Energetically Modified Cement (EMC) is produced by high intensive grinding/activation of Normal Portland Cement (NPC) together with different type and amount of filler. EMC consisting of NPC with 50 % quartz sand has been systematically investigated.
Concrete with such EMC was compared to NPC based concrete in accordance with with prEN 206 using the k-factor concept in order to evaluate the contribution of the quartz. k = 0 means no contribution from quartz, k = 1 means contribution equal to cement. Alternatively, k > 0 would mean more effect of "activated" cement than NPC. The k-value for concrete with w/c = 0.60 - 0.45 was 0.7 - 0.9 for 1 day compressive strength and 1.1 - 1.3 for 28 day compressive strength. k > 1 for both capillary suction of water, water accessible porosity water vapor diffusion and chloride permeability. For carbonation resistance k was in the range 0.5-0.6.
Microstructure of EMC paste with w/c = 0.40 was extensively investigated and compared with simple blends of the same constituents, in order to explain mechanisms. The quartz was extensively ground, but the overall particle size distribution was similar to NPC. However, the BET surface was increased more, which was explained by agglomerates of the smallest cement and quartz grains with high "inner" surface. DTA/TG indicated that the degree of hydration of the cement in EMC was as high as 71% after 1 day compared to 45% for the blend. However, the refiend pore size distribution of EMC versus the blend means even at equal hydration EMC will perform better.
The EMC concept with 50% filler replacing NPC is of particulat interest with respect to environmental issues since it enables a 40% cut in CO2 outlet.