Early age creep and stress relaxation of concrete containing blended cements

The main objective is to investigate key properties that influence the stress development in concrete at early ages and the effect of using blended cements. Mineral additives and amount by weight of total binder used in the blended cements axe fly ash (25%), ground granulated blast furnace slag (25%), and silica fume (10%). The properties investigated include tensile creep, elastic modulus, split tensile strength, and autogenous shrinkage. The relaxation modulus used for stress prediction was obtained from the creep data Fitted using a log-power creep function. These findings show that tensile creep and stress relaxation are important properties of Portland cement concrete. These properties however are reduced in concretes containing blended cements. Blended cements affect the early age strength and elastic modulus moderately but significantly alter the autogenous deformation. Water/cement ratio (w/c), type and dosage of mineral additives were found to influence the magnitude of autogenous deformation. This deformation was found to be significant in low water-cement ratio concretes and should be included in early age stress calculations.