System, method, and composition of vaterite cementitious blends

Abstract

Various aspects present advantageous composition with substituting SCMs in blended cements with vaterite at levels between 5% and 15%. In the cement-fly ash blends, the replacement of 10% of fly ash with vaterite resulted in a 40% increase in strength after 1 day, and the increased compressive strength persisted over a 56-day period when compared to the control cement-fly ash blend. Aspect systems may comprise a first reactor, operating at a first temperature, and configured to calcine limestone and produce Portland cement and a gaseous composition comprising carbon dioxide, a second reactor, operating at a second temperature which is lower than the first temperature, and configured to produce vaterite using a portion of the carbon dioxide, and a blending reactor configured to produce a cementitious blend comprising the Portland cement, the vaterite, and SCM.

Description

Attorney Docket No.6351.088WO1 SYSTEM, METHOD, AND COMPOSITION OF VATERITE CEMENTITIOUS BLENDS Cross-Reference To Related Application

[0001] This application claims the benefit of priority to U.S. Provisional Patent Application Serial No.63 / 561,271 entitled “SYSTEM, METHOD, AND COMPOSITION OF VATERITE CEMENTITIOUS BLENDS,” filed March 4, 2024, the disclosure of which is incorporated herein in its entirety by reference. Background

[0002] As the largest manufactured product in the world, cement production plays a substantial role in anthropogenic CO2 emissions, contributing to approximately 7-8% of these emissions, as well as consuming over 3% of the global energy demand and emitting over 5% of global anthropogenic PM10emissions. Summary

[0003] Some aspects relate to a cement composition including: Portland cement, 5-10% vaterite, and 10-40% SCM.

[0004] Some aspects relate to a cement composition, wherein the SCM includes at least one of fly ash and slag.

[0005] Some aspects relate to a cement composition, wherein the vaterite has a particle size range of 0.1-100 microns.

[0006] Some aspects relate to a cement composition, wherein the vaterite has a significantly spherical particle shape.

[0007] Some aspects relate to a cement composition, further including at least one of admixture, aggregate, additive, and clinker.

[0008] Some aspects relate to a cement composition, wherein the vaterite is at least 90% pure.

[0009] Some aspects relate to a method for ternary mortar preparations, the method including: homogenizing a premix including Portland cement, 10-20% SCM, and 5-10% vaterite, and mixing the mortar using a powder blender.Attorney Docket No.6351.088WO1

[0010] Some aspects relate to a method to form a cementitious composition, the method including: calcining limestone to produce a composition including lime and a gaseous compound including carbon dioxide; treating a first portion of the composition and at least a portion of the carbon dioxide to produce vaterite; using a second portion of the composition to produce Portland cement; blending the vaterite with the Portland cement to produce a first mix; blending the first mix with SCM to produce a second mix including Portland cement, vaterite, and SCM; wherein the vaterite includes 5-15% by weight of the second mix.

[0011] Some aspects relate to a system including: a first reactor, operating at a first temperature, configured to calcine limestone and produce Portland cement and a gaseous composition including carbon dioxide; a second reactor, operating at a second temperature being lower than the first temperature, configured to produce vaterite using a portion of the carbon dioxide; a blending reactor configured to produce a cementitious blend including the Portland cement, the vaterite, and SCM; wherein the vaterite includes 5-15% by weight of the cementitious blend.

[0012] Some aspects relate to a system, wherein the SCM includes at least one of fly ash and slag.

[0013] Some aspects relate to a system, wherein the SCM includes 10-40% by weight of the cementitious blend.

[0014] Some aspects relate to a cement composition formulated for early setting, the cement composition including: less than 50% by weight of Portland cement, at least one of slag and fly ash, and 5-15% by weight of vaterite.

[0015] Some aspects relate to a cement composition, including by weight of: 25- 45% Portland cement, 25-45% slag, 5-25% fly ash, and 5-15% vaterite.

[0016] Some aspects relate to a cement composition formulated for early strength, the cement composition including: At least 40% by weight of Portland cement, 30-60% by weight of slag or fly ash, and 5-15% by weight of vaterite.

[0017] Some aspects relate to a cement composition, including by weight of: 40- 60% Portland cement, 20-40% slag, 5-15% fly ash, and 5-15% vaterite.Attorney Docket No.6351.088WO1

[0018] Some aspects relate to a cement composition including: Portland cement, 10-50% by weight of slag or fly ash, and 5-10% by weight of vaterite. Brief Description of the Drawings

[0019] In the accompanied drawings:

[0020] FIG.1 is an illustration of the morphology of vaterite particles as observed under scanning electron microscopy (SEM).

[0021] FIG.2 is an illustration of the heat flow and heat release of the pastes with vaterite inclusion according to various aspects, and without vaterite inclusion.

[0022] FIG.3 is an illustration of the TGA results of cementitious pastes with and without vaterite in four systems according to various aspects.

[0023] FIG.4 is an illustration of the positive linear correlation between paste bound water and the corresponding mortar strength.

[0024] FIG.5 is an illustration of a comparison of initial setting times between cement pastes with and without vaterite.

[0025] FIG.6 is an illustration of a comparison of compressive strength development in two cementitious systems, featuring varying levels of vaterite inclusions from 0%, to between 5% and 10% according to various aspects.

[0026] FIG.7 is an illustration of the bulk resistivities of different systems.

[0027] FIG.8 is an illustration of the AMBT expansion of mortar bars after 14 days exposure of 80°C alkaline solution.

[0028] FIG.9 is an illustration of the expansion of mortar bars after sulfate exposure for 26 weeks according to various aspects.

[0029] FIG.10 is an illustration of a production method of blended cements according to various aspects which may be implemented in a cement plant.

[0030] FIG.11 is an illustration of various aspects in which in which Portland cement, vaterite, and SCM are all blended together in a single blender.Attorney Docket No.6351.088WO1

[0031] FIG.12 is an illustration of various aspects in which vaterite and SCM are blended first.

[0032] FIG.13 is an illustration of various aspects in which Portland cement and SCM are blended first.

[0033] FIG.14 is an illustration of various aspects in which Portland cement and vaterite are blended first.

[0034] FIG.15 is an illustration of a system for making cementitious blends according to various examples.

[0035] FIG.16 is an illustration of a system for making cementitious blends according to various examples. Detailed Description

[0036] It is to be understood that this invention is not limited to particular aspects described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to be limiting.

[0037] Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges and are also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the invention.

[0038] Certain ranges are presented herein with numerical values being preceded by the term “about.” The term “about” is used herein to provide literal support for the exact number that it precedes, as well as a number that is near to or approximately the number that the term precedes. In determining whether a number is near to or approximately a specifically recited number, the near or approximating unrequited number may be a number, which, in the context inAttorney Docket No.6351.088WO1 which it is presented, provides the substantial equivalent of the specifically recited number.

[0039] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the invention, representative illustrative methods and materials are described herein.

[0040] All publications, patents, and patent applications cited in this specification are incorporated herein by reference to the same extent as if each individual publication, patent, or patent application were specifically and individually indicated to be incorporated by reference. Furthermore, each cited publication, patent, or patent application is incorporated herein by reference to disclose and describe the subject matter in connection with which the publications are cited. The citation of any publication is for its disclosure prior to the filing date and should not be construed as an admission that the invention described herein is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided may be different from the actual publication dates, which may need to be independently confirmed.

[0041] It is noted that, as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as “solely,” “only” and the like in connection with the recitation of claim elements, or use of a “negative” limitation.

[0042] As will be apparent to those of skill in the art upon reading this disclosure, each of the individual aspects described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other several aspects without departing from the scope or spirit of the invention. Any recited method can be carried out in the order of events recited or in any other order, which is logically possible.Attorney Docket No.6351.088WO1

[0043] Cement production is responsible for 7-8% of all anthropogenic CO2 emissions, over 3% of global energy demand, and over 5% of global anthropogenic PM10emissions. With the megatrends of increasing global population and urbanization, these environmental impacts will not decrease if mitigation applications are not adopted.

