Effect of Cement and Bitumen Emulsion on the Drying and Film Formation of Bitumen Emulsion Paste

To obtain a bitumen emulsion paste with a good bitumen film structure and rapid drying rate, the effect of cement content, cement type, and emulsion type on the drying and film formation of bitumen emulsion paste was studied. The drying and film formation mechanism of emulsion was employed to study the drying curve of bitumen emulsion paste. Results indicate that the drying and film formation process of bitumen emulsion paste can be divided into three stages. The solid volume fraction of the beginning of the final stage (phi(2)) and the maximum particle volume fraction (phi(m)) are proposed to evaluate the drying and film formation quality of bitumen emulsion paste. Higher values of phi(2) and phi(m) indicate a denser particle packing state and lower residual water content of the final stage, which are beneficial to the drying and film formation quality of bitumen emulsion paste. The phi(2) and phi(m) of bitumen emulsion paste differ slightly with the increasing content of ordinary portland cement. However, these quantitative indexes vary significantly with changing bitumen emulsions with different values of phi(2) and phi(m). Compared with ordinary portland cement, sulfoaluminate cement can lead to a noticeable decrease in phi(2) and phi(m); thus, its addition is harmful to the film structure of bitumen emulsion paste. Overall, to obtain a bitumen emulsion paste with a good bitumen film structure and rapid drying rate, a bitumen emulsion with good drying and film formation quality is recommended.