WO2024259379A2 - Method of nucleating formation of material and admixture including nucleating agent - Google Patents

Abstract

Methods of forming nucleating formation of material and material formed using the methods are disclosed. Desired features, such as size and morphology of nucleating agents, can be controlled by controlling growth parameters of biomineralizing microorganisms and/or biomineralizing microorganisms to obtain desired nucleating formation properties.

Description

METHOD OF NUCLEATING FORMATION OF MATERIAL AND

ADMIXTURE INCLUDING NUCLEATING AGENT

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No. 63/472,943, entitled METHOD OF NUCLEATING FORMATION OF MATERIAL AND ADMIXTURE INCLUDING NUCLEATING AGENT, and filed June 14, 2023, the contents of which are hereby incorporated herein by reference to the extent such contents do not conflict with the present disclosure.

STATEMENT REGARDI NG FEDERALLY-SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with government support under grant number DE-SC0019293 awarded by the U.S. Department of Energy and grant number CMMI1943554 awarded by the National Science Foundation. The government has certain rights in the invention.

FIELD OF THE DISCLOSURE

The disclosure generally relates to methods of nucleating formation of material, to admixtures comprising nucleating agents, and to materials formed using the methods and/or admixtures. The nucleating agents can be formed from a biomineralizing microorganism or macroorganism.

BACKGROUND OF THE DISCLOSURE

Limestone, which is principally composed of CaCO₃, is used substantially in cementitious systems. Limestone is the key raw material (e.g., about 80% by weight) used to synthesize cement clinker and is often used as an additive or filler material to supplement or replace clinker in concrete mixtures. Accordingly, CaCO₃ can be considered the most important compound for cement and concrete production.

During cement clinker production, CaCO₃ is first decomposed (CaCO₃ -> CaO + CO₂) in a process termed calcination. The resulting CaO then reacts with additional materials (e.g., SiO₂, AI₂O₃, and Fe₂O₃) to produce cement clinker phases (C₃S, C₂S, C₃A, C4AF).

Calcination accounts for about 60-70% of greenhouse gas emissions associated with the cement production process, which accounts for about 7% of global annual greenhouse gas emissions. One of the most common strategies to reduce emissions is to replace a fraction of cement clinker in each mix design with supplementary cementitious materials (SCMs) or limestone filler materials. Limestone fillers are commonly used due to the abundance of limestone at cement plants and their low cost. The use of limestone fillers in cement to produce portland limestone cement (PLC) is standardized around the world. The US currently allows up to 15% replacement of clinker. Limestone or synthesized CaCO₃ particles have also been studied as cement additives instead of filler replacements.

There are four tangible effects that CaCO₃ particles impart in cement: the dilution effect, the filler effect, the nucleation effect, and the chemical effect. The dilution effect refers to the dilution of cement clinker in paste or concrete when replaced by other particles. The filler effect refers to the addition of particles of different sizes to the cementitious matrix, which leads to increased particle packing, density, compressive strength, and durability of cementitious materials. The nucleation effect refers to the tendency of CaCO₃ particles to act as nucleation sites for hydration product formation, which leads to higher early age strength and decreased setting time. The chemical effect refers to the chemical reactions induced by CaCO₃ particles that can occur during cement hydration. These reactions include the formation of C-S-H and carboaluminate phases, the latter of which leads to the stabilization of ettringite from further reaction. These reactions increase the total amount of hydration products, resulting in increased compressive strength and density of hydrated pastes. CaCO₃ is a particularly good nucleating agent due to the CaCO₃ surface structure and interfacial properties, specifically in the calcite phase.

Larger CaCO₃ particles typically lead to dilution and filler effects in cementitious systems. Finer particles, with correspondingly larger surface areas, generally lead to greater hydration product nucleation and can lead to higher particle packing density. For particles approaching the nanoscale, additional dissolution of CaCO₃ from higher surface areas leads to enhanced chemical effects and results in higher C-S-H formation. However, there is a tendency for nanoscale particles to agglomerate, which renders the increased surface area of nanoparticles inaccessible as nucleation agents. High surface area particles (e.g., nanoscale particles) can also exhibit low density, which can result in increased water demand in cementitious pastes, thus limiting their replacement values or requiring chemical additives to control workability. In addition to emissions associated with cement production, the cement industry promotes further pollution and ecosystem damage due to the production of limestone via open pit mining. Limestone must also be ground to the micron scale before use in cement or concrete, which is a highly inefficient and costly process.

Accordingly, there is a general desire for improved nucleating agents, admixtures including the nucleating agents, and methods of using the nucleating agents.

Any discussion of problems and solutions involved in the related art has been included in this disclosure solely for the purposes of providing a context for the present invention and should not be taken as an admission that any or all of the discussion was known at the time the invention was made.

SUMMARY OF THE DISCLOSURE

The disclosure generally relates to methods of nucleating formation of material, to admixtures comprising nucleating agents, and to materials formed using the methods and/or admixtures. As set forth in more detail below, the nucleating agents can have relatively small cross- sectional dimensions and relatively high surface areas to facilitate desired nucleation.

In accordance with embodiments of the disclosure, a method of nucleating formation of material is provided. An exemplary method includes forming a nucleating agent from a biomineralizing microorganism or microorganism, adding the nucleating agent to a composition, and forming the material using the nucleating agent. In accordance with examples of these embodiments, the nucleating agent comprises a cross-sectional dimension of less than 20, 10, or 5 microns or between 1 micron and about 5 microns or between about 15 and about 20 microns. In accordance with further examples, the surface area of the nucleating agent is greater than 5 m²/g or between about 5 m²/g and about 100 m²/g or between about 10 m²/g and about 50 m²/g. In accordance with further examples, the method includes a step of tuning one or more of the size and the surface area. The step of tuning can include, for example, manipulating one or more of: nutrients within a growth medium, amount of the nutrients within the growth medium, a pH of the growth medium, light and dark exposure during growth, elements (e.g., metal) within the growth medium, and compounds (e.g., metal compounds) added to the growth medium, any combination thereof, or the like. In accordance with further examples of the disclosure, the composition comprises a dry cementitious mixture. In some cases, the material can be or include cement paste. In accordance with further examples, the cement can be portland limestone cement or limestone calcined clay cement (LC3). In accordance with further examples, the cement can be or include alkali activated cements, low carbon cements, or the like. In accordance with yet further examples of the disclosure, the biomineralizing microorganism or macroorganism can be or include one or more of microalgae, macroalgae, photosynthetic microorganisms, or photosynthetic marine macroorganisms. For example, the biomineralizing microorganism can be or include one or more of a calcifying microorganism or calcifying macroorganism. By way of particular examples, the biomineralizing microorganism can be or include microalgae and/or macroalgae that produce photosynthetic coccoliths.