[0044] Given the ongoing global trends of population growth and urbanization, these environmental impacts are expected to persist unless mitigation strategies are implemented. In recent years, various technical measures have emerged to mitigate these impacts. For instance, the waste CO2from cement kilns and fossil fuel incinerators may be harnessed through processes such as carbonation curing, secondary chemical reactions for carbon capture, or geological storage. However, these measures frequently encounter technical and economic challenges when applied in cement plants, especially in developing countries where most cement products may be produced and used.

[0045] Adoption of blended cements, such as portland-limestone cement, portland-pozzolan cement containing fly ash, natural pozzolan, or calcined clay, and ternary blended cement containing pozzolan, slag, or calcium carbonate, has increased over recent decades. These blended cements may offer additional hydration or pozzolanic reactions, often resulting in improved properties at various stages of curing. This approach may significantly reduce CO2emissions in the cement industry by minimizing the quantity of clinker required by incorporating supplementary cementitious materials (SCMs), or fillers, into blended cement formulations with optimized mix designs.

[0046] However, the use of SCMs in blended cement may also introduce challenges. For example, calcined clay may lead to increased water demand in blended cements, necessitating the use of superplasticizers, which may escalate production costs. Furthermore, the inclusion of fly ash may prolong setting times and reduce early-age strength. Although certain types of SCMs bring drawbacks in blended cements, effective formulation of blended cements may address some of these issues economically.

[0047] Limestone, primarily composed of calcium carbonate (CaCO3), has traditionally been employed in the cement industry. Portland cement oftenAttorney Docket No.6351.088WO1 contains up to 5% calcium carbonate, while portland-limestone cement may contain up to 15-35% calcium carbonate, depending on the region.

[0048] The addition or co-grinding of calcium carbonate in cement, not only provides additional nucleation sites for C-S-H formation, but also contributes to the clinker phases’ hydration reactions. The physical nucleation effect, particles shearing effect, and improved packing brought about by calcium carbonate additions, accelerate cement hydration.

[0049] Additionally, the reaction between calcium carbonate and aluminates yields carboaluminates as supplementary hydration products, enhancing cement strength and durability. The interaction between reactive aluminates and carbonate ions makes fine calcium carbonate a potential candidate in blended cements to co-substitute for clinker with aluminosilicate-based SCMs, such as slag, fly ash, and calcined clay.

[0050] The optimal utilization of SCMs in blended cement has the potential to reduce CO2 emissions by approximately 44% in the cement industry, and this measure is supported by various standards organizations, including ASTM and AASHTO in the United States, and CEN in Europe.

[0051] Nevertheless, the availability of some SCMs, such as fly ash and slag, is diminishing due to the closure of coal-fired power plants and changes to the steel manufacturing processes globally, prompting the exploration of alternative materials for blending with cement.

[0052] It is therefore desirable to find alternatives to SCMs such as fly ash and slag.

[0053] In recent years, various technical measures were found to alleviate these impacts. For example, the CO2 in the waste gas from the cement kiln and fossil fuels incinerator can be collected for carbonation curing, secondary chemical reactions for carbon capture, geological storage, etc. But these measures often have technical and economic challenges for application in cement plants. Another way to effectively reduce the CO2from the cement industry is to reduce the cement quantities required, by using supplementary cementitious materials (SCMs) or fillers in blended cement with optimized mixture designs. BlendedAttorney Docket No.6351.088WO1 cements have been increasingly used over the past decades. The blended cements may offer extra hydration or pozzolanic reactions, and can often achieve better fresh and hardened properties among different ages. However, the usage of SCMs in blended cement may also cause unwanted issues. For instance, calcined clay typically causes a higher water demand in blended cements. To enhance the workability of calcined clay blended cements, superplasticizers are often required, which may raise the cost of producing the cement or resulting concrete. The use of fly ash in blended cements will often extend their setting times and reduce early-age strength. When the cement replacement level is higher, lower-clinker factor cements often have longer setting times and lower early-age strengths. Proper formulation of blended cements may address some of these issues at a low cost. The optimal use of SCMs in blended cement may potentially achieve about a 44% reduction in CO2emissions by the cement industry and is facilitated by different standards organizations, such as ASTM and AASHTO in the United States, as well as CEN in Europe. However, the availability of many SCMs, such as fly ash and slag, is dwindling due to the termination of coal-fired power plants and changing steel manufacturing processes around the world, necessitating the exploration of alternative materials to blend with cement.

[0054] Limestone has long been used in the cement industry, with the major CaCO3 component as calcite. Portland cement often contains up to 5% calcium carbonate, and Portland-limestone cement may contain up to 15-35% calcium carbonate. Adding or co-grinding calcium carbonate into cement not only offers more nucleation sites for C-S-H gel to grow on, but also contributes to the chemical and hydration reactions. The physical nucleation effect, shearing effect, and improved packing offered by the calcium carbonate additions accelerate cement hydration, and the reaction between calcium carbonate and aluminates forms carboaluminates as extra hydration products, which contribute to the strength and durability of the cement. The reaction between carbonate ions and aluminates makes fine calcium carbonate a potential material for co-substitution with aluminosilicate-based SCMs, such as fly ash, slag, and calcined clay, in blended cements. Calcite is the major mineral phase of limestone, and the other two anhydrous polymorphs of calcium carbonate are aragonite and vaterite.Attorney Docket No.6351.088WO1

[0055] Vaterite can be generated using CO2 from cement kilns. It is cementitious on its own when mixed with water, and it can also be used as a supplementary material for blended cements. Vaterite is a less stable and more soluble polymorph and rarely exists in nature, whereas calcite and aragonite are the more common crystalline polymorphs.

[0056] Vaterite is often used in the food industry and biomedical applications due to its higher specific surface area, higher solubility and higher dispersion compared to the other two polymorphs. Several synthesis methods have been reported for vaterite production, such as CO2bubbling, reverse emulsion, and solution precipitation. Vaterite may be produced by aerating a Ca(OH)2and L- Leucine mixed solution with CO2. Other production methods may include leaching-carbonation process to dissolve the recycled concrete fines and later carbonated the leachate to form vaterite.

[0057] CaCO3 cement paste can achieve 40 MPa ultimate strength after 3 days of curing at 80°C. In addition to vaterite being cementitious on its own when mixed with water, it may also be used as a supplementary material for blended cements. Cement paste with vaterite may have the lowest porosity among the three polymorphs, caused by a higher solid volume formation with vaterite inclusion than calcite or aragonite. Vaterite is also used as an internal curing agent due to its porous structure and have showed reduced autogenous shrinkage of mixtures with vaterite inclusion.

[0058] Calcite constitutes the primary mineral phase in limestone, alongside the less common anhydrous polymorphs of calcium carbonate, aragonite, and vaterite. Vaterite, albeit less stable and more soluble, may be generated from CO2 generated at cement kilns.

[0059] Various synthesis methods, including CO2bubbling, reverse emulsion, and solution precipitation, may be utilized to produce vaterite. As a potential construction material, vaterite-based cement paste has been shown to attain an ultimate strength of 40 MPa after 3 days of curing at 80°C.Attorney Docket No.6351.088WO1 Materials and Methods Materials

[0060] Various aspects relate to the utilization of vaterite in blended cements and present outcomes and advantages of incorporating 5-10% vaterite as a replacement or partial replacement for SCMs in ternary blended cement formulations.

[0061] Aspects encompass various characterization techniques, including isothermal calorimetry and thermogravimetric analysis, to investigate the hydration of blended cement pastes, with and without the inclusion of vaterite.

[0062] Fresh properties such as mortar flow and setting time, as well as hardened properties like mortar compressive strength, bulk resistivity, and durability, were examined in various aspects at different curing ages and compared between cement blends containing 5-10% vaterite and their non- vaterite counterparts.

[0063] In various aspects, ASTM C150 Type II-V cement, ASTM C618 low calcium fly ash, ASTM C989 slag, and lab-synthesized vaterite were employed. The synthesis process for vaterite is described in various aspects. The vaterite utilized in various aspects may be more than 90% pure, and in some aspects produced a composition of 97.1% vaterite and 2.9% calcite.

