Method for obtaining a cement constituent from a concrete element

Abstract

The invention is in the field of concrete. Specifically, the invention is in the field of providing several fractions, in particular a cement constituent, from a concrete element. The invention is further directed to materials for producing concrete and the use of such materials for producing concrete.

Description

[0001] P136273PC00 Title: Method for obtaining a cement constituent from a concrete element The invention is in the field of concrete. Specifically, the invention is in the field of providing several fractions, in particular a cement constituent, from a concrete element. The invention is further directed to materials for producing concrete and the use of such materials for producing concrete. Concrete is a composite material of aggregates (such as sand, gravel) and paste and is a widely used material for i.a. buildings. The paste typically comprises cement and water. This paste coats the surface of the aggregates and hardens due to hydration. For the production of cement several raw materials are needed, such as cement clinker. Cement clinker is generally the main reactive binder component for concrete constructions. However, the production of cement, in particular the production of cement clinker, and accordingly concrete is associated with high CO2 emissions. Therefore efforts have been made to minimize the carbon footprint, such efforts include reducing the clinker content by using clinker replacements. Clinker replacements may for instance be industrial by- products that would otherwise be waste. Examples thereof include gypsum, fly ash, natural pozzolans and calcined clay and other supplementary cementitious materials (SCM). SCM are considered to be materials that contribute to the properties of concrete through hydraulic and / or pozzolanic activity. One such effort is provided in WO2022 / 033877. Herein a method for manufacturing concrete parts is described. This method includes minor carbonation of fresh concrete paste. Another example is given in WO2019 / 115722, where a method for cleaning an exhaust gas from CO2with simultaneous manufacturing of a supplementary cementitious material from recycled concrete fines is described. Disadvantageously, these methods do not provide for optimal recycling and upcycling of concrete. The methods do not apply to end-of-life concrete. The carbon footprint is still too large and the quality of the obtained materials is insufficient to be interchangeably used with the virgin materials (i.e. the material as originally used in the production of the concrete element). Examples are also provided to prepare supplementary cementitious materials. WO2022 / 248179 describes a method comprising hydrothermal treatment of concrete waste and subsequent carbonation of the hydrothermally activated material to provide a supplementary cementitious material. US2023 / 0110452 discloses a method for preparing ground carbonated supplementary cementitious material. The method includes adding water to a carbonatable material to form a carbonatable mixture. The carbonatable mixture is agitated, carbonated and milled. The milled mixture may also be carbonated. US2023 / 0023151 describes various method for preparing carbonated supplementary cementitious materials. These include performing semi-wet carbonation, cyclic carbonation, non-slurry carbonation, high temperature carbonation and granular carbonation of a carbonatable material. The present inventors surprisingly found a method for obtaining a cement constituent from concrete, that overcomes at least part of the above- mentioned drawbacks. In particular, the method allows for obtaining a cement constituent that may be used in the production of cement, in particular the cement constituent may advantageously have pozzolanic and / or hydraulic properties. Further, the method may allow for a minimal carbon footprint, as the produced CO2 may be used in a further step of the method. Additionally, the energy consumption is optimized and waste streams are minimized. Each of the resulting products are typically suitable to be used as materials for the production of concrete. Furthermore, the method may advantageously be performed close to the feedstock to minimize transport. Figure 1 illustrates a schematic overview of a method according to the present invention. Figure 2 illustrates a schematic overview of a preferred method according to the present invention. Figure 3 shows the strength activity index in % of a mortar comprising carbonated cement constituent according to the invention compared to a reference. Figure 4 shows the compressive strength of concrete prepared with 25% unreacted cement constituent or 25% carbonated cement constituent after 7 and 28 days, compared to control. The present invention is directed to a method for obtaining a cement constituent from a concrete element. As illustrated in Figure 1, the method comprises providing a concrete element (1), breaking said concrete element into concrete parts (2). The concrete parts are subjected to a first liberation and separation step to obtain a coarse aggregate fraction (3), a medium fine fraction (4) and a small fine fraction (5). The method further comprises subjecting the medium fine fraction to a second liberation and separation step to obtain a fine aggregate fraction (6) and an ultrafine fraction (7). The method further comprises grinding and optionally carbonating the small fine fraction and the ultrafine fraction to obtain a cement constituent (8). Preferably, the method comprises grinding and carbonation, more preferably the method comprises simultaneous grinding and carbonation. The concrete element may be provided in any form. For instance, if a building is torn down, the resulting concrete elements may be used as a starting (feed) material for the present method. This concrete element may be or comprise end-of-life concrete. This is a term known in the art to refer to concrete that has reached the end of useful service. For instance, the deterioration of the concrete is beyond the point where repair is impractical or uneconomic. Alternatively, or additionally, the concrete may be a freshly produced concrete. For example, it is common that a truck comprising i.a. ready-mixed concrete is not emptied fully, as this is challenging to achieve. The ready-mixed concrete may then be diluted (e.g. with water) and poured onto a substrate. The produced concrete may be used as a concrete element for the present method. It may be appreciated that the concrete element optionally further comprises one or more impurities, such as water and / or residues from demolition waste (e.g. ceramics, glass). The method further comprises breaking said concrete element into concrete parts. As the concrete element comprises a composite material of aggregates and paste, this breaking typically allows for liberation of some of the aggregates and paste. Conventional methods to break concrete elements into concrete parts are typically based on impact breaking. This generally results in breaking the element in random directions, and accordingly results in concrete parts that are only smaller pieces of the concrete element (and thus not have a shape of the virgin material). Further, conventional methods often result in destroying the material in such a manner that the provided material would not be commercially relevant i.e., the crushing damages the aggregate part resulting in a lot of quartz / limestone contaminants in the recycled cement constituent. It is accordingly preferred that the force for breaking is substantially evenly distributed over the concrete element. This allows for breaking the concrete element and liberation of the material essentially along the natural composition lines and accordingly essentially without destroying the internal structure. The breaking therefore preferably comprises crushing, typically crushing wherein the pressure is applied on two surfaces of the concrete element, such as crushing in a jaw crusher and / or in a cone crusher. In particular, it may be preferred to apply the pressure on two opposite surfaces of the concrete element, e.g. a top surface and a bottom surface. A jaw crusher is known in the art and commercially available. The concrete element may be placed in between the jaws. By closing the jaws a force is exerted on the concrete element, thereby breaking the concrete element into concrete parts. A cone crusher is also known in the art and commercially available. The method further comprises subjecting the concrete parts to a first liberation and separation step. This allows for obtaining a coarse aggregate fraction, a medium fine fraction and a small fine fraction. The first liberation and separation step preferably comprises ballistic separation. Ballistic separation may suitably be performed in a ballistic separator, in particular in a separation-apparatus as described in WO2009 / 123452, which is incorporated herein in its entirety. Advantageously, such a ballistic separator may also be suitably used for moist materials. This minimizes the requirements for the feed material and accordingly allows for the ability to process a high variation of feed materials, as the method is generally not sensitive to moisture. It may be appreciated that the present invention is also directed to such a method for liberating and separating of a coarse aggregate fraction, a medium fine fraction and a small fraction from concrete parts. The coarse aggregate fraction is typically considered a product that may be sold and / or used as a substitute for virgin coarse aggregates used in the production of concrete. The medium fine fraction may further be processed. The method thus further comprises subjecting the medium fine fraction to a second liberation and separation step to obtain a fine aggregate fraction and an ultrafine fraction. Preferably, the second liberation and separation step comprises mechanical separation. This may be performed in a separator. Typically, the fine aggregate fraction comprises sand, cement hydrate, unreacted cement particles and / or other contaminants and the ultrafine fraction comprises cement hydrates. Generally, the fine aggregate fraction is bound to the ultrafine fraction. As the thermal expansion of the aggregate fraction and the ultrafine fractions are not identical, the ultrafine fraction and the aggregate fraction may be liberated from one another due to stress caused by the difference in expansion. It may be appreciated that liberation of the fine aggregate fraction and the ultrafine fraction may accordingly be achieved by heating the medium fine fraction. Accordingly, it is preferred that the second liberation and separation step comprises thermo-mechanical separation. Heating may be provided by a flame, such as a flame with a temperature of at least 500 °C, preferably at least 550 °C, such as approximately 600 °C. Even more preferably, the second liberation and separation is performed in a heating air classification system (HAS). A suitable HAS system is described in WO2019 / 212336A1, which is incorporated herein in its entirety. It may be appreciated that the second liberation and separation step may be essentially without adding water. Generally, the second liberation and separation step results in the formation of a flue gas. This flue gas comprises CO2 and may further comprise water vapor. Preferably, the flue gas comprises CO2 and water vapor. Further, it may be appreciated that the temperature of the flue gas is sufficiently high to be used for i.a. drying (vide infra). Preferably, the flue gas comprises up to 25 vol% CO2, more preferably up to 20 vol%, such as between 5 - 15 vol% or between 8 – 12 vol%. Most preferably, the flue gas comprises 9 – 10 vol% CO2. Typically, the flue gas