The role and interaction of superplasticizer and emulsifier in fresh cement asphalt emulsion paste through rheology study

The workability and mechanical properties of cement asphalt emulsion (CA) mortar are unstable due to the complex interaction between cement and asphalt emulsion. To reveal the interaction between cement and asphalt emulsion, the effect of emulsifier and superplasticizer on the rheology of cement paste and asphalt emulsion is investigated, respectively, and the effect of the interaction between emulsifier and superplasticizer on the rheology of cement paste is studied in this paper as well. Results show that the apparent viscosity and yield stress of asphalt emulsion increase with superplasticizer and emulsifier dosage. Emulsifier can change the yield stress and apparent viscosity of cement paste, and its effect on cement paste differs greatly with the type and dosage of emulsifier. Some emulsifiers can increase the yield stress of cement paste, but some emulsifiers can decrease the yield stress of cement paste. Emulsifier has interaction with superplasticizer, thus affecting the reducing water effect of superplasticizer on cement paste. There is a competition relationship between emulsifier and superplasticizer when they are adsorbed by cement particles. The mixing method, in which superplasticizer is mixed with cement before emulsifier added, is beneficial to obtain a lower apparent viscosity of cement paste for all tested emulsifiers.