Rheological Properties of Recycled Aggregate Concrete Incorporating Supplementary Cementitious Materials

The rheological properties of fresh concrete incorporating recycled aggregate and various supplementary cementitious materials (SCMs) were investigated as a function of recycled aggregate replacement percentage, SCM content, and time. The recycled aggregates were obtained from a local recycled aggregates plant in Abu Dhabi that extracts the aggregates from demolished buildings in Abu Dhabi. Two supplementary cementitious materials were used in binary and ternary blends—namely, ground-granulated blast-furnace slag and fly ash. The rheological testing was performed using a concrete rheometer. The test results indicate that the rheological properties (static yield stress, dynamic yield stress, and plastic viscosity) of concrete are significantly affected by changes in amount of recycled aggregate, mixing time, and SCM dosage. The relationship between yield stress and plastic viscosity is used to establish workability control charts for sustainable concrete proportioned with recycled aggregates. These charts are expected to serve as a rational means for assessing the workability of concrete with recycled aggregates using local materials in the United Arab Emirates. The results of this study are of practical significance in providing realistic recommendations for sustainable concrete with recycled aggregates.