A method for conversion of recycled concrete and other mineral construction, mining and metallurgical waste into reactive supplementary cementitious material

Abstract

There is disclosed a process for converting concrete obtained from construction and demolition waste (CDW) and / or from returned concrete (RC) from ready mix concrete trucks and / or other mineral materials into reactive supplementary cementitious materials. The process comprises obtaining crushed recycled concrete, in the form of recycled concrete aggregates (RCA) and fine recycled concrete aggregates (FRCA), and / or crushed mineral material other than recycled concrete. The process further comprises subjecting the recycled concrete and / or the crushed mineral material to one or both of (i) mechanical calcination, and (ii) dry coating with SSCM, to form the reactive (pozzolanic or hydraulic) SCM.

Description

A METHOD FOR CONVERSION OF RECYCLED CONCRETE AND OTHER MINERAL CONSTRUCTION, MINING AND METALLURGICAL WASTE INTO REACTIVE SUPPLEMENTARY CEMENTITIOUS MATERIALTECHNICAL FIELD

[0001] The following generally relates to concrete recycling, and more particularly, to a method for conversion of recycled concrete aggregates (RCA) obtained from Construction and Demolition Waste (CDW) and / or returned concrete (RC) from ready mix concrete trucks and / or other mineral material into reactive Supplementary Cementitious Material (SCM).BACKGROUND

[0002] Concrete recycling is the use of rubble from demolished concrete structures, and the recycling of concrete aggregates produced from crushed Construction and Demolition Waste (CDW), primarily consisting of concrete.

[0003] Generally, strength parameters from recycled-concrete aggregates are consistently somewhat lower than natural aggregates, recycled concrete aggregates (RCA) have played an important role in replacing natural aggregates in concrete production; thereby contributing to a reduction in the extraction of natural resources and the promotion of a circular economy.

[0004] One of the massive by-products of concrete recycling is the crushed concrete fines (0 mm to 4 - 5 mm) reaching the amount of 30 to 50% of the whole mass of crushed concrete. While RCA (> 4 - 5 mm) is a practical reality in concrete production, there is generally no high-quality application for fines, or fine recycled concrete aggregates (FRCA), due to their low density and mechanical strength, high water absorption, and the presence of impurities such as cement paste.

[0005] FRCA is typically considered as a two-phase material including aggregates, such as old sand, and binder, such as old mortar glued together. In particular, FRCA from conventional concrete consisting of coarse (gravel, crushed stone, etc.) and fine (sand) aggregates and cement are considered as two-phase materials. The old mortar attached to the fine particles builds a weak porous layer on their surface and subsequently creates a fragile interface transition zone preventing bonding between the cementitious concrete matrix and the fines, and overall reduces the strength of concrete. Also, it has been observed that RCA and FRCA made from high performance and various types of special concretes also include glued together aggregates comprising silica fume, fly ash and other materials used in production of said special concretes.It has been further observed that upgradation or enrichment of FRCA for their use in concrete production requires the separation of the agglomerated (glued together) components included in the composition of the FRCA particles.

[0006] Taking into consideration the significant importance of preserving natural resources, reduction of CO2 emissions and considering FRCA as a valuable resource and not as a waste, some attempts have been made to recycle FRCA into valuable products like hardened cement and clean sand. However, none of said attempts have been deemed generally accepted by industry for generating clean FRCA to further produce products.SUMMARY OF THE INVENTION

[0007] In an aspect, there is provided a method for converting concrete into reactive supplementary cementitious material (SCM).

[0008] In an aspect, the method comprises receiving the concrete in the form of at least one of construction and demolition waste (CDW) and returned concrete (RC) from a ready-mix concrete truck, as to form recycled concrete; subjecting the recycled concrete to a crushing treatment to form recycled concrete aggregates (RCA); and subjecting the RCA to a mechano- thermo-chemical activation treatment to form the reactive SCM.

[0009] It will be appreciated that mechano-thermo-chemical activation may alternatively be referred to as mechanical calcination.

[0010] In an aspect, a method of converting recycled concrete obtained from Construction and Demolition Waste (CDW) and / or from returned concrete (RC) to Supplementary Cementitious Material (SCM), and more particularly to a process of converting fine recycled concrete aggregates (hereinafter referred to as FRCA) obtained in the process of preparing recycled concrete aggregates from CDW and / or from RC into reactive SCM is disclosed.

[0011] In some examples, the method of converting recycled concrete obtained from CDW and / or from RC in the form of RCA to a reactive, in particular pozzolanic or hydraulic, SCM comprises obtaining crushed CDW and / or RC in the form of RCA by subjecting the CDW and / or RC to a crushing treatment. The method further comprises screening FRCA from the obtained RCA, where a prescribed particle size is screened as FRCA. Further, the method comprises subjecting the screened FRCA to a mechanical calcination to obtain reactive (pozzolanic or hydraulic) SCM.

[0012] In some cases, a prescribed amount of Standard Supplementary Cementitious Materials (SSCMs) is added to FRCA before or in the process of its mechanical calcination to obtain new reactive (pozzolanic or hydraulic) SCM.

[0013] In some cases, a prescribed amount of Standard Supplementary Cementitious Materials (SSCMs) is added to FRCA before or in the process of surface activation thereof by coating the FRCA particles with the smaller SSCMs particles without using mechanical calcination process.

[0014] In some cases, the SSCMs are selected from a group comprising fly ash, slag cement, silica fume, metakaolin, and calcinated shale. In other cases, other commonly available SCMs may also be used.

[0015] In some cases, the prescribed amount of SSCMs is between 5% and 50% by weight of FRCA.

[0016] In some cases, the prescribed amount of SSCMs is between 10% and 20% by weight of FRCA.

[0017] In some examples, screening is performed on the RCA using a screen or filter having a prescribed sieve size between 3 and 7 millimetres as to separate out FRCA sized less than or equal to the prescribed sieve size, thus forming FRCA of the prescribed particle size.

[0018] In some examples, screening is performed using on the RCA using a screen or filter having a prescribed sieve size between 4 and 5 millimetres as to separate out RCA sized less than or equal to the prescribed sieve size, thus forming FRCA of the prescribed particle size.

[0019] In some examples, ultrafine screening is performed using on the RCA using a screen or filter having a prescribed sieve size between 0.1 and 1 millimetres as to separate out RCA sized less than or equal to the prescribed sieve size, thus forming FRCA of the prescribed particle size.

[0020] In some examples, the screening is carried out with vibratory screens, the vibratory screens separate the finer grains FRCA from the larger, gravel-like RCA.

[0021] In some examples, the remaining larger RCA particles are either re-processed and crushed down, or used as it is for mechanical calcination.

[0022] In another example, the method of converting CDW to a reactive, in particular pozzolanic or hydraulic SCM comprises forming RCA by subjecting the CDW to a crushing treatment, and subjecting the RCA to mechanical calcination to form reactive (pozzolanic orhydraulic) SCM.

[0023] In some cases, a certain amount of known SSCMs is added to RCA before or in the process of its mechanical calcination and, in some cases, of its further mechanical calcinationsynthesis, to form new reactive (pozzolanic or hydraulic) SCM.

[0024] In some cases, a certain amount of known SSCMs is added to RCA before or in the process of its surface activation by coating the RCA particles with the smaller SSCMs particles to form new reactive SCM without mechanical calcination of the RCA.

[0025] In another aspect, there is provided a method for converting concrete into reactive SCM, comprising: receiving the concrete in the form of at least one of (i) construction and demolition waste (CDW) and (ii) returned concrete (RC) from a ready-mix concrete truck, as to form recycled concrete; subjecting the recycled concrete to a crushing treatment to form recycled concrete aggregates (RCA); and subjecting the RCA to one or both of (i) mechanical calcination, and (ii) dry coating with standard supplementary cementitious materials (SSCM), as to form the reactive SCM.

[0026] In another aspect, there is provided a method of converting mineral material into reactive supplementary cementitious material (SCM). The method comprises subjecting the mineral material to a crushing treatment to form crushed mineral material; and subjecting the crushed mineral material to a mechanical calcination to form the reactive SCM. For example, the mineral material may be mineral construction, tunneling, mining and metallurgical waste.

[0027] In another aspect, there is provided a method of converting mineral material, such as mineral construction, tunneling, mining and metallurgical waste into reactive supplementary cementitious material (SCM). The method comprises subjecting the mineral material to a crushing treatment to form crushed mineral material; and subjecting the crushed mineral material to a mechanical calcination with addition of a certain amount of known SSCMs to the mineral material before or in the process of its mechanical calcination to form new reactive (pozzolanic or hydraulic) SCM.

[0028] In another aspect, there is provided a method of converting mineral material, such as mineral construction, tunneling, mining and metallurgical waste (slag) into reactive supplementary cementitious material (SCM). The method comprises subjecting the mineral material to a crushing treatment to form crushed mineral material, adding a certain amount of known SSCMs to the crushed mineral material and subjecting the crushed mineral material to surface activation by dry coating the crushed mineral material particles with the smaller SSCMs particles without usingmechanical calcination to form new reactive SCM.

[0029] In some cases, the SSCMs are selected a group comprising fly ash, slag cement, silica fume, metakaolin, and calcinated shale. In other cases, other commonly available SCMs may be used.

[0030] In some cases, the prescribed amount of SSCMs is between 5% and 50% by weight of the crushed mineral material.

[0031] In some cases, the prescribed amount of SSCMs is between 10% and 20% by weight of the crushed mineral material.

[0032] In various examples, the crushing treatment may be carried out, for example, via jaw crushers, impact crushers, twin-shaft crushers or any other type of crushers used in concrete recycling plants.

[0033] In a specific example, the mineral material is Georgian Bay shale which is a multi-phase material containing siltstone / sandstone and limestone.

[0034] In some examples, the mineral material is selected from clay minerals and shale comprising quartz, calcite, kaolinite, montmorillonite, chert, dolomite, ankerite, muscovite, illite, bentonite, pyrophyllite, chlorite, zeolite, feldspar, and other commonly available natural mineral materials, and mineral construction, tunneling, mining and metallurgical waste.

[0035] In some examples, the known SSCMs are fly ash, slag cement, silica fume, metakaolin, calcinated shale, and other commonly available SCMs.

[0036] In some examples, the mechanical calcination of FRCA, RCA or the mineral material other than RCA, FRCA is carried out using an energy-intensive grinding mill.

[0037] In some examples, the energy-intensive grinding mill comprises a mill with loose grinding media, such as a vibratory ball / rod mill, a planetary ball mill and a stirred media mill as well as a high-peripheral-speed mill (high speed disintegrator).

[0038] In a specific example, the stirred media mill is used for mechanical calcination of FRCA / RCA and other mineral material. Examples of a stirred media mill may include, but are not limited to a vertical mill, such as Attritor mill, Stirred Media Detritor, Tower mill, VertiMill, MaxxMill, and a horizontal mill, such as IssaMill, Polysius® booster mill and other similar mills. In some cases, the above stirred media mill may be pressurized with various gases.

[0039] Examples of a high-peripheral-speed mill (high speed disintegrator, high speed rotormill) include a pin mill with special wear resistant grinding tools and, preferably, turbo mill.

[0040] In some examples, the mill with loose grinding media for converting FRCA / RCA or mineral material other than RCA, FRCA into reactive SCM has a power density ranging from 10 to 500 kW / m3. In some examples, the mill with loose grinding media has a power density ranging from 20 to 250 kW / m3. In some examples, the high-peripheral-speed mill for converting FRCA / RCA or inert mineral material other than FRCA / RCA into reactive SCM has rotor speed ranging from 1 ,800 rpm up to 26,000 rpm. In various examples, a predetermined specific grinding energy required to be generated in the energy-intensive grinding mill for mechanical calcination of FRCA / RCA or mineral material other than RCA and FRCA for conversion into reactive (pozzolanic or hydraulic) SCM is above 10 kJ / kg, and preferably in the range from 100 to 40,000 kJ / kg for providing definitely high SCM reactivity.

