Energetically modified cement

[1] 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).

[18] The process was refined by Ronin and others, including Lennart Elfgren (now Professor Emeritus of LTU, Department of Civil, Environmental and Natural Resources Engineering).

[22] The claims made include:[5][23][24][25][26][27] Unlike Portland Cement, an EMC's production releases no carbon dioxide whatsoever.

[8] 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.

[5] 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.

[24] Treating Portland cement with the EMC Activation process may increase the strength development by nearly 50% and also significantly improve the durability, as measured according to generally accepted methods.

[35] In contrast, EMCs exhibit high resistances to chloride and sulphate ion attack, together with low alkali-silica reactivities (ASR).

Samples made of HPC having respective compressive strengths of 180.3 and 128.4 MPa (26,150 and 18,622 psi) after 28 days of curing, were then tested using the Bache method.

As a comparison, the test results showed: In other words, treating Portland cement with the EMC Activation process, may increase the strength development by nearly 50% and also significantly improve the durability, as measured according to generally accepted methods.

These tests confirmed that the cast concrete "showed a low surface specific leachability" with respect to "all environmentally relevant metals.

[43][44] The same tendency been noted and studied in the various supporting structures of Hagia Sophia built for the Byzantine emperor Justinian (now, Istanbul, Turkey).

[45] There, in common with most Roman cements, mortars comprising high amounts of pozzolana were used — in order to give what was thought to be an increased resistance to the stress-effects caused by earthquakes.

[46] EMCs made from pozzolanic materials exhibit "biomimetic" self-healing capabilities that can be photographed as they develop (see picture insert).

[39] Concretes made by replacing at least 50% of the Portland cement with EMCs have yielded consistent field results in high-volume applications.

[47] Volcanic ash deposits from Southern California were independently tested; at 50% Portland cement replacement, the resulting concretes exceeded the requirements of the relevant US standard.

[43][44] This leads to faster and greater strength development of the resulting concrete, at higher replacement ratios, than untreated pozzolans.

For example, strätlingite is metastable, which in a high temperature and water-content environment (that can be generated during the early curing stages of concrete) may of itself yield stable calcium aluminium garnet (see first bullet point above).

[63] This can be represented per the following equation: Per the first bullet point, although the inclusion of calcium aluminium garnet per se is not problematic, if it is instead produced by the foregoing pathway, then micro-cracking and strength-loss can occur in the concrete.

[68] EMC Activation's purpose is to cause a fundamental destruction to the crystalline structure of the material processed, to render it amorphous.

At its simplest, mechanochemistry can be stated as "a field studying chemical reactions initiated or accelerated by the direct absorption of mechanical energy.

"[17] More technically, it can be defined as a branch of chemistry concerned with the "chemical and physico-chemical transformation of substances in all states of aggregation produced by the effect of mechanical energy.

[71][72] More narrowly, "mechanical activation" was a term first defined in 1942 as a process "involving an increase in reaction ability of a substance which remains chemically unchanged.

[43] As stated in a 2023 academic textbook limited to mechanochemistry, EMC Activation has "impressively demonstrated" its effects in causing a change to the reactivity of alternate cement material and the resulting physical characteristics of the concrete cast.

As a result, in the course of the mechanical activation of minerals, reverse "relaxation" processes cannot completely decrease the Gibbs free energy that has been created.

) serves to further distinguish HEBM from general grinding or "milling" (where instead the only aim there is to increase the surface area of the materials processed), thereby accounting for an explanation for the change in entropy

[50] Studies elsewhere have determined that HEBM can significantly lower the temperature required for a subsequent reaction to proceed (up to a three-fold reduction), whereby a major component of the overall reaction-dynamics is initiated at a "nanocrystalline or amorphous phase" to exhibit "unusually low or even negative values of the apparent activation energy" required to cause a chemical reaction to occur.

[78][80] As a possible explanation of why amorphous silica is more reactive than its crystalline version, thermodynamic treatments may give further insight, even if such approaches cannot fully explain the phenomenon.

[95] Experimental data gathered from localised crack-generation, itself an important component of EMC Activation, has confirmed temperatures in this region as long ago as 1975.

In practical terms, EMC Activation deploys a range of grinding media of different sizes, shapes and composites to achieve the required mechanochemical transformation.

[94] For example, the contact time of a two-ball collision can be as short as 20μs, generating a pressure of 3.3 GPa upwards and with an associated ambient temperature increase of 20 kelvins.