[0064] FIG.1 illustrates the morphology of vaterite particles as observed under scanning electron microscopy (SEM). These vaterite particles display a significantly spherical shape with a textured surface and contain agglomerations of numerous microplates and lenses that form a rosette-like mesostructure.

[0065] The median particle size (d50) of the raw materials was determined using a Partica LA-960 laser scattering particle size distribution analyzer. A TA Instruments SDT Q600 TGA was employed to assess the loss on ignition (LOI) of the raw materials. For the particle size distribution (PSD) measurements of cement in isopropyl alcohol (IPA), a refractive index of 1.7 was applied, while a refractive index of 1.58 was used for vaterite in water.

[0066] The density of the raw materials was examined using a Micromeritics gas pycnometer, and the specific surface area of the raw materials was determinedAttorney Docket No.6351.088WO1 through analysis with an Anton Paar Nova 800 physisorption analyzer. The major mineral phases of raw materials were determined by a Bruker D8 Endeavor X-ray powder diffraction analyzer. Detailed characterization results used in some aspects are presented in Table 1. Table 1. Mineral phase compositions (%), LOI (%), d50 values (μm), density (g / cm3) and surface area (m2 / g) of the raw materialsMixture Design

[0067] To assess the effect of SCMs and vaterite, these materials were employed to partially replace 25to 30%, or up to 50% of the cement in the mixtures by mass according to various aspects. Analysis of the hydration process was conducted on paste samples using isothermal calorimetry and thermogravimetric analysis (TGA). Pastes for hydration analysis were formulated according to Table 2 with a fixed water-to-binder ratio (w / b) of 0.6.

[0068] To assess the hardened properties of the materials, including compressive strength and bulk resistivity, mortar cubes were prepared in accordance with the ASTM C109 standard. Durability tests were carried out on mortar bars to evaluate resistance to sulfate attack and alkali-silica reaction (ASR). All mortar cubes and mortar bars used in the ASTM C1012 sulfate resistance tests were formulated according to Table 3. Mortar bars utilized in the ASTM C1567 accelerated mortar bar test (AMBT) were formulated according to Table 4.Attorney Docket No.6351.088WO1 Table 2. Mixture designs of cementitious pastes for hydration analysisTable 3. Mixture designs of all mortar cubes and ASTM 1012 mortar bars given for 100 g of binder (w / b = 0.485, s / b = 2.75)Table 4. Mixture designs of mortar bars in ASTM 1567 accelerated mortar bar test given for 100 g of binder (w / b = 0.47, s / b = 1.90)Attorney Docket No.6351.088WO1 Methods Isothermal Calorimetry

[0069] Using compositions from various aspects, a TAM Air isothermal calorimeter was employed to evaluate the heat of hydration in cementitious paste mixtures. Initially, 20 grams of dry powder were manually mixed for 2 minutes in a beaker, after which 12 grams of deionized water were added. The resulting pastes underwent an additional 2 minutes of manual mixing in the same beaker.

[0070] Approximately 10 grams of the paste were then transferred to glass ampoules. Once all 8 samples were securely sealed in the ampoules, they were placed in the isothermal calorimeter, which had been pre-conditioned to 23 ± 0.05 °C. The entire paste mixing process was completed in under 20 minutes for all 8 samples.

[0071] Heat release was monitored in the calorimeter over 7 days and normalized to the binder mass. Triplicate tests on one sample demonstrated a heat of hydration test coefficient of variation (CoV) of less than 3%. Thermogravimetric Analysis

[0072] Cementitious pastes, according to various aspects, were employed for hydration products analysis using a TA Instruments SDT Q600 TGA. Approximately 70 grams of fresh paste were prepared as detailed previously, which was subsequently loaded into three cylindrical vials, each with a capacity of 10 ml. These vials, once sealed, were affixed to a vertically rotating cylinder, operating at a rotational speed of 20 rpm for a duration of 7 hours, with the aim of mitigating material and water separation prior to their relocation to a controlled environment set at 23°C.

[0073] Hydration was stopped at intervals of 7, 28, and 56 days. The paste was crushed and immersed in isopropyl alcohol (IPA) to facilitate solvent exchange, effectively halting the hydration process. For TGA analysis, quantities ranging from 30 to 50 milligrams of the paste was loaded into the TGA crucible and subjected to a preliminary drying process at 40°C for a period of 20 minutes before the initiation of the heating cycle. The temperature was thenAttorney Docket No.6351.088WO1 incrementally raised at a rate of 10°C per minute, ranging from 40°C to 900°C, all the while maintaining an inert N2 atmosphere.

[0074] The quantification of the mixtures’ hydration products was based on the measurement of mass losses occurring at specific temperature intervals, utilizing the tangential methodology. In the 150-600°C temperature range, the mass loss on the TGA curve indicated the bound water content of the paste.

[0075] Furthermore, the water loss from Ca(OH)2 was denoted by the mass loss between 380-460°C. The release of CO2 from CaCO3 decomposition was signified by the mass loss within the 600-900°C range. It is important to note that the decomposition of carboaluminates resulted in some mass loss at a lower temperature range. Based on their corresponding weight loss values, the content of these hydration products was calculated. The TGA tests exhibited a CoV of less than 2% in triplicate testing on a single sample. Setting Time

[0076] The determination of setting time, for mixtures made according to various aspects, followed the guidelines specified in ASTM C191. To achieve the desired normal consistency, trials were conducted by mixing 650 grams of the binder with varying amounts of water. Subsequently, the paste with normal consistency was placed into a conical ring, and the setting time was measured using a Humboldt Vicatronic automatic Vicat machine. Compressive Strength & Mortar Flow

[0077] In various aspects, mortar preparations were carried out as outlined in ASTM C305, with subsequent casting into 50 mm mortar cubes in accordance with ASTM C109. Prior to mixing, the binders underwent homogenization using a powder blender. A consistent water-to-binder ratio (w / b) of 0.485 was employed for all mixtures.

[0078] Mortar flow measurements were performed following ASTM C1437 guidelines. In each case, a total of 12 mortar cubes were fabricated, with testing conducted on 2 cubes at the ages of 1, 3, and 7 days, and 3 cubes tested at 28 and 56 days. Mortar cubes were stored in a saturated lime bath at 23°C until testing.Attorney Docket No.6351.088WO1 The reported results are based on the average values, and the CoV for the compressive strengths remained below 5% at all specified ages. Bulk Resistivity

[0079] Measurements of bulk resistivity, for mixtures made according to various aspects, were conducted on the mortar cubes prior to compressive strength evaluations. The Giatec RCON resistivity meter was employed to assess the 50 mm mortar cubes following the guidelines of ASTM C1876. These measurements were performed on saturated surface-dry specimens at a frequency of 1 kHz. Corrections for the geometric dimensions of the cube specimens were applied to the obtained data, and the resulting average value across all tested cubes is presented. The CoV for the measurements remained consistently below 6% throughout all stages of the study. Accelerated Mortar-Bar Test for Alkali Silica Reaction (AMBT)

[0080] According to various aspects, mortar bars, equipped with gauge studs at both ends, were fabricated and assessed in accordance with ASTM C305 and ASTM C1567. In some aspects, graded borosilicate glass was prepared as the reactive aggregate in accordance with the grading requirements specified in ASTM C1567. For each mixture, a set of three bars was cast. The water-to- binder ratio (w / b) and the sand-to-binder ratio (s / b) were consistently maintained at 0.47 and 1.90, respectively, for all AMBT mortar bars in the study.

