The effect of the replacement of natural sand by CGA on the rheological and mechanical properties of concrete was investigated in this study. Based on the results, the following conclusions were drawn:
& Tests on cement-based pastes indicated that the replacement of cement by RHA resulted in an increase in the rheological parameters, while maintaining the same 28-day compressive strength of the reference paste.
& In general, the concrete rheology was expressively affected with the use of CGA. The mixture containing CGA required more superplasticizer to maintain the same workability of the reference concrete. The increase of CGA replacement resulted in an increase in the superplasticizer dosage.
& From the BTRHEOM rheometer results, the Herschel-Bulkley model was adequately used to express the behavior of the high-workability concretes with CGA.
& The rheological characterization showed that the effect of high superplasticizer dosages in CGA concretes inhibited the negative influence of the CGA on the plastic viscosity.
& The compressive strength was not negatively affected by the natural sand replacement up to 50% of CGA, after the specific dosages of superplasticizer. No significant change was observed with respect of Young’s modulus results, and the water absorption was reduced when 30 and 50% of the natural sand were replaced by CGA.