CN113490651A

CN113490651A - Activation of natural pozzolans and uses thereof

Info

Publication number: CN113490651A
Application number: CN202080016077.1A
Authority: CN
Inventors: 约翰·M·桂恩
Original assignee: Roman Cement LLC
Current assignee: Roman Cement LLC
Priority date: 2019-01-08
Filing date: 2020-01-08
Publication date: 2021-10-08
Also published as: EP3908559A4; EP3908559A1; MX2021008245A; WO2020146551A1; CA3125963A1

Abstract

An activated pozzolan composition comprising a fine interground particulate mixture of an initially unactivated natural pozzolan and an ancillary cementitious material (SCM) that is different from the initially unactivated natural pozzolan. The initially unactivated natural pozzolan can include pozzolans or other natural pozzolan deposits having a moisture content of at least 3%, and the activated pozzolan composition can have a moisture content of less than 0.5%. The particle size of the initially unactivated natural pozzolan prior to intergrinding with SCM may be less than 1 mm. The SCM used to activate the initial unactivated natural pozzolan may be primary coarse particles or granules having a particle size greater than 1-3 μm, and may include granulated blast furnace slag, steel slag, other metallurgical slag, pumice, limestone, fine aggregate, shale, tuff, volcanic soil, geological materials, waste glass, glass fragments, basalt, sinter, ceramics, recycled brick, recycled concrete, refractory materials, other waste industrial products, sand, or natural minerals.

Description

Activation of natural pozzolans and uses thereof

Technical Field

The present invention relates generally to the field of supplementary cementitious materials, natural pozzolans, activation of natural pozzolans, and mixtures of natural pozzolans and other materials.

Background

Supplementary Cementitious Materials (SCMs), such as coal ash, metallurgical slag, natural pozzolans, biomass ash, post-consumer glass, and limestone, can be used to replace a portion of portland cement in concrete. SCMs can produce improved concrete with increased slurry density, increased durability, lower heat of hydration, lower chloride permeability, reduced creep, increased chemical resistance, lower cost, and reduced environmental impact.

Natural pozzolans, such as pozzolans, pumice and other materials found on earth, can be calcined and/or ground to increase pozzolanic activity. Both processes consume a lot of energy. Grinding natural pozzolans can be difficult due to the hardness of the volcanic glass. Grinding equipment such as vertical roller mills and horizontal roller presses may not be able to grind natural pozzolans due to the difficulty in maintaining a stable bed.

The natural pozzolan can also be interground with portland cement clinker to form 1P-type blended cement. Such interground blended cements have low reactivity unless ground to a much higher fineness than Ordinary Portland Cement (OPC). Although intergrinding of natural pozzolans with cement clinker can be performed in a single step and is therefore significantly less costly and more efficient than processing OPC and natural pozzolans separately and then blending them together, the performance of interground mixtures is generally lower than non-interground mixtures of the components processed separately.

Thus, there is a long felt need to find better and more cost effective methods to activate natural pozzolans.

Disclosure of Invention

Disclosed herein are activated natural pozzolans, pozzolan mixtures, cement-SCM compositions, and methods and systems for activating natural pozzolans, forming pozzolan mixtures, and forming cement-SCM compositions. Natural pozzolans, such as pozzolans, pumice, perlite, other pozzolanic materials, and other naturally derived pozzolans found on earth, can be activated by intergrinding with at least one mineral material (e.g., at least one granular mineral material and/or limestone).

In some embodiments, the coarse starting particulate or granular material (e.g., having a size of 1-3mm or greater, such as 2mm or greater) is interground with a natural pozzolan, such as a pozzolan (e.g., containing a significant amount of particles having a size of less than 1mm, 500 μm, or 200 μm), which may otherwise be difficult to grind in a Vertical Roller Mill (VRM) or a horizontal roller press (high pressure grinding roller) that requires the addition of the coarse starting particulate or granular material to form a stable bed. For example, pozzolans, tuff, pumice or other natural pozzolans that contain moisture, have low surface area, or are not sufficiently reactive when used as part of a cement replacement in concrete, may be interground with a particulate material to form an activated pozzolan or SCM blend having a reduced moisture content, a finer particle size, a higher surface area, and a higher pozzolan reactivity.

By way of example and not limitation, the coarse or granular SCM may be Granulated Blast Furnace Slag (GBFS), steel slag, other metallurgical slag, limestone, fine or medium aggregate, partially ground shale, geological materials, waste glass, glass cullet, glass beads, basalt, sinter, ceramic, recycled brick, recycled concrete, porcelain, used catalyst particles, refractory materials, other waste industrial products, sand, gypsum, bauxite, calcite, dolomite, granite, volcanic rock, volcanic glass, quartz, fused quartz, natural minerals. The natural volcanic ash can be volcanic ash, volcanic soil, pumice, perlite, or other natural volcanic ash. The natural pozzolan may initially have a moisture content (e.g., at least 3% prior to intergrinding), while the interground particulate material may have a reduced moisture content (e.g., less than 0.5%).

When using modern mills (e.g., vertical roller mills, horizontal roller mills, etc. for processing cement clinker) that require a percentage of clinker or particles to be present to form a stable grinding bed, it may be advantageous to interground the clinker or particles with the finer pozzolanic material. If included, the cement clinker is preferably less than 30%, less than 25%, less than 20%, less than 15%, less than 10%, less than 5%, less than 4%, less than 3%, less than 2%, or less than 1% of the total interground material.

In some embodiments, a system for manufacturing an activated natural pozzolan composition comprises one or more grinding devices configured to interground a particulate material and/or limestone with one or more natural pozzolans to form an activated interground pozzolan composition. The grinding apparatus may generate and/or include a heat input, which may advantageously reduce the moisture content of the natural pozzolan during grinding.

In some embodiments, interground particulate materials may be used to replace a portion of the cement and/or pozzolan typically used in concrete or other cementitious compositions. The interground particulate material may be pre-mixed with one or more additional SCM and/or OPC prior to use. For example, interground particulate material may be mixed with auxiliary particulate components (e.g., OPC, magnesium cement, aluminate cement, bottom ash, fly ash, GGBFS, steel slag, limestone, etc.) without intergrinding.

Drawings

FIGS. 1A and 1B are illustrative Particle Size Distribution (PSD) plots of an exemplary Ordinary Portland Cement (OPC) that is subdivided to show fine, medium, and coarse fractions;

FIG. 2A is a PSD graph of finely ground cement clinker subdivided to show fine, medium and coarse fractions;

FIG. 2B is a PSD graph (with an approximate bimodal PSD) comparing the PSD of the fine ground cement clinker of FIG. 2A with the PSD of the fine interground cement clinker and natural pozzolan, wherein the estimated proportions of the cement and pozzolan fractions in the fine, medium and coarse fractions are shown;

FIG. 3A is a PSD chart of another finely ground cementitious material made using cement clinker, which is subdivided to show fine, medium and coarse fractions;

FIG. 3B is a PSD graph (with an approximate bimodal PSD) comparing the PSD of the finely ground cementitious material of FIG. 3A to the PSD of another finely interground cementitious clinker and natural pozzolan, wherein the estimated proportions of the cement and pozzolan fractions in the fine, medium and coarse fractions are shown;

FIG. 3C is a PSD plot of finely interground cement clinker and natural pozzolan, showing estimated proportions of cement and pozzolan fractions in fine, medium and coarse fractions;

FIG. 4A is a graph showing the PSD of another finely interground cement clinker with natural pozzolan (without a significant bimodal PSD), wherein the estimated proportions of the cement and pozzolan fractions in the fine, medium and coarse fractions are shown;