In accordance with additional embodiments of the disclosure, an admixture is provided. An exemplary admixture comprises a biologically derived nucleating agent and a composition. The nucleating agent nucleates a reaction of the composition to form a material. The nucleating agent can include a cross-sectional dimension of less than 20, 10, or 55 microns or between 1 micron and about 5 microns or between about 15 and about 20 microns, a surface area greater than 5 m²/g, between about 10 m²/g and about 50 m²/g, and/or other sizes and features as noted herein. In accordance with examples of these embodiments, the composition comprises a dry cementitious mixture. The material can be a cement paste or concrete. In accordance with further examples, the material is net carbon storing. In accordance with yet further examples, the nucleating agent is 0.01- 50 wt%, or 1-35 wt%, or 1-15 wt%, of the admixture.

In accordance with exemplary embodiments of the disclosure, such as those noted above and elsewhere herein, the nucleating agent can include macro pores (e.g., ranging in size between about 0.1 microns and about 1000 microns) and nanopores (e.g., ranging in size between about 0.1 nm and about 100 nm).

In accordance with various exemplary embodiments, the nucleating agent comprises one or more of a metalloid or metal oxide, metalloid or metal phosphate, or metalloid or metal carbonate. The metal can be selected from, for example, calcium, magnesium, aluminum and iron. By way of particular examples, the nucleating agent comprises one or more of SiO₂, CaCO₃, MgCO₃, Ca₃(PO₄)₂, AI₂O₃, and iron oxide.

These and other embodiments will become readily apparent to those skilled in the art from the following detailed description of certain embodiments having reference to the attached figures; the invention not being limited to any particular embodiment(s) disclosed.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

A more complete understanding of exemplary embodiments of the present disclosure can be derived by referring to the detailed description and claims when considered in connection with the following illustrative figures.

FIG. 1 illustrates a method in accordance with at least one embodiment of the disclosure.

FIG. 2 illustrates (a) XRD, (b) TGA, and (c) ICP elemental analyses of photosynthetic CaCO₃ compared to reagent grade CaCO₃. All tests indicate algae CaCO₃ sources are > 70% CaCO₃ and therefore acceptable for use in cementitious systems.

FIG. 3 illustrates SEM micrographs, along with particle size and BET surface area results of (a) reagent grade CaCO₃, (b) Lithothamnion sp. CaCO₃, and (c) E. huxleyi CaCO₃.

FIG. 4 illustrates SEM micrographs of hydrated dilute cement systems containing control OPC at (a) 2 hr and (b) 4 hr of hydration, OPC + reagent grade CaCO₃ at (c) 2 hr and (d) 4 hr hydration, OPC + Lithothamnion sp. CaCO₃ at (e) 2 hr and (f) 4 hr hydration, and OPC + E. huxleyi CaCO₃ at (g) 2 hr and (h) 4 hr hydration. As measured by EDS (not shown): squares = ettringite, small circles = C-S-H, large circles = coccoliths with hydration products (C-S-H or ettringite) forming on them.

FIG. 5 illustrates ICC results for portland cement pastes (OPC) with 0 wt%, 0.5 wt%, 1 wt%, 3 wt% or 5 wt% additions of reagent grade, Lithothamnion sp., or E. huxleyi CaCO₃.

FIG. 6 illustrates compressive strength results (1, 3, 7 and 28 day) for portland cement pastes (OPC) with 0 wt%, 0.5 wt%, 1 wt%, 3 wt% or 5 wt% additions of reagent grade, Lithothamnion sp., or E. huxleyi CaCO₃.

FIG. 7 illustrates isothermal conduction calorimetry results for OPC Control compared to PLCs incorporating (a) 5% or (b) 15% reagent grade CaCO3 (RG), Lithothamnion sp. CaCO₃ (Litho), or E. Huxleyi CaCO₃ (Ehux), and (c) compressive strength results for PLCs with each CaCO₃ filler.

FIG. 8 illustrates analysis of ICC curve calculations compared to area multipliers for (a, b, c) main hydration peak (C3S hydration) and (d, e) secondary hydration peak (C3A hydration) for seeding and PLC cement pastes with reagent grade, Lithothamnion sp., or E. huxleyi CaCO₃.

FIG. 9 illustrates (a) Clinker recipe and Bogue calculation results and (b) Isothermal conduction calorimetry results for OPC control cement paste compared to clinker synthesized with reagent grade or Lithothamnion sp. CaCO₃.

It will be appreciated that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of illustrated embodiments of the present disclosure.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Although certain embodiments and examples are disclosed below, it will be understood by those in the art that the invention extends beyond the specifically disclosed embodiments and/or uses of the invention and obvious modifications and equivalents thereof. Thus, it is intended that the scope of the invention disclosed should not be limited by the particular disclosed embodiments described below.

Various examples of the present disclosure generally relate to methods of nucleating formation of material, to admixtures comprising nucleating agents, and to materials formed using the methods and/or admixtures. Exemplary methods described herein can reduce an amount of carbon dioxide otherwise emitted during the manufacture of the compositions and products. Several examples described below relate to the formation of cement and concrete. However, unless otherwise noted, the invention is not limited to such examples.

FIG. 1 illustrates a method 100 in accordance with various examples of the disclosure. Method 100 includes the steps of forming a nucleating agent from a biomineralizing microorganism or macroorganism 102, adding the nucleating agent to a composition 104, and forming the material using the nucleating agent 106. Although illustrated with steps 102-106, methods in accordance with the disclosure can include a subset of these steps and/or include additional or alternative steps.

During step 102, a nucleating agent is formed from a biomineralizing microorganism or macroorganism. Step 102 can include providing a suitable growth medium for the growth of the biomineralizing microorganisms and/or biomineralizing macroorganisms. The growth medium can depend on the biomineralizing microorganisms and biomineralizing macroorganisms provided and/or desired polymorphs and/or properties of the formed mineral particles. Exemplary biomineralizing microorganisms and biomineralizing macroorganisms include microalgae, macroalgae, photosynthetic microorganisms, and / or photosynthetic marine macroorganisms, such as one or more of a calcifying microorganism or calcifying macroorganism. By way of particular examples, the biomineralizing microorganisms and/or biomineralizing macroorganisms include algae that produce photosynthetic coccolithophores. In the case of coccolithophores, the growth medium can include seawater with added nutrients.

The nucleating agents can be or include mineral particles. The nucleating agents can include one or more of a metalloid or metal oxide, metalloid or metal phosphate, or metalloid or metal carbonate. The metal can be selected from calcium, magnesium, aluminum, and/or iron. By way of particular examples, the nucleating agents can be or include one or more of SiO₂, CaCO₃, MgC0₃, Ca₃(PO₄)₂, AI₂O₃, and iron oxide, in any combination. By way of specific example, the nucleating agents can include crystalline calcium carbonate particles, such as coccoliths produced through a photosynthetic process known as coccolithogenesis.

