The Optimum Pre-mixing Water Content in Asphalt Emulsion Mixture with Cement

Abstract

The pre-mixing of water is recommended to be added into asphalt emulsion mixture (AEM). However, there is no widely applied method to determine the optimum pre-mixing water (OPW) value during the mixture design. In this study, the OPW values of AEM with cement are determined based on the visual observation of loose mixture, maximum density, and indirect tensile strength (ITS) of compacted mixtures. The effect of different OPW contents on the air voids, ITS, and moisture susceptibility of the mixture is investigated. Furthermore, the cement-asphalt mastic and the mixture with different OPW contents are analyzed by X-ray diffraction analyzer and environmental scanning electron microscope. The results indicate that the different methods lead to more diverse OPW values than the change of cement content or emulsion content does. The visual observation method obviously underestimates or overestimates OPW values compared with other two methods. The higher OPW content from the visual observation is beneficial to reduce the negative effect of asphalt film on hydration reaction, which improves the hydration reaction of cement. However, this OPW value leads to many small pores in the interface zone of the aggregate-mastic, which brings a negative effect on the ITS and moisture resistance of the mixtures. It is suggested that the maximum ITS method should be used to determine the OPW value.