FIG. 4B is a graph showing the PSD (with an approximate bimodal PSD) of interground limestone and natural pozzolan, showing the estimated proportions of limestone and pozzolan fractions in the fine, medium, and coarse fractions;

FIG. 5A is a photograph of screened natural pozzolan particles that are opaque and have a more rounded morphology taken using a conventional microscope;

FIG. 5B is a photograph of sieved natural pozzolan particles having a glassy appearance and a jagged flat morphology taken using a conventional microscope;

FIG. 6 is a flow diagram illustrating an exemplary method of manufacturing a hybrid composition including a fine interground particulate component;

7-9 are flow diagrams illustrating exemplary methods of making cement-SCM compositions and/or components thereof;

FIGS. 10A and 10B schematically illustrate an exemplary milling apparatus for making one or more of the disclosed components, the composition comprising an interground particulate composition or component;

FIG. 11 is a flow chart illustrating an exemplary method of manufacturing a coarse Supplementary Cementitious Material (SCM) including at least a portion of a coarse particulate component;

FIG. 12 schematically illustrates an exemplary separation apparatus for producing one or more components of a cement-SCM composition including crude SCM; and

figures 13A-13C schematically illustrate an exemplary manufacturing system for manufacturing one or more cement-SCM compositions.

Detailed Description

I. Introduction to

Disclosed herein are activated pozzolan compositions and methods and systems of manufacture for making concrete and other cementitious compositions.

Intergrinding processes can be used to make blended SCM materials, such as primary coarse SCM with primary size of 1-3mm and primary fine SCM powder that may be difficult to grind in Vertical Roll Mills (VRMs) or horizontal roll presses. To form a stable bed, the initially coarse SCM is used to form a stable bed and interground with finer SCM. For example, pozzolans or natural pozzolans having insufficient moisture content or reactivity may be interground with a particulate material to form an activated pozzolan or SCM blend having reduced moisture and finer particle size. The coarse SCM may be granulated blast furnace slag, steel slag, other metallurgical slag, pumice, limestone, dolomite, fine aggregate, glass cullet, recycled brick, ceramic or concrete, basalt, shale, tuff, volcanic soil or other geological material.

Activation of natural pozzolans containing significant amounts of moisture (at least 3%, 5%, 7.5%, 10%, 15%, 20%, or 25%) by intergrinding with coarse SCM material in place of cement clinker prevents the moisture from undesirably or prematurely reacting with cement clinker, which may occur in typical interground cement-pozzolan mixtures.

FIG. 1A shows a passage fineness of 376m²PSD plot of data measured by laser diffraction technique of/kg of a commercially available type I/II OPC. The PSD map is further subdivided into three regions or portions, each designated as "fine" (e.g.<5 μm), "medium" (e.g. 5-30 μm) and "coarse"(e.g., in the case of>30 μm). It is to be understood that these particle size ranges and thresholds are for purposes of illustration and comparison and should not be considered absolute or necessarily definitions.

FIG. 1B is a PSD chart showing data measured by a Malvern Mastersizer2000 for ground cement clinker material ground using a Vertical Roller Mill (VRM) to a d90 in a typical range of about 40-45 μm. The PSD of the ground cement clinker in FIG. 1B is steeper than that of the OPC in FIG. 1A, with d90 of about 43.4 μm, d50 of about 18.8 μm, and d10 of about 3.8 μm. The ground cement clinker in fig. 1B has fewer "fine" particles than the OPC in fig. 1A, as indicated by the smaller cross-hatched areas indicated as "fine". However, both portland cement materials have a typical d90 (e.g. about 40-45 μm) and a typical d50 (e.g. about 18-20 μm) and therefore contain a considerable proportion of coarse cement particles which may not be fully hydrated, especially at lower water-cement ratios (w/c).

"Hydraulic cement" and "cement" include Portland cement and similar materials containing one or more of the following four clinker materials: c₃S (tricalcium silicate), C₂S (dicalcium silicate), C₃A (tricalcium aluminate) and C₄AF (tetracalcium aluminoferrite). Hydraulic cements may also include white cements, calcium aluminate cements, high alumina cements, magnesium silicate cements, magnesium oxychloride cements, or oil well cements.

"supplementary cementitious material" and "SCM" include any material commonly understood in the art to constitute a material that can replace a portion of the hydraulic cement in concrete. Non-limiting examples include GGBFS, class C fly ash, steel slag, silica fume, metakaolin, class F fly ash, calcined shale, calcined clay, natural pozzolan, ground pumice, ground glass, ground limestone, ground quartz, and precipitated CaCO₃. Ground quartz and other siliceous materials are understood to be pozzolans when ground to include a large number of finer particles (e.g., 25 μm or less).

In some embodiments, the fine interground material may include one or more types of clinker or particles initially greater than about 1-3mm (e.g., cement, metallurgical slag, limestone, pumice, coal ash, sinter, waste glass, natural pozzolan, brick, ceramic, recycled concrete, refractory material, other waste industrial products, sand, natural minerals with one or more finer SCMs having an initial particle size <1mm (e.g., pozzolan, natural pozzolan, fly ash, waste fines from aggregate processing, red mud)).

In some embodiments, at least one of the SCM fraction of the fine interground particulate component or the coarse SCM particles of the coarse particulate component may comprise one or more SCM materials selected from the group consisting of coal ash, slag, natural pozzolan, ground glass, and non-pozzolanic materials. For example, the coal ash may be selected from fly ash and bottom ash, the slag may be selected from ground granulated blast furnace slag, steel slag and metallurgical slag containing amorphous silica, the natural pozzolan may be selected from natural pozzolan deposits, pozzolans, metakaolin, calcined clay, trass and pumice, the ground glass may be selected from post-consumer glass and industrial waste glass, the non-pozzolanic material may be selected from limestone, CO by industrial origin₂Metastable calcium carbonate, precipitated calcium carbonate, crystalline mineral, hydrated cement and waste concrete generated by reaction with calcium ions.

In some embodiments, an optional auxiliary particulate component may be mixed with the interground particulate composition. The optional auxiliary particulate component may be virtually any hydraulic cement, SCM material, or mixture thereof that is not interground with the interground particulate composition.

Activation of natural pozzolans

A. Intergrinding to activate natural pozzolans

Figures 2B, 3B, 4A and 4B are PSD graphs showing data for exemplary interground particle compositions containing activated natural pozzolan as measured by Malvern Mastersizer 2000. The interground material of fig. 4B may be used as a component in the manufacture of a cement-SCM composition. It may be a final product because it includes activated natural pozzolan that has not been calcined and produced without intergrinding with cement clinker.

For comparison purposes, fig. 2A is a PSD graph of a finely ground cementitious material composed of 100% portland cement, which is illustratively subdivided into fine, medium, and coarse fractions, showing data measured by a Malvern Mastersizer2000, made from the same cement clinker used in fig. 1B and ground using the same VRM. Interestingly, although the two cements had very different d90, the PSD plot of fig. 2A had a very similar shape to that of fig. 1B.