[0041] In some examples, when the known SSCMs are added to FRCA, RCA or a different mineral material, for surface activation thereof by coating the particles of these materials with smaller particles of the known SSCM’s, especially without mechanical calcination, coating is performed using equipment which uses the principle of combined compression and shear forces or by the principle of combined impact and attrition forces. In other words, such equipment is configured to apply combined compression and shear forces, or combined impact and attrition forces.

[0042] Examples of equipment using the principle of combined compression and shear forces may include but are not limited to a Mix-Muller and other similar high shear mixers, a vertical roller mill (VRM) and other similar mills and examples of equipment using the principle of combined impact and attrition forces may include but are not limited to a rod mill and other similar mills.

[0043] A person of ordinary skill in the art would understand that a type of coating performed in the foregoing examples, cases or aspects, where solid bodies are coated with solid, powdered material, is dry coating.

[0044] Other aspects and features of the present application will become apparent to those ordinarily skilled in the art upon review of the following description of embodiments of the invention in conjunction with the accompanying figures.DESCRIPTION OF THE DRAWINGS

[0045] Reference will now be made to the accompanying drawings which show, by way of example only, embodiments of the invention, and how they may be carried into effect, and inwhich:

[0046] FIG. 1 is a flowchart illustrating a method of converting screened FRCA from crushed recycled concrete obtained from CDW and / or from returned concrete (RC) into reactive SCM, in accordance with an embodiment of the present invention;

[0047] FIG. 2 is a flowchart illustrating a method of converting screened FRCA from crushed recycled concrete obtained from CDW and / or from returned concrete (RC) into reactive SCM, in accordance with another embodiment of the present invention;

[0048] FIG. 3 is a flowchart illustrating a method of converting recycled concrete obtained from CDW and / or from RC into reactive SCMs, in accordance with another embodiment of the present invention;

[0049] FIG. 4 is a flowchart illustrating a method of converting recycled concrete obtained from CDW and / or from RC into reactive SCMs, in accordance with another embodiment of the present invention;

[0050] FIG. 5 is a flowchart illustrating a method of converting recycled concrete obtained from CDW and / or from RC into reactive SCMs, in accordance with another embodiment of the present invention;

[0051] FIG. 6 is a flowchart illustrating a method of converting recycled concrete obtained from CDW and / or from RC into reactive SCMs, in accordance with another embodiment of the present invention;

[0052] FIG. 7 is a flowchart illustrating a method of converting mineral material other than RCA / FRCA into reactive SCMs, in accordance with another embodiment of the present invention;

[0053] FIG. 8 is a flowchart illustrating a method of converting mineral material other than RCA / FRCA into reactive SCMs, in accordance with another embodiment of the present invention;

[0054] FIG. 9 is a flowchart illustrating a method of converting mineral material other than RCA / FRCA into reactive SCMs, in accordance with another embodiment of the present invention;

[0055] FIG. 10 is a plot of chemical reactivity (pozzolanic or hydraulic) of the original and activated recycled concrete (FCRA obtained from CDW after crushing and screening it on an example sieve size 4.76 millimeters) with different levels of activation;

[0056] FIG. 11 is a plot of functional dependency of the processed recycled concrete (FRCAobtained from CDW after crushing and screening it on an example sieve size 4.76 millimeters) chemical reactivity on amounts of specific grinding energy;

[0057] FIG. 12 is a plot of chemical reactivity of the original and activated Georgian Bay shale samples with different levels of activation;

[0058] FIG. 13 is a plot of functional dependency of the processed Georgian Bay shale chemical reactivity on amounts of specific grinding energy;

[0059] FIG. 14 is a plot of chemical reactivity of the original and activated steel slag samples with different levels of activation;

[0060] FIG. 15 is a plot of functional dependency of the processed steel slag chemical reactivity on amounts of specific grinding energy;

[0061] FIGS. 16A and 16B are scanning electron microscopy (SEM) images of the grain of the original recycled concrete obtained from returned concrete at 2,000 times magnification and at 20,000 times magnification, respectively;

[0062] FIGS. 17A and 17B are SEM images of the grain of recycled concrete obtained from recycled returned concrete and activated in accordance with an embodiment of the present invention, shown at 2,000 times magnification and at 10,000 times magnification, respectively;

[0063] FIG. 18 is a plot of flow of mortars with various levels of substitution of cement by activated recycled concrete compared to original mortar without the activated recycled concrete additive (control) in accordance with an embodiment of the present invention;

[0064] FIG. 19 is a plot of air content of mortars with various levels of substitution of cement by activated recycled concrete compared to original mortar without the activated recycled concrete additive (control) in accordance with an embodiment of the present invention;

[0065] FIG. 20 is a plot of compressive strength of mortars with various levels of substitution of cement by activated recycled concrete compared to original mortar without the activated recycled concrete additive (control) in accordance with an embodiment of the present invention;

[0066] FIG. 21 is a plot of bulk resistivity of mortars with various levels of substitution of cement by activated recycled concrete compared to original mortar without the activated recycled concrete additive (control) in accordance with an embodiment of the present invention;

[0067] FIG. 22 is a plot of flow of mortars with various levels of substitution of cement by activated Georgian Bay shale compared to original mortar without the activated shale additive (control) in accordance with an embodiment of the present invention;

[0068] FIG. 23 is a plot of air content of mortars with various levels of substitution of cement by activated Georgian Bay shale compared to original mortar without the activated shale additive (control) in accordance with an embodiment of the present invention;

[0069] FIG. 24 is a plot of compressive strength of mortars with various levels of substitution of cement by activated Georgian Bay shale compared to original mortar without the activated shale additive (control) in accordance with an embodiment of the present invention;

[0070] FIG. 25 is a plot of bulk resistivity of mortars with various levels of substitution of cement by activated Georgian Bay shale compared to original mortar without the activated shale additive (control) in accordance with an embodiment of the present invention;

[0071] FIG. 26 is a plot of flow of mortars with various levels of substitution of cement by activated steel slag compared to original mortar without the activated slag additive (control) in accordance with an embodiment of the present invention;

[0072] FIG. 27 is a plot of air content of mortars with various levels of substitution of cement by activated steel slag compared to original mortar without the activated slag additive (control) in accordance with an embodiment of the present invention;

[0073] FIG. 28 is a plot of compressive strength of mortars with various levels of substitution of cement by activated steel slag compared to original mortar without the activated slag additive (control) in accordance with an embodiment of the present invention; and

[0074] FIG. 29 is a plot of bulk resistivity of mortars with various levels of substitution of cement by activated steel slag compared to original mortar without the activated slag additive (control) in accordance with an embodiment of the present invention.DETAILED DESCRIPTION

[0075] The disclosure is provided in order to enable a person having ordinary skill in the art to practice the invention. Exemplary embodiments herein are provided only for illustrative purposes and various modifications will be readily apparent to persons skilled in the art. The general principles defined herein may be applied to other embodiments and applications without departingfrom the scope described herein. The terminology and phraseology used herein is for the purpose of describing exemplary embodiments and should not be considered limiting. Thus, the present disclosure is to be accorded the widest scope encompassing numerous alternatives, modifications, and equivalents consistent with the principles and features disclosed herein. For purposes of clarity, details relating to technical material that is known in the technical fields related to what is described herein have been briefly described or omitted so as not to unnecessarily obscure the present disclosure.

[0076] Various terms used throughout the present description may be read and understood as follows, unless the context indicates otherwise: singular articles and pronouns as used throughout include their plural forms, and vice versa; similarly, gendered pronouns include their counterpart pronouns so that pronouns should not be understood as limiting anything described herein to use, implementation, performance, etc. by a single gender; “exemplary” should be understood as “illustrative” or “exemplifying” and not necessarily as “preferred” over other embodiments. It is to be noted that, as used in the present description, by the term “substantially” it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those skilled in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide. Further definitions for terms may be set out herein; these may apply to prior and subsequent instances of those terms, as will be understood from a reading of the present description.

[0077] For simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the Figures to indicate corresponding or analogous steps of the process. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiments described herein.

[0078] Various studies have been conducted for recycling of FRCA into valuable products, like hardened cement and clean sand, are described herein. These studies can be divided into three general groups: thermal, chemical, and mechanical, or a combination thereof.

[0079] In thermal excitation, FRCA are heated to a high temperature to dehydrate the hydration products so that more active components can be produced and added to mortar replacing part of cement [see, for example, Y. Sui, C. Ou, S. Liu, J. Zhang, Q. Tian, Study on properties of waste concrete powder by thermal treatment and application in mortar, Appl. Sci. 10 (2020) 998,https: / / doi.org / 10.3390 / app10030998] or, as per another option a new recycled Portland cement clinker can be produced from the FRCA by the thermal treatment [see, for example, S. Zhutovsky, A. Shishkin, Recycling of hydrated Portland cement paste into new clinker, Construction and Building Materials 280 (2021)] https: / / doi.Org / 10.1016 / j.conbuildmat.2021.122510], However, thermal processes requiring the use of fuel are environmentally unfriendly since they inevitably release carbon dioxide. Furthermore, the process is relatively inefficient, as demonstrated by the present inventors.

[0080] The mechanical processes and combination of mechanical and thermal treatments [see, for example, Lotfi, S., & Rem, P. (2016) and recycling of End of Life Concrete Fines into Hardened Cement and Clean Sand. Journal of Environmental Protection, 7, 934-950. https: / / doi.org / 10.4236 / jep.2016.76083] are mainly aimed at milling the FRCA (in a regular ball mill) with its preheating (in heating air system) so that it can be used as an inert additive to cement in concrete production. Thermal energy in this case is used mostly to dry the material, and mechanical energy is used to grind it. Efficiency of such mechanical processes, even if it is sometimes called “activation”, is evaluated by specific area of grinded filler and its cleanness and not its reactivity.

[0081] Chemical treatment [see, for example, Z. Prosek, V. Nezerka, R. Hluzek, J. Trejbal, P. Tesarek, G. Karra’a, Role of lime, fly ash, and slag in cement pastes containing recycled concrete fines, Construction and Building Materials 201 (2019) 702-714. https: / / doi.Org / 10.1016 / j.conbuildmat.2018.12.227] uses conversion of inert FRCA into reactive SCM. However, these chemical treatment processes require additional, sometimes rather expensive, chemical materials and may be used only in the process of making concrete but not to manufacture reactive SCM in reserve for future use.

[0082] Advantageously, embodiments of the present invention, by optimizing energy input of an energy-intensive grinding mill, enable preparation of reactive SCMs from recycled concrete in form of recycled concrete aggregates (RCA) and fine recycled concrete aggregates (FRCA) obtained from CDW and RC.

[0083] The optimized mechanical energy input of the grinding mill causes heating of the mineral material being processed and the combined effect of mechanical and thermal energies on the material causes its chemical activation; the process to be described as mechano-thermo- chemical activation, or mechanical calcination of initially inert mineral material such as FRCA and / or RCA by inducing structural disorder, amorphization and increased chemical reactivity inthe mineral crystals of the recycled concrete. In some cases, preparation of reactive SCMs from inert mineral materials other than recycled concrete is also provided. Embodiments of the present invention advantageously afford conversion of recycled concrete in form of FRCA and / or RCA and of mineral materials other than recycled concrete into a usable product by a simple mechano- thermo-chemical activation, in other words mechanical calcination, of the above materials, or by addition of a certain amount of known Standard Supplementary Cementitious Materials (SSCMs) into the above materials and mechanical calcination of these materials in presence of the SSCM. The present inventors found that when SSCMs are added to the mechanical calcination process, the smaller particles of the added SSCMs coat larger particles of the processed mineral material. In this case, mechanical calcination on the one hand changes crystalline structure of the particles of the processed mineral material causing its activation, and, on the other hand, coating of these particles with highly reactive SSCM creates a highly reactive layer on the surface of the mineral particles causing their additional activation. The discovery of this phenomenon allowed the present inventors to suggest that dry coating of the inert mineral particles with reactive SSCM even alone, without activation of the mineral material by mechanical calcination, can cause a certain surface activation of the mineral material. In this case, the particles of the mineral material, which are essentially inert, act as carriers of reactive SSCM and as a whole become reactive themselves.