[0081] After casting, the bars underwent an initial 1-day curing period in a controlled moist environment at 23°C before demolding. Subsequently, they were transferred to an 80 ± 2°C water bath. Following 24 hours in the 80°C water bath, the bars were measured for their zero comparator readings. The bars were then immersed in a 1 M NaOH solution at 80 ± 2°C, and subsequent comparator readings were recorded. In accordance with ASTM C1567, any expansion exceeding 0.1% of the nominal gauge length after 14 days in the NaOH solution would signify potential deleterious expansion attributed to alkali- silica reaction (ASR). The reported expansion values represent the average among the three bars within a given mixture, with the CoV for expansion measurements consistently remained below 2% across all mixtures.Attorney Docket No.6351.088WO1 Sulfate Exposure Resistance Test

[0082] The sulfate exposure test was conducted in accordance with ASTM C1012. Mortar bars, made according to various aspects, were prepared with a consistent water-to-binder ratio (w / b) of 0.485 and sand-to-binder ratio (s / b) of 2.75. The ASTM C778 graded standard sand was used in this test. Following the test procedure, six mortar bars and cubes were prepared following the guidelines of ASTM C305.

[0083] Upon achieving an average strength of 20 MPa for two of the cubes within the same mixture, the initial lengths of the bars were measured. Subsequently, these bars were immersed in a 5% Na2SO4solution and stored in a controlled moist environment at 23 ± 2°C. Periodic measurements were taken, and at each measurement occasion, the sodium sulfate solution was replaced. The reported expansion values reflect the average among the six bars in a specific mixture, with the CoV for the expansion measurements consistently remaining below 2% across all mixtures. Results Heat of Hydration

[0084] FIG.2 illustrates the heat flow and heat release of the pastes with vaterite inclusion according to various aspects, and without vaterite inclusion. The 25% fly ash binary paste (25F) reached the peak heat flow at 11.7 h after mixing. After replacing 10% fly ash with vaterite, the peak heat flow occurred at 10.8 h and reached a higher intensity. The highest peak of heat flow was caused by C3S hydration, and the shoulder peak that occurred later was due to the C3A reaction (When expressing cement phases, C = CaO, S = SiO2, A = Al2O3, F = Fe2O3. For example, C3A = 3CaO·Al2O3). Including 10% of vaterite to replace fly ash according to present aspects promoted the cementitious paste’s C3A reaction. The C3A reaction shoulder peak occurred earlier than without vaterite. Similar reactions were seen in the slag-vaterite mixes, where the aluminate reaction peak was accelerated.

[0085] For the two cement-slag-fly ash-vaterite systems, the acceleration by vaterite according to the present aspects was more significant, with a muchAttorney Docket No.6351.088WO1 shorter induction period, shorter time to peak heat flow, and higher peak intensities. The C3A shoulder peak happened in a faster and more intense way compared to the non-vaterite mixes.

[0086] With both the main hydration peaks of silicates and aluminates being accelerated, the total heat release of pastes with vaterite inclusion according to various aspects was higher than their non-vaterite counterparts. The increase in total hydration heat was more obvious in the cement-slag-fly ash-vaterite quaternary pastes according to some aspects, which only had 30 to 50% cement in the mixture.

[0087] The vaterite-included quaternary mixtures according to these aspects had a higher and faster accelerating heat release value throughout the 7 days testing period, with a 9-10% increase at the end of 7 days. This suggested that 10% vaterite replacement of fly ash, according to these aspects, promoted more hydration reactions than cement blends with higher SCM amounts.

[0088] The acceleration of C3A reactions was expected in the presence of vaterite in various aspects. Due to its higher reactivity and solubility than calcite or limestone, vaterite can react faster with the aluminates at the beginning of the hydration and form carboaluminates while consuming monosulfate, thus stabilizing ettringite. The additional aluminates provided by fly ash and slag to the system during their pozzolanic reaction and hydration further promoted the reaction of vaterite, and the synergistic effects between vaterite and aluminosilicate based SCMs can lead to improved mechanical properties over time according to these aspects. The benefits offered by vaterite inclusion will be more significant when higher amounts of aluminosilicate based SCMs are present in the mixture. Thermogravimetric Analysis

[0089] FIG.3 illustrates the TGA results of cementitious pastes with and without vaterite in four systems according to various aspects. Thermogravimetric analysis can be used to quantify hydration by measuring Ca(OH)2and bound water. In the hydration analysis, the paste mixtures without vaterite were compared with their 10% vaterite inclusion according to these aspects. TheAttorney Docket No.6351.088WO1 phase content calculations were normalized to the dry sample weight or anhydrous binder weight at 600°C.

[0090] Between 7 and 28 days for all systems, the remaining CaCO3in the cementitious paste was reduced by up to 1% due to the vaterite reaction with the reactive alumina in the system. For aspects including cement-fly ash-vaterite system, replacing fly ash with 10% vaterite increased the Ca(OH)2and bound water amount at 7 days, implying more hydration products were generated at early-ages. This was because the finer particle size vaterite (d50 = 5.7 μm) was replacing the coarser fly ash powder (d50= 23.3 μm) and the early-age hydration was much accelerated by the nucleation of C-S-H on the vaterite surface.

[0091] Fly ash is a slowly reacting material and does not provide much hydration benefits to blended cements at early-ages. As a more soluble polymorph of calcium carbonate, vaterite could provide more carbonate ions to react with the reactive alumina, and this can promote blended cements’ early-age hydration and facilitate the reactive alumina dissolution from fly ash particles. These benefits in hydration products were not as significant at 28 days when the fly ash pozzolanic reaction gradually caught up. As for the cement-slag-vaterite systems, using 10% vaterite to replace slag did not enhance hydration as much as in the fly ash system.

[0092] This effect may be due to vaterite replacing a very fine (d50= 6.3 μm) and reactive slag component in the blend. The noteworthy fact may be that the overall bound water content of mixture 20S_10V was not reduced at both ages, compared to mixture 30S, indicating that the 10% vaterite replacement according to these aspects achieved similar hydration benefits as slag itself. The synergy between vaterite, slag, and cement, in these aspects, allowed the reduction of slag, while maintaining similar amounts of hydration products through 28 days.

[0093] In both cement-slag-fly ash-vaterite quaternary systems, the 10% vaterite inclusion, in these aspects, increased the bound water content at 7 days by 16 to 23% and produced a slightly higher and lower amount of bound water at 28 days for 30S_10F_10V and 40S_20F_10V, respectively. The overall hydration in theAttorney Docket No.6351.088WO1 quaternary systems was significantly promoted at early-ages, which was similar to the performance of the cement-fly ash-vaterite system.

[0094] As an indicator of degree of hydration, it’s well known that the bound water of hydrated cements correlates well with mortar or paste strength at various ages. Thus, if the bound water amount is increased in certain cement blends, the total amount of hydration products and the compressive strength will likely also be promoted. The positive linear correlation between paste bound water and the corresponding mortar strength was also shown in this study, illustrated in FIG.4. Using 10% vaterite to replace fly ash in different systems increased the bound water content by about 20%, indicating a 20% higher overall degree of hydration. When replacing slag, the 10% vaterite did not compromise the overall degree of hydration.

[0095] The benefits of vaterite in these aspects comes from both the physical effects such as shearing of the particles, increased water to clinker ratio, more nucleation of C-S-H on the vaterite surface, and the chemical reaction between vaterite and aluminates, resulting in the successful reduction of the SCM amount in the blended cements. Setting Time

[0096] FIG.5 represents a comparison of initial setting times between cement pastes with and without vaterite. According to various aspects, for the cement-fly ash-vaterite and cement-slag-vaterite systems, the inclusion of 10% vaterite reduced the setting time by 18 and 19 min, respectively. For the two cement- slag-fly ash-vaterite quaternary systems, the inclusion of 10% vaterite in these aspects reduced the mixture’s initial setting time by 50 and 118 minutes in the 30S_10F_10V and 40S_20F_10V systems, respectively.