By way of examples, major advantages of the coccolithogenesis process used by E. huxleyi, for example, include (1) CO₂ is consumed during coccolith production and (2) very few nutrients are required for sustained growth of E. huxleyi. The microstructures of CaCO₃ produced by coccolithophores are complex and uniform, with a particle size under 10 microns. As set forth in more detail below, due to this highly complex and intricate design (small particle size and high surface area), biogenic CaCO₃ from E. huxleyi shows increased nucleation of cement hydration products compared to industrial limestone when used as a limestone filler in Portland limestone cements. In accordance with examples of the disclosure, the growth medium and/or growth conditions are controlled to obtain desired nucleating agent properties. In accordance with examples of these embodiments, the nucleating agent comprises a cross-sectional dimension of less than 20, 10, or 5 microns or between about 1 micron and about 5 microns or between about 15 and about 20 microns. Additionally or alternatively, a surface area of the nucleating agent is greater than 5 m²/g or between about 5 m²/g and about 100 m²/g or between about 10 m²/g and about 50 m²/g. The nucleating agent particles can include macro pores (e.g., ranging in size between about 0.1 microns and about 1000 microns) and/or nanopores (e.g., ranging in size between about 0.1 nm and about 100 nm).

Method 100 can also include a step of tuning one or more of the size and the surface area. For example, method 100 can include manipulating one or more of: nutrients within a growth medium, amount of the nutrients within the growth medium, a pH of the growth medium, light and dark exposure during growth, elements (e.g., metal), within the growth medium, and compounds (e.g., metal compounds) added to the growth medium.

During step 104, the nucleating agent is added to a composition. The composition can be or include a dry cementitious mixture.

During step 106, the material is formed using the nucleating agent. The material can be or include, for example, cement paste.

As noted above, method 100 can include additional steps. For example, method 100 can include combining the cement paste with sand and aggregate and optionally other admixtures or supplementary cementitious materials to form concrete.

In some cases, method 100 includes forming portland limestone cement or limestone calcined clay cement (LC3).

In accordance with additional embodiments of the disclosure, an admixture includes a biologically derived nucleating agent and a composition. The nucleating agent nucleates a reaction of the composition to form a material. The nucleating agent can be as described above and elsewhere herein. For example, the nucleating agent can have a cross-sectional dimension of less than 20, 10, or 5 microns and/or a surface area of the nucleating agent can be greater than 5 m²/g. The nucleating agent can be 0.01-50 wt%, or 1-35 wt%, or 1-15 wt% of the admixture. The composition can be or include a dry cementitious mixture. In some cases, the material comprises cement paste. In accordance with various examples of these embodiments, the material is net carbon storing. In accordance with further embodiments, a concrete mixture includes a cement paste as described herein, sand, aggregate plus any other admixtures or supplementary cementitious materials.

Specific Examples

The examples provided below illustrate methods of forming and using nucleating agents. These examples are meant to illustrate embodiments of the disclosure, and are not meant to limit the scope of the disclosure or claims.

Photosynthetic algae grown CaCO₃ was developed as a replacement for quarried limestone as portland cement precursors and additives. Two sources of photosynthetically produced CaCO₃ with high surface areas produced by marine macro- and microalgae were used as (1) potential nucleation seeds and C02-storing mineral replacements for ground limestone in portland cement and portland limestone cement and (2) as a raw material for cement clinker production. The particle size, morphology, and mineralogy of each CaCO₃ source were characterized. The nucleation effects of algae CaCO₃ as seeding agents (0.5, 1, 3, 5 wt% additions) were investigated using surface area analysis, scanning electron microscopy, and isothermal conduction calorimetry. Nucleating effects were also studied for algae CaCO₃ as limestone filler (5, 15 wt% cement replacements) in portland limestone cements using isothermal conduction calorimetry and compressive strength testing. Data reveal that high surface areas of microalgae CaCO₃ (e.g., 12.22 m²/g) induce nucleation and seeding effects during cement hydration, thereby accelerating cement hydration kinetics without detrimentally affecting compressive strength.

In accordance with various examples, photosynthesized, micron-scale, high surface area CaCO₃ particles produced by coccolithophores provide high nucleation, carbon storing CaCO₃ for use as limestone fillers and/or additives. Their small size and high purity are suitable for use as a raw limestone material for cement clinkering. The suitability of coccolithophore CaCO₃, compared to reagent grade CaCO₃ and CaCO₃ produced by photosynthetic marine macroalgae Lithothamnion sp., as a limestone source for cementitious systems is described below.

Lithothamnion sp. and microalgae Emiliania huxleyi

Two sources of algae were selected: macroalgae Lithothamnion sp. and microalgae Emiliania huxleyi. Both strains are marine organisms that naturally produce CaCO₃ using resources present in ocean environments. Lithothamnion sp. CaCO₃ is commercially harvested and available for purchase. E. huxleyi is the most studied and well understood strain of coccolithophore and produces controlled, intricate CaCO₃ coccoliths. E. huxleyi CaCO₃ was grown either by others in our lab at the University of Colorado Boulder or by the University of North Carolina Algal Resources Collection.

Following characterization, the effects of biogenic CaCO₃ in portland cement systems were studied. First, algae CaCO₃ was studied as a nucleation seeding agent, added in small proportions (< 5% by cement mass) to ordinary portland cement systems. Next, algae CaCO₃ was studied as a limestone filler (5, 15 wt% replacement of cement) in accordance with ASTM C595 in portland limestone cement systems. Scanning electron microscopy (SEM), isothermal conduction calorimetry (ICC), and compressive strength were used to probe nucleation effects in each of these systems by investigating morphology, hydration kinetics, and strength development, respectively.

Suitability of photosynthetic CaCO₃ as limestone source for cementitious systems

To substantiate CaCO₃ produced by Lithothamnion sp. and E. huxleyi was suitable as a limestone source for cementitious systems (as governed by ASTM C150 and ASTM C595), these sources of CaCO₃ were characterized using X-ray diffraction (XRD), thermal gravimetric analysis (TGA), and inductively coupled mass spectrometry (ICP) (FIG. 2).

Although not dictated by ASTM standards, the particle size and surface area of materials used in cementitious systems can have a drastic impact on fresh and hardened state properties. Photosynthetic CaCO₃ sources were characterized using SEM, particle size analysis (PSA), and BET specific surface area analysis (SAA) (FIG. 3). Algae CaCO₃ sources are both greater than 93% CaCO₃ (predominantly the most stable calcite phase). These characterization results substantiate that both forms of algae CaCO₃ meet ASTM C150 and ASTM C595 requirements of limestone for use in cementitious systems, namely that CaCO₃ content exceeds 70 wt%. In addition, E. huxleyi CaCO₃ has particularly small particles with high surface areas, which indicate the potential for increased nucleation effects in fresh cement pastes.

