Cementitious composition additive

Abstract

An additive composition comprising activated kaolinite and up to about 5 wt% halloysite based on the weight of kaolinite and halloysite is disclosed. Also disclosed is a method of regulating a rheological property of a cementitious composition.

Description

CEMENTITIOUS COMPOSITION ADDITIVEPRIORITY DOCUMENT

[0001] The present application claims priority from Australian Provisional Patent Application No. 2024903272 titled “CEMENTITIOUS COMPOSITION ADDITIVE” and fded on 10 October 2024, the content of which is hereby incorporated by reference in its entirety.TECHNICAE FIELD

[0002] The present disclosure relates generally to additives for altering one or more property of a cementitious composition. In a particular form the present disclosure relates to rheology modifiers for cementitious compositions, such as concrete or mortar.BACKGROUND

[0003] Cementitious compositions such as concrete, mortar, grout and sealer are used extensively as building materials and engineering structures. Typically, a cementitious composition may comprise one or more cementitious material (also known as cementitious binder), one or more aggregate, optionally one or more additive, optionally one or more reinforcement and water. Upon addition of water the cementitious binder is activated and forms a paste that binds the aggregate together.

[0004] Different workability requirements may be expected for different cementitious compositions. For example, a ready-mix concrete, which is prepared in a mixing station, is typically transported to a construction location and is generally cast by pumping. Thus, long-term slump retention until final casting and low shear-stress during pumping are required. For self-consolidating concrete, high flowability without bleeding and segregation is crucial. For pre-cast concrete, water reduction and fast hardening process are necessary, whereas the slump retention is important only in the first 30 min after placing.

[0005] To ensure smooth processes in applying (for example casting, spraying and 3D printing) a cementitious composition, and to guarantee the final quality of the applied cementitious composition, optimisation and control of their workability are very important. For this purpose, one or more additives other than cementitious material, water and aggregate can be used to adjust properties of a cementitious composition. The additive(s) may be added immediately before or during mixing components of a cementitious composition. Examples of the additives include, but are not limited to, rheology modifiers, accelerators, retarders, air entrainers, corrosion inhibitors, shrinkage preventers, heat evolution reducers, pumping aids, and permeability reducing admixtures.

[0006] Rheology modifiers are typically used to alter a rheological property of a cementitious composition. Known rheology modifiers include superplasticizers, polycarboxylate water reducing agents, naphthalene sulfonate / formaldehyde condensate water reducing agents, melamine sulfonate / formaldehyde condensate water reducing agents, lignosulfonate water reducing agents, viscosity modifying agents (VMA), and mixtures thereof.

[0007] Whilst known additives are used to confer favourable properties on cementitious compositions, they typically increase the overall cost of a cementitious composition. Furthermore, many known additives increase the carbon footprint of a cementitious composition, whereas there continues to be an ongoing need to reduce the carbon footprint of cementitious compositions.

[0008] There is a need for new or improved additives that can be used to modify one or more properties of cementitious compositions, such as concrete or mortar. Alternatively, or in addition, there is a need for an alternative to known additives that can be used to modify one or more properties of cementitious compositions, such as concrete or mortar.SUMMARY

[0009] According to a first aspect, there is provided an additive composition for modifying rheology of a cementitious composition, the additive composition comprising activated kaolinite and from 0 wt% to about 5 wt% halloysite based on the total weight of kaolinite and halloysite.

[0010] In some embodiments, the additive composition comprises activated kaolinite and more than 0 wt% to about 5 wt% halloysite based on the weight of kaolinite and halloysite. In some further embodiments, the additive composition comprises kaolinite and from about 0. 1 wt% to about 5 wt% halloysite based on the weight of kaolinite and halloysite.

[0011] In some embodiments, the kaolinite has a particle size of from about 50 wt% to about 60 wt% < 2 microns equivalent spherical diameter or a particle size distribution with a d50 of about 2 microns.

[0012] In some embodiments, the kaolinite has a surface area of about 10 - 50m2 / g.

[0013] In some embodiments, the combination of surface activity, surface charge and surface area of the kaolinite provides product reactivity in high solids aqueous slurries where ions are present in solution.

[0014] In some embodiments, the halloysite comprises halloysite nanotubes having a length of about 2 microns to about 10 microns and a particle size distribution with a d50 of about 5 microns by equivalent spherical diameter.