[0097] In these aspects, the inclusion of vaterite to replace fly ash and slag achieved a shorter initial setting time, especially when less cement was present. The setting time difference between non-vaterite and vaterite-included mixes was consistent with the measured time of the peak heat flow in the calorimetry test. A shorter time to peak heat flow indicates faster hydration reaction, and the accelerated hydration was attributed to the increased surface area for C-S-H to grow on due to vaterite inclusion, as evidenced by the TGA results.Attorney Docket No.6351.088WO1

[0098] With a higher specific surface area, vaterite particles can provide more nucleation sites at early-ages of hydration than other SCMs or cement particles, thus increasing the gel-space ratio in the hydration matrix structure and leading to a higher compressive strength. Vaterite has a higher solubility and reactivity than other calcium carbonate polymorphs, and the more dissolved carbonate ions can contribute to a higher extent of reaction with aluminates, thus promoting the mixtures’ overall degrees of hydration and forming more hydration products that can offer strength.

[0099] With a greater specific surface area, in various aspects, vaterite particles offer more nucleation sites during the early stages of hydration compared to other SCMs or cement particles, ultimately enhancing the gel-space ratio within the hydration matrix structure and leading to higher compressive strengths. Additionally, vaterite exhibits higher reactivity relative to other calcium carbonate polymorphs.

[0100] The presence of dissolved carbonate ions from vaterite in these aspects contributes to a higher degree of reaction with aluminates, thereby promoting an overall increase in the degree of hydration of the mixtures according to some aspects. This, in turn, leads to the formation of more hydration products that enhance the strength of the final blended cements. Mortar Flow and Compressive Strength

[0101] FIG.6 illustrates a comparison of compressive strength development in the two cementitious systems, featuring varying levels of vaterite inclusions from 0%, to between 5% and 10% according to various aspects. The flow of mortar is an indicator of workability (listed in Table 3), and by replacing 10% fly ash or slag using the spherical vaterite according to these aspects, the flow was either maintained or increased, respectively. For the cement-slag-vaterite system, the 10% vaterite replacement improved the mortar flow by 9%. The spherical vaterite can be very effective in improving the workability of high-water demand mixtures.

[0102] In terms of strength development, For the cement-fly ash-vaterite system, the 5% and 10% vaterite replacement of fly ash achieved a 30 to 40% higher 1- day strength, and a 19% to 31% higher 7-day strength. The higher strength ofAttorney Docket No.6351.088WO1 vaterite-containing mixtures was maintained through 56 days with about a 10% increase in strength compared to the cement blend without vaterite, 25F. In the cement-fly ash-vaterite system, the 10% vaterite replacement contributed more at early-ages and the 5% replacement showed a larger strength increase at later ages.

[0103] However, the replacement of a faster-reacting component, such as the fine slag, may not achieve similar improving effects to replacing fly ash. For the cement-slag-vaterite system, the 5% vaterite replacement according to these aspects achieved the best performance up to 7 days. The strength was increased by more than 20% at 3 days and by about 8% at 7 days. At 28 days and 56 days, the vaterite replacement showed a less than 10% decrease on the strength compared to the slag-cement binary mixture.

[0104] In some aspects, the cement-slag-vaterite system, both 5% and 10% replacement levels showed similar benefits. Although vaterite can still offer early-age physical benefits and have synergy effects with slag, the improvement was not as significant as with fly ash replacement. The reduced hydration improvement in the slag ternary system is also in accordance with the calorimetry and TGA analysis.

[0105] Regarding strength development, the substitution of 5% and 10% of fly ash with vaterite, in accordance with various aspects, led to a substantial increase of 30% to 40% in 1-day strength and a remarkable enhancement of 19% to 31% in 7-day strength.

[0106] The elevated strength observed in vaterite-incorporated mixtures in such aspects persisted for a period of 56 days, demonstrating an approximate 10% increase in strength compared to the cement blend without vaterite, 75% cement and 25% fly ash. Notably, in various aspects, in the cement-fly ash-vaterite system, the 10% vaterite replacement contributed more significantly at early stages, while in some aspects, the 5% replacement exhibited a more pronounced strength increase at later ages.

[0107] Nonetheless, achieving similar enhancement effects to fly ash replacement might not be as straightforward when substituting a faster-reacting component, such as fine slag. In the cement-slag-vaterite system, either a 5% orAttorney Docket No.6351.088WO1 10% replacement of slag with vaterite according to these aspects increased the mortar strength through 7 days. In various aspects, the most substantial strength improvement occurred at 3 days with approximately a 20% increase. The 1- and 7-day strengths were increased by approximately 10%. At 28 and 56 days, 5- 10% vaterite replacement exhibited a reduction in strength of approximately 10% and 5%, respectively, compared to the slag-cement binary mixture. The diminished enhancement of hydration over time in the slag ternary system aligns with the findings from calorimetry and TGA analysis.

[0108] For the cement-slag-fly ash-vaterite quaternary systems, in various aspects, the vaterite inclusion drastically improved the strength performance at early-ages, especially at the lower cement content. The 10% vaterite replacement of fly ash in the 50% cement mixtures, 30S_10F_10V, improved the early-age strength by 30% through 7 days, and the beneficial effects were much larger than the 5% vaterite replacement mixtures, 30S_15F_5V, through all ages. For the 30% cement mixtures, by including 10% vaterite, the 3-day strength was increased by 57%, and both 1- and 7-day strengths were increased by 30%. This is because with higher amounts of cement substitution with fly ash and slag, more reactive alumina from these SCMs is available to react with the vaterite.

[0109] In some aspects, a higher vaterite replacement is more suitable for higher aluminosilicate based SCM amount systems, and such mixtures also have lower clinker factors. The co-substitution of vaterite and aluminosilicate based SCMs result in synergistic effects in blended cement. In both quaternary systems, the early-age strength benefited more from the vaterite addition than the late-age strength, which is consistent with its acceleration of early-age hydration reactions.

[0110] For all systems, the early-age strength improvement was most significant with a higher vaterite inclusion (10%) according to present aspects. The improved early-age strength was in accordance with the heat evolution analysis from isothermal calorimetry, where the 10% vaterite not only increased the peak rate of hydration, but also shortened the induction time. It is known that the early-age strength correlates well with the heat of hydration, and both quaternary systems of the present aspects showed significant increases in heats of hydration when replacing 10% fly ash with vaterite.Attorney Docket No.6351.088WO1

[0111] The shortened setting time also agreed with the improved early-age strength of the cement-slag-fly ash-vaterite quaternary mixes. And the much shorter setting time and higher early-age performance would be beneficial for low temperature or winter construction. The significant improvement at early ages by vaterite in various aspects may be attributed to the physical effects of increased C-S-H nucleation on the surface area of vaterite, increased water to clinker ratio, shearing action of particles, and improved packing are more predominant at early-ages. In addition, the reactivity of vaterite promotes the formation of carboaluminate phases, providing more hydration products at early- ages in these aspects.

[0112] It was also confirmed in these aspects, that vaterite-included mixtures achieved the lowest porosity and highest solid volume in the cement paste compared with its aragonite or calcite counterparts. At later ages of 28 or 56 days, the 5-10% vaterite replacement in all the corresponding aspects achieved 89 to 119% of the original non-vaterite blended cements’ strengths. Bulk Resistivity

[0113] Electrical resistivity or conductivity provides a rapid indication of a material’s resistance to the penetration of fluids and dissolved aggressive ions, such as Cl-, alkali, and SO42-. Bulk electrical resistivity is a material property that depends on the pore structure, pore solution composition, degree of saturation of the specimen, and temperature of the specimen. A higher bulk resistivity value is generally indicative of a more durable material, with a higher resistance to penetration by chloride and other ions. FIG.7 illustrates the bulk resistivities of different systems. According to FIG.7, systems’ bulk resistivities were improved by the inclusion of vaterite to differing degrees according to various aspects.

[0114] When 5% vaterite was used to replace the slow reacting fly ash, the bulk resistivity was increased by 19% at 56 days in the cement-fly ash-vaterite system. For the cement-slag-vaterite systems, the 5% vaterite inclusion increased the 56 days bulk resistivity by 41%. In both low clinker factor quaternary systems, the bulk resistivity was improved significantly at both 28 and 56 days. In the 50% cement quaternary system, a 5-10% vaterite inclusion achieved aAttorney Docket No.6351.088WO1 ≥75% higher bulk resistivity at 28 days, and a ≥39% higher value at 56 days. In the 30% cement quaternary system, a 5-10% vaterite inclusion improved the mortar’s bulk resistivity by ≥91% at 28 days, and ≥63% at 56 days. In various aspects, a higher vaterite replacement offered more benefits to higher aluminosilicate based SCM mixtures.