Photosynthetic CaCO₃ as Seeding Agent in Portland Cement

To understand how accessible the enhanced surface areas of algae CaCO₃, particularly E. huxleyi CaCO₃, are as nucleation sites during cement hydration, two studies were completed. First, early age nucleation precipitates were prepared and imaged using scanning electron microscopy (SEM). To analyze hydration products forming around the main hydration peak, and to ensure visibility of CaCO₃ particles, dilute systems with high CaCO₃ additions were studied. Dilute cement systems with additions of each algae CaCO₃ were prepared, filtered and dried, and imaged in SEM. A water to solids ratio of 20:1 and a cement to calcite ratio of 1:1 by mass were maintained for all mixtures. Once mixed with water, dilute mixtures were allowed to hydrate for 2 or 4 hours, then washed with isopropyl alcohol to halt hydration. Alcohol was removed via filtering and filters were then dried at 70 °C for 1 hour. Samples were coated with platinum (~5.3 nm) to ensure conductivity and imaged at 12 keV, accelerating voltage in SEM (FIG. 4). Electron dispersive spectroscopy (EDS; not shown) was used to identify hydration products: ettringite by the presence of S, and Al and/or Fe and C-S-H by the presence of Si. At 2 hrs of hydration, all samples show the needle-like morphology of ettringite (indicated by orange squares) in FIG. 4. C-S-H particles are also visible at 4 hrs in both OPC and reagent grade CaCO₃ samples (circles in FIG. 4). After 4 hrs of hydration, significant needle-like morphology (ettringite) is still present throughout imaged samples of both algae CaCO₃ sources. This result indicates that algae CaCO₃ sources had begun reacting with C₃A, thereby stabilizing the ettringite phase against further reaction. In both 2 hr and 4 hr E. huxleyi CaCO₃ samples, EDS (not shown) identified small amounts of Si, Al, and S on coccoliths, confirming that coccoliths are acting as hydration product nucleation sites (circles in FIG. 4).

Next, cement pastes were prepared with small additions of algae CaCO₃ as a nucleation seeding agent (0.5, 1, 3, or 5 % by weight of cement). Early age hydration kinetics were monitored using ICC for 72 hours. ICC was completed at 25 °C using siliceous sand as a reference. Twenty-gram batches were made for each mix and samples were run in duplicate. Heat of hydration and total heat data were collected for 72 hours. Data were then normalized by weight of cement powder in each sample. Compressive strength was also analyzed by testing 1 cm³ cubes of each cement paste at 1, 3, 7, and 28 days of hydration.

To make paste for compressive strength testing and hydration kinetics monitoring, CaCO₃ was first mixed with water for 30 sec. E. huxleyi CaCO₃ showed greater agglomeration than other CaCO₃ sources and was mixed for an additional 30 sec. Cement powder (Quikrete Type l/ll) was then added to the CaCO₃/water mix and hand mixed for 2 min. A water-to-cement ratio (w/cm) of 0.5 was used for all samples. Cement paste was mixed and poured into a 1 cm³ silicone cube mold tray, which was placed in a >98% humidity chamber created according to a modified ASTM E104. Cubes were allowed to cure for 24 hours. For 1-day compressive strength data, cubes were tested directly after removing from the molds. For remaining compressive strength data, cubes were removed from the molds and placed into an oversaturated Ca(OH)₂ solution. After curing for 3, 7, or 28 days, cubes were removed from the saturated Ca(OH)₂ solution and thoroughly dried using a paper towel. Compressive strength of cement cubes was measured using an Instron Universal Testing machine with a 50 kN load cell and a 0.1 mm/sec compression rate. Three cubes were tested for each mix design. One-factor ANOVA analysis was used to assess the variability in results between different sources of CaCO₃ used as seeding agents at each hydration period. After ANOVA, Dunnett's single- step test was used to compare each CaCO₃ type/addition to control OPC strength results individually.

ICC data collected for each PLC paste (FIG. 5) were used to analyze hydration kinetics. Pastes with small additions of reagent grade CaCO₃ (< 5 wt%) showed little difference in hydration kinetics from control OPC paste. For pastes with 5 wt% reagent grade CaCO₃, there was a slight decrease in peak heat and cumulative heat, indicating a dilution-type effect. Lithothamnion sp. CaCO₃ additions also exhibited this dilution-type effect, starting at 0.5 wt% and progressively increasing up to 5 wt% addition. Conversely, E. huxleyi CaCO₃ additions led to increases in peak heat, with larger additions showing larger peak heat increases. Total cumulative heat for E. huxleyi CaCO₃ pastes showed little difference with differences in CaCO₃ addition.

Compressive strength results (FIG. 6) support the conclusions of ICC testing. One factor ANOVA analysis indicated that there were no statistical differences between compressive strength values at 7-days of hydration. ANOVA indicated that there were statistical differences between compressive strength values tested at 1, 3, and 28-days of hydration. According to Dunnett's test, compressive strengths of the 0.5 wt% and 3 wt% addition of Lithothamnion sp. CaCO₃ were statistically lower than OPC control strength at 1-day of hydration, which could indicate agglomeration or inadequate mixing as 1 wt% and 5 wt% Lithothamnion sp. CaCO₃ were both statistically similar to control OPC. Strengths were statistically greater than the OPC control at 1-day of hydration for 5 wt% E. huxleyi CaCO₃. This 1-day compressive strength result, combined with SEM microscopy nucleation test results, indicates that E. huxleyi CaCO₃ acts as a successful nucleation agent for hydration products in cement paste. All other samples achieved statistically similar strength as OPC control samples at 1-day of hydration. Despite differences at early ages, Dunnett's analysis revealed that compressive strength values for all CaCO₃ sources and additions at 3, 7, and 28-days of hydration were statistically similar to control OPC strengths. Differences in compressive strengths at 1-day evened out by 3-days of hydration and no CaCO₃ sources induced later age strength changes out to 28-days of hydration.

Photosynthetic CaCO₃ as Filler in Portland Limestone Cement

To assess the nucleation effects of each CaCO₃ source as a filler for portland limestone cement, cement pastes with 5% and 15% CaCO₃ replacement by weight of cement were prepared (ASTM C595). Cement hydration was analyzed using ICC. Compressive strength was analyzed by testing 1 cm³ cubes of each PLC cement paste at 7 and 28 days after hydration. To make cement paste, CaCO₃ was first thoroughly dry mixed with OPC powder for 5 min. Water was then added and the paste was mixed by hand for two minutes. A water-to-cementitious materials ratio (w/cm) of 0.5 was used for all samples; E. huxleyi CaCO₃ showed enhanced water demand and additional water was added to the 15% replacement mix to achieve workability (effective w/cm = 0.6).

