Effects of aggregate gradations and binder contents on engineering properties of cement emulsified asphalt mixtures

Cement emulsified asphalt mixtures are widely used as construction and building materials in pavement engineering and high-speed railway engineering. Consequently, engineering properties of the mixtures have been paid more attention, which can be enormously affected by variations of aggregate gradations and binder (emulsified asphalt and cement) contents. Therefore, the objective of this study was to evaluate the effects of aggregate gradations and binder contents on engineering properties of the cement emulsified asphalt mixtures. Three aggregate gradations were designed to calculate fractal dimension values based on fractal geometry. Two binders (emulsified asphalt and cement) and six contents were utilized to prepare the mixture specimens. Engineering properties of the mixtures were tested in laboratory, such as high-temperature stability, cracking resistance properties, moisture susceptibility and adhesion characteristic. In addition, scanning electron microscopy (SEM) and optical microscope (OP) were adopted to conduct a microstructure analysis of cement emulsified asphalt mixtures. The results showed that a given aggregate gradation was proved to have a specific fractal dimension value. Gradation with great fractal dimension values represented high surface irregularity, but didn't always get good mechanical properties. The reasonable aggregate fractal feature and addition of cement both improved the high temperature stability of cement emulsified asphalt mixtures. Indirect tensile strength and moisture susceptibility were mostly affected by aggregate gradations and binder dosages. The Cantabro loss index was mainly dependent on aggregate gradation other than emulsified asphalt and cement contents. Reasonable aggregate gradation fractal and suitable binder contents jointly played an importance role in improving performance of cement emulsified asphalt mixtures.