[0115] In various aspects, in the presence of vaterite, the reactions of clinker and SCMs were increased due to the continuous hydration reactions enhanced by the surface area of vaterite, and the dissolved carbonate ions reacting with the reactive alumina from the SCMs. These effects lead to more hydration products formed over time and create a more tortuous pore structure.

[0116] A refined pore structure and more hydration products, such as the interlayer structured carboaluminates, inhibit ion mobility and absorb ions, thus improving the electrical resistivity of the sample. Aspects with vaterite and SCM inclusion, both an increased pore refinement and a lower pore solution alkalinity were likely achieved, reducing the mass transport within the sample, thus increasing the electrical resistivity. AMBT Expansion

[0117] FIG.8 shows the AMBT expansion of mortar bars after 14 days exposure of 80°C alkaline solution. The corresponding ASTM standard C1567 states that an expansion less than 0.10% at 14 days of testing (16 days after casting) is likely to produce acceptable expansions when tested in concrete and to have a low risk of the deleterious ASR expansion under field conditions. From the AMBT results, in various aspects, all the tested groups expanded much less than 0.10%, and the aspects with vaterite included mixtures showed a decreasing expansion trend while their non-vaterite counterparts had increasing expansion at the end of AMBT. This aligned with the bulk resistivity results which showed that at later ages, the durability benefits provided by vaterite addition were more obvious. For both cement-slag-fly ash-vaterite quaternary systems, the 10% fly ash reduction by vaterite inclusion didn’t reduce the mixture’s ASR resistance.

[0118] When replacing 10% fly ash with vaterite in some aspects, the difference in expansion between the non-vaterite control and the vaterite-included mortar bars was negligible throughout the 14-day testing period. This indicates thatAttorney Docket No.6351.088WO1 vaterite can be an effective material to supplement or replace fly ash or slag in blended cements according to the present aspects. Sulfate Exposure Expansion

[0119] FIG.9 is an illustration of the expansion of mortar bars after sulfate exposure for 26 weeks according to various aspects. To be designated as a high sulfate resistant cement when testing according to ASTM C1012, the 6-month expansion limit is 0.05%, and the 1-year expansion limit is 0.10%.

[0120] For the two quaternary systems, all four mixes expanded less than 0.05% in the 6-month testing period and can be designated as high sulfate resistant blended cements so far. Moreover, the vaterite included mortar bars of the present aspects expanded a smaller amount compared to their non-vaterite counterparts during the testing period. This may be because sulfate expansion is largely caused by gypsum formation and secondary ettringite formation, and the key components of secondary ettringite formation are unhydrated calcium aluminate and monosulfoaluminate.

[0121] In various aspects, by adding vaterite, the calcium aluminate in cement would react with carbonate ions and form the stable carboaluminates and make the ettringite in the mixture stable as well, instead of transforming to monosulfoaluminate. Stabilizing ettringite and forming carboaluminates results in denser cement paste matrix and reduced pore connectivity. And the addition of vaterite promoted the SCMs pozzolanic reaction, consuming more Ca(OH)2 in the system, and avoiding its transformation to CaSO4 when exposed to sulfate. Hence, the addition of vaterite reduced the risk of secondary ettringite and gypsum formation and lead to a lower expansion when the mortar bars were exposed to a sulfate solution. Including vaterite in these aspects resulted in slightly lower expansion in the two quaternary systems compared to their non- vaterite counterparts, which is consistent with their greater increases in bulk resistivity as well.

[0122] During the testing phase in both systems, the expansion of mortar bars in aspects containing vaterite was lower than that of their non-vaterite counterparts. Expansion due to chemical sulfate attack in concrete is attributed to theAttorney Docket No.6351.088WO1 formation of secondary minerals that exert pressure on the hardened cement paste.

[0123] Early stages of the reaction are often associated with the formation of ettringite, a process contingent upon the presence of two critical constituents, unhydrated calcium aluminate and monosulfoaluminate. The inclusion of vaterite in the present aspects diminishes the risk of secondary ettringite formation, resulting in reduced expansion when the mortar bars are exposed to sulfate solutions.

[0124] The incorporation of vaterite in the cement matrix according to various aspects initiates a reaction where the calcium aluminate component interacts with carbonate ions, leading to the formation of stable carboaluminates. This chemical transformation effectively stabilizes the ettringite within the mixture, preventing its conversion into monosulfoaluminate and then into secondary ettringite. The addition of vaterite promoted the SCMs pozzolanic reaction, consuming more Ca(OH)2 in the system, and avoiding its transformation to CaSO4when exposed to sulfate. A denser cement paste matrix with a reduction in pore connectivity can also be achieved by vaterite inclusion.

[0125] In a 6-month testing period, according to various aspects, the inclusion of 10% vaterite to replace fly ash or slag, produced expansion levels smaller than their non-vaterite counterparts, consistent with their performance in bulk resistivity measurements.

[0126] In various aspects, the amount of fly ash and slag included is sufficient to densify the microstructure enough to limit ion mobility and to stifle slower sulfate attack reactions such as the formation of gypsum from calcium in the pore solution, which is mostly from calcium hydroxide and to a lesser extent from C-S-H. The amounts of SCM used in the two mixes are sufficient to control sulfate attack and the addition of 10% vaterite can further suppress the outside sulfate attack expansion. Industrial Implementation

[0127] Various aspects may be implemented in existing plants such as cement or concrete plants. Portland clinker is manufactured through mining a variety ofAttorney Docket No.6351.088WO1 ores such as silica, alumina and iron oxide sources, such as limestone, clay, and shale. These materials are then crushed, ground, and proportioned to make a feed for a kiln. In the kiln, the feed is heated typically to 1450℃ and forms Portland clinker. Blended cements, according to various aspects, may be produced in a variety of ways.

[0128] Production of calcium compound by calcining limestone may be carried out using various types of kilns, such as, but not limited to, a shaft kiln, a rotary kiln, an electric kiln, etc. These apparatuses for calcining are suitable for calcining limestone in the form of lumps having diameters of several to tens millimeters. Cement plant waste streams include waste streams from both wet process and dry process plants, which may employ shaft kilns or rotary kilns, and may include pre-calciners. These industrial plants may each burn a single fuel, or may burn two or more fuels sequentially or simultaneously.

[0129] Limestone obtained from a limestone quarry is subjected to calcination in a cement plant resulting in the formation of calcium compounds such as calcium oxide, calcium hydroxide, or combination thereof, and CO2gas. The calcium compound may be calcium oxide in the form of a solid from dry kilns or cement processes or may be a combination of calcium oxide and calcium hydroxide in the form of slurry in wet kilns or cement processes. When wet, the calcium oxide (also known as a base anhydride that converts to its hydroxide form in water) may be present in its hydrated form such as calcium hydroxide. While calcium hydroxide (also called slaked lime) is a common hydrated form of calcium oxide, other intermediate hydrated and / or water complexes may also be present in the slurry and are all included within the scope of the present aspects.

[0130] FIG.10 is an illustration of a production method of blended cements according to various aspects which may be implemented in a cement plant. In a cement plant, a portion of the feed may be used to produce vaterite by reabsorbing the carbon dioxide produced in a kiln when heating and decomposing the limestone.

[0131] As seen in FIG.10, limestone 101 is calcined to produce lime 102. Traditionally, a byproduct of this process is carbon dioxide which is otherwise emitted to the atmosphere. A portion of the lime is used to produce PortlandAttorney Docket No.6351.088WO1 cement 104. In some aspects carbon dioxide 103 is recaptured and precipitated to produce vaterite 105. SCM 106 is added to Portland cement 104 and vaterite 105 in blending 107, where the mix is finely blended to produce blended cement 108.