comprises 5-25 vol%, preferably 10 – 15 vol%, water vapor. It may be appreciated that the remainder of the flue gas may comprise nitrogen gas. As release of CO2is undesirable due to its negative impact on the environment, it is preferred that the flue gas is used for carbonation (vide infra). This is illustrated in Figure 2, wherein the flue gas (9) formed in the second liberation and separation step is led to the grinding and carbonation step. Accordingly, beneficially, the present method may allow for internal use of the CO2and does not substantially release CO2into the environment, nor does it need CO2provided from another (external) source. The present invention is accordingly also directed to such a method for liberating and separating a fine aggregate fraction and an ultrafine fraction from a medium fine fraction. The fine aggregate fraction is suitable to be sold and used as a substitute material in the production of concrete. The ultrafine fraction and the small fine fraction are further processed. The method therefore further comprises grinding and optional carbonation of the small fine fraction and the ultrafine fraction to obtain a cement constituent. This may be performed in a mill. It may be appreciated that advantageously, the small fine fraction does not necessarily need to be subjected to the second liberation and separation step and may directly be subjected to grinding and optional carbonation. This minimizes the energy consumption and therefore costs, while improving the yield, i.e. percentage of coarse aggregate material, fine aggregate material and in particular cement constituent obtained from subjecting the concrete elements to a method according to the invention. Advantageously, the yield of coarse aggregate material, fine aggregate material and cement constituent is, each independently, at least 50%, preferably at least 70%, more preferably at least 80%, even more preferably at least 90%, in particular at least 95%. Herein, a yield of 100% would relate to a yield wherein all materials present in the concrete element are recovered therefrom. It may be appreciated that the method of grinding is not particularly limiting. In principle any mill may be employed. Examples of suitable mills include a ball mill, a roller press, a vertical roller mill and a booster mill. Good results have been achieved with a ball mill, preferably an agitated ball mill. In such a mill, said ultrafine fraction and / or small fine fraction are agitated, thereby colliding the individual particles within the fraction(s) together and / or to mill parts. These collisions promote liberation of a cementitious fraction from a quartz fraction and / or further reduces the particle size of said cementitious fraction. The force exerted on the particles of the ultrafine fraction and small fraction during grinding is usually at least 0.5 GPa, preferably at least 1 GPa, in particular at least 2 GPa. Usually, the force exerted on the particles during grinding is at most 8 GPa, preferably at most 6 GPa, more preferably at most 5 GPa, such as at most 4 GPa. Usually the force exerted on the particles during grinding is between about 0.5 GPa and about 8 GPa, preferably between about 1 GPa and about 6 GPa, such as between about 2 GPa and about 4 GPa. It was found that at such force the particles are advantageously reduced in size whilst liberating the quartz fraction from the cementitious materials. Said force may advantageously be exerted by agitating the mill, thereby causing friction between the particles of the ultrafine fraction and / or small fraction and / or causing friction between the walls of the mills and the particles. Additionally or alternatively, said mill, preferably said ball mill, may comprise grinding bodies, such as balls or rods. These grinding bodies may facilitate grinding. Preferably, said grinding bodies have a density of at most 8 g / cm3, more preferably at most 7 g / cm3, even more preferably at most 6 g / cm3, even more preferably at most 5 g / cm3, most preferably at most 4 g / cm3. Advantageously, the density of said grinding bodies is between about 2 and about 8 g / cm3, preferably between about 3 and about 7 g / cm3. Alternatively or additionally, said grinding bodies consist substantially of metallic material, preferably steel, ceramics material, polymeric material or a combination thereof. Preferably, said grinding bodies consist of ceramics material. Suitable examples of ceramics material include Al2O3, ZrO2, SiC, Si3N and porcelain. As the skilled person will appreciate, the grinding conditions may be selected based upon the composition of the small fine fraction and / or ultrafine fraction. It is within the skilled persons common general knowledge, routine experimentation and information provided herein to select appropriate grinding conditions. In a particularly preferred embodiment, the rotational speed is between about 50% and about 90% of the critical speed (i.e. the speed required to centrifuge the grinding bodies within the mill). More preferably between about 65% and about 85%, most preferably between about 70% and about 75% of such critical speed. At such rotational speeds, the force exerted to the particles is optimal, and quartz is most advantageously liberated from the cementitious material. As the skilled person will appreciate, the critical speed to centrifuge a grinding body depends on various aspects, including the diameter of the mill and the weight of the grinding bodies. The skilled person is capable of determining the critical speed based on common general knowledge and the information provided herein. The residence time of the ultrafine fraction and / or small fine fraction usually depend on various aspects, such as the composition of the fractions and the grinding parameters. Usually, the grinding parameters are chosen such that the particle size is sufficiently reduced and cementitious materials is sufficiently liberated, while preventing grinding of quartz. Common residence times include between about 30 s and about 600 s, preferably between about 60 s and about 400 s, such as between 90 s and about 300 s. Advantageously, an airflow is applied into the mill. Such airflow allows carrying the cement constituent out of the mill, whilst leaving the quartz fraction behind. Such airflow may be provided by flue gas. It may be appreciated that said step of grinding may be advantageously applied to any fraction derived from concrete comprising particular having a d90 size in the range of less than 3 mm, preferably less than 2 mm, more preferably less than 1 mm. Accordingly, the invention further relates to a method for preparing a cement constituent, comprising: - providing a small fine fraction having a d90 size of less than 3 mm obtainable from a concrete element; - grinding said small fine fraction in a mill, wherein the force exerted on the particles in the fraction is at most 5 GPa, preferably between about 0.5 GPa and about 5 GPa to obtain a cement constituent and a silica fraction, preferably a quartz fraction; - separating said cement constituent from said silica fraction; - carbonating said cement constituent to obtain a carbonated cement constituent. Said grinding is preferably performed in a ball mill, more preferably an agitated ball mill, even more preferably an agitate ball mill comprising grinding bodies. Preferably, said the grinding settings, rotational speed and residence time is as defined herein. The ultrafine fraction and the small fine fraction typically comprise hydrated pastes. The BET surface of the ultrafine fraction and / or the small fines fraction is typically between 0.2 – 2 m2 / g, preferably between 0.5 – 1 m2 / g. It is preferred to activate the ultrafine fraction and the small fine fraction by carbonating the amorphous content while maintaining a relative humidity and / or moisture content in the process environment and / or in the small fine and / or ultrafine fraction itself. Preferably the relative humidity in the process environment is at least 40%, preferably at least 60%, more preferably at least 80%, such as at least 90%. In particular, it is advantageous to have a relative humidity in the range of 50 – 99%, preferably between 60 – 95%, even more preferably between 80 – 90%. This relative humidity is defined as the amount of water vapour present in the process environment relative to the amount of water vapour required to achieve saturation at the same temperature and pressure. Reactivity of the ultrafine fraction and the small fine fraction may be further improved if the grinding and optional carbonation comprises heating. The heating further advantageously allows for the disruption of the hydrated structure, thereby forming a reactive silica alumina gel, reactive silica and / or reactive alumina gel from amorphous phases of the ultrafine fraction and the small fines fraction. Additionally, the heating further increases the process efficiency and enhances the properties of the obtained cement constituent, in particular SCM. The heating is preferably to a temperature of 50 – 200 °C, more preferably 80 – 170 °C, even more preferably 100 – 160 °C, most preferably 130 – 150 °C. This temperature may advantageously be provided by the flue gas. It may be appreciated that the flue gas leaving the thermo-mechanical separator typically has a temperature within this range, therefore essentially no further addition of energy is needed. Typically, the cement constituent comprises a binder and / or filler. The specific type of cement constituent is dependent on the starting material. Nonetheless, the person skilled in the art is aware of possible suitable cement constituents. For instance, the cement constituent may comprise a reactive binder. Reactive binder is herein used as a term to describe a material that has hydraulic (i.e. a material that sets and hardens by chemical reaction with water and is capable of doing so under water) or pozzolanic (i.e. a material that needs both water and calcium hydroxide as reactants in order to harden) constituent and may comprise a supplementary cementitious material. Preferably, the binder, in particular the reactive binder, comprises a SCM comprising 15-50 wt% calcium or calcium complexes based on the total weight of the SCM, preferably a SCM with similar or improved properties to e.g. fly ash, slag cement, raw and calcined natural pozzolans, more preferably a SCM in accordance with standard ASTM C1709-22 and / or EN206:2014 type II addition. The cement constituent may alternatively or additionally comprise a filler, preferably a filler comprising an inert material (providing an inert filler), preferably the filler comprises less than 1 wt%, preferably less than 0.5 wt%, more preferably less than 0.1 wt% chloride and / or less than 0.5 wt%, more preferably less than 0.2 wt%, most preferably less than 0.05 wt% sulfur based on the total weight of the filler. It may be particularly advantageous to have an inert filler according to standard EN 12620:2002 + A1:2008, more preferably a EN206:2014 type 1 filler. Inert fillers are also well known in the art and may for instance be a silica fraction (e.g. quartz; SiO2). The (inert) fillers are typically finely divided materials, less than e.g.70 microns or less than 63 microns in size, used in concrete in order to improve certain properties or to achieve special properties. It may be understandable that for the preparation of an (inert) filler, it is often not required to carbonate the small fine fraction and the ultrafine fraction, while for the preparation of a (reactive) binder, this is typically required. It may further be appreciated that the method for carbonation is not particularly limiting. Preferably, the flue gas originating from the second liberation and separation step is employed for carbonation. This allows for the