Sammendrag
Energetically Modified Cement (EMC) consists of mechanochemical processed blend of ordinary Portland Cement (OPC) and filler or pozzolan by multiple high intensity grinding mills to increase surface activation of the OPC and filler/pozzolan particles. Performance of EMC with 50% quartz or fly ash is compared with simple blends of the same components. Examples are also shown where fly ash of low reactivity can be activated as pozzolan by the same process and used as additive to concrete. Performance of EMC with 50% quartz or 50%-70% fly ash is compared to OPC and simple blends of OPC and quartz or fly ash as binder in mortar and concrete in terms of setting time, strength development, drying shrinkage, sulphate resistance and alkali-silica reactivity. Strength of EMC with 50% quartz or fly ash is comparable to OPC, setting time is similar, and alkali-silica reactivity and drying shrinkage are lowered for the fly ash version.Microstructure investigations showed that improved performance of EMC versus OPC/quartz or fly ash blends can be explained by increased early hydration and better distribution of hydration products resulting in an extensive pore size refinement of the hardened binder. The pozzolanic activity of quartz or fly ash determined after 950 days of curing will also contribute positively to the long-term strength development and durability of EMC concrete. Environmental benefits are activation/use of fly ash that was not suitable for addition to concrete, reduced CO2 emission to the atmosphere by using much less cement clinker, and reduced energy consumption in the concrete binder production.