FIG. 2B illustrates and compares the PSD of the 100% ground Portland cement clinker of FIG. 2A (thick line curve) and a 50:50(w/w) interground mixture of the same batch of cement clinker and natural pozzolan (thin line curve). The PSD plot of the 50:50 mixture in fig. 2B is clearly bimodal and is further subdivided to illustratively show the fine, medium and coarse fractions of each of the cement and pozzolan fractions. For illustrative purposes, the PSD curve of FIG. 2A is overlaid on the PSD plot of a 50:50 mixture for extrapolation and estimation of the relative proportions of fine cement and pozzolan in the fine, medium and coarse fractions. It is assumed that the PSD curve of the cement portion in fig. 2B is similar to the PSD curve shape of fig. 1B and 2A, with the apparent bimodal character due to the different grinding characteristics of the intergrinding of the softer natural pozzolan with the harder cement clinker.

For comparison purposes, fig. 3A is a PSD graph of another finely ground cementitious material made from cement clinker using VRM, which is illustratively subdivided into fine, medium, and coarse fractions, showing data measured by a Malvern Mastersizer 2000. The finely ground cementitious material had a d90 of about 24.4 μm, a d50 of about 10.2 μm and a d10 of about 2.1 μm. The fine cement material of fig. 3A has a significantly lower d90, higher reactivity, and significantly fewer particles that are not fully hydrated within 28 days, compared to the PSD of the conventional portland cement material shown in fig. 1A and 1B.

FIG. 3B illustrates and compares the PSD of the finely ground cementitious material of FIG. 3A (fine line curve) and another 50:50(w/w) interground mixture of cement clinker and natural pozzolan (bold line curve). The clinker and pozzolan are initially pre-mixed and then ground using a VRM. The interground mixture had a d90 of about 24.6 μm, a d50 of about 9.2 μm, and a d10 of about 1.8 μm. Similar to fig. 2B, the PSD of the 50:50(w/w) interground mixture in fig. 3B appears to have an approximately bimodal shape, but is less pronounced than in fig. 2B, again indicating a non-uniform distribution of cement and pozzolan particles in the interground mixture. For illustrative purposes, the PSD curve of FIG. 3A is overlaid on the PSD plot of the 50:50 mixture for extrapolation and estimation of the relative proportions of cement and pozzolan in the fine, medium and coarse fractions. It is assumed that the PSD curve of the cement portion in fig. 3B is similar to the PSD curve shape of fig. 3A, with the apparent bimodal character due to the different grinding characteristics of the softer natural pozzolan and the harder cement clinker.

FIG. 3C is a PSD plot of an interground mixture of cement clinker and natural pozzolan without a significant bimodal shape. However, it is assumed that the shape of the PSD curve of the cement portion is the same as that of the PSD curve in fig. 1B and 2A for the same cement material. Based on this assumption, fig. 3C is subdivided between cement and pozzolanic materials throughout the PSD curve, and also shows the higher predominance of fine pozzolan particles in the fine particle region and the higher predominance of cement particles in the medium particle region and the coarse particle region, even though there is no significant bimodal distribution throughout the interground mixture.

FIG. 4A is a PSD plot of a 50:50(w/w) interground mixture of cement clinker and pozzolan from Utah. The PSD of the interground mixture does not appear to have a bimodal shape, which might indicate a fairly uniform distribution of cement and natural pozzolan particles throughout the interground mixture. For purposes of illustration, the PSD chart is subdivided to show the relative preponderance of cement and pozzolan particles within the fine, medium and coarse regions of the PSD curve.

FIG. 4B is a PSD plot of a 50:50(w/w) interground mixture of limestone and Utah volcanic ash. Limestone and natural pozzolan are initially pre-mixed and then ground using a VRM. The interground mixture of limestone and natural pozzolan had a d90 of about 24.2 μm, a d50 of about 6.3 μm, and a d10 of about 1.4 μm. The PSD of the interground mixture had an approximately bimodal shape, indicating a non-uniform distribution of limestone and pozzolan particles in the interground mixture. Because limestone is generally softer than cement clinker, because this natural pozzolan appears to be as hard or harder as cement clinker, and because this PSD is broadened in comparison to the other indicated PSDs, it is assumed that the finer particles (e.g., below d 50) in this 50:50 interground mixture consist primarily of limestone particles, while the coarser particles (e.g., above d 50) consist primarily of natural pozzolan particles. The PSD plots are subdivided for illustrative purposes based on extrapolation of the PSD curves shown in FIGS. 2A-4B. The addition of fine ground limestone particles can advantageously offset the retarding effect of many pozzolans in cement-SCM mixtures.

Figure 5A is a photograph taken using a conventional microscope of screened raw natural pozzolan particles provided by Drake cement used to make the fine interground blendstocks described with reference to figures 2B, 3B, and 3C. The coarse particles appear substantially opaque, having a generally rounded and somewhat spherical morphology. Coarse SCM particles having a generally round morphology should provide higher flowability and lower water demand than jagged particles. However, because pozzolan particles are not perfectly spherical, they have some uneven surfaces that can provide improved pozzolan reactivity. Intergrinding with particles or clinker to produce the fine interground particulate materials disclosed herein may significantly increase their pozzolanic reactivity.

Fig. 5B is a photograph taken using a conventional microscope of sieved crude natural pozzolan particles provided by Jack B. The coarse particles have a glassy, more transparent appearance (indicating an amorphous rather than a crystalline structure) and a jagged and flatter morphology. The glassy and jagged nature of these particles can increase their pozzolanic activity compared to similarly sized spherical pozzolan particles (e.g., fly ash). However, their flat plate-like morphology can reduce flowability and increase water demand compared to similarly sized particles having a round morphology. Intergrinding with particulate materials to produce finely interground particulate materials can increase pozzolanic reactivity and reduce water demand.

In some embodiments, the d90 of the fine interground particle mixture may be equal to or less than about 45 μm, 42.5 μm, 40 μm, 37.5 μm, 35 μm, 32.5 μm, 30 μm, 27.5 μm, 25 μm, 23 μm, 21 μm, or 20 μm. In this case, d90 may be selected to be greater than about 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 17 μm, or 19 μm. In other embodiments, the d90 of the mixture of fine interground particles is equal to or less than about 25 μm, 23 μm, 21 μm, 19 μm, 17.5 μm, 16 μm, 15 μm, 14 μm, 13 μm, 12 μm, or 11 μm. In this case, d90 may be selected to be equal to or greater than 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm.

In some embodiments, the d10 of the mixture of fine interground particles may be equal to or less than about 5 μm, 4.5 μm, 4 μm, 3.5 μm, 3 μm, 2.75 μm, 2.5 μm, 2.25 μm, 2 μm, 1.75 μm, 1.5 μm, 1.35 μm, 1.25 μm, 1.15 μm, 1.07 μm, or 1 μm. In some embodiments, the d10 of the fine interground particle mixture may be equal to or greater than about 0.2 μm, 0.25 μm, 0.3 μm, 0.35 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, or 1.0 μm.

In some embodiments, the d50 of the mixture of fine interground particles may be equal to or less than about 18 μm, 16 μm, 14.5 μm, 13 μm, 12 μm, 11 μm, 10 μm, 9 μm, 8 μm, or 7 μm and/or equal to or greater than 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, or 12 μm.

In some embodiments, the natural pozzolan portion of the fine interground particulate mixture comprises at least about 5%, 10%, 15%, 20%, 25%, 35%, 40%, or 45% by weight and less than about 9%, 0%, 80%, 70%, 60%, or 50% by weight of the fine interground particulate mixture, and/or the initial clinker or particulate material portion of the fine interground particulate mixture comprises at least about 10%, 20%, 30%, 40%, or 50% by weight and less than about 95%, 90%, 85%, 80%, 75%, 70%, 65%, or 55% by weight of the fine interground particulate mixture.