ICC was completed as described herein. Cement paste was mixed and poured into a 1 cm³ silicone cube mold tray to create cubes for compressive strength testing. Cubes were then cured as described above. Compressive strength of cement cubes was measured at 7 and 28-days of hydration. Three cubes were tested for each mix design. One-factor ANOVA analysis was used to assess the variability in results between CaCO₃ filler sources and Dunnett's single-step test was used as a post-hoc test to ANOVA to compare strengths for each PLC to control OPC strengths individually at each hydration time.

ICC data collected for each PLC paste (FIG. 7) were used to analyze hydration kinetics. All PLCs showed increased peak heat compared to OPC control cement paste, except 5% Lithothamnion sp. CaCO₃ PLC, which showed a slight peak heat decrease, similar to that seen in seeding test results. PLC with E. huxleyi CaCO₃ showed significant peak heat increases (>20% increase for 15% PLC). PLC with 15% E. huxleyi CaCO₃ also showed a >12% increase in max cumulative heat at 72 hrs.

Statistical results, calculated through one factor ANOVA analysis, revealed that all PLC pastes achieved statistically similar strength after 7-days of hydration (FIG. 7(c)). ANOVA indicated statistical differences at 28 days of hydration; however, Dunnett tests indicated that all samples achieved strength statistically similar to control OPC cement samples at both 7 and 28-days of hydration. PLCs with 15% cement replacement by both algae CaCO₃ sources overcame cement dilution effects to achieve strength statistically similar to OPC control samples. This result is notable for 15% E. huxleyi CaCO₃ PLC paste prepared with higher w/cm, which would typically be expected to cause a decrease in compressive strengths on the order of 20%.

Algae CaCO₃ as seeding agents and fillers

To further analyze the effects of surface area of each CaCO₃ source on cement hydration, area multipliers (AM) were calculated for each seeding and PLC cement paste studied. These area multipliers are a numerical value representing the "surface area of filler per unit surface area of cement in the system." AM values were calculated according to equation 1 (seeding) and 2 (fillers), where r is percentage of CaCO₃ added and SSA is specific surface area as calculated by BET (shown in FIG. 3 for CaCO₃ sources). SSA of cement was measured as 1.3569 m²/g.

'■ SSA_CaCo₃

AMseeding ~ 1 + 100 SSA_cement (Eq- 1)

To understand how additional surface areas impacted cement hydration, area multipliers were plotted against the slope of acceleration, the maximum peak heat achieved, and the inverse of the time to reach peak heat (FIG. 8), as calculated from ICC results (FIGS. 5 and 7). The dashed lines in each plot indicate the linear relationship between slope of acceleration, peak heat flow, and inverse time to peak heat flow versus AM exhibited by each CaCO₃ source in cement pastes. This linearity indicates that peak heat increases are as expected based on surface area increases; CaCO₃ particles are not unnecessarily agglomerating and limiting hydration acceleration. This finding is interesting for E. huxleyi CaCO₃, which has the smallest size and largest surface area, but whose data shows the best fit to its linear trend line. Despite the linearity seen for E. huxleyi CaCO₃ additions in FIG. 8(c), the slope of this line is relatively shallow. This difference can also be seen by the lack of a significant leftward shift of the main hydration peak on ICC figures (FIGS. 5 and 7), despite large increases in AM with E. huxleyi CaCO₃ addition. This result indicates that E. huxleyi CaCO₃ is not necessarily accelerating the hydration reactions. However, E. huxleyi CaCO₃ is amplifying the main hydration peak leading to more, but not earlier, C-S-H formation.

Inspection of FIGS. 5 and 7 shows that there is a leftward shift and peak heat increase of the secondary hydration peak corresponding to C3A hydration in pastes with E. huxleyi CaCO₃. FIG. 8 (d) and (e) shows AM figures for this secondary peak. For pastes with E. huxleyi CaCO₃, this C3A hydration peak is responding linearly to increases in surface area, both in maximum peak heat and in peak time. This shift indicates that E. huxleyi CaCO₃ accelerates C3A hydration, likely through the formation of stable carboaluminate phases. Similar C3A hydration effects have been highlighted for various CaCO₃ additions in cementitious systems. EDS results (not shown) showing S and Al on coccoliths (FIG. 4) also indicate that E. huxleyi CaCO₃ is acting as a nucleation site for AFm phase formation.

Overall, a few broad conclusions can be drawn from the results of studying these two sources of algae CaCO₃ as seeding agents and fillers in portland cement systems. First, both algae CaCO₃ sources are highly pure, calcite polymorphs of CaCO₃, which indicates their applicability as limestone sources to cementitious systems. The relatively high surface area of E. huxleyi CaCO₃ leads to amplified C3S hydration and accelerated C3A hydration. Both effects increase with increased CaCO₃ addition. Lithothamnion sp. CaCO₃ behaves more similarly to reagent grade CaCO₃, with less evidence of significant nucleation effects than those seen for E. huxleyi CaCO₃ and possible hydration deficits when added in low proportions. These results are likely due to the lower surface area, higher particle size, and lower Ca content of Lithothamnion sp. CaCO₃ as compared to E. huxleyi CaCO₃. With optimization, both algae CaCO₃ sources can be used as fillers in portland cement systems and E. huxleyi CaCO₃ can also be used as a seeding agent at relatively high additions in cementitious systems.

Clinkering

An optimized mix of pre-clinker raw materials was identified based on Bogue equations (FIG. 9). Clinker nodules were formed by hand and then heated using an optimized heating protocol in a high temperature bottom loading box furnace. Clinker nodules were heated from room temperature to 900 °C, held for 30 min, then heated to 1450 °C, all at a rate of 10 °C/min. After a soak time of 30 min at 1450 °C, clinker was removed from the furnace and air quenched to maintain the high temperature, C3S phase. Once cool, clinker nodules were crushed with a hammer, then ball milled in isopropyl alcohol at 450 rpm for 5 min. The ground clinker powder was dried at 70 °C, then sieved to pass through a 75 pm sieve, and hand mixed with 5 wt% gypsum. Clinker phase formation was tested using ICC analyses, as shown in FIG. 9. Clinker synthesized with reagent grade CaCO₃ shows similar heat evolution to that of OPC control cement paste; the slight leftward shift may be due to a difference in clinker fineness between lab clinker and commercial OPC, or due to undersulfation of lab clinker. Initial tests with Lithothamnion sp. CaCO₃ resulted in less reactive clinker due to the reduced Ca content as compared to that of reagent grade CaCO₃ (FIG. 2).

Photosynthetic CaCO₃ as raw material for cement clinker production

Algae CaCO₃, particularly E. huxleyi CaCO₃, as nucleation seeds and low percentage fillers in portland cement pastes. The high purity and naturally small particle sizes of algae CaCO₃ also indicate suitability as a raw material replacement for quarried limestone in cement clinker production. High surface areas lead to faster clinkering reactions or reduced clinkering temperatures needed to produce cement clinker. Pre-clinker powder can be produced by mixing reagent grade raw materials (CaCO₃, SiO₂, AI₂O₃, and Fe₂O₃) in proportions described above. Synthetic diamond powder can be added as an internal standard to enable quantitative XRD analysis.

