During the past decadc;blended cements have attracted strong interest worldwide due to their advantages of low energy cost, high strength and good durability.A major incentive for further development of such cements is generated by a great quantity of annual generation of wastes, which cause a need to find new uses for them.Nowadays the cements with pozzolanic and hydraulic additions are an important option to decrease the environmental impact of the cement production, since besides substituting partially the cement;they allow the consumption of industrial wastes that are potentially environmental pollutants.In line with this, the aim of this research was the study of composite concretes with up to 50% of supplementary cementitious materials (SCM) as fly ash (FA), metakaolin (MK), ground granulated blast furnace slag (GGBFS) and silica fume (SF) and ordinary Portland cement;a superabsorbent polymer was used to help to improve the internal curing, with a w/b of 0.35.The samples were cured up to 90 days.After the compressive strength tests the composite concretes were analyzed by means of XRD and SEM.The results indicated that the compressive strength was improved with the incorporation of the replacement materials, mainly due to their pozzolanic and hydraulic behavior;accelerating the hydration reactions and helping in the CSH gel generation.The fine and uniform particle size distribution of the SF provided a higher specific surface increasing the reaction rate and the formation of new hydration products through the calcium hydroxide consumption.The depletion of the CH was corroborated by means of XRD analyses.Furthermere, the SCM diminished the porosity, observing more compact structures (using SEM) compared to the concretes with neat cement.