B. Mixing interground material with auxiliary particles

The interground particulate mixture may be mixed with a separately processed secondary particulate material to form a mixed particulate composition. The auxiliary particulate material may be one or more commercially available hydraulic cements, such as OPC for example, or commercially available SCMs, such as fly ash (class C and/or F), GGBFS, metakaolin, silica fume, quick-setting cement, super-sulphate cement, magnesium cement, aluminate cement, low CO cement₂Cement, low C₃S and high C₂S cement, calcium, magnesium, alkali or geopolymericAnd (3) cement. A mixed particulate composition having a broader PSD can be provided by mixing a fine interground particulate mixture with a secondary particulate material that provides a greater amount of coarser particles.

In some cases, activated natural pozzolans having certain chemical properties can be blended with pozzolans having other chemical properties to produce a pozzolan blend having desired chemical properties. Such blending of two or more pozzolans can be performed to produce a blended pozzolan material having desired chemical and/or physical properties. Examples of desired chemical modifications that can be achieved by mixing two or more different pozzolans include adjusting one or more of silica content, alumina content, iron oxide content, alkaline earth metal content, alkali metal content, sulfate content.

One example is blending a natural pozzolan having a high silica and/or aluminosilicate content and a low carbon content with a pozzolan lacking silica and/or aluminosilicate and/or having a high carbon content, such as fly ash, to produce a blended pozzolan having a desired silica and/or aluminosilicate and/or carbon content. To meet the conditions of ASTM C-618 class C fly ash, the fly ash must contain at least 50% of the combined weight of silica, alumina, and iron oxide ("SAF") and a maximum Loss On Ignition (LOI) of 6%. To meet the requirements of class F fly ash in ASTM C-618, the SAF content of the fly ash must be at least 70% and the maximum LOI 6%. Off-spec fly ash lacking SAF can be blended with natural pozzolans (e.g., activated by intergrinding with another mineral material) to produce a pozzolan blend having an SAF that meets the SAF requirements for a class C or class F fly ash. In this way, even if the blend itself is not technically satisfactory for fly ash (i.e., because it is a blended material containing non-fly ash components), the off-spec fly ash can be repaired to produce a blended pozzolan having a SAF meeting the ASTM standard class C or class F fly ash SAF requirements.

Another problem is that fly ash supply decreases in certain areas as coal fired power plants are decommissioned or converted to other fuels. Activated natural pozzolans can increase fly ash supply in these regions, either by pre-mixing with fly ash or adding directly to concrete to replace some or all of the fly ash.

In rare cases, there may be a supply of already activated natural pozzolans that do not require grinding and/or additional heating or processing to be suitable as a blending material and/or as a partial replacement for fly ash. For example, calcined shale dust is available in utah as pozzolans that are coarser than OPC and coarser than commercial fly ash, but still have a high SAF. Such calcined shale dust is a by-product of Utelight production of lightweight aggregates by colervier, utah. The raw shale is mined, calcined in a rotary kiln at about 1500 ° f (815 ℃) and then classified into coarse, medium and fine aggregates. Waste shale fines, including baghouse dust, are collected and typically discarded or used as an inexpensive filler in bitumen or soil classification. The inventors have for the first time used spent shale fines in several concrete compositions and have had great success in producing high quality concrete mixes. In some cases, unmodified waste shale dust received from Utelight has been used to replace at least a portion of fly ash in the manufacture of concrete. The waste shale dust is also blended with natural pozzolan that is activated by intergrinding with granulated limestone to form a blended pozzolan that has a higher SAF and a lower LOI than the interground pozzolan-limestone material. The shale dust was also mixed with another calcium carbonate rich aggregate manufacturing by-product (i.e., quarry fines from Keigley aggregate works in therma, utah, processed to 200 mesh in a Raymond mill and used as mineral rock dust). Calcium carbonate accelerates the development of strength of ternary mixtures containing portland cement, shale dust, and mineral rock dust. The mixture is used to make a concrete having a 28 day strength of 3800psi to 6500psi at 28 days and a reduced portland cement content. Sometimes these mixtures are further supplemented with supplementary lime (e.g. S-lime or quicklime) and/or supplementary sulphate (e.g. plaster of paris or gypsum).

In some embodiments, the auxiliary particulate material may provide very fine SCM particles having a d90 less than the d90, d50, or d10 of the fine interground particulate mixture. Examples include any of a variety of microsilica materials known in the art, such as the industrial by-product silicon powder formed during the manufacture of silicon and ferrosilicon materials, and metakaolin. Another example is ultra fine fly ash produced by air classifying fly ash, sometimes also off-spec fly ash (e.g., Huntington and Hunter power plants from the middle of utah). The superfine fly ash produced by air classification can only partially repair unqualified fly ash, and the fly ash can be further repaired by mixing with activated natural volcanic ash. Very fine secondary materials may be required when the fine interground particulate material lacks very fine particles, particularly very fine SCM particles (e.g., less than 2 μm, which is generally more desirable than cement particles less than 2 μm; very fine cement particles increase water demand and cement slurry porosity, while very fine SCM particles may reduce water demand and reduce cement slurry porosity).

In some embodiments, the auxiliary particulate material may provide coarse SCM particles having a d90, d50, or d10 that is greater than the d90 of the fine interground particulate material. The secondary particulate component may include ultra-coarse particles such as ground limestone, ground recycled concrete, quartz, minerals, bottom ash, coarse fractions of air-classified fly ash, shale dust, crystalline metallurgical slag, or industrial waste with low reactivity. Coarse SCM may help balance if the fine interground particulate material in the material itself is insufficient or excessive. For example, if the amount of limestone used to activate natural pozzolans produces a fine particle blend with an LOI above 10% (maximum of natural pozzolans), a coarse SCM with a lower LOI may be used to produce a blend with a maximum LOI of 10%.

Activated natural pozzolan compositions can be prepared using commercially available milling, separation and mixing equipment known in the art, sometimes modified to obtain mixtures and compositions having a desired PSD. Non-limiting examples of grinding equipment include vertical roller mills, high pressure grinding rollers, horizontal roller presses, ball mills, rod mills, hammer mills, jaw mills, Raymond mills, jet mills, dry bead mills, ultrasonication mills, and the like. Non-limiting examples of separating apparatus include stand-alone classifiers, classifiers integrated with vertical roller mills, and screening apparatus. Non-limiting examples of mixing equipment include planetary mixers, dry rotary mixers, dry mixing equipment, dry vibrating screens, and concrete mixing equipment, such as concrete mixing trucks and batch mixers.

To ensure that the interground particulate composition and the secondary particulate component have their respective PSDs within the desired parameters, it is often advantageous to periodically sample and accurately determine the particle size and PSD (e.g., by using particle size analyzers and techniques known in the art). For example, laser diffraction techniques may be used to determine the PSD. One example of a particle size analyzer commonly used to determine the PSD of cement and SCM is a Malvern Mastersizer 2000. Another example is an online laser diffraction particle size Analyzer, such as a Malvern instrument fine Analyzer available from Malvern Instruments (work shift, UK), which automatically collects a series of PSD measurements of a product in real time and uses this information via a feedback loop to modify the milling and/or classification process to maintain the PSD within a desired range. Other methods for determining or estimating particle size include, but are not limited to, sieving, optical or electron microscopy analysis, X-ray diffraction, sedimentation, elutriation, microscopic counting, coulter counter, and dynamic light scattering.

