Rheological Performance Study On Cement Emulsified Asphalt Composite Binder

Cement emulsified asphalt composite binder(CEACB),composed of cement,emulsified asphalt,and a certain amount of additives in accordance with a certain proportion of mixing,is a kind of organic-inorganic composite after a period of curing set hardening.CEACB is the binder of cement emulsified asphalt mortar(CEAM)and cement emulsified asphalt concrete(CEAC),which are widely used as cushion layer in ballastless track of high-speed railway,semi-rigid base of road,and cold regenerated pavement.The performance of CEAM and CEAC are very important.CEACB is a typical viscoelastic material,its viscoelastic energy is affected by many factors.studying the viscoelastic properties of CEACB and the influence of various factors on its viscoelastic performance based on the rheological theory can provide a reference for the design of high-performance cement emulsified asphalt composite.In view of the above background,the research contents of this paper are as follows:Firstly,DSR is used to obtain the rut factor and high temperature critical temperature of CEACB,as well as the fatigue factor and medium temperature critical temperature.BBR was used to obtain the creep stiffness S value and creep rate m value of CEACB as well as the continuous grading temperature at low temperature.Through the analysis of these indicators,it can be concluded that the increase in temperature will lead to the deterioration of CEACB's anti-rut performance at high temperature,the anti-fatigue performance at medium temperature,and the anti-cracking performance at low temperature.Curing can improve CEACB's resistance to rutting at high temperature and reduce its resistance to cracking at low temperature.CEACB first increases and then weakens with the curing period,and the medium-temperature antifatigue performance is the best at 14 days of curing.With the increase of cement content,CEACB has stronger resistance to rutting at high temperature,worse resistance to fatigue at medium temperature,and worse resistance to cracking at low temperature.Secondly,through creep experiment and frequency scanning experiment,the creep flexibility of CEACB and the amount of energy storage modulus with asphalt and cement were compared to the variation of asphalt and cement.By analysis,the static and dynamic mechanical properties of CEACB are consistent,and the elastic performance of CEACB decreases with the increase of temperature,and the dynamic mechanical analysis can be obtained by the temperature sensitivity of CEACB in the high temperature area is well below the temperature sensitivity of the medium temperature.The elastic performance of CEACB is enhanced with maintenance,and dynamic mechanical analysis can be found in high frequency/low temperature area,CEACB,and the anti-crack performance of CEACB is significantly weaker with the maintenance.The elastic performance of CEACB increases with the increase of cement content,especially in low frequency/high temperature area,which indicates that CEACB high temperature resistance to the furling performance increases significantly with the increase in cement content.The mechanical behavior of CEACB is closer to viscoelastic solid material when A/C= 0.6 and A/C= 1.In the A/C= 1.4,the mechanical behavior of CEACB is closer to viscoelastic fluid material.Thirdly,the high temperature rheological properties of CEACB were further studied through MSCR experiment.According to the frequency scanning experimental data,the CEACB dynamic shear modulus and the main curve of phase Angle established by the 2S2P1 D model can well represent the rheological properties of CEACB in the broadband domain.Through analysis,it can be concluded that the dynamic shear modulus of CEACB decreases gradually with the increase of temperature,and the deformation resistance of CEACB decreases.The phase Angle of CEACB increases gradually with the increase of temperature,and the viscosity property is enhanced.Curing improves CEACB's anti-deformation ability as a whole,and the anti-rutting performance at high temperature is enhanced while the anti-cracking performance at low temperature is weakened.The fatigue resistance at medium temperature first increased and then weakened with the curing,and was optimal on the 14 th day.Increasing cement content can improve the overall deformation resistance of CEACB,and enhance the rutting resistance at high temperature and crack resistance at low temperature.In the intermediate frequency region,the CEACB phase Angle of A/C=1 is the largest,and the fatigue resistance at medium temperature is the strongest.Therefore,CEACB with A curing period of 14 days and A/C=1 has good high-temperature and low-temperature performance,and the medium-temperature performance is the strongest.The conclusion can provide reference for the design and optimization of cement emulsified asphalt composites.