Cement Hydration Kinetics of LC3 Paste Synthesized with Biologically Architected CaCO₃

ASTM C150 Type l/ll PC was supplied by Quikrete. Reagent-grade (RG) CaCO₃ (>99%) was obtained from Sigma Aldrich. Lithothamnion Powder (L corallioides) was purchased from Aquamin (Ireland). Lyophilized E. huxleyi biomass (CaCO₃ and organic cell matter) was purchased from the Algal Resource Collective (ARC) at the University of North Carolina, Wilmington, USA. The organics were removed from the E. huxleyi biomass. MK was obtained from BASF Chemical Corporation (Georgia, USA). A PCE superplasticizer (ADVA® Cast 575) was obtained from GCP Applied Technologies (Cambridge, MA, USA). The composition of all raw materials was analyzed using ICP- OES (Table 1). The median particle size of the reagent grade, L. corallioides, and E. huxleyi CaCO₃ were 18.8 ± 0.274 pm, 6.74 ± 0.069 pm, and 1.77 ± 0.170 pm, respectively, as measured as of the reagent grade, L. corallioides, and E. huxleyi CaCO₃ were 0.71 m²/g, 8.26 m²/g, and 12.22 m²/g, respectively, as measured by BET analysis.

Table 1. Oxide composition of raw materials from ICP-OES analysis as percentages

RG CaCCh <0.01 56.4 <0.007 <0.006 0.02 0.015 <0.01 <0.267 <0.0008 43.6

L. corallioides 0.756 41.7 1.10 0.110 3.8 1.16 0.060 3.4 0.149 47.8

E. huxleyi 0.011 51.9 0.0114 <0.006 0.058 0.11 0.055 <0.267 <0.0008 47.9

One PC control paste and three LC3 paste samples were prepared, yielding a total of four mixture formulations. All samples were prepared using a water-to-cementitious ratio (w/cm - 0.5). Each LC3 mixture was prepared using the same proportions of PC (55%), MK (15%), and CaCO₃ (15%) by mass. The differentiating factor between the four mixes was the type of CaCO₃ integrated into the corresponding mix. To prepare the mixtures, first, all dry materials in each sample mixture were combined and hand-mixed for five minutes. Then, the samples were mixed with water for 2 minutes. Lastly, SP was added to the mixes to ensure workability of all mixtures at ~1.5% mass. Once the mixtures were prepared, ~ 7 g of each paste were placed into an ampoule. Heat flow and cumulative heat were measured using isothermal was performed using a modified ASTM C1702-17. Data were collected over the course of 7 days. Each paste sample was tested in duplicate.

SEM micrographs of the RG CaCO₃, L. corallioides, and E. huxleyi showed that the morphologies and the particle sizes differ between the CaCO₃ sources. In particular, the biogenic sources are both smaller and less angular than the RG CaCO₃. Images substantiate the mean particle size and surface area data obtained via laser diffraction and BET, respectively.

Normalized heat flow and cumulative heat data for all samples showed that all LC3 pastes exhibited a higher peak heat compared to PC, which was expected. In addition, the LC3 pastes containing biogenic CaCO₃ demonstrated higher peak heats than the LC3 control, owing to a possible nucleation effect due to smaller particle size and higher specific surface areas. The higher peaks at 60 h induced by the LC3 pastes containing biogenic CaCO₃ have been shown to correspond to the latent aluminate hydration peaks, specifically the formation of monocarboaluminate and hemicarboaluminate phases. The L. corallioides sample has higher fractions of silica and alumina than the other CaCO₃ sources, which could be why it exhibited the highest cumulative heat and earliest third peak (see Table 1). Existing literature substantiates that alumina present in calcined clays leads to the formation of early carboaluminate phases instead of sulfoaluminate phases. Formation of carboaluminates could lead to an increase in sulfate available for ettringite formation. The LC3 samples containing biologically architected CaCO₃ exhibited the highest total cumulative heats, indicating an overall higher degree of reaction compared to the PC and LC3 controls. A higher degree of reaction could be caused by the nucleation effects induced by these particles, along with higher quantities of carboaluminate phases that form at later ages.

These examples illustrate how different CaCO₃ sources can have a significant impact on the heat flow and heat evolved in LC3 systems. LC3 pastes that incorporate biologically architected limestone from corallioides and E. huxleyi with small particle sizes, high surface areas, and different chemical compositions exhibit higher cumulative heat compared to LC3 pastes produced using reagent-grade CaCO₃. More specifically, biologically architected CaCO₃ affects the kinetics of cement hydration at 60 hours in LC3 systems, owing to the possible formation of additional carboaluminate phases.

In another example, biogenic CaCO₃ produced by E. huxleyi was evaluated as a filler for PLC, corresponding to both US (ASTM C595, up to 15% replacement) and EU (EN 197-1, up to 35% replacement) standards.

Reagent grade CaCO₃ (>99%) was purchased from Sigma Aldrich. ASTM C150 Type l/ll portland cement was purchased from Quikrete.

Lyophilized E. huxleyi biomass (containing both CaCO₃ and organic cell materials) was purchased from the Algal Resource Collective (ARC) at the University of North Carolina, Wilmington, USA. CaCO₃ was then purified to remove organics. Approximately 0.15 g of freeze-dried biomass was added to 50 mL centrifuge tubes and suspended in MilliQ water to a volume of 40 mL, which then sedimented for at least 24 hours. Tubes were then centrifuged for 17 min at 4696 x g and 4 °C. Supernatants were removed to the 10 mL marking, and contents were re-suspended via vortexing. Next, 3.3 mL of 12% NaOCI was added to each tube, shaken lightly, and allowed to sit for 15 min. Then 6 mM NaHCO₃ was added to the 40 mL marking and tubes were centrifuged for 6 min at 1500 x g and 4 °C. Supernatants were again removed to the 10 mL marking before vortexing to resuspend pellets. Washing with 6 mM NaHCO₃ and subsequent centrifugation was repeated four more times. Following the final wash, supernatant was removed to the < 5 mL marking. Pellets were resuspended through gentle shaking and contents from 8 tubes were combined in a separate centrifuge tube before centrifugation for 6 min at 1500 x g and 4 °C. Maximum volume of supernatant was removed without disturbing the pellet, and purified CaCO₃ was dried in an oven at 80-90 °C for at least 24 hours.

