show that after the addition of warm mixing agent,the contact angle between asphalt and water increases,the surface energy increases,the polarity component of surface energy component decreases,and the dispersion component increases,and the contact angle of warm mix asphalt on the aggregate surface decreases with the increase of warm mixing agent content and temperature.The results show that the oil-soluble surface active warm mixing agent enhances the hydrophobicity of asphalt and the ability to wrap aggregate,increases the surface area of asphalt,and has better spreading performance on the surface of aggregate.it is concluded that the warm mixing mechanism of the warm mixing agent is realized by changing the interface between asphalt and aggregate.Based on the above studies,it is shown that the oil-soluble surface active warm mixing agent used in the test weakens the high temperature performance of asphalt and reduces its rutting resistance,and improves the low temperature performance of asphalt and weakens its brittleness;the warm mixing mechanism is not achieved by directly reducing the viscosity of asphalt,but by improving the spreadability of asphalt on the aggregate surface and changing the interface between asphalt and aggregate.