[0084] Referring to FIG. 1, a flowchart illustrating a method for converting concrete from construction and demolition waste (CDW) and / or from returned concrete (RC) into reactive SCMs is shown, in accordance with an embodiment of the present invention.

[0085] At block 100 recycled concrete comprising at least one of CDW and RC is provided, that is, recycled concrete comprising CDW and / or RC. In other words, this block represents a step of receiving concrete in the form of at least one of CDW and RC, as to form recycled concrete.

[0086] It will be appreciated that typically, in practice or in industry, CDW and RC are processed separately in the process for converting concrete to reactive SCM, that is, they are not provided as a mixed or combined input material at the receiving step of the novel process.

[0087] At block 101 , crushed recycled concrete in the form of RCA and FRCA is obtained from CDW and / or crushed RC. In an example, the recycled concrete from CDW and / or RC is obtained and crushed recycled concrete from CDW and / or RC is obtained, in the form of RCA and FRCA, by subjecting the recycled concrete from CDW and / or RC to a crushing treatment. The crushing treatment may be carried out via jaw crushers, impact crushers, twin-shaft crushers, or any othertype of crushers used in concrete recycling. The crushed CDW generally comprises RCA and FRCA.

[0088] At block 102, FRCA is screened from the crushed recycled concrete obtained or derived from CDW and / or RC. In some examples, the screening is carried out with vibratory screens. In an illustrative example, particles that have a size of less than 4 - 5 mm in the crushed recycled concrete from CDW and / or from crushed RC, in the form of RCA, are screened as FRCA. The vibratory screens separate the finer grains FRCA (with particle size, for example, less than 4 - 5 mm) from the larger, gravel-like RCA (with particle size, for example, more than 4 - 5 mm). In some cases, the remaining larger RCA particles can be either used as a final product or reprocessed and crushed down, or used as is for mechanical calcination as described herein with reference to FIG. 4 and FIG. 5.

[0089] In some examples, the FRCA is screened with a screen or filter having a prescribed sieve size between 3 and 7 millimetres and in some examples, the FRCA is screened with a screen or filter having a prescribed sieve size between 0.1 and 1 millimetres. In a preferred example, the FRCA is screened with a prescribed sieve size between 4 and 5 millimetres.

[0090] At block 103, the screened FRCA is subjected to mechanical calcination to obtain reactive (pozzolanic or hydraulic) SCM. The mechanical calcination of FRCA can be carried out, for example, using an energy-intensive grinding mill. In various examples, the energy-intensive mill is operated at predetermined mill power for a predetermined time to produce predetermined energy. The produced predetermined specific grinding energy, initiating mechanical calcination of the FRCA, causes chemical activation of the FRCA (which is initially inert) to convert it into a reactive FRCA. In operation, the predetermined specific grinding energy released by operating the energy-intensive mill at predetermined mill power for a predetermined time induces a series of strong impacts. These may be constrained impacts when material particles are caught between two grinding media (usually balls) and subjected to stroke between the grinding media or between grinding media and wall, or collision when materials particles are subjected to hits (free impact) by grinding tool moving at high speed. Local temperature in the collision zone of grinding balls during their impact, and consequently temperature of the material particles caught between two grinding balls and between grinding balls and mill wall (or material particles subjected to hits by grinding tool moving at high speed), rise significantly in and for a very short time. The produced impacts combined with high temperature causes generation of crystal lattice defects or other metastable forms in the mineral particle (i.e. , the FRCA particle), thereby converting initially inert FRCA into a reactive material. This reactive material can be further used as a reactive (pozzolanicor hydraulic) SCM.

[0091] In some examples, the energy-intensive grinding mill comprises a mill with loose grinding media, such as a vibratory ball / rod mill, a planetary ball mill and a stirred media mill, as well as a high-peripheral-speed mill (high speed disintegrator). In some examples, the mill with loose grinding media has a power density ranging from 10 to 500 kW / m3. In a preferred example, the mill with loose grinding media has a power density ranging from 20 to 250 kW / m3.

[0092] In a specific example, the stirred media mill is used for mechanical calcination of FRCA. Examples of the stirred media mill may include, but are not limited to, a vertical mill, such as Attritor mill, Stirred Media Detritor, Tower mill, VertiMill, MaxxMill, and a horizontal mill, such as IssaMill, Polysius® booster mill and other similar mills.

[0093] Examples of the high-peripheral-speed mill, also referred to as a high speed disintegrator or high speed rotor mill, include a pin mill with special wear resistant grinding tools and, preferably, a turbo mill. In some examples, the high-peripheral-speed mill has a rotor speed ranging from 1 ,800 rpm up to 26,000 rpm.

[0094] In various examples, the predetermined energy generated in the energy-intensive grinding mill for mechanical calcination of FRCA and its conversion into reactive (pozzolanic or hydraulic) SCM is above 10 kJ / kg, and preferably in the range from 100 to 40,000 kJ / kg for providing definitely high SCM reactivity. However, as understood by a person skilled in the art, different mills will have different mill speeds and other various parameters.

[0095] Referring to FIG. 2, a flowchart illustrating a method for converting concrete from construction and demolition waste (CDW) and / or from returned concrete (RC) into reactive SCMs is shown, in accordance with another embodiment of the present invention.

[0096] At block 200 concrete from CDW and / or RC is provided, as to form recycled concrete.

[0097] At block 201 , crushed recycled concrete from CDW and / or RC in the form of RCA and FRCA is obtained. In an example, the recycled concrete from CDW and / or RC is obtained and crushed recycled concrete from CDW and / or RC is obtained, in the form of RCA and FRCA, by subjecting the recycled concrete from CDW and / or RC to a crushing treatment. The crushing treatment may be carried out via jaw crushers, impact crushers, twin-shaft crushers, or any other type of crushers used in concrete recycling. The crushed CDW generally comprises RCA and FRCA.

[0098] At block 202, FRCA is screened from the crushed recycled concrete. In someexamples, the screening is carried out with vibratory screens. In an illustrative example, particles that have a size of less than 4 - 5 mm in the crushed recycled concrete in the form of RCA, are screened as FRCA. The vibratory screens separate the finer grains FRCA (with particle size for example less than 4 - 5 mm) from the larger, gravel-like RCA (with particle size for example more than 4 - 5 mm). In some cases, the remaining larger RCA particles can be either used as a final product or re-processed and crushed down, or used as is for mechanical calcination as described herein with reference to FIG. 4 and FIG. 5.

[0099] In some examples, the FRCA is screened with a screen or filter having a prescribed sieve size between 3 and 7 millimetres and in some examples, the FRCA is screened with a screen or filter having a prescribed sieve size between 0.1 and 1 millimetres. In a preferred example, the FRCA is screened with a prescribed sieve size between 4 and 5 millimetres.

[0100] At block 203 Standard Supplementary Cementitious Material (SSCM) is provided and added to the screened FRCA.

[0101] At block 204, the screened FRCA together with the added SSCM, which SSCM has particles sized in the order of three - four orders of magnitude smaller than the particles of the FRCA, is subjected to mechanical calcination to obtain reactive (for example, pozzolanic or hydraulic) SCM. In the process of mechanical calcination, the particles of the FRCA are not only crushed and activated in their entire volume but also covered with ultra- fine particles of the SSCM. In other words, in the mechanical calcination process, the FRCA particles are coated with the SSCM such that there are at least partial layers of SSCM on respective FRCA particles as to cover the same. In this way at block 204 the screened FRCA subjected to mechanical calcination and dry coating with SSCM. That is, when both mechanical calcination and dry coating are performed, they are performed simultaneously in a common equipment as a single treatment.

[0102] In some examples, a prescribed amount of SSCM which is added to the FRCA is from 5 to 10 weight percent of amount of the FRCA to provide partial coating of the FRCA particles by the SSCM particles. In some examples, the prescribed amount of SSCM is from 10 to 50 weight percent of amount of the FRCA for complete mono- or multilayer coating of the FRCA particles by the SSCM particles. In a preferred example, the amount of SSCM is from 10 to 20 weight percent of amount of the FRCA for complete monolayer and partially monolayer coating of the FRCA particles by the SSCM particles. Thus, in general, the prescribed amount of SSCM is between 5% and 50% by weight of the crushed recycled concrete, as to provide at least partial coating with SSCM.

[0103] The mechanical calcination and coating of the FRCA can be carried out, for example, using an energy-intensive grinding mill. In various examples, the energy-intensive mill is operated at predetermined mill power for a predetermined time to produce predetermined energy. The produced predetermined specific grinding energy, initiating mechanical calcination of the FRCA, causes chemical activation of the FRCA (which is initially inert) to convert it into a reactive material. In operation, the predetermined specific grinding energy released by operating the energy-intensive mill at predetermined mill power for a predetermined time induces a series of strong impacts. These may be constrained impacts when material particles are caught between two grinding media (usually balls) and subjected to stroke between the grinding media or between grinding media and wall, or collision when materials particles are subjected to hits (free impact) by grinding tool moving at high speed. Local temperature in the collision zone of grinding balls during their impact, and consequently temperature of the material particles caught between two grinding balls and between grinding balls and mill wall (or material particles subjected to hits by grinding tool moving at high speed), rise significantly in and for a very short time. The produced impacts combined with high temperature causes generation of crystal lattice defects or other metastable forms in the mineral particle (i.e. , the FRCA particle), thereby converting inert FRCA into a reactive FRCA. In addition, the FRCA reactivity is increased by coating the FRCA particles with highly reactive SSCM. The reactive FRCA can be further used as a reactive (pozzolanic or hydraulic) SCM.

[0104] In some examples, the energy-intensive grinding mill comprises a mill with loose grinding media, such as a vibratory ball / rod mill, a planetary ball mill and a stirred media mill as well as a high-peripheral-speed mill (high speed disintegrator). In some examples, the mill with loose grinding media has a power density ranging from 10 to 500 kW / m3. In a preferred example, the mill with loose grinding media has a power density ranging from 20 to 250 kW / m3.

[0105] In a specific example, the stirred media mill is used for mechanical calcination of FRCA. Examples of stirred media mills may include, but are not limited to a vertical mill, such as Attritor mill, Stirred Media Detritor, Tower mill, VertiMill, MaxxMill, and a horizontal mill, such as IssaMill, Polysius® booster mill and other similar mills.

[0106] Examples of the high-peripheral-speed mill, also referred to as a high-speed disintegrator or high speed rotor mill, include a pin mill with special wear resistant grinding tools and, preferably, a turbo mill. In some examples, the high-peripheral-speed mill has a rotor speed ranging from 1 ,800 rpm up to 26,000 rpm.

[0107] Referring to FIG. 3, a flowchart illustrating a method for converting concrete from construction and demolition waste (CDW) and / or from returned concrete (RC) into reactive SCMs is shown, in accordance with another embodiment of the present invention.

[0108] At block 300 concrete from CDW and / or RC is provided, as to form recycled concrete.

