Energetically modified cements (EMCs) are a class of cements made from pozzolans (e.g. fly ash, volcanic ash, pozzolana), silica sand, blast furnace slag, or Portland cement (or blends of these ingredients). The term "energetically modified" arises by virtue of the mechanochemistry process applied to the raw material, more accurately classified as "high energy ball milling" (HEBM). At its simplest this means a milling method that invokes high kinetics by subjecting "powders to the repeated action of hitting balls" as compared to (say) the low kinetics of rotating ball mills. This causes, amongst others, a thermodynamic transformation in the material to increase its chemical reactivity. For EMCs, the HEBM process used is a unique form of specialised vibratory milling discovered in Sweden and applied only to cementitious materials, here called "EMC Activation".
By improving the reactivity of pozzolans, their strength-development rate is increased. This allows for compliance with modern product-performance requirements ("technical standards") for concretes and mortars. In turn, this allows for the replacement of Portland cement in the concrete and mortar mixes. This has a number of benefits to their long-term qualities.
Energetically modified cements have a wide range of uses. For example, EMCs have been used in concretes for large infrastructure projects in the United States, meeting U.S. concrete standards.
Justification
The term "energetically modified cement" incorporates a simple thermodynamic descriptor to refer to a class of cements produced using a specialised highly intensive milling process first discovered in 1992 at Luleå University of Technology (LTU) in Sweden. The transformatory process is initiated entirely mechanically as opposed to heating the materials directly. The mechanisms of mechanochemical transformations are often complex and different from "traditional" thermal or photochemical mechanisms. HEBM can transform both the physical and thermodynamic properties that for example, "can lead to glass formation from elemental powder mixtures as well as by amorphization of intermetallic compound powders". The effects of HEBM-transformation cause a thermodynamic change that resides ultimately in a modified Gibbs Energy. The process increases the binding capacity and chemical reactivity rates of the materials transformed.
Continuing academic work and research regarding "self-healing" properties of energetically modified cements is ongoing at LTU. For example, EMCs has received awards from the Elsa ō Sven Thysells stiftelse för konstruktionsteknisk forskning (Elsa & Sven Thysell Foundation for Construction Engineering Research) of Sweden. The contribution of EMCs to the domain of mechanochemistry itself has also been recognised.
Etymology The term "energetically modified cement" was first used in 1992 by Vladimir Ronin, introduced in a paper by Ronin et al. dated 1993 and presented at a formal meeting of the academic Nordic Concrete Research group. The process was refined by Ronin and others, including Lennart Elfgren (now Professor Emeritus of LTU, Department of Civil, Environmental and Natural Resources Engineering). In 2023, LTU awarded Elfgren the "Vice-Chancellor's Medal for Merit for outstanding and meritorious work" by virtue of his work "...for the spread of new knowledge and understanding of, in particular, the concrete construction field".
At the 45th World Exhibition of Invention, Research and Innovation, held in 1996 in Brussels, Belgium, EMC Activation was awarded a gold medal with mention by EUREKA, the European inter-governmental (research and development) organisation, for "modification énergique de ciments".
The term "energetically modified" has been used elsewhere—for example as recently as 2017—although such usage does not denote the method used was EMC Activation as defined here.
Overview The claims made include:
An EMC is a fine powder (typical of all cements) whose colour depends on the material processed. EMCs are produced using only a "fraction" of the energy used in Portland cement production (claimed ~100 KWh/tonne, <8% of Portland cement). No is released by the process. It is "zero emissions". The purpose of an EMC is to replace the Portland cement requirement in the mortar or concrete being used. More than 70% replacement is claimed. EMC Activation is a dry process. No noxious fumes are released. EMC Activation is a low-temperature process, even though temperatures can be "momentarily extreme" at "sub-micron" scales. EMCs require no chemicals for their thermodynamic transformation. There are several types of EMCs, depending on the raw materials transformed. Depending on user-requirements, delivered dry products may comprise also a minority proportion of "high clinker" Portland cement. Each type of EMC has its own performance characteristics, including mechanical load and strength development. Concretes cast from EMCs may yield significant "self-healing" capabilities. The most frequently used EMCs are made from fly ash and natural pozzolans. These are relatively abundant materials, and the performance characteristics can exceed those of Portland cement. In 2009, fly ash EMCs were demonstrated to exceed the 'Grade 120 Slag' benchmark per ASTM C989 — the most reactive form of cementitious blast furnace slag. Silica sand and granite can also be treated by the process to replace Portland cement. As regards the former, 2025 testing of cores from a long-term structural installation showed a 27-year strength gain of 8% in a harsh sub-arctic climate (see section on "Early usage in Sweden", below). EMC products have been extensively tested by independent labs and certified for use by several US DOTs including in Federal Highway Administration projects. EMCs comply with respective technical standards, such as ASTM C618-19 (U.S.); EN-197, EN-206 and EN 450-1:2012 (CEN territories, including EEA); BS 8615‑1:2019 (U.K.). Compared to using Portland cement, the resulting concrete-mix using EMC does not require a higher "total cementitious content" to meet strength-development requirements. In testing by BASF, the 28-day strength-development for 55% replacement of Portland cement by a natural pozzolanic EMC was 14,000 psi / 96.5 MPa (i.e. > C95). This comprised a "total cementitious content" of 335 kg/m^3 (564 lbs/CY) concrete mix.