[0015] According to a second aspect, there is provided use of the additive composition of the first aspect in a cementitious composition.

[0016] In some embodiments, in use, the yield stress of a cementitious composition is increased, and it demonstrates a thixotropic nature when the additive composition is used in the composition.

[0017] According to a third aspect, there is provided a cementitious composition containing the additive composition of the first aspect.

[0018] In some embodiments, the additive composition is present in an amount of from about 0.1wt% to about 5 wt% based on the weight of the cementitious composition.

[0019] In some embodiments, the cementitious composition comprises a cementitious material or binder which is selected from the group consisting of Portland cement, lime, GGBFS (ground granulated blast furnace slag and fly ash.

[0020] In some embodiments, the cementitious composition comprises an aggregate which is selected from the group consisting of gravel, natural sand, manufactured sand, coarse aggregate, and crushed rock.

[0021] In some embodiments, the cementitious composition is selected from the group consisting of concrete, render, grout, plaster, and mortar.

[0022] According to a fourth aspect, there is provided a method of regulating a rheological property of a cementitious composition, wherein the method comprises introducing an effective amount of the additive composition of the first aspect to the cementitious composition.

[0023] In some embodiments, the effective amount of the additive composition is about 0. 1 wt% to about 5 wt% based on the weight of the cementitious composition.

[0024] In some embodiments, the additive composition is introduced to a cementitious composition which is in dry state. In some other embodiments, the additive composition is introduced to a cementitious composition which is in wet state.

[0025] In some embodiments, the cementitious composition is selected from the group consisting of concrete and mortar.

[0026] In some embodiments, the yield stress of a cementitious composition is increased, and it demonstrates a thixotropic nature when the additive composition is used in the composition.BRIEF DESCRIPTION OF THE FIGURE

[0027] Embodiments of the present disclosure will be discussed with reference to the accompanying figure wherein:

[0028] Figure 1 is a plot of viscosity (mPa.s) vs time (seconds) for activated kaolinite containing from 0 wt% to about 5 wt% halloysite based on the total weight of kaolinite and non -activated kaolinite containing from 0 wt% to about 5 wt% halloysite based on the total weight of kaolinite.DESCRIPTION OF EMBODIMENTS

[0029] The present disclosure arises from the inventors’ finding that the use of activated kaolinite with up to about 5 wt% halloysite based on the total weight of kaolinite and halloysite may modify one or more rheological properties of a cementitious composition (for example concrete) to suit a desired situation. It was also surprisingly found that, compared to use of other kaolin materials, it is possible to achieve comparable rheological properties in a cementitious composition using a smaller amount of the additive composition disclosed herein. Without being bound by any theory, it is considered that some surface properties of the activated kaolinite may affect interactions between particles and are likely responsible for the modification of the rheological properties, which in turn may give rise to improved workability, pumpability and / or finishability of the cementitious composition in an application. These interactions are observed with neat kaolinite (i.e. 0 wt% halloysite) but they increase with increasing halloysite content due to the additional surface area and particle structure of the halloysite. Some advantageous technical effects achieved by these interactions include reduced bleeding, reduced segregation of aggregate, optimised spread and slump characteristics, slump retention, pumping / flow improvements and better workability. This in turn allows the cementitious compositions to incorporate more coarse aggregate which reduces water demand. The lower water demand allows the binder (cement or other) to be reduced proportionally without detriment to application end properties.

[0030] The term “rheology” used herein refers to the science of the flow and deformation of materials and is concerned with the relationship between shear stress, shear strains and time.

[0031] The term “rheology modifier” used herein refers to an agent that is capable of regulating one or more rheological properties of a cementitious composition. The rheological properties may include, but not limited to, yield stress, viscosity, storage modulus and thixotropy. In practice, yield stress is increased and the cementitious composition demonstrates thixotropy with the agent causing the composition to gain a structure that can be broken down by shear and reformed.

[0032] The term “cementitious material” used herein refers to a material (with or without an aggregate) that provides plasticity, cohesive, and adhesive properties when it is mixed with water. It is also known as cementitious binder.

[0033] The term “aggregate” used herein refers to an aggregation of non-metallic minerals obtained in particulate form. It is the material that the cementitious material coats and binds together. It decreases the consumption of a cementitious material and water and contributes to the mechanical strength of a cementitious composition.