[0109] At block 301 , crushed recycled concrete from CDW and / or RC in the form of RCA and FRCA is obtained. In an example, the recycled concrete from CDW and / or RC is obtained and crushed recycled concrete from CDW and / or RC is obtained, in the form of RCA and FRCA, by subjecting the recycled concrete from CDW and / or RC to a crushing treatment. The crushing treatment may be carried out via jaw crushers, impact crushers, twin-shaft crushers, or any other type of crushers used in concrete recycling. The crushed CDW generally comprises RCA and FRCA.

[0110] At block 302, FRCA is screened from the crushed recycled concrete. In some examples, the screening is carried out with vibratory screens. In an illustrative example, particles that have a size of less 4 - 5 mm in the crushed recycled concrete in the form of RCA, are screened as FRCA. The vibratory screens separate the finer grains FRCA (with particle size for example between 0.1 - 1 mm) from the larger RCA (with particle size for example less than 4 - 5 mm). In some cases, the remaining larger RCA particles can be either used as a final product or reprocessed and crushed down, or used as is for surface activation by dry coating as described herein with reference to FIG. 6.

[0111] In some examples, the FRCA is screened with a screen or filter having a prescribed sieve size between 3 and 7 millimetres and in some examples, the FRCA is screened with a screen or filter having a prescribed sieve size between 4 and 5 millimetres. In a preferred example, the FRCA is screened with a prescribed sieve size below 4 - 5 millimetres.

[0112] At block 303 Standard Supplementary Cementitious Material (SSCM) is provided and added to the screened FRCA.

[0113] At block 304, the screened FRCA together with the added SSCM, which SSCM has particles sized in the order of three - four orders of magnitude smaller than the particles of the FRCA, is subjected to process of grinding and surface activation of the FRCA particles by dry coating of the larger FRCA particles with smaller reactive SSCM particles to obtain reactive (pozzolanic or hydraulic) SCM. In the process of surface activation, the particles of the FRCA are ground and covered with highly reactive ultra-fine particles of the SSCM. It will be appreciated that grinding as such does not ensure the activation of the particles in their entirety, but theparticles activation occurs by coating them with highly reactive SSCM.

[0114] In some examples, a prescribed amount of SSCM which is added to the FRCA is from 5 to 10 weight percent of amount of the FRCA to provide partial coating of the FRCA particles by the SSCM particles. In some examples, the prescribed amount of SSCM is from 10 to 50 weight percent of amount of the FRCA for complete mono- or multilayer coating of the FRCA particles by the SSCM particles. In a preferred example, the amount of SSCM is from 10 to 20 weight percent of amount of the FRCA for complete monolayer and partially monolayer coating of the FRCA particles by the SSCM particles. Thus, in general, the prescribed amount of SSCM is between 5% and 50% by weight of the crushed recycled concrete, as to provide at least partial coating with SSCM.

[0115] Dry coating of the FRCA particles with smaller highly reactive SSCM particles is carried out by equipment using the principle of combined compression and shear forces or by the principle of combined impact and attrition forces.

[0116] Examples of equipment using the principle of combined compression and shear forces may include but are not limited to a Mix-Muller and other similar high shear mixers, a vertical roller mill (VRM) and other similar mills and examples of equipment using the principle of combined impact and attrition forces may include but are not limited to a rod mill and other similar mills.

[0117] Referring to FIG. 4, a flowchart illustrating a method for converting concrete from construction and demolition waste (CDW) and / or from returned concrete (RC) into reactive SCMs is shown, in accordance with another embodiment of the present invention.

[0118] At block 400 concrete from CDW and / or RC is provided, as to form recycled concrete.

[0119] At block 401 , crushed concrete from CDW and / or crushed RC in the form of RCA and FRCA is obtained. In an example, the recycled concrete from CDW and / or RC is obtained and crushed recycled concrete from CDW and / or RC is obtained, in the form of RCA and FRCA, by subjecting the recycled concrete from CDW and / or RC to a crushing treatment. The crushing treatment may be carried out via jaw crushers, impact crushers, twin-shaft crushers, or any other type of crushers used in concrete recycling. The crushed concrete from CDW and / or crushed RC generally comprises RCA and FRCA. According to this particular embodiment of the present invention the FRCA is not screened from the RCA and the whole mixture of the FRCA and the RCA is subjected to further processing.

[0120] At block 402, the crushed concrete from CDW and / or RC in the form of RCA and FRCAis subjected to a mechanical calcination to obtain reactive (such as pozzolanic or hydraulic) SCM. In particular, the crushed concrete from CDW and / or RC comprising RCA and FRCA is subjected to mechanical calcination. The mechanical calcination of crushed concrete from CDW and / or RC can be carried out using, for example, an energy-intensive grinding mill, as described herein. In various examples, the energy-intensive mill can be operated at predetermined mill power for a predetermined time to produce predetermined energy. The produced predetermined grinding energy, initiating mechanical calcination of the processed together RCA and FRCA causes chemical activation of the FRCA and RCA (which are initially inert) to convert them into a reactive material. In an example, the predetermined energy produced in the energy-intensive grinding mill for mechanical calcination of FRCA and RCA and their conversion into reactive (pozzolanic or hydraulic) SCM is above 10 kJ / kg, and preferably, in the range from 100 to 40,000 kJ / kg for providing definitely high SCM reactivity. In operation, the predetermined energy above 10 KJ / Kg released by operating the energy-intensive mill at predetermined mill power for a predetermined time induces a series of strong impacts on the RCA and FRCA particles in the crushed concrete from CDW and / or crushed RC. These may be constrained impacts when material particles are caught between two grinding media (usually balls) and subjected to stroke between the grinding media or between grinding media and wall, or collision when materials particles are subjected to hits (free impact) by grinding tool moving at high speed. Local temperature in the collision zone of grinding balls during their impact, and consequently temperature of the material particles caught between two grinding balls and between grinding balls and mill wall (or material particles subjected to hits by grinding tool moving at high speed), rise significantly in and for a very short time. The produced impacts combined with high temperature causes generation of crystal lattice defects or other metastable forms in the mineral particle, i.e., the RCA and FRCA particles, thereby converting initially inert FRCA and RCA into a reactive material. In some cases, this reactive material can be further used as a reactive (pozzolanic or hydraulic) SCM.

[0121] In some examples, the energy-intensive grinding mill comprises a mill with loose grinding media, such as a vibratory ball / rod mill, a planetary ball mill and a stirred media mills as well as a high-peripheral-speed mill (high speed disintegrator). In some examples, the mill with loose grinding media can have a power density ranging from 10 to 500 kW / m3. In a preferred example, the mill with loose grinding media has a power density ranging from 20 to 250 kW / m3.

[0122] In a specific example, the stirred media mill is used mechanical calcination of RCA and FRCA. Examples of the stirred media mill may include, but are not limited to a vertical mill, such as Attritor mill, Stirred Media Detritor, Tower mill, VertiMill, MaxxMill, and a horizontal mill, such asIssaMill, Polysius® booster mill and other similar mills.

[0123] Examples of the high-peripheral-speed mill, also referred to as a high-speed disintegrator or high speed rotor mill, include a pin mill with special wear resistant grinding tools and, preferably, a turbo mill. In some examples, the high-peripheral-speed mill can have a rotor speed ranging from 1 ,800 rpm up to 26,000 rpm.

[0124] Referring to FIG. 5, a flowchart illustrating a method for converting concrete from construction and demolition waste (CDW) and / or from returned concrete (RC) into reactive SCMs is shown, in accordance with another embodiment of the present invention.

[0125] At block 500 concrete from CDW and / or RC is provided, as to form recycled concrete.

[0126] At block 501 , crushed concrete from CDW and / or crushed RC in the form of RCA and FRCA is obtained. In an example, the recycled concrete from CDW and / or RC is obtained and crushed recycled concrete from CDW and / or RC is obtained, in the form of RCA and FRCA, by subjecting the recycled concrete from CDW and / or RC to a crushing treatment. The crushing treatment may be carried out via jaw crushers, impact crushers, twin-shaft crushers, or any other type of crushers used in concrete recycling. The crushed concrete from CDW and / or crushed RC generally comprises RCA and FRCA. According to this particular embodiment of the present invention the FRCA is not screened from the RCA and the whole mixture of the FRCA and the RCA is subjected to further processing.

[0127] At block 502 Standard Supplementary Cementitious Material (SSCM) is provided and added to the crushed concrete comprising RCA and FRCA.

[0128] At block 503, the crushed concrete from CDW and / or RC (RCA and FRCA) together with the added SSCM, with particles sized three to four orders of magnitude smaller than the particles of the crushed recycled concrete (including RCA and FRCA), is subjected to mechanical calcination to obtain reactive (for example, pozzolanic or hydraulic) SCM. In the process of mechanical calcination, the particles of the FRCA are not only crushed and activated in their entire volume but also covered with ultra-fine particles of the SSCM. In other words, in the mechanical calcination process, the FRCA particles are coated with the SSCM such that there are at least partial layers of SSCM on respective FRCA particles as to cover the same. In this way, at block 503, the RCA and FRCA are subjected to mechanical calcination and dry coating with SSCM.

[0129] In some examples, a prescribed amount of SSCM which is added to the RCA andFRCA is from 5 to 10 weight percent of amount of the FRCA to provide partial coating of the processed RCA and FRCA particles by the SSCM particles. In some examples, the prescribed amount of SSCM is from 10 to 50 weight percent of amount of the RCA and FRCA for complete mono- or multilayer coating of the FRCA particles by the SSCM particles. In a preferred example, the amount of SSCM is from 10 to 20 weight percent of amount of the RCA and FRCA for complete monolayer and partially monolayer coating of the FRCA particles by the SSCM particles. Thus, in general, the prescribed amount of SSCM is between 5% and 50% by weight of the crushed recycled concrete, as to provide at least partial coating with SSCM.

[0130] The mechanical calcination and coating of the RCA and FRCA can be carried out, for example, using an energy-intensive grinding mill. In various examples, the energy-intensive mill is operated at predetermined mill power for a predetermined time to produce predetermined energy. The produced predetermined specific grinding energy, initiating mechanical calcination of the RCA and FRCA, causes chemical activation of the RCA and FRCA (which are initially inert) to convert them into a reactive material. In operation, the predetermined specific grinding energy released by operating the energy-intensive mill at predetermined mill power for a predetermined time induces a series of strong impacts. These may be constrained impacts when material particles are caught between two grinding media (usually balls) and subjected to stroke between the grinding media or between grinding media and wall, or collision when materials particles are subjected to hits (free impact) by grinding tool moving at high speed. Local temperature in the collision zone of grinding balls during their impact, and consequently temperature of the material particles caught between two grinding balls and between grinding balls and mill wall (or material particles subjected to hits by grinding tool moving at high speed), rise significantly in and for a very short time. The produced impacts combined with high temperature causes generation of crystal lattice defects or other metastable forms in the mineral particle (i.e. , the RCA and FRCA particles), thereby converting inert RCA and FRCA into a reactive material. In addition, the RCA and FRCA reactivity is increased by coating the processed RCA and FRCA particles with highly reactive SSCM. The obtained reactive material can be further used as a reactive (pozzolanic or hydraulic) SCM.

[0131] In some examples, the energy-intensive grinding mill comprises a mill with loose grinding media, such as a vibratory ball / rod mill, a planetary ball mill and a stirred media mill as well as a high-peripheral-speed mill (high speed disintegrator). In some examples, the mill with loose grinding media has a power density ranging from 10 to 500 kW / m3. In a preferred example, the mill with loose grinding media has a power density ranging from 20 to 250 kW / m3.

[0132] In a specific example, the stirred media mill is used for mechanical calcination of FRCA. Examples of the stirred media mill may include, but are not limited to a vertical mill, such as Attritor mills, Stirred Media Detritor, Tower mill, VertiMill, MaxxMill, and a horizontal mill, such as IssaM ill, Polysius® booster mill and other similar mills.