internal usage of the formed CO2. Favorably, the water content and temperature of the flue gas allow for ideal conditions for carbonation. That is, the flue gas may provide for an optimal balance between keeping the temperature high enough to stay above the dew point and minimize condensation, while the water content allows for good carbonation. Alternatively or additionally, chemicals may be used for carbonation. Suitable chemicals are for instance carbonic acid and / or dry ice. It may be appreciated that external CO2may also be employed. However, this would minimize the advantages of the internal usage of the formed CO2. The present invention is also directed to this method for grinding and optional carbonation of a small fine fraction and an ultrafine fraction to obtain a cement constituent. Each of the fractions typically individually have a different size. The particle size may be determined using any suitable method known in the art, but are preferably determined using sieve analysis, in accordance with EN 933-1. These sizes are typically determined by the desired application and / or the apparatuses used for the subsequent method steps. The sizes of each individual fraction may easily be changed by adjusting one or more parameters (or settings) during the method. For instance, the rotor speed and / or the pressure of the airknife of the ballistic separator may be adjusted and / or the grinding settings and / or residence time in the mill may be adjusted to provide smaller or larger cement constituents. The apparatuses used for the method steps may each have requirements for the size. For instance, the ballistic separator may not be suitable for large concrete parts. This could potentially damage the ballistic separator. To ensure that no larger particles enter the ballistic separator, a safety screen or filter may be employed. The concrete parts may have a d90 size of less than 100 mm. The coarse aggregate fraction typically comprises coarse aggregates having a d90 size in the range of 7 – 20 mm. The medium fine fraction typically comprises medium fines having a d90 size in the range of 3 – 7 mm. The small fine fraction may comprise small fines having a d90 size in the range of less than 3 mm. The fine aggregate fraction may comprise fine aggregates having a d90 size in the range of 0.5 – 7 mm. The ultrafine fraction may comprise ultrafines having a d90 size of less than 0.5 mm. Alternatively, the concrete parts may have a d90 size of less 50 mm, the coarse aggregate fraction may comprise coarse aggregates having a d90 size in the range of 5 – 15 mm. The medium fine fraction may comprise medium fines having a d90 size in the range of 2 – 5 mm, the small fine fraction may comprise small fines having a d90 size of less than 2 mm. The fine aggregate fraction may comprise fine aggregates having a d90 size in the range of 0.3 – 5 mm. The ultrafine fraction may comprises ultrafines having a d90 size of less than 0.3 mm. Alternatively, the concrete parts may have a d90 size of less than 20 mm. The coarse aggregate fraction may comprise coarse aggregates having a d90 size in the range of 4 – 12 mm. The medium fine fraction may comprise medium fines having a d90 size in the range of 1 – 4 mm. The small fines fraction may comprise small fines having a d90 size of less than 1 mm. The fine aggregate fraction may comprise fine aggregates having a d90 size in the range of 0.25 – 4 mm. The ultrafine fraction may comprises ultrafines having a d90 size of less than 0.25 mm. The sizes of each of the individual fractions allow for increased surface area and / or surface reactivity. The surface area may determine the particle packing and / or provide nucleation sites for cementitious reactions to occur. The surface reactivity is particularly interesting for the cement constituent. Namely, the cement constituent sizes allow for a high reactive surface that allows for usage in the production of concrete. Accordingly, the cement constituent has an average particle size d50 of at most 200 µm, preferably at most 150 µm, more preferably at most 120 µm. Typically, the filler has such average particles sizes, while the sizes of the binder may be even smaller. Preferably, the binder has an average particle size d50 of at most 50 µm, preferably at most 30 µm, more preferably at most 20 µm or at most 15 µm, such as approximately 10 µm. The sizes may even be adjusted such that the cement constituent, in particular the binder, has a d50 size of at most 2 µm. As detailed above, the cement constituent, in particular the filler may comprise a silica fraction. The content thereof, based on the weight of the cement constituent, is dependent on the composition of the starting material, i.e. the concrete element. The silica content is mainly attributed to quartz. It may be appreciated that, for an SCM, while some silica (or quartz) content is not detrimental (e.g. at most 5 wt% based on the total weight of the SCM) and often present as fine filler material, too much silica negatively affects the properties of the SCM. For instance, the reactivity of the SCM is negatively affected by the presence of silica. Favorably, the quartz, i.e. most of the silica fraction, is generally harder to grind than the rest of ultrafine fraction and the small fine fraction and may accordingly be easily rejected. Therefore, it may be appreciated that the cement constituent may be further subjected to a purification step. This purification step allows for separating it into a filler (e.g. the silica fraction) and a binder (e.g. the supplementary cementitious material). Such a purification step may be easily implemented after the grinding and carbonation. For instance, the method may comprise classification of the cement constituent with a certain cut-off particle size. Preferably by air classification. This cut-off value is typically 70 µm, preferably 65 µm, more preferably 63 µm. To ensure a constant quality of the output, the concrete element, one or each of the fractions and / or cement constituent may be analyzed. Therefore it is preferred that the method further comprises analysis of the coarse aggregate fraction, the fine aggregate fraction and / or the cement constituent. Further, it may be appreciated that depending on the analysis results, the settings for the method may be adjusted accordingly to ensure that the resulting fractions have the desired properties. The analysis means are not particularly limiting and may be by any analysis methods known in the art. For instance, one or more sensors (e.g. moisture sensors) may be included to analyze the contents of the individual fractions and / or cement constituent throughout the method. Alternatively or additionally, an expert in the field may also analyze the fractions and / or cement constituent by eye. Preferably, the analysis method comprises infra-red (IR) spectroscopy and / or laser-induced breakdown spectroscopy (LIBS). LIBS is a technique known in the art that may be applied to analysis samples both quantitatively and qualitatively. The results of the LIBS may advantageously be used to certify the fractions. For instance, the data may be used to provide RFID tags and as such use it as a certification. LIBS is therefore preferred. It was found that high yields of the fractions may be obtained. There is minimal to no waste streams associated with the present method. For instance, 60% of a coarse aggregate fraction, 15% of a fine aggregate fraction and 25% cement constituent, such as supplementary cementitious material, may be obtained based on a starting concrete element. Usually, between about 40% and about 80% of a coarse aggregate fraction, preferably between about 50% and about 70% of a coarse aggregate fraction is obtained based on starting concrete element. Typically, between about 5% and about 20% of a fine aggregate fraction is obtained, preferably between about 10% and about 20%, based on starting concrete element. Preferably, at least 15% of a cement constituent is obtained, more preferably at least 20%, even more preferably at least 25% of a cement constituent, based on starting concrete element. Typically, the amount of a cement constituent obtained from a starting concrete element is in the range of between about 15% and about 35%, more preferably between about 20% and about 30%. Another favorable aspect of the present invention is that the method may be easily implemented on a construction and / or demolition site. The method may thus be (semi-)mobile and as such enables local operation close to the feed material. This minimizes transportation and accordingly costs and CO2 emissions. The pressure during any one and / or each of the individual method steps may be endogenous. In other words, no external pressure is applied and the pressure is at what sets itself. The invention is further directed to each of the individually liberated fractions. Each of these individual fractions may advantageously have pozzolanic and / or hydraulic properties. In particular, the invention is further directed to a coarse aggregate material for producing concrete. Preferably, the quartz content in the fine aggregate is at least 50 wt%, more preferably at least 70 wt%, even more preferably at least 80 wt%, most preferably at least 85 wt%, based on the total weight of the fine aggregate. Alternatively or additionally, the content of calcium and / or calcium complexes and / or reactive silica alumina gel, reactive silica and / or reactive alumina gel is preferably at most 50 wt%, more preferably at most 30 wt%, even more preferably at most 20 wt%, even more preferably at most 15 wt%, most preferably at most 10 wt%, based on the total weight of the fine aggregate. This coarse aggregate material has a particle size d50 in the range of 4 – 20 mm, preferably 4 – 16 mm. In addition, the coarse aggregate material has one or more of: - a resistance to crushing between 15 – 60 %, such as between 20 - 60%, preferably between 20 – 50%, such as between 30 – 50%, more preferably between 15 – 30%; - a bulk density of at least 1400 kg / m3, preferably at least 1600 kg / m3, more preferably at least 1800 kg / m3, even more preferably at least 2000 kg / m3, even more preferably at least 2200 kg / m3, Preferably, said bulk density is in a range of between about 1400 kg / m3 and about 3000 kg / m3, more preferably between about 1600 kg / m3 and about 2800 kg / m3, even more preferably between about 1800 kg / m3 and about 2600 kg / m3, even more preferably between about 2000 kg / m3 and about 2400 kg / m3, such as about 2200 kg / m3; - a water absorption of at most 8.0%, preferably at most 6.0%, more preferably at most 4.0%. Preferably, the water absorption is in the range of 2.0 – 8.0%, more preferably in the range of 2.0 – 6.0%, most preferably in the range of 2.0 – 4.0%. The coarse aggregate material further advantageously has a good particle shape suitable for concrete workability and strength. Preferably, at most 15 wt%, more preferably at most 10 wt%, even more preferably at most 5 wt%, of the particles have a length to thickness ratio of more than 3 to 1, preferably at most 2 to 1. Alternatively or additionally, the coarse aggregate material has a flakiness index of FI15. The coarse aggregate material further preferably has a particle density of at least 1400 kg / m3, preferably at least 1600 kg / m3, more preferably at least 1800 kg / m3, even more preferably at least 2000 kg / m3, even more preferably at least 2200 kg / m3. Preferably, said particle density is in a range of between about 1400 kg / m3 and about 3000 kg / m3, more preferably between about 1600 kg / m3 and about 2800 kg / m3, even more preferably between about 1800 kg / m3 and about 2600 kg / m3, even more preferably between about 2000 kg / m3 and about 2400 kg / m3, such as about 2200 kg / m3. The coarse