[0034] The term “cementitious composition” used herein refers to a composition that comprises a cementitious material as an essential component. The cementitious composition includes concrete, mortar, grout, sealer, stucco, etc. The cementitious composition disclosed herein may be in wet state, in dry state, intermediate state or cured state.

[0035] The term “activated kaolinite” used herein refers to kaolinite that has one or more desirable surface properties. Kaolinite may be activated by a natural activation process carried out in-situ by the geological environment. Alternatively, or in addition, kaolinite may be activated by washing. The tests described herein can be used to determine whether or not a kaolinite is activated.

[0036] Disclosed herein is an additive composition comprising activated kaolinite and up to about 5wt% halloysite based on the weight of kaolinite and halloysite. The amount of halloysite may be selected to be more than 0 wt% to about 5 wt%, about 0.1 wt% to about 5 wt%, for example to about 4 wt%, to about 3 wt%, to about 2 wt%, or to about 1 wt%, based on the weight of kaolinite and halloysite. In some embodiments, the halloysite is present in the additive composition in an amount of about 0.1 wt% to less than about 5 wt%, for example, to less than about 4 wt%, to less than about 3 wt%, to less than about 2 wt%, or to less than about 1 wt%.

[0037] The additive composition may consist of activated kaolinite and more than 0 wt% to about 5 wt% halloysite based on the weight of kaolinite and halloysite. The amount of halloysite may be selected to be about 0.1 wt% to about 5 wt%, for example to about 4 wt%, to about 3 wt%, to about 2 wt%, to about 1 wt%, based on the weight of kaolinite and halloysite. In some embodiments, the halloysite is present in the additive composition in an amount of about 0. 1 wt% to less than about 5 wt%, for example, to less than about 4 wt%, to less than about 3 wt%, to less than about 2 wt%, or to less than about 1 wt%.

[0038] The additive composition may be supplied as a powder product and then introduced to a cementitious composition when needed.

[0039] Kaolinite is an aluminosilicate clay mineral with the empirical formula A12Si2Os(OH)4 and typically occurs in platy morphology. The kaolinite used herein can be obtained from any suitable source.

[0040] For the purpose of the present disclosure, the kaolinite has a particle size of about 1 to about 10 microns, such as about 2 microns by equivalent spherical diameter or a particle size distribution. The kaolinite has a surface area of about 10 - 40m2 / g, such as about 20m2 / g. In some circumstances, the kaolinite used herein has high surface activity quantified using rheological testing in slurry form which may contribute to improving the rheological properties of a cementitious composition.

[0041] Halloysite is also an aluminosilicate clay mineral. It has a similar composition to kaolinite except that the unit layers in halloysite are separated by a monolayer of water molecules. Halloysite may display tubular, spheroidal or platy morphologies, but most commonly has a tubular morphology. For the purpose of the present disclosure, the halloysite used herein substantially has a tubular morphology, for example at least about 50% of the halloysite has a tubular morphology. In some embodiments, close to 100% of the halloysite has a tubular morphology but there will generally be some tubes that are broken so that the total is not 100%. The halloysite used herein can be obtained from any suitable source and many commercial sources or kaolinite are available.

[0042] For the present disclosure, the halloysite comprises halloysite nanotubes having a length of about 2 microns to about 10 microns. The halloysite has a particle size of from about 2 to about 10 microns, such as about 5 microns equivalent spherical diameter or a particle size distribution (d50) of about 5 microns. The halloysite has a surface area of from about 10 to about 50m2 / g, such as about 20m2 / g.

[0043] The above properties of kaolinite and halloysite used herein can be determined through known methods. For example, particle size can be determined by sedimentation and surface area can be measured by nitrogen absorption.

[0044] The additive composition disclosed herein may be used as a rheology modifier. In particular, the additive composition is used to regulate a rheological (flow) property of a cementitious composition. The rheological properties such as yield stress and plastic viscosity may affect not only proper placement, consolidation, and finishing but also the hardened state properties such as strength and durability. For the present disclosure, a Marsh Cone test was used to determine the fluidity and viscosity as it is a standard test used in the cement industry to determine the optimum dosage of rheology modifiers such as plasticisers.

