Rheological Properties of Sulfoaluminate Cement–Asphalt Emulsion Paste

Sulfoaluminate cement (SAC)-asphalt emulsion (AE) mortar is a promising repair mortar for cement and asphalt emulsion (CA) mortar (CAM) used in high-speed railways. This paper deals with the rheological performance of SAC-AE pastes. The effects of AE charge type (cationic and anionic emulsions) and AE/SAC mass ratios (A/C) on rheological performance are investigated. Results show that the rheological performance of SAC-AE pastes are affected both by interactions between SAC particles and AE particles and by the cement volume fraction. Compared with SAC-anionic asphalt emulsion (AAE) pastes, SAC-cationic asphalt emulsion (CAE) pastes have a higher shear stress with A/C ratios of 0.1-0.7, but slightly lower shear stress with A/C ratios of 1.3-1.6. SAC-AAE with an A/C ratio of 0.3 demonstrates premium rheological performance. Both the Herschel-Bulkley model and the Bingham model fit well with the rheological curves for pastes with A/C ratios of 0-0.7. The non-Newtonian fluidity indicator also confirms this. However, the Bingham model is not fit for SAC-AE paste with A/C ratios of 1.0-1.7. With similar water content, SAC-AE paste with high A/C ratios demonstrates less shear stress than that with low A/C ratios. The rheological performances of portland cement-AE pastes (A/C 0-0.7) are also briefly studied for comparison.