aggregate material further preferably has an alkali- silica reactivity of at most 0.1%, preferably at most 0.05%, even more preferably at most 0.02%. Such alkali-silica reactivities advantageously reduce the risk of expansive cracking in concrete. The freeze-thaw resistance of the coarse aggregate material is preferably at least 2 kg / m2, more preferably at least 2.5 kg / m2. Typically, the freeze-thaw resistance is in the range of between about 2 and about 5 kg / m2, preferably between about 2.5 and about 3 kg / m2. The coarse aggregate material further preferably has a sulfate content soluble in acid of at most 1%, more preferably at most 0.5%, even more preferably at most 0.2%. Such properties advantageously allow good durability in sulfate-rich environments. The coarse aggregate material further preferably has a chloride content of at most 1%, more preferably at most 0.1%, even more preferably at most 0.01%. Such properties advantageously reduce the risk of reinforcement corrosion. The water absorption, resistance to crushing, bulk density, particle shape, particle density, alkali-silica reactivity, freeze-thaw resistance, sulfate content and chloride content may each be independently measured in accordance with EN12620:2002 + A1:2008. The coarse aggregate material may comprise a coarse aggregate fraction, typically obtained in the method of the present invention. The invention is further directed to a fine aggregate material for producing concrete. The fine aggregate material typically comprises a sand and / or sand-like material. Preferably, the quartz content in the fine aggregate is at least 50 wt%, more preferably at least 70 wt%, even more preferably at least 80 wt%, most preferably at least 85 wt%, based on the total weight of the fine aggregate material. Alternatively or additionally, the content of calcium and / or calcium complexes and / or reactive silica alumina gel, reactive silica and / or reactive alumina gel is preferably at most 50 wt%, more preferably at most 30 wt%, even more preferably at most 20 wt%, even more preferably at most 15 wt%, most preferably at most 10 wt%, based on the total weight of fine aggregate material. The fine aggregate material has a particle size d50 in the range of 0.25 – 5 mm, preferably 0.25 – 4 mm or 2 - 5 mm. Advantageously, the fine aggregate material comprises a relatively small fraction of particles having a particle size of <63 μm. A small content of such particles is advantageously associated with low water absorption. Preferably, the fine aggregate material comprises, based on the total weight of the fine aggregate material, less than 7 wt% of particles of below 63 μm, more preferably less than 5 wt%, even more preferably less than 4 wt%, even more preferably less than 3 wt%, even more preferably less than 2 w.%, most preferably less than 1 wt%. Preferably, the content of particles having a particle size of 63 μm or less is between about 0.1 and about 7 wt%, more preferably between about 0.2 and about 5 wt%, in particular between about 0.5 and about 3 wt%. In addition, the fine aggregate material has: - a bulk density of at least 1200 kg / m3, preferably at least 1300 kg / m3, more preferably at least 1500 kg / m3, even more preferably at least 1800 kg / m3, even more preferably at least 2000 kg / m3, even more preferably at least 2200 kg / m3, most preferably at least 2400 kg / m3. Preferably, the bulk density is between about 1200 - 3000 kg / m3, such as 1200 - 1600 kg / m3, preferably 1300 - 2500 kg / m3, such as 1300 - 1600 kg / m3, more preferably 1500 - 2200 kg / m3, such as 1500 - 1600 kg / m3; and / or - a water absorption of at most 9.0%, preferably at most 7%, even more preferably at most 5%, even more preferably at most 4%, even more preferably at most 3%, even more preferably at most 2%, most preferably at most 1%. Preferably, the water absorption is in the range of 1.0 – 9.0%, more preferably 2.0 – 7.0%, more preferably 2.0 – 5.0% Preferably, the water absorption is in the range of 2.0 – 9.0%, more preferably in the range of 2.0 – 7.0%, most preferably in the range of 2.0 – 5.0%. The fine aggregate material further preferably has a particle density of at least 1400 kg / m3, preferably at least 1600 kg / m3, more preferably at least 1800 kg / m3, even more preferably at least 2000 kg / m3, even more preferably at least 2200 kg / m3, Preferably, said particle density is in a range of between about 1400 kg / m3 and about 3000 kg / m3, more preferably between about 1600 kg / m3 and about 2800 kg / m3, even more preferably between about 1800 kg / m3 and about 2600 kg / m3, even more preferably between about 2000 kg / m3 and about 2400 kg / m3, such as about 2200 kg / m3. The fine aggregate material further preferably has an alkali-silica reactivity of at most 0.1%, preferably at most 0.05%, even more preferably at most 0.02%. The fine aggregate material further preferably has a sulfate content soluble in acid of at most 1%, preferably at most 0.5%, even more preferably at most 0.4%. The fine aggregate material further preferably has a chloride content of at most 1%, more preferably at most 0.1%, even more preferably at most 0.04%. The water absorption, bulk density, alkali-silica reactivity, particle density, sulfate content soluble in acid and chloride content may each be independently measured in accordance with EN12620:2002 + A1:2008. The fine aggregate material typically comprises the fine aggregate fraction as liberated by the method according to the present invention. The invention is further directed to the cement constituent, preferably to a cement constituent comprising a binder, such as an SCM. Preferably this cement constituent, particular a supplementary cementitious material, is obtainable by the method according to the present invention. The cement constituent typically comprises, based on the total dry weight of the cement constituent - less than 60 wt%, more preferably less than 50 wt%, more preferably less than 45 wt%, even more preferably less than 40 wt%, even more preferably less than 35 wt%, even more preferably less than 30 wt%, even more preferably less than 25 wt%, even more preferably less than 20 wt%, even more preferably less than 15 wt%, even more preferably, less than 10 wt%, even more preferably less than 8 wt%, most preferably less than 7 wt% SiO2, preferably quartz; and - at least 10 wt% calcium and / or calcium complexes, preferably at least 12 wt%, even more preferably at least 14 wt% of calcium and / or calcium complexes. Typically, said cement constituent comprises 10 – 50 wt%, preferably 20 – 50 wt% calcium and / or calcium complexes; and / or - at least 5 wt% of reactive silica alumina gel, reactive silica and / or reactive alumina gel, preferably at least 6 wt%, even more preferably 7 wt%, most preferably at least 8 wt% of reactive silica alumina gel, reactive silica and / or reactive alumina gel. Typically, the cement constituent comprises 5 – 30 wt%, preferably 15 – 20 wt% of a reactive silica alumina gel, reactive silica and / or reactive alumina gel. The invention further relates to a cement blend, preferably a powder cement blend, comprising a cement constituent according to the invention. Said cement blend further comprises non-recycled cement, such as ordinary Portland cement or sulfate-resistant cement. Typically, a cement blend according to the invention comprises at least about 5 wt% of cement constituent according to the invention, preferably at least 10 wt%, more preferably at least 25 wt%, even more preferably at least 50 wt%, based on the dry weight of the cement blend. Preferably, a cement blend comprises between about 5 wt% and about 100 wt% of cement constituent, based on the dry weight of the cement blend. More preferably between about 10 wt% and about 90 wt%, even more preferably between about 20 wt% and about 80 wt%, even more preferably between about 25 wt% and about 70 wt%, such as between about 30 wt% and about 50 wt% of cement constituent, based on dry weight of the cement blend. The invention further relates to a cement slurry for preparing concrete, comprising a cement blend according to the invention and water. The term ‘slurry’ is generally known in the art to describe mixtures of a fluid in which a particulate (e.g. pulverised) material is dispersed that (in unhardened state) is flowable or pumpable. The cement slurry can be made from the cement powder blend according to the invention by mixing with water in a manner known per se. The resultant slurry, such as the paste, can thereafter by used in a manner known per se for any application of interest, in particular in the production of a concrete according to the invention, as mortar or for a use specified elsewhere herein. Typically, the weight to weight ratio of water to the cement blend is in the range of 0.2 - 0.7, preferably in the range of 0.3 -0.5. Said cement slurry is usually allowed to cure, to form a hardened cement slurry. Accordingly, the invention further relates to a hardened cement slurry of a cement blend according to the invention. The invention further relates to a concrete composed of a cement blend according to the invention and / or comprising a fine aggregate material and / or a coarse aggregate material according to the invention. A concrete according to the invention may be prepared in a manner known per se. Typically, aggregate is added to the cement slurry. The aggregate may be fine aggregate material, coarse aggregate material or a combination thereof. Advantageously, said fine aggregate material and / or coarse aggregate material is according to the invention. Optionally, the concrete may also comprise natural fine aggregate and / or natural coarse aggregate. The concrete according to the invention may advantageously further comprise one or more further components, such as reinforcement materials or additives. Examples of reinforcement materials include steel reinforcement materials, carbon fibers and polymeric fibers. Examples of additives for concrete include plasticizers, corrosion inhibiters (in particular in case a steel reinforcement material is present), shrinkage-reducing materials, anti- washout materials, additives to improve freeze-thaw resistance, additives to reduce setting time, etc. The proportions of components may depend on the intended application. The skilled person is capable of determining suitable proportions based on common general knowledge and the information provided therein. Said hardened cement slurry and concrete according to the invention have advantageous properties. Preferably, said concrete according to the invention have high compressive strength. As the skilled person will appreciate, the compressive strength of the hardened cement slurry or concrete according to the invention depends on the composition, e.g. the type of cement that is used to prepare the mortar or concrete and / or the presence of additives therein. Usually, the compressive strength after 28 d is at least 30 MPa, preferably at least 35 MPa, even more preferably at least 40 MPa, even more preferably at least 45 MPa, most preferably at least 50 MPa. Usually, the compressive strength is between about 30 MPa and about 100 MPa, even more preferably between about 35 MPa and about 70 MPa. Preferably, said hardened cement slurry and concrete according to the invention have a compressive strength that is comparable to a reference mortar or concrete, i.e., a hardened cement slurry or concrete that lacks the cement constituent and / or cement blend according to the invention, but is otherwise the same. Preferably, said compressive strength after 28 days is at least 50% of the compressive strength of a suitable reference hardened cement slurry or reference concrete, preferably at least 60%, even more preferably at least 70%, even more preferably at least 80%, even