Research On Rheological Properties Of Nano-TiO₂/CaCO₃ Modified Asphalt And Its Mixture

Nano-materials are applied to modified asphalt with its unique physical properties,while the current on nano-modified asphalt and its mixture of research focused on the conventional road performance test,such as asphalt penetration,ductility test of asphalt,and the high temperature rutting test the low temperature bending test of the mixture,and so on.However,the indexes obtained by these tests have great experience and can't be explained or predicted from the mechanics theory.Therefore,this paper relies on the Jilin Provincial Department of Communications Science and Technology Project “Frozen section of nano-composite materials to promote research”,selected the nano-TiO₂/CaCO₃ material to modify the asphalt based on the preliminary research.The paper does the experimental research and theoretical analysis on the rheological properties of the asphalt and its mixture.The main contents and conclusions of this paper are as follows:?1?The effect of nano-TiO₂/CaCO₃ on the viscosity and temperature of asphalt was studied by using asphalt rotation viscosity?RV?test.The results show that nano-TiO₂/CaCO₃ can improve the viscosity of asphalt,and increase with the increase of temperature.After adding nano-TiO₂/CaCO₃,the viscosity index?VTS?of asphalt decreases and the temperature of asphalt decreases.?2?The effects of nano-TiO₂/CaCO₃ on the shear modulus and phase angle of asphalt were investigated by dynamic shear rheometer?DSR?at different temperatures and frequencies.The results show that the temperature sensitivity of nano-TiO₂/CaCO₃ modified asphalt is lower than that of matrix asphalt.The incorporation of nano-TiO₂/CaCO₃ improves the high temperature anti-rutting performance and medium temperature fatigue resistance of asphalt.?3?The influence of nanometer TiO₂/CaCO₃ on the creep stiffness and its change rate m at low temperature was studied by bending beam rheometer?BBR?.The results show that the stiffness modulus of nanometer TiO₂/CaCO₃ modified asphalt is slightly higher than that of matrix asphalt,and the m value is slightly smaller than that of matrix asphalt.The low temperature cracking resistance of asphalt is decreased,but it still meets the requirements.?4?The effects of nano-TiO₂/CaCO₃ on the viscoelastic characteristics of asphalt mixture were studied by uniaxial compression creep test.The results show that the incorporation of nano-TiO₂/CaCO₃ reduces the steady-state creep rate of asphalt mixture,reduces the permanent deformation of the mixture and improves the anti-rutting ability of the mixture to high temperature.The modified Burgers model can reflect the consolidation effect of the mixture compared with the Burgers model.The results of the two methods show that the addition of nano-TiO₂/CaCO₃ increases the viscosity of the mixture and the high temperature resistance to deformation.?5?The effect of nano-TiO₂/CaCO₃ on the dynamic modulus of asphalt mixture at different temperatures and frequencies was studied by uniaxial compression dynamic modulus test.The results showed that nano-TiO₂/CaCO₃ could improve the dynamic modulus of asphalt mixture at high temperature or low frequency The dynamic modulus of the mixture at low or high frequencies is slightly reduced.The main curve of dynamic modulus is fitted by Sigmodial function and CAM equation.The results show that the incorporation of nano-TiO₂/CaCO₃ can improve the antirutting ability of asphalt mixture and improve the low temperature crack resistance of asphalt mixture.