[0045] It has been surprisingly found that, by use of the additive composition disclosed herein, rheological properties such as yield stress and plastic viscosity of a cementitious composition (for example concrete) can be improved sufficiently to allow incorporation of significantly higher levels of coarse aggregate without experiencing segregation and bleeding issues typically associated with the use of higher levels of coarse aggregate.

[0046] In order to regulate its rheological properties, a cementitious composition may only require as low as about 0.1 wt% of the additive composition disclosed herein. This amount is significantly lower compared to the situation wherein kaolin is used in a cementitious composition as an extender. When control kaolin is used as an extender in cementitious compositions it can aid surface finish but does not offer any significant rheological benefits. Although it may be possible to use more than about 0. 1 wt% of the additive composition, a lower amount is recommended from a cost perspective.

[0047] The additive composition disclosed herein may be available as a powder additive or as a dried lump.

[0048] The additive composition disclosed herein can be introduced into a dry cementitious composition or a cementitious composition mixed with water. It can also be suspended in water as a stabilised slurry and then pumped to a cementitious composition (for example concrete). In some embodiments, additive composition disclosed herein is pre-dispersed in the cementitious material or binder (cement or other) at an appropriate addition level. Alternatively, the additive composition disclosed herein can be added to cementitious compositions during the mixing / batching process. It must be noted that a cementitious mixture becomes saturated with additives at a certain ratio, meaning that adding more amounts of additives will not further enhance the properties of a cementitious composition.

[0049] A cementitious composition disclosed herein may include various products, such as concrete, mortar, grout, sealer and stucco. Concrete is a very strong structural building material and typically comprises a cementitious material and aggregates (such as sand and gravel) in dry state. It can be used to form structural slabs, poured foundations, and other permanent structures. Concrete may further contain fibres and / or additives to enhance its performances and render it more suited to a specific application. When concrete is freshly mixed with water and the mixture obtained thereby sets, a hydration reaction between the cementitious material and water causes the mixture to harden and gain strength. Mortar normally comprises a cementitious binder, fine aggregates such as sand, and lime in dry state. It is used as a binding material to hold bricks, blocks, and stones etc. together. Grout is similar to mortar in that it acts like glue, holding ceramic tiling in place. It can be seen as a form of mortar but formulated without the lime additive. While grout in a wet state still contains the same ingredients of a cementitious material, water and find aggregates (such as sand), grout is more fluid than mortar and concrete, which makes it ideal in certain civil engineering applications.

[0050] The key components of a cementitious composition in dry state includes a cementitious material and aggregates. A cementitious material, also known as a cementitious binder, allows a cementitious composition to form a plastic paste when the cementitious composition is mixed with a liquid, such as water. Aggregates act as inert material in a cementitious composition. Selection of these components and their contents plays an important role in making a cementitious composition tailored specifically for the purpose it is intended for.

[0051] The cementitious material (or binder) that can be used includes, but is not limited to, hydraulic cements and supplementary cementitious materials (SCMs). Hydraulic cements set and harden by reacting chemically with water. During the reaction, which is called hydration, heat is given off as the water-cement paste hardens and binds the aggregate particles together. Portland cement is the most common hydraulic cement and typically consists of over 90% Portland cement clinker, up to 5% gypsum and up to 5% other minor constituents. Portland cement clinker is a hydraulic material consisting mainly of dicalcium silicate (2CaO.SiC>2), tricalcium silicate (SCaO.SiCE), tricalcium aluminate (SCaO.AhCh) and tetra-calcium aluminoferrite (4CaO.AhO3Fe2O3). It is possible to use more than one cementitious material in a cementitious composition. In some circumstances, a supplementary cementitious material may be used in conjunction with a hydraulic cement to improve the workability of fresh concrete and reduce thermal cracking in massive structures by reducing the heat of hydration. Generally, the supplementary cementitious materials are ground granulated blast furnace slag (GGBFS; waste from steel manufacture), fly ash (waste from coal combustion), lime, silica fume and metakaolin. In some embodiments, the cementitious material is a hydratable cementitious material. Although a higher proportion of the cementitious material usually means greater strength, the amount of the cementitious material used can be to be chosen by the person skilled in the art according to a specific application.