[0133] Examples of the high-peripheral-speed mill, also referred to as a high speed disintegrator or high speed rotor mill, include a pin mill with special wear resistant grinding tools and, preferably, a turbo mill. In some examples, the high-peripheral-speed mill has a rotor speed ranging from 1 ,800 rpm up to 26,000 rpm.

[0134] Referring to FIG. 6, a flowchart illustrating a method for converting concrete from construction and demolition waste (CDW) and / or from returned concrete (RC) into reactive SCMs is shown, in accordance with another embodiment of the present invention.

[0135] At block 600 concrete from CDW and / or RC is provided, as to form recycled concrete.

[0136] At block 601 , crushed concrete from CDW and / or crushed RC in the form of RCA and FRCA is obtained. In an example, the recycled concrete from CDW and / or RC is obtained and crushed recycled concrete from CDW and / or RC is obtained, in the form of RCA and FRCA, by subjecting the recycled concrete from CDW and / or RC to a crushing treatment. The crushing treatment may be carried out via jaw crushers, impact crushers, twin-shaft crushers, or any other type of crushers used in concrete recycling. The crushed concrete from CDW and / or crushed RC generally comprises RCA and FRCA. According to this particular embodiment of the present invention the FRCA is not screened from the RCA and the whole mixture of the FRCA and the RCA is subjected to further processing.

[0137] At block 602 Standard Supplementary Cementitious Material (SSCM) is provided and added to the crushed concrete comprising RCA and FRCA.

[0138] At block 603, the crushed concrete from CDW and / or RC (RCA and FRCA) together with the added SSCM, with particles sized three to four orders of magnitude smaller than the particles of the crushed recycled concrete (including RCA and FRCA), is subjected to surface activation of the RCA and FRCA particles by dry coating of the larger RCA and FRCA particles with smaller reactive SSCM particles to obtain reactive (pozzolanic or hydraulic) SCM. In the process of surface activation, the particles of the RCA and FRCA are ground and covered with highly reactive ultra-fine particles of the SSCM. It will be appreciated that grinding as such does not ensure the activation of the particles in their entirety, but the particles activation occurs bycoating them with highly reactive SSCM.

[0139] In some examples, the amount of SSCM is from 5 to 10 weight percent of amount of the FRCA for partial coating of the RCA and FRCA particles by the SSCM particles. In some examples, the amount of SSCM is from 10 to 50 weight percent of amount of the RCA and FRCA for complete mono- or multilayer coating of the RCA and FRCA particles by the SSCM particles. In a preferable example, the amount of SSCM is from 10 to 20 weight percent of the amount of the RCA and FRCA for complete monolayer and partially monolayer coating of the RCA and FRCA particles by the SSCM particles. Thus, in general, the prescribed amount of SSCM is between 5% and 50% by weight of the crushed recycled concrete, as to provide at least partial coating with SSCM.

[0140] Dry coating of the RCA and FRCA particles with smaller highly reactive SSCM particles is carried out by equipment using the principle of combined compression and shear forces or by the principle of combined impact and attrition forces.

[0141] Examples of equipment using the principle of combined compression and shear forces may include but are not limited to a Mix-Muller and other similar high shear mixers, a vertical roller mill and other similar mills.

[0142] Referring to FIG. 7, a flowchart illustrating a method of converting mineral material, other than recycled concrete, into reactive SCMs is shown, in accordance with another embodiment of the present invention.

[0143] At block 700 mineral material is provided.

[0144] At block 701 , crushed mineral material is obtained. Mineral material is subjected to a crushing treatment. In some examples, the mineral material is selected from clay minerals and shale comprising quartz, calcite, kaolinite, montmorillonite, chert, dolomite, ankerite, muscovite, illite, bentonite, pyrophyllite, chlorite, zeolite, feldspar, and other commonly available natural mineral materials. In some examples, the mineral material is selected from solid waste, comprising a mixture of different mineral phases, produced by metallurgical industry, such as steel slag, copper slag and others. In a specific example, the mineral is Georgian Bay shale which is a multi-phase material containing siltstone / sandstone and limestone. In another specific example, the mineral material is Basic Oxygen Furnace (BOF) slag comprising calcium oxide, silica, iron oxide, magnesium oxide, aluminium oxide and some other metal oxides, and presenting great mineralogical similarity to raw materials for cement manufacture. The crushing treatment may becarried out via jaw crushers, impact crushers, twin-shaft crushers or any other type of crushers used in concrete recycling plants or in the mining industry. In other cases, instead of crushing the material, the crushed inert mineral material can be received by the system.

[0145] When mentioning conversion of metallurgical slag into reactive SCM it should be noted that ground granulated blast furnace slag (GGBFS), a byproduct of iron production, has seen wide adoption by the concrete industry, and is ubiquitous in the world concrete scene. On the other hand, Basic Oxygen Furnace (BOF) slag another abundantly available byproduct of steel production, that is converted into Supplementary Cementitious Materials (SCM) by the proposed method, has seen practically no use as SCM, due to the fact that, unlike GGBFS, many of its phases are crystallized and inert, and accordingly cannot react with water within cementitious mixture, while others are free oxides, and prone to delayed hydration and related unwanted expansion.

[0146] At block 702, the crushed mineral material is subjected to a mechanical calcination to obtain reactive (such as pozzolanic or hydraulic) SCM. The mechanical calcination of crushed mineral material can be carried out using, for example, an energy-intensive grinding mill, as described herein. In various examples, the energy-intensive mill can be operated at predetermined mill power for a predetermined time to produce predetermined energy. The produced predetermined grinding energy, initiating mechanical calcination of the processed mineral material causes chemical activation of the mineral material (which is initially inert) to convert it into a reactive material. In an example, the predetermined energy produced in the energy-intensive grinding mill for mechanical calcination of mineral material and its conversion into reactive (pozzolanic or hydraulic) SCM is above 10 kJ / kg, and preferably, in the range from 100 to 40,000 kJ / kg for providing definitely high SCM reactivity. In operation, the predetermined energy above 10 KJ / Kg released by operating the energy-intensive mill at predetermined mill power for a predetermined time induces a series of strong impacts on the mineral material particles. These may be constrained impacts when material particles are caught between two grinding media (usually balls) and subjected to stroke between the grinding media or between grinding media and wall, or collision when materials particles are subjected to hits (free impact) by grinding tool moving at high speed. Local temperature in the collision zone of grinding balls during their impact, and consequently temperature of the material particles caught between two grinding balls and between grinding balls and mill wall (or material particles subjected to hits by grinding tool moving at high speed), rise significantly in and for a very short time. The produced impacts combined with high temperature causes generation of crystal lattice defects or othermetastable forms in the mineral particle, i.e., the mineral material particles, thereby converting initially inert mineral material into a reactive material. In some cases, this reactive material can be further used as a reactive (pozzolanic or hydraulic) SCM.

[0147] As described herein, the energy-intensive grinding mill can be a mill with loose grinding media, such as a vibratory ball / rod mill, a planetary ball mill and a stirred media mill as well as a high-peripheral-speed mill (high speed disintegrator). In some examples, the mill with loose grinding media can have a power density ranging from 10 to 500 kW / m3. In a preferred example, the mill with loose grinding media has a power density ranging from 20 to 250 kW / m3.

[0148] In a specific example, the stirred media mill is used for mechanical calcination of such mineral materials as Georgian Bay shale and BOF slag. Examples of a stirred media mill may include, but are not limited to, a vertical mill, such as Attritor mill, Stirred Media Detritor, Tower mill, VertiMill, MaxxMill, and a horizontal mill, such as IssaMill, Polysius® booster mill and other similar mills.

[0149] Examples of a high-peripheral-speed mill, also referred to as a high-speed disintegrator or high-speed rotor mill, include a pin mill with special wear resistant grinding tools and, preferably, a turbo mill. In some examples, the high-peripheral-speed mill can have a rotor speed ranging from 1 ,800 rpm up to 26,000 rpm.

[0150] Referring to FIG. 8, a flowchart illustrating a method of converting mineral material, other than RCA and / or FRCA and / or recycled concrete, into reactive SCMs is shown, in accordance with another embodiment of the present invention.

[0151] At block 800 inert mineral material is provided.

[0152] At block 801 , crushed mineral material is obtained. Mineral material is subjected to a crushing treatment. In some examples, the mineral material is selected from clay minerals and shale comprising quartz, calcite, kaolinite, montmorillonite, chert, dolomite, ankerite, muscovite, illite, bentonite, pyrophyllite, chlorite, zeolite, feldspar, and other commonly available natural mineral materials. In some examples, the mineral material is selected from solid waste, comprising a mixture of different mineral phases, produced by metallurgical industry, such as steel slag, copper slag and others. In a specific example, the mineral is Georgian Bay shale which is a multi-phase material containing siltstone / sandstone and limestone. In another specific example, the mineral material is Basic Oxygen Furnace (BOF) slag comprising calcium oxide, silica, iron oxide, magnesium oxide, aluminium oxide and some other metal oxides, and presenting greatmineralogical similarity to raw materials for cement manufacture. The crushing treatment may be carried out via jaw crushers, impact crushers, twin-shaft crushers or any other type of crushers used in concrete recycling plants or in the mining industry. In other cases, instead of crushing the material, the crushed inert mineral material can be received by the system.

[0153] At block 802 Standard Supplementary Cementitious Material (SSCM) is provided and added to the crushed minerals.

[0154] At block 803, the crushed mineral material together with added to it SSCM, with particles size on three - four orders of magnitude lower than the particles size of the crushed mineral material, is subjected to mechanical calcination to obtain reactive (for example, pozzolanic or hydraulic) SCM. In the process of mechanical calcination, the particles of the mineral material are not only crushed and activated in their entire volume but also covered with ultra-fine particles of the SSCM. In other words, in the mechanical calcination process, the mineral particles are coated with the SSCM such that there are at least partial layers of SSCM on respective mineral particles as to cover the same. In this way, at block 803, the mineral material subjected to mechanical calcination and dry coating with SSCM.

[0155] In some examples, the amount of SSCM is from 5 to 10 weight percent of amount of the minerals for partial coating of the mineral particles by the SSCM particles. In some examples, the amount of SSCM is from 10 to 50 weight percent of amount of the minerals for complete mono- or multilayer coating of the mineral particles by the SSCM particles. In a preferable example, the amount of SSCM is from 10 to 20 weight percent of amount of the mineral for complete monolayer and partially monolayer coating of the mineral particles by the SSCM particles. Thus, in general, the prescribed amount of SSCM is between 5% and 50% by weight of the crushed inert mineral material, as to provide at least partial coating with SSCM.

[0156] The mechanical calcination and coating of the mineral material can be carried out, for example, using an energy-intensive grinding mill. In various examples, the energy-intensive mill is operated at predetermined mill power for a predetermined time to produce predetermined energy. The produced predetermined specific grinding energy, initiating mechanical calcination of the mineral material, causes chemical activation of the mineral material (which is initially inert) to convert it into a reactive material. In operation, the predetermined specific grinding energy released by operating the energy-intensive mill at predetermined mill power for a predetermined time induces a series of strong impacts. These may be constrained impacts when material particles are caught between two grinding media (usually balls) and subjected to stroke betweenthe grinding media or between grinding media and wall, or collision when materials particles are subjected to hits (free impact) by grinding tool moving at high speed. Local temperature in the collision zone of grinding balls during their impact, and consequently temperature of the material particles caught between two grinding balls and between grinding balls and mill wall (or material particles subjected to hits by grinding tool moving at high speed), rise significantly in and for a very short time. The produced impacts combined with high temperature causes generation of crystal lattice defects or other metastable forms in the mineral particle (i.e. , the mineral material particle), thereby converting inert mineral material into a reactive mineral material. In addition, the mineral material reactivity is increased by coating the processed of the mineral material particles with highly reactive SSCM. The obtained reactive material can be further used as a reactive (pozzolanic or hydraulic) SCM.