6-9 are flow diagrams illustrating exemplary methods of activating natural pozzolans and manufacturing cement-SCM and other blended pozzolan compositions and/or components thereof. Although these descriptions often refer to intergrinding of clinker and pozzolan, it is understood that "clinker" may refer to particulate materials other than cement clinker used to make Ordinary Portland Cement (OPC).

Figure 6 illustrates a basic method 600 of making a blended composition (e.g., an activated pozzolan composition or interground cement and SCM), the method comprising: step 602-intergrinding clinker (e.g. cement clinker) or particles (e.g. metallurgical slag, aggregate or ground minerals) with one or more SCMs (e.g. natural pozzolans) to form a fine interground particulate component; step 604-forming or providing a coarse particle component that is not interground with the fine interground particle component; and step 606-mixing the fine interground particulate component with the coarse particulate component without intergrinding to form a blended composition (e.g., a cement-SCM composition). One or more other additional components disclosed herein, such as hydraulic cement, SCM, or other components, may optionally be added to the mixed composition to produce a modified cement-SCM composition.

Fig. 7 illustrates a method 700 of making a cement-SCM composition, the method comprising: step 702-intergrinding clinker (e.g. cement clinker or particles) with one or more SCMs (e.g. natural pozzolans) to form a fine interground particulate component; step 704-forming or providing a coarse particle component that is not interground with the fine interground particle component; step 706-dry blending the fine interground particulate component with the coarse particulate component without intergrinding to form a dry mixture; and step 708, optionally mixing the dry mixture with one or more of aggregate, water, or a blend. After

steps

706 or 708, one or more other additional components disclosed herein may optionally be added to the cement-SCM composition to produce a modified cement-SCM composition.

Figure 8 illustrates another method 800 of making a cement-SCM composition, the method comprising: step 802-intergrinding clinker (e.g. cement clinker or particles) with one or more SCMs (e.g. natural pozzolans) to form a fine interground particulate component; step 804 — forming or providing a coarse particle component that is not interground with the fine interground particle component; and step 806-mixing the fine interground particulate component, the coarse particulate component, and one or more of aggregate, water, or admixture. As part of step 806 or after step 806, one or more other additional components disclosed herein can be added to the cement-SCM composition to produce a modified cement-SCM composition.

Figure 9 illustrates another method 900 of making a cement-SCM composition, the method comprising: step 902-intergrinding clinker or particles (e.g. cement or SCM) with one or more SCMs (e.g. natural pozzolan) to form a fine interground particulate component; step 904-forming or providing a coarse particulate component that is not interground with clinker or particles used to make the fine interground particulate component; step 906 — forming or providing an auxiliary particulate component, such as hydraulic cement or SCM; and step 908-blending the fine interground particulate component, the coarse particulate component, and the supplemental particulate component without intergrinding to form the cement-SCM composition. One or more of the other additional components disclosed herein may be added to the cement-SCM composition to produce a modified cement-SCM composition.

While some of the foregoing methods determine that "cement clinker" is interground with one or more SCMs to produce a fine particulate component, it is to be understood that particles or clinker other than cement clinker may be used to form the fine particulate component, such as a fine particulate component that includes a plurality of SCMs. In this case, a hydraulic cement source (e.g., OPC) can be mixed with the fine particulate component to produce a ternary mixture of two separate feed streams. This mixture can be mixed with the crude SCM without intergrinding to produce a quaternary mixture of three different feed streams.

In some embodiments, a system for manufacturing a cement-SCM composition comprises: (A) one or more grinding apparatuses configured to interground hydraulic cement (e.g., cement clinker) or other particulate material with one or more SCMs (e.g., natural pozzolans) to form a fine interground particulate component; (B) one or more mixing devices configured to mix the fine interground particulate component with a coarse particulate component comprised of coarse SCM particles without intergrinding; and optionally (C) one or more devices for combining the secondary particulate component with the fine particulate component and the coarse particulate component without intergrinding.

In some embodiments, a system for manufacturing a cement-SCM composition comprises: (A) one or more grinding devices configured to interground one or more clinkers or particles initially greater than about 1-3mm with one or more finer particles or powders having an initial particle size of less than about 1mm to form a fine interground particulate component; (B) one or more mixing devices configured to combine the fine interground particulate component with a coarse particulate component consisting of coarse SCM particles without intergrinding; and optionally (C) one or more devices for mixing the secondary particulate component with the fine particulate component and the coarse particulate component without intergrinding. When the fine interground component (a) is insufficient in hydraulic reactivity, the auxiliary particulate component may advantageously include hydraulically reactive particles.

In some embodiments, a system for manufacturing a cement-SCM composition comprises: (A) one or more milling devices configured to interground (1) a first SCM component with (2) a second SCM component to form a fine interground particulate component; (B) one or more mixing devices configured to mix the fine interground particulate component with the hydraulic cement component without intergrinding; and (C) one or more mixing devices configured to combine the fine interground particulate component and the hydraulic cement component with the coarse particulate component without intergrinding; and optionally (D) one or more devices for mixing an auxiliary particulate component (e.g., OPC, SCM or other material) with components (a), (B), and (C) without intergrinding.

Fig. 10A and 10B schematically illustrate an exemplary milling apparatus that may be used to produce a fine interground particulate component, and optionally at least a portion of a coarse particulate component and/or an optional auxiliary particulate component.

Fig. 10A discloses, in more detail, a grinding circuit 1000 that includes a transport pipe, conveyor, or apparatus 1002, the pipe, conveyor, or apparatus 1002 configured to convey a stream or mixture of particles, clinker, and/or other materials to a grinder 1004, the grinder 1004 grinding or otherwise reducing the particle size of the materials to form a ground stream 1005. A separator 1006, integrated with or separate from the grinder 1004, further processes the pulverized stream 1005 and separates it into a coarse fraction 1008 and a fine fraction 1010, the coarse fraction 1008 can be collected as product and/or recycled back to the grinder 1004 for further pulverization, and the fine fraction 1010 can be collected as product and/or intermediate material for further processing using known processing equipment, including, for example, the processing equipment disclosed herein. The grinder 1004 and/or the separator 1006 may be adjusted or modified to produce a fine fraction 1010 having a desired d90, d50, d10, and/or fineness.

The grinder 1004 may be any grinder used in the grinding or milling arts. Where grinder 1004 and separator 1006 are separate rather than integrated devices, grinder 1004 can be any known grinder that does not include an integrated or internal separator. Non-limiting examples include ball mills, rod mills, horizontal roller presses, high pressure grinding rollers, hammer mills, jaw mills, Raymond mills, jet mills, bead mills, high speed impact mills, acoustic fracturing mills, and the like. The individual separators 1006 may be any known separator, such as a high efficiency air classifier, a cyclone separator, or a screening device.

Fig. 10B discloses more specifically a vertical roller mill system 1020 comprising a feed bin 1021 for storing and transporting feed material to be processed, a metering device 1022 (e.g., an auger) for transporting the feed material at a predetermined rate, and a vertical roller mill 1023 that receives the feed material and grinds the feed material using a rotating table (not shown) and rotating stationary rollers (not shown) positioned above the rotating table. High efficiency classifier 1024 is integrated with vertical roller mill 1023 and located above vertical roller mill 1023. The hot gas generator 1025 may be powered by natural gas, other fuel, or waste heat from the cement kiln to produce hot gases that are introduced into the vertical roller mill 1023 at a desired temperature, pressure, and velocity. The hot gases move upward within the vertical roller mill 1023 around the periphery of the rotating table where they contact the abrasive particles discharged from the rotating table by centrifugal force and carry at least a portion of the abrasive particles upward to the high efficiency classifier 1024. The hot gas also dries the milled particles. Coarse particles (not shown) that are not carried by the upwardly moving gas to the high efficiency classifier 1024 instead fall below the rotary table where they are carried by the bucket elevator 1030, pass through the magnetic separator 1031, which separates the scrap iron-containing stream from the remainder of the coarse particles, and which is returned to the vertical roller mill 1023 (e.g., with feed material from the feed bin 1021).