more preferably at least 85%, most preferably at least 90% of the compressive strength of a suitable reference hardened cement slurry or concrete. It is appreciated that the compressive strength of the hardened cement slurry or concrete according to the invention is determined under the same conditions as the reference mortar or reference concrete. The strength activity index (SAI) at 28 d of a hardened cement slurry or concrete according to the invention is usually at least 50%, preferably at least 70%, even more preferably at least 80%, most preferably at least 90%. Usually, the SAI is between about 50-100%, preferably between about 70% and about 90%. Said hardened cement slurry and concrete according to the invention advantageously have good settleability. In a preferred embodiment, the hardened cement slurry and concrete according to the invention have an initial setting time of 100-170 min, preferably 120-150 min. Preferably, the hardened cement slurry and concrete according to the invention have a final setting time of 170-270 min, preferably 180-250 min, in particular 190-230 min. An advantage of a fast setting time is that fewer time is needed for the construction process, hence making the overall process more time and cost efficient. The invention further relates to a product comprising hardened cement slurry or concrete according to the invention. Said product is preferably selected from an infrastructural element, such a pavement, a road, a parking place, an airplane landing strip; and a building element, such as a floor, a wall, a ceiling, a bank and a pipe. The invention is further directed to the use of a coarse aggregate material, a fine aggregate material, a cement constituent and / or a cement blend as detailed herein for producing cement, mortar and / or concrete. In particular, the cement constituent, more particular an SCM may be used as a substitute of cement in concrete and / or of cement clinker in cement. For the purpose of clarity and a concise description, features are described herein as part of the same or separate embodiments, however, it will be appreciated that the scope of the invention may include embodiments having combinations of all or some of the features described. In particular, it will be appreciated that the scope of the invention may also relate to any and each of the method steps individually and independently. The invention is demonstrated by the following examples. Example 1: Preparation of a cement constituent according to the invention. Concrete elements with an approximate size of about 400 mm were crushed to obtain concrete parts having a d90 size of at most 20 mm. The concrete parts were subsequently subjected to a step of advanced dry recovery (ADR) as described in WO2009 / 123452, at a rotor speed between 900 and 1100 rpm and an air knife pressure (or airspeed) of 5 kPa, to obtain a coarse fraction, a medium fine fraction and a small fraction. The d90 particle size of the coarse, medium fine, and small fine fractions were determined to be in the range of 4-12 mm, 1-4 mm and less than 1 mm, respectively. Particle size was determined by sieve analysis according to EN 933-1. The medium fine fraction was subsequently subjected into an upper part of a HAS as described in WO 2019 / 12336, at a temperature of between about 500 °C and about 600 °C. A fine aggregate fraction with a d90 particle size in the range of 0.25-4 mm was collected at the bottom of the HAS, whereas an ultrafine fraction was carried out of an upper part of the HAS with an airflow, and subsequently carried into a cyclone. The ultrafine fraction was collected at the bottom of the cyclone and determined to have a d90 of less than 0.25 mm as determined by sieve analysis. The composition of the small fine fraction obtained from the ADR, the ultrafine fraction obtained from the HAS and the fine aggregate fraction obtained from the HAS were analysed (table 2). The ultrafine and small fine fractions were further subjected to a step of grinding using a ball mill operating at 75% of the critical speed. The ground materials were separated using dynamic air separation to separate the quartz fraction from an uncarbonated cement constituent (supplementary cementitious material). The uncarbonated cementitious material was subsequently subjected to a step of carbonation using flue gas originating from the HAS to obtain a carbonated cement constituent. The composition of the uncarbonated and carbonated cement constituents were analysed using X-ray Fluorescence analysis and shown in table 1. Table 1: Composition of the ultrafine fraction obtained from the HAS (before grinding – ultrafines), the ultrafine fraction after grinding (uncarbonated cement constituent), the ultrafine fraction after grinding and carbonation (carbonated cement constituent) and the fine aggregate fraction obtained from the HAS. Composition (wt.%) Oxides Ultrafines Uncarbonated Carbonated Fine cement cement aggregate constituent constituent SiO2 68.3 52.7 48.6 88.4CaO 13.3 21.1 19.4 3.9Al2O3 4.2 5.6 5.2 2.9Fe2O3 1.4 2.1 1.9 1.5MgO 0.9 1.9 1.8 0.3K2O 0.9 0.9 0.8 0.6Na2O 0.4 0.3 0.4 -SO3 0.7 1.5 1.4 0.3TiO2 0.3 0.4 0.3 -Minor0.8 0.2 0.3 0.3constituents* Loss of8.8 13.3 19.9 1.7ignition (LOI) * Minor constituents were considered oxides with ≤ 0.10 wt.% and included P2O5, SrO, Cl, Mn2O3, ZnO, BaO and Cr2O3. The ultrafine fraction, uncarbonated cement constituent and carbonated cement substituent were further subjected to X-ray diffraction (XRD) quantification. The results are shown in table 2. Table 2: XRD quantification of ultrafine fraction, uncarbonated cement constituent and carbonated cement constituent Composition (wt.%) Phase Ultrafines Uncarbonated Carbonated cement cement constituent constituent Quartz 57.0 34.2 32.2Calcite 4.3 8.7 8.0Vaterite 0.1 0.4 4.2Dolomite 0.4 1.7 0.6Gypsum - 1 0.2Hematite 0.2 0.2 0.2Albite 2.9 17.3 3.8Microcline 2.8 3.2 3.2Muscovite - 1.2 1.2Kaolinite - 0.6 0.2Alite (C3S) 1.5 1.6 1.4Belite (C2S) 0.7 0.7 -C3A - 0.6 0.3Ferrite (C4AF) 0.3 - -Portlandite 0.1 0.1 0.1Minor0.2 3.7 0.2constituents* Amorphous29.5 24.8 44.2content As can be derived from Table 2, ultrafine fraction has a higher quartz content of 57% and CaCO3 content of 4.3%, most of it being calcite, and amorphous content of 29%. After the ultrafine fraction was milled and carbonated, the content of quartz reduced significantly to 32.2%. By separating the silica particles, there was also a higher proportion of amorphous material in the final product, increasing the content to 44.2%. The carbonation result was evident by the presence of 12.2% of CaCO3in the carbonated material, three times higher than the ultrafine fraction. 4.2% was identified as vaterite, which has higher reactivity and can contribute to the material’s properties when used in cementitious materials. Moreover, the carbonation process could also have contributed to the higher content of amorphous products. Example 2: Mortar and concrete properties comprising cement constituent according to the invention The reactivity of the carbonated cement constituent obtained in Example 1 was assessed through strength activity index (SAI) tests (EN 196-1) at 7 and 28 days (Figure 3) by substituting 25% of the cement (CEM II 32.5R) by the carbonated cement constituent according to the invention. The SAI of a mortar comprising the carbonated cement constituent at 7 days was 85% when compared to the reference prepared with 100% CEM I cement at the same age. At 28 days, the SAI of mortar comprising carbonated cement constituent according to the invention was 89% when compared to the reference at the same age. The results show the potential of carbonated cement constituent to perform as a pozzolanic material. If compared with fly ash limits to be considered pozzolanic (SAI of 75%), the carbonated cement constituent presents good results, above fly ash limits. Carbonated and uncarbonated cement constituent according to the invention were added in cement pastes to compare their performance, and the results of compressive strength at 7 and 28 days are presented in Figure 4. Cement type CEM I 52.5R was used substituted by 25 wt% of uncarbonated cement constituent and carbonated cement constituent according to the invention, respectively, in the mixtures. The pastes presented water / binder ratio of 0.4 (here the uncarbonated and carbonated cement constituents were also considered binders). The results show that pastes with carbonated cement constituent presented significant better performance than the pastes with uncarbonated cement constituent. Cement pastes with carbonated cement constituent achieved 94% of the strength of the reference paste at 7 days and 90% of the strength of the reference paste at 28 days. In another experiment, concrete samples were prepared from CEM I 42.5 R supplemented with 15% or 25% of carbonated cement substituent according to the invention. The setting time (min), water requirement (%), expansion (mm) and mortar compression strength (MPa) were determined and shown in Table 3. Table 3: properties of concrete comprising carbonated cement constituent according to the invention Reference 75% CEM I 42.5 R 85% CEM I 42.5 CEM 42.5 R + 25% carbonated R + 15% cement carbonated constituent cement according to the substituent invention according to the invention Mortar Comp. strength (MPa) 2d 29.1 23.5 25.7 7d 41.8 33.4 36.0 28 d N / D 38.9 N / D Setting time 150 / 250 140 / 200 120 / 200 Water 29.2 31.2 29.8 requirement (%) Expansion 0.8 0.9 1.0 (mm) In a further test, a concrete comprising 50 wt% of carbonated cement constituent according to the invention and 50 wt% of CEM I 52.5R Spen or 50% CEM I 52.5R Enci was prepared and compared to a concrete prepared to a commercially available cement constituent (Ecofiller, commercially available from REKO B.V.). The results are shown in Table 4. Table 4: properties of concrete comprising carbonated cement constituent according to the invention (cCC). Concrete Comp. Comp. strength Comp. strength composition strength (2 d) (7 d) (N / mm2) (28 d) (N / mm2) (N / mm2) 50% CEM I 17.6 28.4 39.4 52.5 R Spen + 50% Ecofiller 50% CEM I 18.9 36.3 42.5 52.5R Spen + 50% cCC 50% CEM I 17.0 37.5 40.0 52.5R Enci + 50% cCC CEM III / B 18.9 38.4 56.0 42.5 Cemmin CEM III / B 18.4 27.5 40.0 42.5 Cemmin + 25 cCC It can be derived from table 3 that concrete samples prepared with a cement constituent according to the invention had good compressive strength, in particular in comparison to a commercially available reference (Ecofiller). Example 3: Composition of coarse and fine aggregate according to the invention The coarse aggregate fraction obtained from the ADR and the fine aggregate fraction collected from the bottom of the HAS were analysed in terms of resistance to crushing (according to NEN-EN 1097-2), water absorption (according to NEN-EN 1097-6), particle density (according to NEN-EN 1097-6) and aggregate crushing value (according to ISO 20290-3) and compared to natural coarse and fine aggregate. The results are shown in table 5. Table 5: Properties of coarse and fine aggregates according to the invention compared to reference Coarse Natural Fine Natural aggregate coarse aggregate fine aggregate aggregate (Ref) (Ref) Particle 2.26 2.4-2.65 2.18 2.62 density (g / cm3) Water 4-5.8 1-2.5 7-8.5 <3% absorption (%) Los Angeles 26 15-30 N / A N / A abrasion value (%) Aggregate 21.5 15-20 N / A N / A crushing value (%) The overall aggregates’ property data (table 5) indicates that the coarse and fine aggregates according to the invention exhibit properties comparable to natural aggregates, with slight variations in water absorption and crushing value. Coarse and fine aggregate materials according to the invention were further analyzed in conformity with the standard EN 12620:2002 + A12008. The results are shown in Table 6.