[0157] In some examples, the energy-intensive grinding mill comprises a mill with loose grinding media, such as a vibratory ball / rod mill, a planetary ball mill and a stirred media mills as well as a high-peripheral-speed mill (high speed disintegrator). In some examples, the mill with loose grinding media has a power density ranging from 10 to 500 kW / m3. In a preferred example, the mill with loose grinding media has a power density ranging from 20 to 250 kW / m3.

[0158] In a specific example, the stirred media mill is used for mechanical calcination of the mineral material. Examples of the stirred media mill may include, but are not limited to, a vertical mill, such as Attritor mills, Stirred Media Detritor, Tower mill, VertiMill, MaxxMill, and a horizontal mill, such as IssaMill, Polysius® booster mill and other similar mills.

[0159] Examples of a high-peripheral-speed mill, also referred to as a high-speed disintegrator or a high-speed rotor mill, includes a pin mill with special wear resistant grinding tools and, preferably, a turbo mill. In some examples, the high-peripheral-speed mill has a rotor speed ranging from 1 ,800 rpm up to 26,000 rpm.

[0160] Referring to FIG. 9, a flowchart illustrating a method for converting mineral material into reactive SCMs is shown, in accordance with another embodiment of the present invention.

[0161] At block 900 mineral material is provided.

[0162] At block 901 , crushed mineral material is obtained. Mineral material is subjected to a crushing treatment. In some examples, the mineral material is selected from clay minerals and shale comprising quartz, calcite, kaolinite, montmorillonite, chert, dolomite, ankerite, muscovite, illite, bentonite, pyrophyllite, chlorite, zeolite, feldspar, and other commonly available naturalmineral materials. In some examples, the mineral material is selected from solid waste, comprising a mixture of different mineral phases, produced by metallurgical industry, such as steel slag, copper slag and others. In a specific example, the mineral is Georgian Bay shale which is a multi-phase material containing siltstone / sandstone and limestone. In another specific example, the mineral material is Basic Oxygen Furnace (BOF) slag comprising calcium oxide, silica, iron oxide, magnesium oxide, aluminium oxide and some other metal oxides, and presenting great mineralogical similarity to raw materials for cement manufacture. The crushing treatment may be carried out via jaw crushers, impact crushers, twin-shaft crushers or any other type of crushers used in concrete recycling plants or in the mining industry. In other cases, instead of crushing the material, the crushed inert mineral material can be received by the system.

[0163] At block 902 Standard Supplementary Cementitious Material (SSCM) is provided and added to the crushed mineral material.

[0164] At block 903, the mineral material together with the added SSCM, with particles sized three to four orders of magnitude smaller than the particles of the crushed mineral material, is subjected to surface activation of the mineral material particles by dry coating of the larger mineral material particles with smaller reactive SSCM particles to obtain reactive (pozzolanic or hydraulic) SCM. In the process of surface activation, the particles of the mineral material are ground and covered with highly reactive ultra-fine particles of the SSCM. It will be appreciated that grinding as such does not ensure the activation of the particles in their entirety, but the particles activation occurs by coating them with highly reactive SSCM.

[0165] In some examples, the amount of SSCM is from 5 to 10 weight percent of amount of the mineral material for partial coating of the mineral material by the SSCM particles. In some examples, the amount of SSCM is from 10 to 50 weight percent of amount of the mineral material for complete mono- or multilayer coating of the mineral material particles by the SSCM particles. In a preferable example, the amount of SSCM is from 10 to 20 weight percent of the amount of the mineral material for complete monolayer and partially monolayer coating of the mineral material particles by the SSCM particles. Thus, in general, the prescribed amount of SSCM is between 5% and 50% by weight of the crushed mineral material, as to provide at least partial coating with SSCM.

[0166] Dry coating of the mineral material particles with smaller highly reactive SSCM particles is carried out by equipment using the principle of combined compression and shear forces or by the principle of combined impact and attrition forces. That is, such equipment is configured toapply combined compression and shear forces, or combined impact and attrition forces, upon content placed in the equipment.

[0167] Examples of equipment using the principle of combined compression and shear forces may include but are not limited to a Mix-Muller and other similar high shear mixers, a vertical roller mill (VRM) and other similar mills and examples of equipment using the principle of combined impact and attrition forces may include but are not limited to a rod mill and other similar mills.Experimental Analysis

[0168] An experimental analysis was performed to verify the substantial advantages of the present embodiments; in particular, the nature of the impact on the material to be activated, the type and amount of energy required for “pure” (without use of activating additives) activation of recycled concrete and other mineral materials described in the present embodiments as well as the type and amount of energy required for activation of recycled concrete and other mineral materials with use of activating additives and also type and amount of the activating additives.

[0169] The example experiments first confirmed the possibility of converting the inert recycled concrete (FRCA obtained from CDW and RC was used in the experiments) into reactive SCMs. After that, the example experiments determined the optimal process for FRCA activation; in particular the type of equipment for carrying out the activation process and the type and amount of energy to activate the FRCA material. Accordingly, the FRCA particles were subjected to a combined action of pressure and shear forces using a high shear mixer (HSM), which caused successful activation of the cementitious materials as described in US Pat. Nos. 10,590,040 and 11 , 148,972. The FRCA particles were processed in the mixer for different time periods from 30 minutes (sufficient for activation of the cementitious materials) up to 4 hours. Subsequent x-ray diffraction (XRD) analysis of the processed FRCA particles and measuring of its reactivity by isothermal calorimetry showed that the FRCA remained inert after any of the processing time period from 30 minutes to 4 hours in the HSM. Upon further review, it was concluded that the combined action of shear and compression (for example, in HSM) resulted in accumulation of structural defects at the surface and in the near-surface layers of the processed FRCA particles, which was sufficient for increasing activity of already reactive cementitious material as described in the above-mentioned patents but not sufficient for converting an inert FRCA as well as inert shale and slag into reactive material.

[0170] It was observed that the first type of impact, which is the constraint impact, can be realized in a vibration mill, a planetary mill and a stirred media mill. The second type of impactcan be realized in a high-peripheral-speed mill (high speed disintegrator, high speed rotor mill), for example, with two wheels rotating at different speeds, usually in opposite directions.

[0171] These types of impact on the inert mineral material with the purpose of its activation are known and are usually referred to as mechanochemical activation. At that in the broadest sense, mechanochemistry is defined as the initiation of chemical reactions (chemical activation in this particular case) by mechanical phenomena. By separating the mechanical and thermal effects on the material during its processing by introducing mechanical energy with heat removal, i.e. grinding with simultaneous active cooling, the present inventors discovered that efficient chemical activation of mineral materials cannot be achieved due to mechanical phenomena alone as it described by classical definition of mechanochemistry. At the same time, the present inventors found that efficient chemical activation of mineral materials cannot be achieved due to thermal treatment alone, i.e. heating without mechanical impact, which is defined as calcination.

[0172] The inventors found that local temperature in the collision zone of grinding balls during their impact (in a stirred media mill), and consequently temperature of the material particles caught between two grinding balls and between grinding balls and mill wall, can raise for a very short time (during time span of the impact measured in microseconds) above 700°C and up to 2,000°C. The inventors discovered that interaction of mechanical effect on processed recycled concrete particles (FRCA) and / or other inert mineral material in the form of strong impacts and high local temperatures in the collision zones, resulting from the media collisions, leads to a synergistic effect that promotes the most effective transformation of the inert recycled concrete and / or other inert mineral material into reactive SCMs. Thus, the mechanical impact on the inert mineral material causes, on the one hand, instant and short time significant increase in its temperature and, on the other hand, enables the accumulation of mechanical and thermal energy as defects in the volume of the particles and increase the excess enthalpy of the solid particles (as a result of combination of mechanical and resulting thermal shocks) providing physical transformation and increased chemical reactivity of the particles. Accordingly, this type of activation can be called mechano-thermo-chemical activation, or mechanical calcination.

[0173] Additionally, the authors found that when reactive Standard Supplementary Cementitious Materials (SSCM’s) are added to mechanical calcination process, the smaller particles of the added SSCMs coat larger particles of the processed mineral material. In this case mechanical calcination on the one hand change crystalline structure of the particles of the processed mineral material causing its activation, and, on the other hand coating of these particles with highly reactive SSCM creates a highly reactive layer on the surface of the mineral particlescausing their additional activation.

[0174] The discovery of this phenomenon allowed the authors to suggest that just dry coating of the inert mineral particles with reactive SSCM even without activation of the mineral material by mechanical calcination can cause a certain surface activation of the mineral material. In this case, the particles of mineral material that are essentially inert, act as carrier of reactive SSCM and as a whole the particles become reactive themselves.

[0175] Considering numerous advantages of a stirred media mill (SMM) in comparison with other impact energy-intensive mills, exemplified above, the example experiment for carrying out mechanical calcination of the FRCA, the shale and the slag and their mechanical calcination combined with dry coating with reactive SSCM was conducted using the SMM, vertical attritor in this particular case, in order to determine the amount of energy to activate the FRCA, the shale and the slag.

[0176] Direct dry coating of the FRCA, shale and slag without activation of these mineral materials by mechanical calcination was conducted using High Shear Mixer (HSM), Simpson Mix- Muller in this particular case.

[0177] In the first experiment, recycled concrete obtained from the large Canadian cement and concrete manufacturer St. Marys CBM was used as an experimental material. The recycled concrete was represented by the FRCA obtained from returned concrete (RC) passing sieve with 4.76 mm.

[0178] During preliminary example experiments on processing the FRCA in the stirred media mill (SMM) in mechanical calcination mode the following input parameters were used:7 grinding media (steel balls) was with sizes 5 mm, 10 mm and 20 mm;7 the degree of filling of the mill volume by the grinding media (steel balls) was 25%, 50% and 75%;7 the ratio weight between the processed material and grinding media was 1 :5, 1 :10 and 1 :20;7 the speed of the rotor was 350 rpm, 400 rpm and 500 rpm; and7 the processing time was 18 min, 72 min and 180 min.

[0179] During preliminary example experiments on processing the FRCA in the stirred media mill (SMM) in mechanical calcination mode combined with use of reactive SSCM’s in dry coatingmode the following input parameters were added: SSCM types: silica fume (SF), slag cement (SC), and fly ash (FA); SSCM dosage rates: 10%, 20% and 30%.

[0180] During preliminary example experiments on processing the FRCA in the high shear mixer (HSM) in dry coating mode the following input parameters were: SSCM types: silica fume (SF), slag cement (SC), and fly ash (FA); SSCM dosage rates: 10%, 20% and 30%; the processing time was 90 min, 180 min and 240 min.

[0181] The input factor in the experiment was the amount of energy for processing the FRCA to a specified response - reactivity of the processed FRCA measured by isothermal calorimetry (according to ASTM C1897-2).

[0182] Based on the analysis of the data from the preliminary experiments, the ultimate experiment was designed with use of grinding ball with size 10 mm; the degree of filling of the mill volume by the grinding media 75%; the ratio weight between the processed material and grinding media 1 : 20; the speed of the rotor 500 rpm; in the case of using SSCM - SF with dosage rate 20%; processing time in SSM varied and 18, 72 and 180 minutes were chosen; processing time in HSM 90 and 180 minutes were chosen.