High efficiency classifier 1024 separates the ground particles received from vertical roller mill 1023 into a finer fraction, which is carried by the upwardly moving gas to cyclone collector 1026, and a coarser fraction (not shown) which falls back onto the rotating table of vertical roller mill 1023 for further grinding. The finer fraction d90 can be controlled by varying various parameters of the vertical roller mill system 1020, such as the rate at which the feed material is introduced into the vertical roller mill 1023, the pressure applied to the rotating stationary rollers and delivered to the particle grinding bed, the velocity and/or pressure of the hot gases, and the velocity of the rotor containing fins or vanes within the high efficiency classifier 1024. D90 may be measured periodically using known PSD measurement devices known in the art, such as laser diffraction measurement devices. Mill 1027 helps to flow hot gases upward through vertical roller mill 1023 and high efficiency classifier 1024 and separate milled product 1032 from ultra fine particles, which are collected by filter 1028 and then combined with milled product 1032 from cyclone collector 1026. The filter fan 1029 helps to move the ultra fine particles from the cyclone collector 1026 to the filter 1028 and to discharge the exhaust into the air.

FIG. 11 is a flow chart illustrating an exemplary method 1100 of manufacturing a coarse supplementary cementitious material, the method including: step 1102-optionally grinding and/or sorting the initial SCM; step 1104-de-dusting the SCM to form a crude SCM product; and step 1106, optionally collecting the fine fraction after dust removal and using it as needed. For example, the fine fraction after dedusting can be used as a microsilica component of concrete and/or blended cement and/or as an SCM feed component for making fine interground particulate components. The dust removal process may be performed using known equipment, such as high efficiency air classifiers, screening devices or combinations thereof capable of sharp cutting or separation.

Fig. 12 schematically illustrates an example separation apparatus 1200 that may be used to produce one or more particulate components, such as a coarse particulate component, and optionally, a fine interground particulate component and/or an auxiliary particulate component. Separation apparatus 1200 also includes one or more separation mechanisms 1204, known in the art of particle separation, that receive a stream of particles 1202 and separate the particles into at least a finer particle fraction 1206 and a coarser particle fraction 1208. The one or more separation mechanisms 1204 may also be configured to produce other particulate fractions, such as an intermediate particulate fraction (not shown) that is less fine than the finer particulate fraction 1206 and/or less coarse than the coarser particulate fraction 1208. Examples of one or more separation mechanisms 1204 include equipment associated with a high efficiency classifier, a cyclone, screening equipment, or a filter.

Figure 13A schematically illustrates an exemplary system 1300 for manufacturing the cement-SCM compositions disclosed herein. The system 1300 more particularly includes at least a first bin or other container 1302 for pozzolan or other SCM and a second bin or other storage container 1304 for clinker (e.g., cement clinker or particles), which may be raw or partially ground clinker, other hydraulic cement materials, or other large particulate, clinker, or tuberculous materials. The clinker and SCM from the

storage vessels

1302, 1304 are processed according to the methods disclosed herein and/or other methods known to one of ordinary skill in the art, such as by one or more grinders 1306 or other grinding devices and one or more classifiers 1308 or other separation devices, to produce the desired materials for use in the manufacture of the cement-SCM composition. These include at least (1) a fine interground particulate component comprising a hydraulic cement portion and an SCM portion (or a first SCM portion and a second SCM portion) that is storable in a fine interground particulate bin 1310, and (2) a coarse particulate component comprising coarse SCM particles that is storable in a coarse particulate bin 1312. In addition, optional auxiliary particulate material may be stored in auxiliary particulate bin 1314.

In some embodiments, as indicated by the dashed arrow pointing to coarse bin 1312, the coarse component may be used as is without grinding, dedusting, or further processing (e.g., fly ash, GGBFS, or other SCM with sufficient proportions of coarse particles supplemented with fine component). While this may sometimes result in a cement-SCM composition that is less desirable than cement-SCM compositions made using ground, dedusted or other further processed SCM, the simplification of the manufacturing process may justify such a result (e.g., by reducing capital and/or operating costs of the manufacturing facility). In some embodiments, the optional secondary particle component can be pre-treated and need not be further processed by the equipment used to process the fine interground particle component and/or the coarse particle component, as indicated by the dashed arrow pointing to the secondary particle bin 1314.

The mixer 1316 may be used to mix the fine interground particulate material, the coarse particulate material, and the optional auxiliary particulate material to form a finished product, which in the case of a dry mix composition, may be stored in a finished product bin 1318. In other instances, mixer 1316 may be a concrete mixer, such as a stationary mixer for mixing and batching concrete, or a concrete mixer truck for mixing and transporting concrete.

For example, fig. 13B shows an improved system 1300 that includes a mixer 1316, the mixer 1316 being a stationary mixer for making a dry mix or a fresh concrete mix that is then fed to a concrete transport vehicle or vehicle 1320. If the mixer 1316 produces a dry mix, the water and admixture may be added directly to the concrete transport cart 1320 to form a freshly mixed concrete at a concrete batching plant, during transport, or at the job site.

Fig. 13C shows yet another improved system 1300 in which the mixing apparatus is a concrete transporter or vehicle 1320. For example, the fine interground particle bin 1310, the coarse particle bin 1312, and the optional auxiliary particle bin 1314 may be located at a concrete manufacturing plant for distributing and mixing these materials directly within the concrete transport vehicle 1320. As shown in fig. 13B, the water and admixture may be added directly to the concrete transport cart 1320 to form freshly mixed concrete at the concrete batching plant, during transport, or at the job site.

A. Other aspects of Natural pozzolan activation

The ratio of clinker or particles to natural pozzolan may be 5:95, 10:90, 15:85, 20:80, 25:75, 30:70, 35:65, 40:60, 45:55, 50:50, 55:45, 60:40, 65:35, 70:30, 75:25, 80:20, 85:15, 90:10, 95:5, or any range between any of the above values.

Typically, clinker or particulate material is a millable grinding medium that transfers grinding forces to small pozzolan particles. The advantage of fine or coarse interground particles from the initial clinker or granular material or natural pozzolan is generally dependent on their grindability or hardness. The following are hardness values for various materials that can be used to determine or estimate the effectiveness of a particular clinker or granular material in transferring the grinding force down to the activated natural pozzolan:

generally, the use of harder materials (e.g., steel slag) will tend to result in finer ground natural pozzolan particles having a higher surface area than when softer materials are used (e.g., particles smaller than d50 in the interground mixture can have a higher percentage of natural pozzolan particles by number, volume, or weight than particles larger than d 50). Conversely, the use of a softer material (e.g., limestone) will tend to result in coarser ground natural pozzolan particles, having a lower surface area than when a harder material is used (e.g., particles less than d50 in the interground mixture may have a lower percentage of natural pozzolan particles by number, volume, or weight than particles greater than d 50).