[0002] Table 6. Technical characteristics of coarse and fine aggregate materials according to the invention. Rcu95: At least 95% is crushed concrete, concrete products, and unbound aggregates Rb10-: No more than 10% is crushed brick or other masonry XRg1: No more than 1% is glass Ra1-: No more than 1% is asphalt X1-: No more than 1% is other materials (clay, soil, metals, wood, plastic, gypsum) FL0,2-: No more than 0.2% is floating material by volume. coarse fine aggregate aggregate Geometrical properties Size range 4 – 16 mm 0 – 4 mm D / d 4 Grading category Gc 90 / 15 Gf 85 Tolerance GT 17,5 NPD Granular shape (flakiness FI15 n.d. index) Grain shape index SI15 n.d. Shell content NPD n.d. Fines content f1,5 f3 Quality fine parts no swelling clay minerals Physical properties Particle density 2.3 g / cm32.4 g / cm3Water absorption 5 ± 2% 4.3 ± 2% Resistance to fragmentation LA30 n.d. Freeze / thaw resistance 2.,5 – 3 kg / m2n.d. Alkali-silica reactivity Na2O-eq= Na2O-eq= 0,02% 0,02% Classification Rc 90, Rcu 95, Rb Rc 90, Rcu 95, Rb 10-, Ra 1-, XRg 1-, 10-, Ra 1-, XRg 1-, XRg 1-, FL 0,2- XRg 1-, FL 0,2- Chemical properties Chloride < 0,01% < 0,04% Acid-soluble sulfate AS 0,2 AS 0,5 Total sulfur NPD n.d. Water soluble sulfate SS 0,2 n.d. Regarding the particle size distribution of the aggregate, the coarse aggregate material has at least 90% of the aggregate passing the upper sieve size (D 16 mm) and no more than 15% passing the lower sieve size (d 4 mm), ensuring a consistent size distribution. The allowed deviation from the declared typical grading is ±17.5%, providing flexibility in production while maintaining consistency. No more than 15% of the particles are considered "flaky" (having a thickness significantly less than their length or width), indicating good particle shape for concrete workability and strength. Also, no more than 15% of the particles have a length-to-thickness ratio greater than 3:1, further confirming good particle shape. The physical properties of the coarse aggregate material include average particle density of 2.3 g / cm3 and water absorption of 5 ± 2%. In the Los Angeles abrasion test, the aggregate experiences up to 30% mass loss, indicating moderate resistance to wear and impact. The alkali-silica reactivity was 0.02%, with low potential for alkali-silica reaction, reducing the risk of expansive cracking in concrete. At least 90% is crushed concrete and concrete products. Regarding the chemical properties of the coarse aggregate material, it was found that the sulfate content soluble in acid is ≤0.2%, important for durability in sulfate-rich environments. There is negligible amount of sulfates that are soluble in water, reducing risks of sulfate attack and very low chloride content, minimizing the risk of reinforcement corrosion. As regards the fine aggregate, the particles are between 0 and 4 mm in size, of which at least 85% of the aggregate passes the upper sieve size (4 mm), ensuring a consistent size distribution. The content of fines (particles smaller than 0.063 mm) is limited to 3% by mass. The fines do not contain swelling clay minerals, which could negatively affect concrete performance. Regarding the chemical properties of the fine aggregate composition, it was found that the sulfate content soluble in acid is ≤0.4%, important for durability in sulfate-rich environments. Example 4: Characterisation of thermal spalling of small fine and medium fine fractions Both wet and dry samples are used as HAS feed material. The input material is prepared based on its particle size and moisture content. The details of these materials are given in 8. Table 8: Type and amount of sample prepared and the amount collected at HAS exit; moisture content between brackets. Sample (mm) Wt. of Feed (kg) Wt. output (kg)4-2 (10%) 5.2 4.854-2 (8%) 5.1 4.894-2 (6%) 5 4.791-2 (10%) 5 4.511-2 (8%) 5 4.561-2 (6%) 5 4.6760.5-1 (12%) 5 4.40.5-1 (10%) 5 4.710.5-1 (8%) 5 4.693After running all tests, the particle size distribution of HAS output samples is determined by sieving each output sample according to EN 933-1. Table 9 shows the particle size distribution for all samples. From this table, the extent of spalling can be deduced as follows. It is assumed that all particles having a size below the particle size of the feed material are produced by spalling (e.g. for the 2-4 mm fractions, all particles having a particle size of below 2 mm are produced during HAS, for the 1-2 mm fractions, all particles having a particle size of below 1 mm, etc.). This is shown in the row “amt. spalling”. The fraction of particles that have spalled is the amount of spalled particles divided by the total particles (e.g.18.9% for 2-4 mm (6% moisture). When assuming only the particles having a particle size of below 0.5 mm are the result of spalling, the percentage of spalled particles decreases (e.g.3.6% for 2-4 mm (6% moisture). Table 9: PSD of the samples after being processed with HAS 2-4 mm (6%) (g) 2-4 mm 2-4 mm 1-2 mm 1-2 mm 1-2 mm 0.5-1 mm 0.5-1 mm 0.5-1 mm(8%) (g) (10%) (g) (6%) (g) (8%) (g) (10%) (g) (8%) (g) (10%) (g) (12%) (g) >4 0 0 0 0 0 0 0 0 0> 2 1626.5 2132 870.6 2.7 2.6 15.7 0 0 01-2 285 506.7 327.2 1670.2 2256.5 2035.5 13.5 4.4 18.10.5-1 21.6 98.7 193.6 93.6 192.6 206.4 1902.9 1281 1495.10.25-0.5 28.3 136 107.3 15.8 22 32.5 81 92.2 97.80.125-0.25 23.1 66.5 35.3 16.7 21.2 34 27.3 17.8 18.60.063-0.125 10.1 13.3 18.7 12.6 12.7 12.4 15.8 11.4 11.3< 0.063 10 22.3 22.4 12.2 19.7 11.5 19.4 10.7 10Total 2004.6 2975.5 1575.1 1821.1 2524.7 2332.3 2046.4 1413.1 1632.8Amt. spalling (less) 378.1 843.5 704.5 150.9 268.2 296.8 143.5 132.1 137.7Spalling (%) 18.9 28.3 44.7 8.3 10.6 12.7 7.0 9.3 8.4**Spalling (%) 3.6 8.0 11.7 3.1 3.0 3.9 7.0 9.3 8.4** When only particles having a particle size of less than 0.5mm are considered for spalling