[0132] In some aspects, a calcium compound obtained from the cement plant is treated or solvated with a solubilizer, such as the N-containing salt to improve its solubility. In some aspects, a calcium compound slurry obtained from a wet process cement plant may be optionally subjected to dewatering, where the residual water may be removed and the dewatered residue may be subjected to further treatment such as solvation with solubilizer such as the N-containing salts. The calcium compound slurry may be dewatered using any technique such as, but not limited to, centrifugation.

[0133] Various aspects may be implemented at a given cement plant using a limestone quarry as a calcium source and capture carbon dioxide from the kilns to produce vaterite. The vaterite can then be blended with the Portland cement and SCM consequently in the same plant.

[0134] In some aspects, a blend of Portland cement, vaterite, and the SCM, may be obtained in a facility such as a concrete plant and the mix may be blended with aggregate to produce concrete.

[0135] FIG.11 is an illustration of various aspects in which in which Portland cement, vaterite, and SCM are all blended together in a single blender. Portland cement 111, vaterite 112, and SCM, such as fly ash and / or slag, are blended in blending 114 step and to produce and store blended cement 115.

[0136] In some aspects, vaterite and SCM, such as fly ash and / or slag, may be blended in ratios according to these aspects, and then the mix may be blended with Portland cement in ratios according to these aspects.

[0137] FIG.12 is an illustration of various aspects in which vaterite and SCM are blended first. Vaterite 122 and SCM 123 go through blending 124 process to form blend 125. Portland cement 121 and blend 125 are obtained next and go through blending 126 to produce blended cement 127.Attorney Docket No.6351.088WO1

[0138] In some aspects, the SCM such as fly ash or slag, are blended with the Portland cement and the mix is then blended with vaterite in ratios according to these aspects.

[0139] FIG.13 is an illustration of various aspects in which Portland cement and SCM are blended first. Portland cement 131 and SCM 133 go through blending 134 process to form blend 135. Vaterite 132 and blend 135 are obtained next and go through blending 136 to produce blended cement 137.

[0140] In some aspects, Portland cement and vaterite may be blended in ratios accordingly. The SCM, such as a fly ash and / or slag, may then be blended with the mix of Portland cement and vaterite in ratios according to various aspects.

[0141] FIG.14 is an illustration of various aspects in which Portland cement and vaterite are blended first. Portland cement 141 and vaterite 142 go through blending 143 process to form blend 145. SCM 146 and blend 145 are obtained next and go through blending 147 to produce blended cement 148.

[0142] In some aspects, vaterite, SCM, and Portland cement may be blended simultaneously in the same blending reactor and in ratios according to these aspects.

[0143] FIG.15 is an illustration of a system for making cementitious blends according to various examples. Kiln 151 is configured to calcine limestone which produces lime and a gaseous exhaust comprising carbon dioxide. Calcined lime is used in reactor 152 to produce portland cement which then goes through crusher 155, where it gets prepared for blending. In another path, calcined lime produced in kiln 151 is received in rector 153, which may be a dissolution tank, preparing for precipitation. The precipitation is done in precipitation reactor 156 which also receives the carbon dioxide produced by the process of calcination. In precipitation reactor 156, the lime reabsorbs the carbon dioxide under one or more precipitation conditions and produces precipitated calcium carbonate such as vaterite.

[0144] The vaterite, along with crushed portland cement from crusher 155, and SCM particles from SCM storage 157, are then blended in blender 158Attorney Docket No.6351.088WO1 according to various embodiments, which may then be stored in cement storage 159.

[0145] FIG.16 is an illustration of a system for making cementitious blends according to various examples. Kilns 161 and 164 are separated for different purposes, one for producing portland cement and one for producing vaterite. Both kilns are configured to calcine limestone which produces lime and a gaseous exhaust comprising carbon dioxide. Calcined lime from kiln 161 is used in reactor 162 to produce portland cement which then goes through crusher 165, where it gets prepared for blending. In another path, calcined lime produced in kiln 164 is received in rector 163, which may be a dissolution tank, preparing for precipitation. The precipitation is done in precipitation reactor 166 which also receives the carbon dioxide produced by the process of calcination. In precipitation reactor 166, the lime reabsorbs the carbon dioxide under one or more precipitation conditions and produces precipitated calcium carbonate such as vaterite.

[0146] The vaterite, along with crushed portland cement from crusher 165, and SCM particles form SCM storage 167, are the blended in blender 158 according to various embodiments, which may then be stored in cement storage 169.

[0147] In some aspects, vaterite may be produced at a different plant than the cement plant. Once Porland cement is produced in the plant, the obtained vaterite and SCM may be blended with the Portland cement according to any of the aspects described above.

[0148] In some aspects, Portland cement, vaterite, and the SCM, are obtained and blended in a concrete plant. The blending may be done according to any of the aspects described above. The blend is then mixed with aggregate to produce concrete. Typical ratio of the blend to aggregate may be from 1-10 to 1-1 by weight.

[0149] In some aspects, a cement plant may have one kiln for calcining limestone, operating at a temperature of about 1,450°C. This kiln serves to produce Portland cement from limestone. In some aspects, a portion of the limestone source may be used at the second kiln which may run at lowerAttorney Docket No.6351.088WO1 temperature followed by a treatment reactor to reabsorb carbon dioxide and produce vaterite.

[0150] In some aspects, fine powders of vaterite and SCM may be blended in air cyclones, ribbon mixers, or paddle mixers. Alternatively, clinker and mined SCM, such as natural pozzolans, can be co-ground in a vertical roller or ball mill and then later blended with vaterite. In some aspects, fine materials may also be introduced into the air separator of the finish mill to achieve blending. In various aspects, the materials can be combined in a concrete mixer to make the cement blend during batching of the concrete.

[0151] Blended cements according to various aspects, may be made with materials abundant to a specific region. In some aspects the blend ratios may be tailored to optimize the engineering properties of the material, such as strength development, setting time, and durability. For instance, in the western United States there are natural pozzolan deposits, slag is often imported to coastal regions, and fly ash availability is determined by proximity to a coal fired power plant. The most cost-efficient blends may be made from locally available materials to limit the transportation costs.

[0152] Ternary blended cements, according to various aspects, may be utilized in ready mix concrete, precast concrete, bagged concrete mix, bagged cement, mortars, screeds, grouts, pavers, concrete masonry units, and building materials.

[0153] In various aspects, the ternary or quaternary blend may be used in suitable order of addition so long as the blending is performed in a manner that produces a homogenous cement blend. The blended cement components need to be finely distributed. Portland clinker, slag and many natural pozzolans require griding and classifying. Vaterite and fly ash are produced as fine materials. Once finely distributed, the materials need to be blended to form a homogenous blend as discussed above. After blending, the ternary or quaternary blended cement may be transferred to a silo for storage, ready for transportation for its intended use.

[0154] In various aspects, ternary and quaternary blended cements may be composed of supplementary cementitious materials, which can be hydraulic or pozzolanic. Pozzolans include coal ash, fly ash, bottom ash, raw naturalAttorney Docket No.6351.088WO1 pozzolans, calcined natural pozzolans, ground glass, rice husk ash, and manufactured materials. Hydraulic supplementary cementitious materials may include slag and high-calcium coal ash.

[0155] The vaterite manufacturing process can utilize many types of limestone with various impurities. High calcium or high purity limestones can be utilized to make lime and vaterite which in turn has high purity. Limestones that contain impurities can be first made into lime. Then the lime is brought into the ReCarbTMprocess where it is solubilized in the process solution (ReCarbTMis a trademark of Fortera Inc.) The insoluble lime impurities can then be removed from the process solution via filtration. During the calcination of magnesium bearing limestones, such as magnesian limestone, dolomitic limestone, or dolomite, magnesium oxide is formed and can be separated from the process solution. Silica rich lime deriving from the calcination of silica rich limestones, such as sandy limestone, cherty limestone, or siliceous limestone, can have the lime solubilized in the ReCarbTMprocess and the silica impurities filtered off. Alternatively, the impurities could be finely divided by milling or grinding and then allowed to pass through the ReCarbTMprocess unchanged. Clay bearing limestones, such as argillaceous limestone or marl, can provide additional benefits to ReActTMblend. During the calcination of the clay bearing limestone, the clay loses water and order making it dissolve easier and become more reactive in hydraulic cements systems. In other words, the clay fraction becomes more pozzolanic. Consequently, clay bearing limestones can be used to make ReAct Blend that contains both a carbonate and pozzolanic component.

