Microstructure and performance of energetically modified cement (EMC) with high filler content

Energetically modified cement (EMC) has been produced by high intensive grinding/activation of normal portland cement (NPC) together with 20% and 50% quartz sand. EMC concretes were compared to NPC based concrete using the k-factor concept. The k-factor for concrete with w/c = 0.60–0.45 was 0.7–0.9 for 1 d and 1.1–1.3 for 28 d compressive strength. k > 1 for both capillary suction, porosity, vapor diffusion and chloride permeability. For carbonation resistance k was ≈0.55.Microstructure of EMC paste with 50% quartz sand and w/c = 0.40 showed that the quartz was extensively ground and formed agglomerates with cement having a high inner surface. The degree of hydration of the cement in EMC was as high as 71% after 1 d compared to 45% for untreated blend. Refined pore size distribution of EMC versus the blend means that even for equal hydration at higher ages EMC will perform better.