[0003] As can be derived from table 9, fractions with a higher moisture content typically spall more than fractions with a low moisture content (e.g.44.7% compared to 18.9% for the same particle size). Likewise, it can be derived that fractions with a higher particle size spall more than fractions with a lower particle size (e.g. 44.7% for 4-2 mm compared to 12.7% for 1-2 mm and 9.3% for 0.5-1 mm). The feed and output materials are subjected to acid dissolution tests. Herein, a sample is mixed with HCl for about 6 to 8 h. The mixture is decanted and the residue is repeatedly washed with hot water. The undissolved sandy fraction is washed, dried and weight. The solution is filtered and dried to obtain a residue. The results are shown in table 10. Table 10: Amount of cement for the feed and output materials, based on acid dissolution method; amt diss / dry wt.: amount dissolved / dry weight; amt. diss. / int.wt.: amount dissolved / initial weight. Sample Weight HCl weight Residue Amount of cement sample (g) (ml) after (g) Amt. Amt. acid (g) diss. / dry wt. diss. / int. wt. Feed materials 4-2400 350 ml 312.3 22.6 19.44 16.28mm 1-2400 350 ml 302.3 34.5 18.76 15.80mm 0.5-1350 350 ml 270.5 26.2 17.96 15.23mm <0.5350 350 ml 254.6 18 28.39 22.11mm Output Materials 4-2400 350 308.7 39.4 14.91 12.98mm (6%) 4-2400 350 305.5 42 15.11 13.13mm (10%) 1-2350 350 270.1 32.1 15.82 13.66mm (6%) 1-2350 350 272.9 33 14.42 12.60mm (10%) 0.5-1350 350 265 35.1 16.63 14.26mm (8%) 0.5-1350 350 256.6 66.7 8.26 7.63mm (12%) As can be derived from table 10, all fractions showed a reduction in the amount of cement after being subjected to HAS, i.e. for 4-2 mm fraction, the fraction of cement was reduced from 19.44% to 15% (average of 6% and 10% moisture fractions), for the 1-2 mm fraction the fraction of cement was reduced from 18.76% to about 15.12% (average of 6% and 10% moisture fractions), and for the 0.5-1 mm fraction, the fraction of cement was reduced from 17.96% to 12.4% (average of 8% and 12% moisture fractions). This is an indication that cement fines (particle size <0.5 mm) were separated from the larger aggregates during HAS treatment.