Both CaCO₃ sources were imaged using a Hitachi SU3500 scanning electron microscope (SEM). Samples were coated in platinum prior to imaging to ensure sufficient conductivity. Images of both reagent grade and biogenic calcite were taken in secondary electron mode using 15 keV accelerating voltage, 2,500 x and 10,000 x magnifications, with < 9 mm working distances.

Particle size distributions (PSD) of both CaCO₃ sources was measured using laser diffraction in a Malvern Panalytical Mastersizer3000. Particles were suspended in ultra-pure MilliQ water, dispersed using ultrasonication prior to size analysis. Mean particle size and standard deviation were calculated using results from 5 replicate samples.

Mineralogy of both CaCO₃ sources was confirmed using qualitative X-ray diffraction (XRD) with a Bruker D8 Advance X-ray diffractometer. Cu Ka X-ray radiation (wave-length 1.5406 A) was used to scan from 5° to 90° 20 with a step size of 0.02° and a dwell time of 1.5 seconds per step. The resulting patterns were analyzed with the Bruker DIFFRAC.EVA software that was equipped with the International Center for Diffraction Data (ICDD) PDF-4 AXIOM 2019 database to identify phases.

Cement pastes with a water-to-cement (w/c) ratio of 0.65 were mixed according to the mixture proportions given in Table 2. A w/c = 0.65 was chosen due to the anticipated workability concerns of high-CaCO₃ replacement percentage mixtures at lower w/c ratios, especially for samples containing biogenic CaCO₃. CaCO₃ was dry mixed with cement by hand for 5 min. Dry cement mixtures were then added to water and thoroughly mixed by hand for at least 2 min. A polycarboxylate-based superplasticizer (SP) was added dropwise to the 35% biogenic CaCO₃ PLC paste up to 0.18 g until a thick paste consistency was achieved. SP was only necessary for the 35% E. huxleyi cement paste, as acceptable workability was achieved for remaining pastes.

Table 2 Cement paste mix proportions

Approximately 7 g of paste was added to each of two glass ampoules and sealed for ICC analysis across from a corresponding reference sample (siliceous sand). ICC was operated at 25 °C using an 8 channel Thermometric TAM Air calorimeter. For each CaCO₃ source, heat of hydration data were collected for a control mix (OPC), a 5%, 15%, and 35% CaCO₃ replacement mix. Heat of hydration and total heat data were collected for at least 72 hours. Data were then normalized by weight of cement powder in each sample.

Following mixing, 16.5 g of cement paste were poured into a silicone 1 cm³ cube mold tray. A small metal rod was used to ensure even spreading of cement paste to the cube corners. The tray was then placed in a > 94% humidity chamber (created according to a modified ASTM E104 standard) and cured for 24 hours. Cubes were then removed from the humidity chamber and placed in a supersaturated Ca(OH)₂ solution. Samples were tested for 7 days using an Instron Universal Testing machine with a 50 kN load cell and a 0.1 mm/sec compression rate. Samples were tested in triplicate.

Similar to above, reagent grade CaCO₃ exhibited a significantly larger particle size than that of biogenic CaCO₃ grown from E. huxleyi. Particle size analysis revealed that the median particle sizes (dso) of the reagent-grade and biogenic CaCO₃ were 18.8 ± 0.274 pm and 1.77 ± 0.17 pm. respectively, which is an order of magnitude difference. The differences in particle size were evident in the SEM micrographs.

Although some small, angular particles were seen for reagent grade CaCO₃, the majority of particles were much larger than those seen for E. huxleyi CaCO₃. The microstructures of biologically architected CaCO₃ appear much more intricate than the more granular and rigid microstructure of reagent grade CaCO₃. It can be inferred from the SEM micrographs that biogenic CaCO₃ also exhibits higher surface area than reagent grade CaCO₃ due to decreased particle sizes and their biologically architected, intricate shapes.

Also, similar to above, XRD results showed nearly identical phases present for both reagent grade and biogenic CaCO₃. Both samples exhibit distinct peaks at expected angles characteristic of the calcite phase of CaCO, with minor peaks associated with additional, minor phases in each sample, specifically those shown near 27° 20.

The rate of heat evolution and cumulative heat evolved were similar for the 5% and 1 % PLC with reagent grade CaCO₃ filler, as compared to the OPC control. A slight increase and leftward shift of the main hydration peak was evident for the 35% PLC with reagent grade CaCO₃ filler. The cumulative heat also increased slightly with each increased addition of reagent grade CaCO₃ filler. PLC with 5% biogenic CaCO₃ exhibited a slight main hydration peak increase, as well as a slight cumulative heat increase, which was lower than the increase exhibited by 5% reagent grade CaCO₃ PLC. PLC with 15% biogenic CaCO₃ showed a significant heat increase and leftward shift of the main hydration peak. Notably, PLC with 35% biogenic CaCO₃ and SP showed a significantly delayed rate of heat evolution, reaching a maximum around 20 hours, roughly 12 hours later than other PLC pastes with lower amounts of biogenic CaCO₃. Both 15% and 35% biogenic CaCO₃ PLC exhibited increased cumulative heat at 72 hours as compared to OPC and 5% biogenic CaCO₃ PLC paste, with 35% biogenic CaCO₃ PLC reaching approximately the same cumulative heat as 15% biogenic CaCO₃ PLC despite significantly delayed hydration. PLC with 35% biogenic CaCO₃ also shows a significant increase in the second hydration peak, associated with the reaction of C₃A and the formation of a calcium aluminate phase (ettringite).

The lowest 7-day compressive strength was observed for the 35% reagent grade CaCO₃ pastes. The 5% and 15% reagent grade CaCO₃ pastes displayed comparable strengths slightly lower than that of OPC. Contrarily, the highest compressive strength was observed for the 15% biogenic CaCO₃ PLC paste by a large, statistically significant margin. Both 5% and 35% biogenic CaCO₃ PLC pastes displayed similar strength, the latter of which is lower than that of OPC. At all tested replacement values of 5% or greater, PLC pastes with biogenic CaCO₃ showed increased compressive strength over their reagent grade CaCO₃ counterparts. Pastes with both types of LF at a 5% replacement value had comparable compressive strengths and did not show excessively decreased compressive strengths compared to OPC.

The replacement of cement with 35% biogenic CaCO₃ LF yielded a comparable maximum rate of heat evolution and cumulative heat. However, maximum rate of heat evolution was delayed by roughly 12 hours as compared to the remaining PLC pastes studied. The addition of SP to the 35% biogenic CaCO₃ paste most likely contributed to its significantly delayed hydration, a phenomenon well-documented in literature. The mechanism of hydration retardation by polycarboxylate-based SPs, such as the one used here, is largely based on sorption to solid phases, as well as steric and electrostatic dispersion mechanisms. It has been found that high charge density in the form of carboxylate ions on the SP backbone led to higher SP adsorption onto cement grains and resulted in the longest retardation of hydration reactions. Because the main hydration peak still occurred at the 20-hour mark, the presence of SP does not appear to significantly affect cumulative heat development at the 72-hour timepoint.

