Rheological Properties of Sulfoaluminate Cement–Asphalt Emulsion Paste

Abstract

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.