[0183] Quantification of the reactivity of the certain activated FRCA samples of interest processed under different conditions and measured by isothermal calorimetry (estimated by amount released heat of hydration) is shown in TABLE 1 and in FIG. 10.TABLE 1

[0184] Considering that the recommended threshold to distinguish between the inert and reactive material is 98 J / g of SCM (as per Report of RILEM TC 267-TRM phase 3: validation of the R3 reactivity test across a wide range of materials, Materials and Structures (2022) 55: 142), it was concluded that the following FRCA samples became reactive material and can be used as reactive SCM: treated in the SMM without added SSCM over 30 minutes (based on the data obtained and calculated by interpolation); treated in the SMM with added SSCM for 18 minutes and over; treated in the HSM with added SSCM for 90 minutes and over.

[0185] Referring now to FIG. 11 , functional dependency of the processed FRCA reactivity on amounts of specific grinding energy is shown in a graph. It can be observed that the reactivity of the processed FRCA (i.e., FRCA subjected to grinding) increases with an increase in specific grinding energy and with addition of the SSCM to the processed FRCA.

[0186] Extrapolating the graph in FIG. 11 it is possible to conclude that FRCA can be converted to reactive SCM by applying grinding energy above 30 kJ / kg and preferably in the range of energies from 100 kJ / kg to 30,000 kJ / kg for providing definitely high reactivity.

[0187] It was further determined based on calculations that the optimization of mill parameters may reduce grinding energy consumption for converting FRCA to reactive SCM down to 10 kJ / kg. Accordingly, it was concluded that recycled concrete can be converted to reactive SCM by applying grinding energy above 10 kJ / kg and preferably in the range of energies from 100 kJ / kg to 30,000 kJ / kg for providing definitely high SCM reactivity using the energy-intensive mill with loose grinding media having power density in the range from 10 to 500 kW / m3or using high shear mixer / mill with addition of reactive SSCM and applying grinding energy above 10 kJ / kg and preferably above 100 kJ / kg for providing definitely high SCM reactivity.

[0188] In view of successful conversion of mineral based recycled concrete in the form of FRCA into reactive SCM by a mechanical calcination, by a mechanical calcination combined with dry coating, and by dry coating without mechanical calcination, further experiments were conducted to determine the possibility of converting inert mineral materials other than recycled concrete into reactive SCM using the same method.

[0189] In the second experiment, North American Georgian Bay shale, that is construction andtunneling waste, obtained from Canadian construction company Ontario Transit Group Inc., was used as an experimental material.

[0190] Based on the analysis of the data from the preliminary experiments, the ultimate experiment was designed with use of grinding ball with size 10 mm; the degree of filling of the mill volume by the grinding media 75%; the ratio weight between the processed material and grinding media 1 : 20; the speed of the rotor 500 rpm; in the case of using SSCM - SF with dosage rate 20%; processing time in SSM varied and 18, 72 and 180 minutes were chosen; processing time in HSM 90 minutes were chosen.

[0191] Quantification of the reactivity of the certain activated shale samples of interest processed under different conditions and measured by isothermal calorimetry (estimated by amount released heat of hydration) is shown in TABLE 2 and FIG. 12.TABLE 2

[0192] Considering that the recommended threshold to distinguish between the inert and reactive material is 98 J / g of SCM (as per Report of RILEM TC 267-TRM phase 3: validation of the R3 reactivity test across a wide range of materials, Materials and Structures (2022) 55:142), it was concluded that the following shale samples became reactive material and can be used as reactive SCM treated in the SMM without and with added SSCM for 18 minutes and over; treated in the HSM with added SSCM for 90 minutes and over.

[0193] Referring now to FIG. 13, functional dependency of the processed shale reactivity on amounts of specific grinding energy is shown in a graph. It can be observed that the reactivity ofthe processed shale (i.e., shale subjected to grinding) increases with an increase in specific grinding energy and with addition of the SSCM to the processed shale.

[0194] Extrapolating the graph in FIG. 13 it is possible to conclude that shale can be converted to reactive SCM by applying grinding energy above 60 kJ / kg and preferably in the range of energies from 100 kJ / kg to 30,000 kJ / kg for providing definitely high reactivity.

[0195] It was further determined based on calculations that the optimization of mill parameters may reduce grinding energy consumption for converting shale to reactive SCM down to 10 kJ / kg. Accordingly, it was concluded that shale can be converted to reactive SCM by applying grinding energy above 10 kJ / kg and preferably in the range of energies from 100 kJ / kg to 30,000 kJ / kg for providing definitely high SCM reactivity using the energy-intensive mill with loose grinding media having power density in the range from 10 to 500 kW / m3or using a high shear mixer / mill with addition of reactive SSCM and applying grinding energy above 10 kJ / kg and preferably above 100 kJ / kg for providing definitely high SCM reactivity.

[0196] In the third experiment, Basic Oxygen Furnace (BOF) slag produced by US Steel Corporation at their steel plant in Pittsburgh and obtained from TMS International Corporation, was used as an experimental material.

[0197] Based on the analysis of the data from the preliminary experiments, the ultimate experiment was designed with use of grinding ball with size 10 mm; the degree of filling of the mill volume by the grinding media 75%; the ratio weight between the processed material and grinding media 1 : 20; the speed of the rotor 500 rpm; in the case of using SSCM - SF with dosage rate 20%; processing time in SSM varied and 18, 72 and 180 minutes were chosen; processing time in HSM 90 minutes were chosen.

[0198] Quantification of the reactivity of the certain activated slag samples of interest processed under different conditions and measured by isothermal calorimetry (estimated by amount released heat of hydration) is shown in TABLE 3 and FIG. 14.TABLE 3

[0199] Considering that the recommended threshold to distinguish between the inert and reactive material is 98 J / g of SCM (as per Report of RILEM TC 267-TRM phase 3: validation of the R3 reactivity test across a wide range of materials, Materials and Structures (2022) 55:142), it was concluded that the following shale samples became reactive material and can be used as reactive SCM treated in the SMM without and with added SSCM for 18 minutes and over; treated in the HSM with added SSCM for 90 minutes and over.

[0200] Referring now to FIG. 15, functional dependency of the processed slag reactivity on amounts of specific grinding energy is shown in a graph. It can be observed that the reactivity of the processed slag (i.e. , slag subjected to grinding) increases with an increase in specific grinding energy and with addition of the SSCM to the processed slag.

[0201] Extrapolating the graph in FIG. 15 it is possible to conclude that slag can be converted to reactive SCM by applying grinding energy above 20 kJ / kg and preferably in the range of energies from 100 kJ / kg to 30,000 kJ / kg for providing definitely high reactivity.

[0202] It was further determined based on calculations that the optimization of mill parameters may reduce grinding energy consumption for converting BOF steel slag to reactive SCM down to 10 kJ / kg. Accordingly, it was concluded that BOF slag can be converted to reactive SCM by applying grinding energy above 10 kJ / kg and preferably in the range of energies from 100 kJ / kg to 30,000 kJ / kg for providing definitely high SCM reactivity using the energy-intensive mill with loose grinding media having power density in the range from 10 to 500 kW / m3or using high shear mixer / mill with addition of reactive SSCM and applying grinding energy above 10 kJ / kg and preferably above 100 kJ / kg for providing definitely high SCM reactivity.

[0203] As a results of the analysis of the above experiments on the activation of the recycled concrete, shale and slag samples, it can be concluded that use of the reactive SSCM allowed to reach the highest reactivity of the obtained SCM. The explanation of this phenomenon was given above and the conducted scanning electron microscopy (SEM) analysis, in this particularcase of the FRCA particles, clearly illustrates this explanation that ultra-fine reactive SSCM particles cover larger recycled concrete as well as shale and slag particles.

[0204] SEM images of the grains of the original recycled concrete obtained from returned concrete, showed that such the grains are fine aggregates (old sand) covered by hydrated cement in the form of mostly ettringite needles and some portlandite plates (FIG. 16A - magnification 2,000, FIG. 16B - magnification 20,000).

[0205] SEM analysis further confirmed that ultrafine reactive SSCM powder added to the recycled concrete (or other mineral material) in the process of its mechanical calcination or in the process of its processing under high shear forces, is not simply distributed throughout of the minerals mass but coat the larger grains of the mineral particles with finer SSCM particles (FIG. 17A- magnification 2,000, FIG. 17B - magnification 10,000). Such a grain structure with the most reactive grain surface allowed us to obtain the highest possible reactivity of the produced SCM.Examples

[0206] The following examples are exemplary in nature and are not to be construed as promises as to the effectiveness of the claimed invention.Example 1 :

[0207] The first example illustrates viability and usefulness of the proposed method for conversion of recycled concrete into reactive supplementary cementitious material to be used for partial cement substitution in production of concrete, mortar and other cement-based materials.

[0208] Special mortar samples were prepared for laboratory testing. Type GUL Portland cement, ASTM C778 standard sand, and City of Toronto tap water were used in mortar production. Standard 50 mm mortar cubes were cast with a water to binder ratio of 0.485, and a sand to binder ratio of 2.75. Mortar mixing was performed according to ASTM C305. The mortar mixtures were prepared using 20%, 30% and 40% mass replacement of cement with the SCMs made from recycled concrete (certain activated FRCA samples of interest) according to the proposed method. A separate control mixture was prepared with no replacement of cement in mortar mixture.

[0209] Flow and air content (fresh mortars properties) were determined according to ASTM C1437 and ASTM C185, respectively. Furthermore, the compressive strength and bulk resistivity (hardened properties) of mortar were determined according to ASTM C109 and ASTM C1876,respectively.

[0210] Tables 4 and FIGS. 18, 19, 20 and 21 present respectively the measured flow, air content, compressive strength and bulk resistivity of the mortars that were tested.TABLE 4

[0211] As shown in Table 4 and FIG. 18, cement replacement with the SCMs made from recycled concrete generally reduced the workability of some mortar samples, but to a limited extent. Such a limited reduction can be easily corrected in practice, if necessary, by using waterreducing admixtures that increase the mixture workability.

[0212] As shown in Table 4 and FIG. 19, cement replacement with the SCMs made from recycled concrete generally increase air content in certain mortar samples, but to a limited extent.Such a limited increase can be easily corrected in practice, if necessary, by using air-detraining admixtures that decrease air content in the mixture.

[0213] As shown in Table 4 and FIG. 20, compressive strength of mortars made with cement replacement with the SCMs (with 20%, 30% and 40% substitution levels) produced from recycled concrete with added SSCM was statistically (with confidence probability 95%) equal to the corresponding compressive strength of the control. Compressive strength of mortars made with cement replacement with the SCMs (with 20%, 30% and 40% substitution levels) produced from recycled concrete without added SSCM, was generally somehow lower than that of control but to a limited extent. The analysis showed that such a decrease in strength was mainly due to increased air content in the samples, which can be easily corrected in practice, if necessary, by using air-detraining admixtures that decrease air content in the mixture.

[0214] As shown in Table 4 and FIG. 21 , bulk resistivity of mortars (characterizing mortars durability) made with cement replacement with the SCM (with 20%, 30% and 40% substitution levels) produced from recycled concrete without added SSCM, with was statistically (with confidence probability 95%) equal to the corresponding bulk resistivity of the control. Bulk resistivity of mortars made with cement replacement with the SCM (with 20%, 30% and 40% substitution levels) produced from recycled concrete with added SSCM, was significantly higher that of control, which means that use of this SCM significantly increased durability of mortars.

[0215] Overall, the above described experiments conducted allow us to conclude that the SCM made from recycled concrete in accordance with the proposed method can be used for cement replacement at substitution levels up to 40% without compromising workability of fresh mixtures and strength and durability characteristics of the produced mortars / concretes.Example 2:

[0216] The second example illustrates viability and usefulness of the proposed method for conversion of shale into reactive supplementary cementitious material to be used for partial cement substitution in production of concrete, mortar and other cement-based materials.