[0052] Aggregates come in various shapes, sizes, and materials. Common mineral aggregates are gravel, natural sand, manufactured sand, coarse aggregate, and crushed rock. Recycled plastic aggregates have been proposed as a substitute for natural stone aggregates. Aggregates can be classified according to their particle size. Coarse aggregate normally has a size greater than 5 mm. Examples of coarse aggregates are brick chips (broken bricks), stone chips (broken stones), gravels and pebbles. Fine aggregate is normally an aggregate less than 5 mm in size and examples thereof are silica fume, burnt clays and stone screenings. The selection of an aggregate is determined, in part, by the desired characteristics of the cementitious composition. For example, the density of a concrete is influenced by the density of the aggregate. Soft, porous aggregates can result in weak concrete with low wear resistance, while using hard aggregates can make strong concrete with a high resistance to abrasion. The amount of aggregates may vary depending on the type of a cementitious composition and can be readily determined by the person skilled in the art. For instance, aggregates might account for about 60 to 80% of the total volume of concrete. Aggregates are usually washed to remove any dust, silt, clay, organic matter, or other impurities that would interfere with the bonding reaction with the cementitious material.

[0053] Optionally, the cementitious composition further comprises an additive or an additive composition other than the additive composition disclosed herein. It will be appreciated that an additive must be compatible with other components of a cementitious composition. Additives such as water reducers, retarders, and / or superplasticizers may be added in order to reduce the water content in a mixture or to slow the setting rate of a cementitious composition while retaining the flowing properties of the cementitious composition. Acidic agents such as citric acid may be used to maintain workability.Defoamers are able to reduce or prevent the formation of foam or the entrainment of gas within a cementitious composition to be applied. Inclusion of guar ether, starch ether, cellulose ether may improve viscosity. A superplasticiser may be used to optimise workability of a cementitious composition. Air entraining agents include detergents in an amount sufficient to improve durability, and can be used to improve workability, to reduce bleeding, or to reduce freezing / thawing problems. Retarders include sugar, sucrose, sodium gluconate, glucose, citric acid or tartaric acid and can be used to delay setting time, to add long term strength, or to offset adverse high temperature weather.

[0054] A cementitious composition in dry state is to be mixed with a liquid such as water in order to form a paste that binds the aggregates together. Taking concrete as an example, an amount of water is added to concrete such that it is workable so that it may be consolidated and shaped into desired forms. Too much water reduces concrete strength, while too little will make the concrete unworkable. The amount of water is defined as a W / C ratio, in which W is the mass of the water, and C is the mass of the one or more cementitious binder. In some embodiments, the W / C ratio ranges from 0.20 to 0.70. In some embodiments, the W / C ratio ranges from 0.35 to 0.60 or from 0.40 to 0.50. In some embodiments, the W / C ratio ranges from 0.35 to 0.45 or from 0.20 to 0.30.

[0055] The cementitious composition disclosed herein can be prepared by a suitable method known in the art, for example by mixing the components. It is recommended that the additive composition disclosed herein is added to the cementitious composition as early in the process as possible to allow better dispersion and homogeneity.

[0056] The cementitious composition disclosed herein can be applied using any suitable process, such as casting, spraying and 3D printing.

[0057] The additive composition disclosed herein is significantly lower in cost than other known additives that are used to modify rheology and allows mix design cost savings unlike the other known additives that increase overall cost. The additive composition disclosed herein also offers carbon footprint reductions in end products unlike the chemical rheology modifiers that increase the carbon footprint.EXAMPLE

[0058] Example - Concrete composition formed using Great White HRM™ (kaolinite / halloysite)

[0059] Activated kaolinite (100 -75 wt%) containing halloysite in amounts of 0-5 wt% was obtained from Andromeda Metals Limited. The kaolinite had been activated by a natural activation process carried out in-situ and / or by washing. The composition is termed Great White HRM™ herein.3

[0060] Great White HRM™ was added to concrete formed according to Table 1 at the rate of Ikg / m .

[0061] Table 1 - 32Mpa concrete mix design, excluding admixtures

[0062] To form the concrete composition, water, the dry components and Great White HRM™ were added to a high shear blender or mixer. An objective during mixing was to disperse Great White HRM™ particles with the dry components. This is a physical reaction as Great White HRM™ is not soluble and must have sufficient shear to intermingle and activate. The components were then mixed in the high shear blender or mixer set on high shear for a minimum of 5 minutes to provide the concrete composition.

