Multiple techniques of microstructural characterization of DEF: Case of study with high early strength Portland cement composites

[Display omitted] •EBSD - showed a natural sand with a few strained quartz grains and other minerals.•Sigmoidal characteristics of DEF were more expressive for degradation Modulus of elasticity in induced DEF was distinctive for mechanic evolution.•The mass gain in the DEF with sigmoidal characteristic had behavior like the expansion evolution.•Mortar specimens seem to be not significant to certify the presence and effects of DEF in a short time. Multiple physicochemical and microstructural techniques were successfully conducted to characterize materials and cement composites induced to delayed ettringite formation (DEF). Backscattered electron diffraction, with elemental analysis by energy dispersive spectroscopy in a scanning electron microscope, showed a natural sand with strained quartz and other minor minerals. DEF was observed in distinctive behaviors for mortars and concretes regarding expansion, being quasi-linear and sigmoidal, respectively. Concrete specimens registered high expansions at 450 days (about 0.40%). The resulting effects between composites were distinctive for microstructural and mechanic evolution, especially the modulus of elasticity, with a decrease of 51%, on average.