Factors Influencing the Rheology of Fresh Cement Asphalt Emulsion Paste

Cement asphalt emulsion paste (CA paste) is known to be a low-yield stress suspension suitable for many applications in which high flowability is desired. The factors that lead to the low yield stress of CA paste are still unknown, however. The effect of the components in CA paste on the rheology of fresh CA paste is studied to reveal the primary factors that lead to the low yield stress. The effect of emulsifier and superplasticizer on cement paste, the effect of asphalt emulsion, and viscosity modifying agents on CA paste are studied. Results indicate that emulsifier can reduce the yield stress and apparent viscosity of cement paste, but the effect of emulsifier is small compared to the effect of the superplasticizer. The low yield stress of CA pastes is primarily because of the combined effect of superplasticizer and asphalt emulsion. Both CA paste without superplasticizer and cement paste have high yield stress. Viscosity modifying agents can significantly increase yield stress of CA paste without changing minimum apparent viscosity, which is an efficient way to change the rheological behavior of CA paste with low yield stress. (C) 2016 American Society of Civil Engineers.