A report published by the Japanese Concrete Institute has highlighted techniques that can make concrete more sustainable, in particular through the addition of ‘supplementary cementing materials’ (SCMs). This approach replaces cement in concrete with combinations of SCMs leading to reactions which enhance strength, produce leaner concrete with less cement per m3.
One of the pioneers of this approach is the Swedish company EMC which has developed ‘Energetically Modified Cement’ (EMC) technology.
Their approach consists of processing a blend of ordinary Portland Cement and a pozzolan through multiple high intensity grinding mills to impart increased surface activation of the OPC and pozzolan particles.
Fly ash of low reactivity was selected as pozzolan to mix with cement forming ready cement, or alternatively ground with a small amount of cement (»5%) and used as a pozzolan added to the concrete mixer.
EMC says the approach offers considerable environmental benefits and a reduction of CO2 emission to the atmosphere (40 % using 50% fly ash) and 3) reduce the energy consumption in the binder production.
The performance of EMC with 50% fly ash is comparable to ordinary Portland Cement. The setting time is similar, and alkali-silica reactivity is lowered as well as drying shrinkage. Activated fly ash used as pozzolan can replace up to 70% of cement in concrete.
The EMC technology which was developed 25 years ago has matured and gained widespread acceptance. It was recognised as a world class invention (and Gold Medal) by the European EUREKA research organisation.
EMC now has a portfolio of references of full scale industrial projects (parking lot and highway pavements) in Texas (see photo), USA, with concrete based on EMC (CemPozz).