[0156] In various aspects, different blends of vaterite and SCMs, such as coal ash, natural pozzolan, or slag, bring about various advantages. The following benefits compared to just utilizing the SCM: increased early-age strength, increased late-age strength, increased bulk resistivity, decreased setting times, pore refinement, reduced heat of hydration, reduced water demand, increased workability, reduced cementitious material’s carbon footprint, and durability enhancements.

[0157] Table 5 is an illustration of the carbon emission reduction according to various aspects as compared with Portland cement. The numbers represent the percentage by weight of different constituents. The letters indicate variousAttorney Docket No.6351.088WO1 constituents in which “C” stands for regular cement, “F” stands for fly ash, “S” stands for slag, and “V” stands for vaterite according to various aspects. Table 5. Carbon emission reduction according to various aspects Cement Blend Cement Vaterite Slag Fly kg CO2Ash CO2 / t Reduction 100C 100% - - - 922 - 75C_15F_10V 75% 10% - 15% 719 22% 70C_20S_10V 70% 10% 20% - 702 24% 50C_30S_10F_10V 50% 10% 30% 10% 532 42% 30C_40S_20F_10V 30% 10% 40% 20% 363 61%

[0158] As seen in the table, various aspects provide considerable reduction in carbon dioxide emissions. A typical emission for regular cement (100C) may be about 922 kg of carbon dioxide per ton of cement produced. The table illustrates how this number changes when different mixes are used. In particular, the addition of 10% vaterite used together with SCMs provides between 22% and 61% reduction in carbon dioxide emission in these aspects. Exemplary Aspects.

[0159] The following exemplary embodiments are provided, the numbering of which is not to be construed as designating levels of importance.

[0160] Clause 1. A cement composition comprising: Portland cement, 5-10% vaterite, and 10-40% SCM.

[0161] Clause 2. The cement composition of clause 1, wherein the SCM comprises at least one of fly ash and slag.

[0162] Clause 3. The cement composition of any preceding clause, wherein the vaterite has a particle size range of 0.1-100 microns.

[0163] Clause 4. The cement composition of any preceding clause, wherein the vaterite has a significantly spherical particle shape.Attorney Docket No.6351.088WO1

[0164] Clause 5. The cement composition of any preceding clause 1, further comprising at least one of admixture, aggregate, additive, and clinker.

[0165] Clause 6. The cement composition of any preceding clause, wherein the vaterite is at least 90% pure.

[0166] Clause 7. A method for ternary mortar preparations, the method comprising: homogenizing a premix comprising Portland cement, 10-20% SCM, and 5-10% vaterite, and mixing the premix using a powder blender.

[0167] Clause 8. A method to form a cementitious composition, the method comprising: calcining limestone to produce a composition comprising lime and a gaseous compound comprising carbon dioxide; treating a first portion of the composition and at least a portion of the carbon dioxide to produce vaterite; using a second portion of the composition to produce Portland cement; blending the vaterite with the Portland cement to produce a first mix; and blending the first mix with SCM to produce a second mix comprising Portland cement, vaterite, and SCM; wherein the vaterite comprises 5-15% by weight of the second mix.

[0168] Clause 9. A system comprising: a first reactor, operating at a first temperature, configured to calcine limestone and produce Portland cement and a gaseous composition comprising carbon dioxide; a second reactor, operating at a second temperature being lower than the first temperature, configured to produce vaterite using a portion of the carbon dioxide; and a blending reactor configured to produce a cementitious blend comprising the Portland cement, the vaterite, and SCM; wherein the vaterite comprises 5-15% by weight of the cementitious blend.

[0169] Clause 10. The system of any preceding clause, wherein the SCM comprises at least one of fly ash and slag.

[0170] Clause 11. The system of any preceding clause, wherein the SCM comprises 10-40% by weight of the cementitious blend.

[0171] Clause 12. A cement composition formulated for early setting, the cement composition comprising: less than 50% by weight of Portland cement, at least one of slag and fly ash, and 5-15% by weight of vaterite.Attorney Docket No.6351.088WO1

[0172] Clause 13. The cement composition of clause 12, comprising by weight of: 25-45% Portland cement, 25-45% slag, 5-25% fly ash, and 5-15% vaterite.

[0173] Clause 14. A cement composition formulated for early strength, the cement composition comprising: At least 40% by weight of Portland cement, 30- 60% by weight of slag or fly ash, and 5-15% by weight of vaterite.

[0174] Clause 15. The cement composition of any preceding clause, comprising by weight of: 40-60% Portland cement, 20-40% slag, 5-15% fly ash, and 5-15% vaterite.

[0175] Clause 16. A cement composition comprising: Portland cement, 10-50% by weight of slag or fly ash, and 5-10% by weight of vaterite.

[0176] Examples given in the present disclosure are for illustrative purposes. One of ordinary skills in the art would appreciate that one could depart from some specific limitations of such examples without departing from the scope of the present employments.

Claims

Attorney Docket No.6351.088WO1 CLAIMS 1- A cement composition comprising: Portland cement, 5-10% vaterite, and 10-40% SCM. 2- The cement composition of claim 1, wherein the SCM comprises at least one of fly ash and slag. 3- The cement composition of claim 1, wherein the vaterite has a particle size range of 0.1-100 microns. 4- The cement composition of claim 1, wherein the vaterite has a significantly spherical particle shape. 5- The cement composition of claim 1, further comprising at least one of admixture, aggregate, additive, and clinker. 6- The cement composition of claim 1, wherein the vaterite is at least 90% pure. 7- A method for ternary mortar preparations, the method comprising: homogenizing a premix comprising Portland cement, 10-20% SCM, and 5-10% vaterite, and mixing the premix using a powder blender. 8- A method to form a cementitious composition, the method comprising: calcining limestone to produce a composition comprising lime and a gaseous compound comprising carbon dioxide; treating a first portion of the composition and at least a portion of the carbon dioxide to produce vaterite; using a second portion of the composition to produce Portland cement; blending the vaterite with the Portland cement to produce a first mix; and blending the first mix with SCM to produce a second mix comprising Portland cement, vaterite, and SCM; wherein the vaterite comprises 5-15% by weight of the second mix.Attorney Docket No.6351.088WO1 9- A system comprising: a first reactor, operating at a first temperature, configured to calcine limestone and produce Portland cement and a gaseous composition comprising carbon dioxide; a second reactor, operating at a second temperature being lower than the first temperature, configured to produce vaterite using a portion of the carbon dioxide; and a blending reactor configured to produce a cementitious blend comprising the Portland cement, the vaterite, and SCM; wherein the vaterite comprises 5-15% by weight of the cementitious blend. 10- The system of claim 9, wherein the SCM comprises at least one of fly ash and slag. 11- The system of claims 9-10, wherein the SCM comprises 10-40% by weight of the cementitious blend. 12- A cement composition formulated for early setting, the cement composition comprising: less than 50% by weight of Portland cement, at least one of slag and fly ash, and 5-15% by weight of vaterite. 13- The cement composition of claim 12, comprising by weight of: 25-45% Portland cement, 25-45% slag, 5-25% fly ash, and 5-15% vaterite. 14- A cement composition formulated for early strength, the cement composition comprising: At least 40% by weight of Portland cement, 30- 60% by weight of slag or fly ash, and 5-15% by weight of vaterite. 15- The cement composition of claim 14, comprising by weight of: 40-60% Portland cement, 20-40% slag, 5-15% fly ash, and 5-15% vaterite. 16- A cement composition comprising: Portland cement, 10-50% by weight of slag or fly ash, and 5-10% by weight of vaterite.

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