Rheological and mechanical behavior of concrete made with pre-saturated and dried recycled concrete aggregates

• Superplasticizer dosage decreases with pre-saturated recycled concrete aggregates.
• Rheological parameters increase with the replacement level of recycled aggregates.
• Pre-saturated recycled aggregates improve rheological parameter.
• Pre-saturated recycled aggregates decrease slightly compressive strength.

This investigation aims to determine the influence of pre-saturation and dried recycled concrete aggregates (RCA) on mechanical and rheological properties of concrete. Coarse ordinary aggregates (COA) were partially substituted with RCA and an amount of superplasticizer was added to keep the same workability. The results found show that concrete with dried RCA aggregates requires a great dosage of superplasticizer and achieves high compressive strength and rheological parameters. However, for concrete with pre-saturated RCA aggregates, the needed dosage of superplasticizer is reduced and the compressive strengths and the rheological parameters are decreased. The use of pre-saturated RCA aggregates is better to keep adequate superplasticizer dosage and relevant rheological parameters. Mathematical relationships are proposed to express the variation of the compressive strengths and the rheological parameters according to the concrete composition with fair correlation coefficients.