[0217] Special mortar samples were prepared for laboratory testing. Type GUL Portland cement, ASTM C778 standard sand, and City of Toronto tap water were used in mortar production. Standard 50 mm mortar cubes were cast with a water to binder ratio of 0.485, and a sand to binder ratio of 2.75. Mortar mixing was performed according to ASTM C305. The mortar mixtures were prepared using 20%, 30% and 40% mass replacement of cement with the SCMs made from shale (certain activated shale samples of interest) according to the proposed method. A separatecontrol mixture was prepared with no replacement of cement in mortar mixture.

[0218] Flow and air content (fresh mortars properties) were determined according to ASTM C1437 and ASTM C185, respectively. Furthermore, the compressive strength and bulk resistivity (hardened properties) of mortar were determined according to ASTM C109 and ASTM C1876, respectively.

[0219] Tables 5 and FIGS. 22, 23, 24 and 25 present respectively the measured flow, air content, compressive strength and bulk resistivity of the mortars that were tested. TABLE 5

[0220] As shown in Table 5 and FIG. 22, cement replacement with the SCMs made from shale generally reduced the workability of some mortar samples; in some samples this reduction wasvery small, in some others it was somewhat larger. Such a limited reduction can be easily corrected in practice, if necessary, by using water-reducing admixtures that increase the mixture workability.

[0221] As shown in Table 5 and FIG. 23, cement replacement with SCMs made from shale statistically did not change air content in certain mortar samples and somewhat increased air content in certain mortar samples, but to a limited extent. Such a limited increase can be easily corrected in practice, if necessary, by using air-detraining admixtures that decrease air content in the mixture.

[0222] As shown in Table 5 and FIG. 24, compressive strength of mortars made with cement replacement with the SCMs (with 20%, 30% and 40% substitution levels) produced from shale without added SSCM, was somewhat higher than the corresponding compressive strength of the control; compressive strength of mortars made with cement replacement with the SCMs (with 20%, 30% and 40% substitution levels) produced from shale with added SSCM was statistically (with confidence probability 95%) equal to the corresponding compressive strength of the control. The analysis showed inverse correlation between air content and compressive strength of the mortars. Accordingly, compressive strength of mortar / concrete with increased air content can be easily corrected in practice, if necessary, by using air-detraining admixtures that decrease air content in the mixture.

[0223] As shown in Table 5 and FIG. 25, bulk resistivity of all mortars (characterizing mortars durability) made with cement replacement with the SOM (with 20%, 30% and 40% substitution levels) produced from shale was significantly higher than that of control, which means that use of this SOM significantly increased durability of mortars.

[0224] Overall, the above described experiments conducted allow us to conclude that the SCM made from shale in accordance with the proposed method can be used for cement replacement at substitution levels up to 40% without compromising workability of fresh mixtures and strength and durability characteristics of the produced mortars / concretes.Example 3:

[0225] The third example illustrates viability and usefulness of the proposed method for conversion of slag into reactive supplementary cementitious material to be used for partial cement substitution in production of concrete, mortar and other cement-based materials.

[0226] Special mortar samples were prepared for laboratory testing. Type GUL Portland cement, ASTM C778 standard sand, and City of Toronto tap water were used in mortar production.Standard 50 mm mortar cubes were cast with a water to binder ratio of 0.485, and a sand to binder ratio of 2.75. Mortar mixing was performed according to ASTM C305. The mortar mixtures were prepared using 20%, 30% and 40% mass replacement of cement with the SCMs made from slag (certain activated slag samples of interest) according to the proposed method. A separate control mixture was prepared with no replacement of cement in mortar mixture.

[0227] Flow and air content (fresh mortars properties) were determined according to ASTM C1437 and ASTM C185, respectively. Furthermore, the compressive strength and bulk resistivity (hardened properties) of mortar were determined according to ASTM C109 and ASTM C1876, respectively.

[0228] Table 6 and FIGS. 26-29 present respectively the measured flow, air content, compressive strength and bulk resistivity of the mortars that were tested.TABLE 6

[0229] As shown in Table 6 and FIG. 26, cement replacement with the SCMs made from slag did not change flow in certain mortar samples and somewhat decreased flow in certain mortar samples, but to a limited extent. Such a limited reduction can be easily corrected in practice, if necessary, by using water-reducing admixtures that increase the mixture workability.

[0230] As shown in Table 6 and FIG. 27, cement replacement with the SCMs made from slag practically (with confidence probability 95%) did not change air content in certain mortar samples and somewhat increase air content in certain mortar samples, but to a limited extent. Such a limited increase can be easily corrected in practice, if necessary, by using air-detraining admixtures that decrease air content in the mixture.

[0231] As shown in Table 6 and FIG. 28, compressive strength of certain mortars made with cement replacement with the SCMs (with 20%, 30% and 40% substitution levels) produced from slag was somewhat higher than the corresponding compressive strength of the control; compressive strength of certain mortars made with cement replacement with the SCMs (with 20%, 30% and 40% substitution levels) produced from slag was statistically (with confidence probability 95%) equal to the corresponding compressive strength of the control; compressive strength of certain mortars was somewhat lower than the corresponding compressive strength of the control but to the limited extend. The analysis showed inverse correlation between air content and compressive strength of the mortars. Accordingly, compressive strength of mortar / concrete with increased air content can be easily corrected in practice, if necessary, by using air-detraining admixtures that decrease air content in the mixture.

[0232] As shown in Table 6 and FIG. 29, bulk resistivity of the mortars made with cement replacement with the SOM (with 20%, 30% and 40% substitution levels) produced from slag without added SSCM was somewhat lower than that of control. This is explained by the fact that the produced from steel slag SOM is electrically conductive and therefore the bulk resistivity test cannot be used to determine the durability of concrete. Bulk resistivity of all mortars made with cement replacement with the SOM (with 20%, 30% and 40% substitution levels) produced from slag with added SSCM (such SCM is not electrically conductive) was significantly higher than that of control, which means that use of this SCM significantly increased durability of mortars.

[0233] Overall, the above-described experiments conducted allow us to conclude that the SCM made from FOB steel slag in accordance with the proposed method can be used forcement replacement at substitution levels up to 40% without compromising workability of fresh mixtures and strength and durability characteristics of the produced mortars / concretes. Calculations and preliminary experiments showed that by proposed method not only basic oxygen furnace (BOF) steel slag, but also electric arc furnace (EAF) steel slag, copper and other metal slags can be activated and converted into reactive SCM.

[0234] The invention has been described with reference to certain specific embodiments, various other aspects, advantages and modifications thereof will be apparent to those skilled in the art without departing from the spirit and scope of the invention as outlined in the claims appended hereto.

Claims

CLAIMS:1 . A method for converting concrete into reactive supplementary cementitious materials (SCM), the method comprising: receiving the concrete in the form of at least one of (i) construction and demolition waste (CDW) and (ii) returned concrete (RC) from a ready-mix concrete truck, as to form recycled concrete; subjecting the recycled concrete to a crushing treatment to form recycled concrete aggregates (RCA); and subjecting the RCA to one or both of (i) mechanical calcination, and (ii) dry coating with standard supplementary cementitious materials (SSCM), as to form the reactive SCM.

2. The method of claim 1 , wherein subjecting the RCA to one or both of (i) mechanical calcination, and (ii) dry coating with standard supplementary cementitious materials (SSCM) to form the reactive SCM further comprises screening the RCA to form fine recycled concrete aggregates (FRCA) subjected to one or both of (i) mechanical calcination, and (ii) dry coating with standard supplementary cementitious materials (SSCM), wherein a particle size of less than a prescribed sieve size is screened as FRCA.

3. The method of claim 2, wherein the screening is performed with vibratory screens, the vibratory screens separating finer grains of the FRCA with a particle size of less than the prescribed sieve size from grains of RCA with a particle size of more than the prescribed sieve size.

4. The method of claim 3, wherein the prescribed sieve size is between 3 millimeters and 7 millimeters.

5. The method of claim 3, wherein the prescribed sieve size is between 4 millimeters and 5 millimeters.

6. The method of claim 3, wherein the prescribed sieve size is between 0.1 millimeters and 1 millimeters.

7. The method of claim 1 , wherein the SSCMs are selected from a group comprising fly ash, slag cement, silica fume, metakaolin, and calcinated shale.

8. The method of claim 1 , wherein the SSCMs are provided in a prescribed amountbetween 5% and 50% by weight of FRCA.

9. The method of claim 1 , wherein the SSCMs are provided in a prescribed amount between 10% and 20% by weight of FRCA.

10. A method of converting mineral material into reactive supplementary cementitious materials (SCM), the method comprising: subjecting the mineral material to a crushing treatment to form crushed-mineral material; and subjecting the crushed mineral material to one or both of (i) mechanical calcination, and (ii) dry coating with standard supplementary cementitious materials (SSCM), as to form the reactive SCM.

11. The method of claim 10, wherein mineral material is selected from a group comprising construction waste, tunneling waste, mining waste and metallurgical waste.

12. The method of claim 10, wherein the SSCMs are selected a group comprising fly ash, slag cement, silica fume, metakaolin, and calcinated shale.

13. The method of claim 10, wherein the SSCMs are provided in a prescribed amount between 5% and 50% by weight of the crushed inert mineral material.

14. The method of claim 10, wherein the SSCMs are provided in a prescribed amount between 10% and 20% by weight of the crushed inert mineral material.

15. The method of claim 1 or 10, wherein the crushing treatment uses one or more of jaw crushers, impact crushers, and twin-shaft crushers.

16. The method of claim 10, wherein the mineral material is Georgian Bay shale comprising limestone and at least one of siltstone and sandstone.

17. The method of claim 10, wherein the mineral material is selected from a group comprising clay minerals and shale comprising quartz, calcite, kaolinite, montmorillonite, chert, dolomite, ankerite, muscovite, illite, bentonite, pyrophyllite, chlorite, zeolite, and feldspar.

18. The method of claim 11, wherein the metallurgical waste comprises metal slag.

19. The method of claim 18, wherein the metal slag is selected from a group comprising basic oxygen furnace (BOF) steel slag, electric arc furnace (EAF) steel slag, and copper slag.

20. The method of claim 1 or 10, wherein the mechanical calcination is performed using an energy-intensive grinding mill.

21. The method of claim 20, wherein the energy-intensive grinding mill comprises a mill with loose grinding media.

22. The method of claim 21 , wherein the mill with loose grinding media is selected from a group comprising a vibratory ball / rod mill, a planetary ball mill, and a stirred media mill.

23. The method of claim 20, wherein the energy-intensive grinding mill has a power density ranging from 10 to 500 kW / m3.

24. The method of claim 20, wherein the energy-intensive grinding mill has a power density ranging from 20 to 250 kW / m3.

25. The method of claim 20, wherein the energy-intensive grinding mill comprises a high- peripheral-speed mill.

26. The method of claim 25, wherein the high-peripheral-speed mill has a rotor speed ranging from 1 ,800 rpm up to 26,000 rpm.

27. The method of claim 1 or 10, wherein the mechanical calcination is performed using an energy-intensive grinding mill operated at a predetermined mill power for a predetermined time to produce predetermined specific grinding energy, the predetermined specific grinding energy being above 10 kJ / kg.

28. The method of claim 1 or 10, wherein the mechanical calcination comprises operating an energy-intensive grinding mill at a predetermined mill power for a predetermined time to produce predetermined specific grinding energy, the predetermined specific grinding energy ranges from 100 to 40,000 kJ / kg.

29. The method of claim 1 or 10, wherein, when the crushed mineral material is subjected only to the dry coating with SSCM, the dry coating with SSCM is performed using equipment configured to apply one of (i) combined compression and shear forces and (ii) combined impact and attrition forces.

30. The method of claim 29, wherein said equipment comprises one of a high shear mixer, a vertical roller mill (VRM) and a rod mill.

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