[0063] The viscosity of Great White HRM™ and non-activated kaolinite containing from 0 wt% to about 5 wt% halloysite based on the total weight of kaolinite was measured and the results are shown in Figure 1 which compares the thixotropy of activated kaolinite (i.e. Great White HRM™) samples and non-activated kaolinite samples. The Great White HRM™ samples showed an increased rate of structural recovery and an improved ratio between the viscosity during low shear and the high shear trough relative to the non-activated kaolinite.

[0064] It will be understood that the terms “comprise” and “include” and any of their derivatives (e.g. comprises, comprising, includes, including) as used in this specification is to be taken to be inclusive of features to which the term refers, and is not meant to exclude the presence of any additional features unless otherwise stated or implied.

[0065] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement of any form of suggestion that such prior art forms part of the common general knowledge.

[0066] It will be appreciated by those skilled in the art that the disclosure is not restricted in its use to the particular application or applications described. Neither is the present disclosure restricted in its preferred embodiment with regard to the particular elements and / or features described or depicted herein. It will be appreciated that the disclosure is not limited to the embodiment or embodiments disclosed, butis capable of numerous rearrangements, modifications and substitutions without departing from the scope as set forth and defined by the following claims.

Claims

CLAIMS1. An additive composition for modifying rheology of a cementitious composition, the additive composition comprising activated kaolinite and from 0 wt% to about 5 wt% halloysite based on the total weight of kaolinite and halloysite.

2. The additive composition of claim 1, wherein the additive composition comprises activated kaolinite and more than 0 wt% to about 5 wt% halloysite based on the weight of kaolinite and halloysite.

3. The additive composition of any one of claims 1 to 2, wherein the additive composition comprises activated kaolinite and from about 0. 1 wt% to about 5 wt% halloysite based on the weight of kaolinite and halloysite.

4. The additive composition of any one of claims 1 to 3, wherein the additive composition consists of activated kaolinite and more than 0 wt% to about 5 wt% halloysite based on the weight of kaolinite and halloysite.

5. The additive composition of any one of claims 1 to 4, wherein the additive composition consists of activated kaolinite and about 0.1 wt% to about 5 wt% halloysite based on the weight of kaolinite and halloysite.

6. The additive composition of any one of claims 1 to 5, wherein the kaolinite has a particle size of from about 50 wt% to about 60 wt% < 2 microns equivalent spherical diameter or a particle size distribution with a d50 of about 2 microns.

7. The additive composition of any one of claims 1 to 6, wherein the kaolinite has a surface area of about 10 - 50m2 / g.

8. The additive composition of any one of claims 1 to 7, the halloysite is tubular in form.

9. The additive composition of claim 8, wherein the halloysite comprises halloysite nanotubes having a length of about 2 microns to about 10 microns.

10. The additive composition of any one of claims 1 to 9, wherein the halloysite has a particle size distribution with a d50 of about 5 microns by equivalent spherical diameter.

11. The additive composition of any one of claims 1 to 10, wherein the additive composition is a rheology modifier.

12. Use of the additive composition of any one of claims 1 to 11 in a cementitious composition.

13. The use of claim 12, wherein the additive composition is used as a rheology modifier.

14. A cementitious composition comprising the additive composition of any one of claims 1 to 11.

15. The cementitious composition of claim 14, wherein the additive composition is present in an amount of from about 0.1 wt% to about 5 wt% based on the weight of the cementitious composition.

16. The cementitious composition of any one of claims 14 to 15, wherein the cementitious composition further comprises a cementitious material which is selected from the group consisting of Portland cement, lime, GGBFS (ground granulated blast furnace slag), and fly ash.

17. The cementitious composition of any one of claims 14 to 16, wherein the cementitious composition further comprises an aggregate which is selected from the group consisting of gravel, natural sand, manufactured sand, coarse aggregate, and crushed rock.

18. The cementitious composition of any one of claims 14 to 17, wherein the cementitious composition is selected from the group consisting of concrete and mortar.

19. A method of regulating a rheological property of a cementitious composition, the method comprising introducing an effective amount of the additive composition of any one of claims 1 to 11 to the cementitious composition.

20. The method of claim 19, wherein the effective amount of the additive composition is from about 0. 1 wt% to about 5 wt% based on the weight of the cementitious composition.

21. The method of any one of claims 19 to 20, wherein the cementitious composition is selected from the group consisting of concrete and mortar.

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