In some embodiments, activated natural pozzolans can be blended with pozzolans (e.g., fly ash that is otherwise out of specification) to beneficiate such materials (e.g., to meet ASTM C-618 requirements for minimum silica plus alumina plus iron oxide (SAF) for class C or class F fly ash). Particles containing high silica content (e.g., granite, basalt, quartz) can be particularly beneficial when beneficiating off-spec fly ash. Examples of blending methods for altering one or more chemical properties of blended pozzolans (e.g., silica content, alumina content, iron oxide content, calcium oxide or sulfate content) are disclosed in U.S. patent No.9,067,824 to Hansen et al, which is incorporated herein by reference.

In some embodiments, it may be desirable to interground natural pozzolan with bauxite to increase aluminate content and early strength.

In some embodiments, it may be desirable to incorporate one or more additives, such as amines, accelerators, alkali metal salts, calcium salts, lime, gypsum, salts of weak acids, citric acid, and tartaric acid, during or after intergrinding.

Natural pozzolans can be blended or interground with silica dust to make an interground material with a higher silica content, which can make the blend more pozzolanic. Alternatively, natural pozzolans can be blended or interground with limestone rock dust to produce a less pozzolanic, more accelerated interground material.

In some embodiments, steel slag may be a useful millable grinding media. It is extremely cheap, hard, expensive to grind, and it itself produces poor quality SCM. However, because it is very hard, it can effectively transfer the abrasive force down to the tiny pozzolan (volcanic ash) particles to further reduce the size.

Cementitious compositions

In some embodiments, the activated pozzolan and cement-SCM compositions disclosed herein can be used as general purpose or special purpose cements to replace OPC and other hydraulic cements known in the art. They may be used as sole or supplemental binders to make concrete, ready mixed concrete, bagged cement, mortar, bagged mortar, grout, bagged grout, oil well cement, molding compositions or other fresh or dry cementitious compositions known in the art. The cement-SCM compositions are useful in the manufacture of concrete and other cementitious compositions including a hydraulic cement binder, water, and aggregates (e.g., fine and coarse aggregates). Mortars typically include cement, water, sand, and lime, and may be sufficiently stiff to support the weight of a brick or concrete block. Oil well cement refers to a cementitious composition that is continuously mixed and pumped into a wellbore. Grout "is used to fill spaces such as cracks or fissures in concrete structures, spaces between structural objects, and spaces between tiles. The moulding compositions are used for the manufacture of moulded or cast objects such as pots, troughs, columns, walls, floors, fountains, ornamental stones and the like.

The activated natural pozzolan may comprise one or more of the following auxiliary components: calcium-based accelerators, e.g. calcium oxide (CaO), calcium chloride (CaCl)₂) Calcium nitrite (Ca (NO)₂)₂) Or calcium nitrate (Ca (NO)₃)₂) And/or alkali metal salts capable of raising the pH of the mixed water, such as sodium hydroxide (NaOH), sodium citrate, or alkali metal salts of other weak acids. The calcium ions provided by the calcium-based set accelerator will not only accelerate the hydration of hydraulic cements (e.g., in cold weather or other situations where increased early strength is desired)Next), they may also advantageously react with silicate ions in the pozzolan to form additional cement binder products. Alternatively or additionally, the increased pH provided by the alkali metal salt may accelerate the pozzolan reaction by accelerating the dissolution of silicate and/or aluminate ions from the pozzolan and making them more reactive with calcium and/or magnesium ions provided by the hydraulic cement portion.

Example IV

The following examples are provided to illustrate exemplary cementitious compositions prepared using interground limestone and natural pozzolan particulate mixtures. Further, examples of cementitious compositions utilizing interground mixtures of limestone and natural pozzolans are set forth in U.S. provisional patent application No.62/337,424 filed 5/17/2016; U.S. provisional patent application No.62/451,533 filed on 27.1.2017; U.S. patent nos. 9,957,196; U.S. provisional patent application No.62/444,736 filed on 10.1.2017; U.S. provisional patent application No.62/451,484 filed on 27.1.2017; us provisional patent application No.62/522,274 filed 2017, month 6, day 20; U.S. patent nos. 10,131,575; us provisional patent application No.16/028,398 filed on 5.7.2018; and us provisional patent application No.16/180,323 filed on 5.11.2018. The above patents and patent applications are incorporated herein by reference.

Example 1

Concrete compositions were prepared using the following components, expressed as amount of concrete per cubic yard.

The concrete composition was cast into 4 x 8 inch cylinders and tested for a 28 day compressive strength of 5200psi, similar to a control concrete containing 564lb of OPC per cubic yard.

Practice ofExample 2

The concrete composition was cast into 4X 8 inch cylinders and tested for a 28 day compressive strength of 4450 psi.

Example 3

The concrete composition was mixed with superplasticizer, air entraining agent and viscosity modifier to form concrete, cast into 4 x 8 inch cylinders and found to have a 28 day compressive strength of 7940 psi.

Example 4

The concrete composition was mixed with superplasticizer, air entraining agent and viscosity modifier to form concrete, cast into 4 x 8 inch cylinders and found to have a 28 day compressive strength of 7950 psi.

Example 5

The concrete composition was cast into 4 x 8 inch cylinders and tested for a 28 day compressive strength of 4440 psi.

Example 6

Mortar cube compositions were prepared using the following components.

The mortar cube composition was cast into a 2 x 2 inch cube and tested for a 28 day compressive strength of 6470 psi.

Example 7

Mortar cube compositions were prepared using the following components.

The mortar cube composition was cast into a 2 x 2 inch cube and tested for a 28 day compressive strength of 6950 psi.

Example 8

Mortar cube compositions were prepared using the following components.

The mortar cube composition was cast into a 2 x 2 inch cube and tested for 6780psi compressive strength over 28 days.

Example 9

Mortar cube compositions were prepared using the following components.

The mortar cube composition was cast into a 2 x 2 inch cube and tested for a 28 day compressive strength of 7250 psi.

Example 10

Mortar cube compositions were prepared using the following components.

The mortar cube composition was cast into 2 x 2 inch cubes and tested for 5795psi compressive strength for 28 days.

Example 11

Mortar cube compositions were prepared using the following components.

The mortar cube composition was cast into a 2 x 2 inch cube and tested for 6705psi 28 day compressive strength.

Example 12

Mortar cube compositions were prepared using the following components.

The mortar cube composition was cast into a 2 x 2 inch cube and tested for 6550psi compressive strength over 28 days.

Example 13

Mortar cube compositions were prepared using the following components.

Example 14

Mortar cube compositions were prepared using the following components.

The mortar cube composition was cast into a 2 x 2 inch cube and tested for compressive strength of 6710psi over 28 days.

Example 15

Mortar cube compositions were prepared using the following components.

The mortar cube composition was mixed with a superplasticizer and cast into a 2 x 2 inch cube for testing at 9155psi compressive strength for 28 days.

Example 16

Mortar cube compositions were prepared using the following components.

The mortar cube composition was mixed with a low efficiency water reducer and cast into 2 x 2 inch cubes which were tested for 8040psi 28 day compressive strength.

Example 17

Mortar cube compositions were prepared using the following components.

The mortar cube composition was mixed with a low efficiency water reducer and cast into 2 x 2 inch cubes which were tested for a 28 day compressive strength of 7915 psi.

Example 18

Mortar cube compositions were prepared using the following components.

The mortar cube composition was mixed with a superplasticizer and cast into 2 x 2 inch cubes which were tested for a 28 day compressive strength of 12,315 psi.

Example 19

Mortar cube compositions were prepared using the following components.

The mortar cube composition was mixed with a superplasticizer and cast into 2 x 2 inch cubes which were tested for a 28 day compressive strength of 9735 psi.

Example 20

Mortar cube compositions were prepared using the following components.

