Rheological models for fresh cement asphalt paste

• The most suitable rheological model is Herschel–Bulkley.
• The mechanism of the rheological behavior was discussed.
• It is a shear dependent microstructure.
• The rheological parameters are related with the microstructure and Zeta potential.

The workability of cement asphalt (CA) mortar plays a key role in the construction quality and durability of the parking layers in the slab track structure of high speed railways of China. Whereas, the workability of CA mortar is mainly controlled by the rheology of CA paste. In the present paper, the rheological curves of CA paste were measured at 25 °C using a rotating coaxial cylinder viscometer. The Bingham, modified Bingham, Herschel–Bulkley and Casson rheological models were used to fit the data of shear stress–shear rate. The mechanism of the rheological behavior of CA paste was analyzed. The results show that the Hereshel–Bulkley model, which is usually applied for cement pastes, is also the most suitable model for CA paste. The yield stress, consistency index and non-Newton index of CA paste are influenced by the Zeta potential of particles and strengthen of flocculated structure.