The use of superplasticizers (SP) addition reduces water demand in PLC, though simultaneously retards hydration significantly. However, SP addition may have a positive effect on mechanical strength. It has been found that SP addition enhanced mechanical strength while reducing water demand by 20%. In the compositions of these examples, the mix design containing 35% biogenic CaCO₃ showed the most pronounced water demand (nucleation and filler effect) and used superplasticizer (SP) addition (0.05 g/g CaCO₃). These results are consistent with literature suggesting that LF finer than cement particles induces nucleation and filler effects. While traditional LF typically increases workability and may decrease water demand, fine LF, such as biogenic LF used here, augments the nucleation effect and increases water demand. The 35% biogenic CaCO₃ PLC paste was the only paste to require SP addition, demonstrating the phenomenon that a smaller particle size and increased surface area of the LF leads to increased water adsorption onto LF surfaces, as well as increased nucleation of cement hydration products.

Compressive strength testing revealed that the 15% biogenic CaCO₃ PLC paste showed the highest compressive strength compared to all other mixtures, likely due to increased nucleation. Though the PLC paste containing 35% reagent grade CaCO₃ showed significantly decreased compressive strength compared to the 5% reagent grade CaCO₃ PLC paste, the 35% biogenic CaCO₃ PLC paste had (i) a higher compressive strength compared to its reagent grade counterpart due to enhanced nucleation and (ii) comparable compressive strength to the 5% biogenic CaCO₃ PLC paste. It is possible that both LF sources experienced some particle agglomeration, especially at high replacement percentages, which would reduce the propensity for nucleation, and the inert filler effect is likely most responsible for decreased strength in both pastes with 35% replacement compared to OPC.

As noted above, advantages of using biogenic CaCO₃ as limestone filler are numerous. While traditional mined limestone takes centuries to regenerate, biogenic limestone is an unlimited resource on the human timescale. The mining of limestone in quarries causes dust emissions and erosion, impacts groundwater flow, contamination, and overall water quality and, in the majority of cases, increases CO₂ emissions due to operational energy demand and the need for product transportation. The cultivation of biogenic CaCO₃ has the potential to be conducted on-site at cement production plants, bypassing the need for transportation-related CO₂ emissions. Perhaps most significantly, biogenic CaCO₃ has a significantly reduced carbon footprint as compared to mined limestone, as it actively consumes CO₂ during its production and can be used for carbon storage in PLCs.

In this disclosure, any two numbers of a variable can constitute a workable range of the variable, and any ranges indicated may include or exclude the endpoints. Additionally, any values of variables indicated (regardless of whether they are indicated with about or not) may refer to precise values or approximate values and include equivalents, and may refer to average, median, representative, majority, etc. in some embodiments. Further, in this disclosure, the terms including, constituted by, having and related words can refer independently to typically or broadly comprising, comprising, consisting essentially of, or consisting of in some embodiments. In accordance with aspects of the disclosure, any defined meanings of terms do not necessarily exclude ordinary and customary meanings of the terms.

The present invention has been described above with reference to a number of exemplary embodiments and examples. It should be appreciated that the particular embodiments shown and described herein are illustrative of the preferred embodiments of the invention and its best mode, and are not intended to limit the scope of the invention. Further examples of the disclosure are set forth in the claims. It will be recognized that changes and modifications may be made to the embodiments described herein without departing from the scope of the present invention. These and other changes or modifications are intended to be included within the scope of the present invention.

Claims

Claims:

1. A method of nucleating formation of material, the method comprising: forming a nucleating agent from a biomineralizing microorganism or macroorganism; adding the nucleating agent to a composition; and forming the material using the nucleating agent, wherein the nucleating agent comprises a cross-sectional dimension of less than 20, 10, or 5 microns, and wherein a surface area of the nucleating agent is greater than 5 m²/g.

2. The method of claim 1, wherein the cross-sectional dimension is between about 1 micron and about 5 microns or between about 15 and about 20 microns.

3. The method of claim 1 or claim 2, wherein the surface area is between about 5 m²/g and about 100 m²/g or between about 10 m²/g and about 50 m²/g.

4. The method of any of claims 1-3, further comprising a step of tuning one or more of the size and the surface area.

5. The method of claim 4, wherein the step of tuning comprises manipulating one or more of: nutrients within a growth medium, amount of the nutrients within the growth medium, a pH of the growth medium, light and dark exposure during growth, elements within the growth medium, and compounds added to the growth medium.

6. The method of any of claims 1-5, wherein the composition comprises a dry cementitious mixture.

7. The method of any of claims 1-6, where the material comprises cement paste.

8. The method of claim 7, further comprising combining the cement paste with sand and aggregate and optionally any other admixtures or supplementary cementitious materials to form concrete.

9. The method of any of claims 1-8, further comprising forming portland limestone cement or limestone calcined clay cement (LC3).

10. The method of any of claims 1-9, wherein the biomineralizing microorganism or macroorganism comprises microalgae, macroalgae, photosynthetic microorganisms, and / or photosynthetic marine macroorganisms.

11. The method of any of claims 1-10, wherein the biomineralizing microorganism comprises one or more of a calcifying microorganism or calcifying macroorganism.

12. The method of any of claims 1-11, wherein the biomineralizing microorganism comprises a photosynthetic coccolithophore.

13. An admixture comprising: a biologically derived nucleating agent; and a composition, wherein the nucleating agent nucleates a reaction of the composition to form a material, wherein the nucleating agent comprises a cross-sectional dimension of less than 20, 10, or 5 microns, and wherein a surface area of the nucleating agent is greater than 5 m²/g-

14. The admixture of claim 13, wherein the composition comprises a dry cementitious mixture.

15. The admixture of claim 13 or claim 14, wherein the material comprises cement paste.

16. A concrete mixture comprising the cement paste, sand, aggregate plus any other admixtures or supplementary cementitious materials.

17. The admixture of any of claims 13-15, wherein the material is net carbon storing.

18. The admixture of any of claims 13-15 and 17, wherein the nucleating agent comprises macropores and nanopores.

19. The admixture of any of claims 13-15, 17 and 18, wherein the nucleating agent is 0.01-50 wt%, or 1-35 wt%, or 1-15 wt%, of the admixture.

20. The admixture of any of claims 13-15 and 17-19, wherein the nucleating agent comprises one or more of a metalloid or metal oxide, metalloid or metal phosphate, or metalloid or metal carbonate.

21. The admixture of claim 20, wherein the metal is selected from calcium, magnesium, aluminum, and iron.

22. The admixture of any of claims 13-15 and 17-21, wherein the nucleating agent comprises one or more of SiO₂, CaCO₃, MgCO₃, Ca₃(PO₄)2, AI₂O₃, and iron oxide.