The mortar cube composition was mixed with a superplasticizer and cast into 2 x 2 inch cubes which were tested for a 28 day compressive strength of 7520 psi.

Example 21

Mortar cube compositions were prepared using the following components.

The mortar cube composition was mixed with a superplasticizer and cast into 2 x 2 inch cubes which were tested for a 28 day compressive strength of 7290 psi.

Example 22

Mortar cube compositions were prepared using the following components.

The mortar cube composition was mixed with a superplasticizer and cast into 2 x 2 inch cubes which were tested for a 28 day compressive strength of 10,670 psi.

Example 23

Mortar cube compositions were prepared using the following components.

The mortar cube composition was mixed with a superplasticizer and cast into 2 x 2 inch cubes which were tested for a 28 day compressive strength of 12,860 psi.

Example 24

Ready-mixed concrete compositions were prepared using the following components, expressed as amount of concrete per cubic yard.

The concrete compositions were prepared in a concrete mixer/transporter having a slump of 6 inches. Most of the composition was cast as a portion of a 6 inch thick railroad slab and reinforced with rebar. The concrete has similar casting and finishing properties to conventional concrete and is ready for final finishing within about 2-3 hours after casting. The concrete panels were exposed to periodic freeze-thaw cycles and were motored throughout the winter, showing no signs of flaking or other damage.

A portion of the concrete composition was cast into 4X 8 inch cylinders and tested for 4000psi compressive strength for 28 days and 4500psi compressive strength for 91 days. Although the strength is less than expected, this may be due to the combined use of air entraining agent and water reducing agent resulting in excessive air entrainment.

Example 25

The concrete compositions were prepared in a concrete mixer/transporter having a slump of 6 inches. Most of the composition was cast as a portion of a 6 inch thick railroad slab and reinforced with rebar. The concrete has similar casting and finishing properties to conventional concrete and is ready for final finishing within about 2-3 hours after casting. The cost savings of $10.73 per cubic yard compared to a commercial mix designed to have a strength of 4500psi and a slump of 4 inches. The concrete panels were exposed to periodic freeze-thaw cycles and were motored throughout the winter, showing no signs of flaking or other damage.

A portion of the concrete composition was cast into 4X 8 inch cylinders and tested for 4270psi compressive strength for 28 days and 5270psi compressive strength for 56 days. The lower strength is due to the higher slump obtained by adding more water. By 56 days, the strength far exceeded the design strength. Strength can be improved by increasing the ratio of coarse to fine aggregate.

Claims

1. A method of increasing the pozzolanic activity of a natural pozzolan, comprising:

intergrinding natural pozzolans with an ancillary cementitious material (SCM) selected from limestone, granulated blast furnace slag, steel slag, other metallurgical slags, fine aggregates, medium aggregates, shales, geological materials, waste glass, glass fragments, glass beads, basalt, sinter, ceramics, recycled bricks, recycled concrete, porcelain, used catalyst particles, refractory materials, other waste industrial products, sand, gypsum, bauxite, calcite, dolomite, granite, volcanic rock, volcanic glass, quartz, fused quartz, natural minerals, and combinations thereof, to form an interground particulate material, characterized in that:

the natural pozzolan has an initial water content, and

the interground particulate material has a moisture content less than the initial moisture content and less than 0.5%.

2. A method according to claim 1, wherein the SCM is particulate, having particles of a size of at least 1mm, such as a size of at least 2mm or at least 3 mm.

3. A method according to claim 1 or 2, wherein the natural pozzolan has an initial moisture content of at least 3%, such as at least 5%, 7.5%, 10%, 15%, 20% or 25%.

4. The method of any one of claims 1 to 3, wherein the intergrinding is performed at least in part by at least one of a vertical roller mill, a high pressure grinding roller, a horizontal roller press, a ball mill, a rod mill, a hammer mill, a jaw mill, a Raymond mill, a jet mill, a dry bead mill, or an ultrasonic crushing mill.

5. The method of any one of claims 1 to 4, wherein the natural pozzolan has an initial particle size of less than 1mm prior to intergrinding.

6. The method according to any one of claims 1 to 5, characterized in that:

the interground particle mixture has a d90 of 45 μm or less, for example 40 μm, 35 μm, 30 μm, 25 μm, 20 μm, 17.5 μm, 15 μm, 13 μm or 11 μm,

the interground particle mixture has a d50 of 18 μm or less, for example 16 μm, 14.5 μm, 13 μm, 12 μm, 11 μm, 10 μm, 9 μm, 8 μm or 7 μm, and

the interground particle mixture has a d10 of 5 μm or less, for example 4.5 μm, 4 μm, 3.5 μm, 3 μm, 2.75 μm, 2.5 μm, 2.25 μm, 2 μm, 1.75 μm, 1.5 μm, 1.35 μm, 1.25 μm, 1.15 μm, 1.07 μm or 1 μm.

7. The method of any one of claims 1 to 6 further comprising combining the interground particulate material with at least one auxiliary particulate component that is not interground with the interground particulate material, the auxiliary particulate component being selected from the group consisting of fly ash, bottom ash, ground granulated blast furnace slag, ground pumice, metakaolin, calcined clay, microsilica, and silica fume.

8. The method of any one of claims 1 to 7, further comprising combining the interground particulate material with at least one additive selected from the group consisting of a blend, an amine, an accelerator, an alkali metal salt, a calcium salt such as calcium oxide, calcium chloride, calcium nitrite, or calcium nitrate, lime, gypsum, a weak acid salt such as sodium citrate or a weak acid alkali metal salt, and citric acid.

9. The method of any one of claims 1 to 8, further comprising mixing the interground particulate material with a graded fly ash, such as ultrafine fly ash, fine fly ash, or coarse dusting fly ash.

10. An interground particulate mixture made according to any one of claims 1 to 9.

11. The interground particle mixture of claim 10, wherein the interground particle mixture has a d50 of 16 μm or less and a d10 of 2.5 μm or less.

12. A cementitious binder composition prepared by mixing the interground particulate mixture of claim 10 or 11 with a binder selected from the group consisting of portland cement, white cement, quick-setting cement, persulfate cement, magnesium silicate cement, magnesium oxychloride cement, oil well cement, calcium aluminate cement, high alumina cement, low CO₂At least one of cement, low C3S and high C2S cement, and geopolymer cement.

13. A cementitious composition formed by combining the cementitious binder of claim 12 with water and aggregate and optionally a superplasticizer, low-effect water reducer, or medium-effect water reducer.

14. A method of activating a natural pozzolan, comprising:

intergrinding natural pozzolans with a particulate material selected from the group consisting of limestone, granulated blast furnace slag, steel slag, other metallurgical slags, fine aggregates, medium aggregates, shales, geological materials, waste glass, glass fragments, glass beads, basalt, sinter, ceramics, recycled bricks, recycled concrete, porcelain, used catalyst particles, refractory materials, other waste industrial products, sand, gypsum, bauxite, calcite, dolomite, granite, volcanic rock, volcanic glass, quartz, fused quartz, natural minerals, and combinations thereof, to form an interground particulate material, characterized in that:

the particulate material comprises particles having a size of at least 1mm, for example a size of at least 2mm or at least 3mm, and

the initial particle size of the natural volcanic ash is less than 1 mm.

15. The method of claim 14, wherein:

the natural pozzolan has an initial moisture content of at least 3%, such as at least 5%, 7.5%, 10%, 15%, 20%, or 25%, and

the interground particulate material has a moisture content of at least 0.5%.