EMCs as "low carbon" cements Unlike Portland Cement, an EMC's production releases no carbon dioxide whatsoever. This makes EMCs "low carbon cements".
The first cited claims for EMC's CO2-reduction capabilities were made in 1999, when worldwide Portland cement production stood at 1.6 billion tonnes per year. From 2011 to 2019, worldwide Portland cement production increased from 3.6 to 4.1 billion tonnes per year. Energetically modified cement's potential for contributing to a worldwide reduction of CO2 has been externally recognised since 2002 and has been ongoing. Recent recognition has included the 2019 Energy Transitions Commission (Lord Adair Turner and Lord Stern) report Mission Possible sectoral focus: cement (2019). Recognition of the "Zero-Carbon" potential was set out by McKinsey & Co in its 2020 report Laying the foundation for zero-carbon cement. In 2023, the contribution offered by EMCs in achieving "low carbon" materials was further acknowledged within the academic domain of mechanochemistry.
Production and field-usage
No noxious emissions or toxic chemicals during production EMC Activation is purely a mechanical process. As such, it does not involve heating or burning or indeed any chemical treatments. This means no fumes at all are produced during an EMC's manufacture.
History EMCs have been produced for project usage since 1992 for a wide range of uses. By 2010, the volume of concrete poured containing EMCs was about 4,500,000 cu yd (3,440,496 m3), largely on US DOT projects. To place this into context, that is more than the entire construction of the Hoover Dam, its associated power plants and appurtenant works, where a total of 4,360,000 cu·yds (3,333,459 m3) of concrete was poured—equivalent to a U.S. standard highway from San Francisco to New York City.
Early usage in Sweden using EMC Activated silica sand (subarctic road bridge) An early project used a concrete comprising a 50% Portland cement substitution using a silica sand EMC (i.e. activated sand). This was deployed for the construction of a road bridge in Karungi, Sweden, in 1998, with Swedish construction firm Skanska. The Karungi road bridge has withstood Karungi's harsh subarctic climate and divergent annual and diurnal temperature ranges. Core testing in 2025 in partnership with Luleå University of Technology (LTU), Skanska and the Swedish Transport Administration demonstrated that the "mean compressive strength was 71.3 MPa, representing an 8 % increase compared with the 28-day strength. The concrete was in excellent condition, exhibiting only minor shrinkage cracks up to 0.3 mm wide", and that:"These results confirm the long-term durability of the EMC concrete and demonstrate that mechanically activated local quartz fines can reduce cement-related carbon emissions by approximately 50%, while still providing higher long-term strength after more than 25 years in a harsh sub-Arctic climate."
Usage in the United States In the United States, energetically modified cements have been approved for usage by a number of state transportation agencies, including PennDOT, TxDOT and Caltrans.
In the United States, highway bridges and hundreds of miles of highway paving have been constructed using concretes made from EMC derived from fly ash. These projects include sections of Interstate 10. In these projects, EMC replaced at least 50% of the Portland cement in the concrete poured. This is about 2.5 times more than the typical amount of fly ash in projects where energetic modification is not used. Independent test data showed 28-day strength-development requirements were exceeded in all projects. In 2009, fly ash EMCs were demonstrated to exceed the 'Grade 120 Slag' benchmark per ASTM C989.
Another project was the extension of the passenger terminals at the Port of Houston, Texas, where energetically modified cement's ability to yield concretes that exhibit high resistances to chloride– and sulphate–ion permeability (i.e., increased resistance to seawater) was a factor.
Developments in 2024 In February 2024 it was jointly announced that a manufacturing plant for EMCs made from volcanic materials will be jointly developed by "EMC Cement" and HES International at the Port of Amsterdam, and further, that the "all-electric zero-emissions plant, of an initial capacity of 1.2 million tonnes, will cut CO2 emissions by 1 million tonnes annually — using less than 10% of the energy of a conventional Portland cement plant".
Properties of concretes and mortars made from EMCs
Custom design for end-usage The performance of mortars and concretes made from EMCs can be custom-designed. For example, EMC concretes can range from general application (for strength and durability) through to the production of rapid and ultra-rapid hardening high-strength concretes (for example, over 70 MPa / 10,150 psi in 24 hours and over 200 MPa / 29,000 psi in 28 days). This allows energetically modified cements to yield High Performance Concretes.
Durability of EMC concretes and mortars Any cementitious material undergoing EMC Activation will likely marshal improved durability—including Portland cement treated with EMC Activation. As regards pozzolanic EMCs, concretes made from pozzolanic EMCs are more durable than concretes made from Portland cement.