Claims

Claims 1. Method for obtaining a cement constituent from a concrete element, said method comprising: - providing a concrete element; - breaking said concrete element into concrete parts; - subjecting said concrete parts to a first liberation and separation step to obtain a coarse aggregate fraction, a medium fine fraction and a small fine fraction; - subjecting said medium fine fraction to a second liberation and separation step to obtain a fine aggregate fraction and an ultrafine fraction, wherein said second liberation and separation step comprises thermo-mechanical separation; - grinding and optional carbonation of said small fine fraction and the ultrafine fraction to obtain a cement constituent.

2. Method according to the previous claim, wherein the method further comprises analysis, preferably by laser-induced breakdown spectroscopy, of the coarse aggregate fraction, the fine aggregate fraction and / or the cement constituent.

3. Method according to any of the previous claims, wherein saidcement constituent comprises a binder and / or a filler, preferably a reactive binder and / or an inert filler, more preferably wherein said cement constituent comprises a silica fraction and / or a supplementary cementitious material, most preferably wherein said cement constituent comprises a supplementary cementitious material.

4. Method according to any of the previous claims, wherein the cement constituent is further subjected to a purification step therebyobtaining a quartz fraction and a supplementary cementitious material, preferably wherein said purification comprises a step of air classification.

5. Method according to any of the previous claims, wherein said breaking comprises crushing, preferably in a jaw crusher and / or in a cone crusher.

6. Method according to any of the previous claims, wherein said first liberation and separation step comprises ballistic separation.

7. Method according to any of the previous claims, wherein said concrete parts have a d90 size of less than 100 mm, said coarse aggregate fraction comprises coarse aggregates having a d90 size in the range of 7 – 20 mm, said medium fine fraction comprises medium fines having a d90 size in the range of 3 – 7 mm, said small fine fraction comprises small fines having a d90 size in the range of less than 3 mm, wherein said fine aggregate fraction comprises fine aggregates having a d90 size in the range of 0.5 – 7 mm and / or said ultrafine fraction comprises ultrafines having a d90 size of less than 0.5 mm.

8. Method according to any of the previous claims 1-6, wherein said concrete parts have a d90 size of less 50 mm, said coarse aggregate fraction comprises coarse aggregates having a d90 size in the range of 5 – 15 mm, said medium fine fraction comprises medium fines having a d90 size in the range of 2 – 5 mm, said small fine fraction comprises small fines having a d90 size of less than 2 mm, said fine aggregate fraction comprises fine aggregates having a d90 size in the range of 0.3 – 5 mm and / or said ultrafine fraction comprises ultrafines having a d90 size of less than 0.3 mm.

9. Method according to any of the previous claims 1-6, wherein said concrete parts have a d90 size of less than 20 mm, said coarse aggregate fraction comprises coarse aggregates having a d90 size in the range of 4 – 12 mm, said medium fine fraction comprises medium fines having a d90 size in the range of 1 – 4 mm, said small fines fraction comprises small fines having a d90 size of less than 1 mm, said fine aggregate fraction comprises fine aggregates having a d90 size in the range of 0.25 – 4 mm and / or said ultrafine fraction comprises ultrafines having a d90 size of less than 0.25 mm.

10. Method according to any of the previous claims, wherein said second liberation and separation step comprises formation of a flue gas comprising CO2, preferably wherein said method further comprises using said flue gas for said carbonation.

11. Method according to any of the previous claims, wherein said grinding and optional carbonation comprises heating, preferably to a temperature of 50 – 200 °C, more preferably 80 – 170 °C, even more preferably 100 – 160 °C, most preferably 130 – 150 °C.

12. Method according to any of the previous claims, wherein said cement constituent has an average particle size d50 of at most 200 µm, preferably at most 150 µm, more preferably at most 120 µm, preferably wherein said binder has an average particle size of at most 50 µm, preferably at most 30 µm, more preferably at most 20 µm or at most 15 µm, such as approximately 10 µm.

13. A coarse aggregate material for producing concrete, said coarseaggregate material having a particle size d50 in the range of 4 – 20 mm, preferably 4 – 16 mm, and one or more of: - a resistance to crushing between 15 – 60 %, preferably between 20 – 50%;- a bulk density of at least 1400 kg / m3, preferably at least 1600 kg / m3, more preferably at least 1800 kg / m3; - a water absorption of at most 8.0%, preferably at most 6.0%, more preferably at most 4.0%.

14. A fine aggregate material for producing concrete, said fineaggregate material having a particle size d50 in the range of 0.25 – 5 mm, preferably 0.25 – 4 mm, and one or more of: - a bulk density of 1200 – 3000 kg / m3, preferably 1300 - 2500 kg / m3, more preferably 1500- 2200 kg / m3; - a water absorption of at most 9.0%, more preferably at most 7.0%, more preferably at most 5.0%.

15. Cement constituent for producing concrete comprising:- less than 50 wt%, preferably less than 35 wt.%, even more preferably less than 10 wt%, even more preferably less than 8 wt%, even more preferably less than 7 wt% SiO2 (Quartz); and - 10-50% calcium and / or calcium complexes; and / or - 5-30% of a reactive silica alumina gel, reactive silica and / or reactive alumina gel, preferably wherein the cement constituent is obtainable by the method according to any of the previous claims 1-14.

16. Cement blend comprising a cement constituent according to claim 15.

17. Cement slurry comprising a cement constituent according to claim15 and / or a cement blend according to claim 16 and water.

18. Hardened cement slurry of a cement slurry according to claim 17.

19. Concrete comprising a coarse aggregate material according toclaim 13 and / or a fine aggregate material according to claim 14 and / or composed of a cement constituent according to claim 15 and / or a cement blend according to claim 16.

20. Product comprising hardened cement slurry according to claim 18 and / or concrete according to claim 19.

21. Use of a coarse aggregate material according to claim 13, a fine aggregate material according to claim 14 and / or a cement constituent according to claim 15 and / or a cement blend according to claim 16 for producing cement, cement slurry and / or concrete.