Cementitious material additive

Abstract

A cementitious material containing an additive composition comprising from about 5% to about 100% by weight halloysite and from about 95% to about 0% by weight kaolinite is disclosed. Also disclosed is a method of controlling the rheology of a cementitious material and a method of controlling the early strength of a cementitious material.

Description

CEMENTITIOUS MATERIAL ADDITIVEPRIORITY DOCUMENT

[0001] The present application claims priority from Australian Provisional Patent Application No. 2022900116 titled “CEMENTITIOUS MATERIAL ADDITIVE” and filed on 21 January 2022, the content of which is hereby incorporated by reference in its entirety.TECHNICAL FIELD

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

[0003] Cementitious materials such as concrete, mortar and grout are used extensively as building materials and engineering structures. In this regard, cementitious materials include one or more cement binder, one or more aggregate, optionally one or more additive, optionally one or more reinforcement and water. Upon addition of water the cement binders are activated and form a paste that binds the aggregate together. When the aggregate has a fine particle size, then the product is a mortar. When the aggregate contains fine particle size material and coarse-grained stone material, then the product is a concrete.

[0004] Additives are components of cementitious materials other than cement, water and aggregate, which are added to the mixture immediately before or during mixing. Generally, additives chemically interact with the other components of the cementitious material and modify one or more property or characteristics of the fresh or hardened cementitious material.

[0005] Newly mixed (i.e. fresh) concrete is a heterogeneous multiphase material the rheological properties of which can impact significantly on the workability of the fresh concrete. Important rheological properties include yield stress and plastic viscosity. The workability of fresh concrete is conventionally quantified in terms of “slump” which is a measurement of concrete rheology. Rheology modifiers are typically used to modify one or more rheological property of a concrete mixture. Known rheology modifiers include water, polycarboxylate water reducing agents, naphthalene sulfonate / formaldehyde condensate water reducing agents, melamine sulfonate / formaldehyde condensate water reducing agents, lignosulfonate water reducing agents, cellulose derivatives, or mixtures thereof.

[0006] For many applications, such as pavement repairs, concrete and mortar having high early strength is required. Agents that enhance the early strength of concrete or mortar can be added to concreteor mortar to achieve a desired strength earlier than would otherwise be possible. Known agents that can be used to achieve high early strength include pozzolanic fly ash, granulated blast furnace slag, silica fumes, metakaolin, rice husk ash, and super-plasticisers or hyper-plasticisers such as poly carboxylic ethers.

[0007] There is a need for new or improved additives that can be used to modify one or more property 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 property of cementitious compositions, such as concrete or mortar.SUMMARY

[0008] According to a first aspect, there is provided a cementitious material containing an additive composition comprising from about 5% to about 100% by weight halloysite and from about 95% to about 0% by weight kaolinite.

[0009] In some embodiments, the additive composition modifies the rheology of the cementitious material.

[0010] In some embodiments, the additive composition enhances early strength of a concrete or mortar product formed using the cementitious material.

[0011] According to a second aspect, there is provided a concrete composition comprising a hydratable cementitious binder material, fine aggregate, coarse aggregate, water and the additive composition of the first aspect.

[0012] In some embodiments of the second aspect, the additive composition is present in an amount of from about 0.01 wt% to about 1 wt%.

[0013] In some embodiments of the second aspect, the concrete composition comprises from about 10 wt% to about 15 wt% hydratable cementitious binder material, from about 60 wt% to about 75 wt% coarse aggregate and from about 15 wt% to about 20 wt% water.

[0014] According to a third aspect, there is provided a mortar composition comprising a hydratable cementitious binder material, fine aggregate, water and the additive composition of the first aspect.

[0015] In some embodiments of the third aspect, the additive composition is present in an amount of from about 1 wt% to about 10 wt%.

[0016] According to a fourth aspect, there is provided a concrete or mortar rheology modifying composition comprising from about 5% to about 100% by weight halloysite and from about 95% to about 0% by weight kaolinite.

[0017] According to a fifth aspect, there is provided a concrete or mortar early strength enhancing composition comprising from about 5% to about 100% by weight halloysite and from about 95% to about 0% by weight kaolinite.

[0018] According to a sixth aspect, there is provided a method of controlling the rheology of a cementitious material, the method comprising adding an effective amount of the concrete or mortar rheology modifying composition of the fourth aspect to the cementitious material.

[0019] According to a seventh aspect, there is provided a method of controlling the early strength of a cementitious material, the method comprising adding an effective amount of the concrete or mortar early strength enhancing composition of the fifth aspect to the cementitious material.BRIEF DESCRIPTION OF FIGURES

[0020] Embodiments of the present disclosure will be discussed with reference to the accompanying figures wherein:

[0021] Figure 1 is a plot of load (thin line, left axis) and energy (bold line, right axis) vs displacement for a 50MPa Mining Shot-Crete formed according to embodiments of the present disclosure. The flexural toughness of HRM#110 was tested in accordance with ASTM C-1550;

[0022] Figure 2 is a plot of Compressive Strength (MPa) vs age for two 40MPa Self-Compacting Concrete (SCC) 650mm spread samples and three samples of 40MPa Self-Compacting Concrete (SCC) 650mm spread formed according to embodiments of the present disclosure; and

[0023] Figure 3 is a plot of Bleed Reduction (mF) vs Halloysite-Kaolin (Kaolinite) amount for a control 40MPa Self-Compacting Concrete (SCC) 650mm spread and three samples of 40MPa SelfCompacting Concrete (SCC) 650mm spread formed according to embodiments of the present disclosure;

[0024] Figure 4 is a plot of MPA vs age for a control 40MPa Self-Compacting Concrete (SCC) 80mm slump and three samples of 40MPa Self-Compacting Concrete (SCC) 80mm slump formed according to embodiments of the present disclosure; and

[0025] Figure 5 is a plot of shear strain (%) vs shear stress (Pa) for performed on a 20 wt% solids slurry of the additive composition according to embodiments of the present disclosure to demonstrate the rheological effect.DESCRIPTION OF EMBODIMENTS

[0026] Disclosed herein is a cementitious material containing an additive composition. The additive composition comprises from about 5% to about 100% by weight halloysite and from about 95% to about 0% by weight kaolinite.

[0027] The halloysite and / or the kaolinite may be unrefined or refined. The halloysite and / or the kaolinite may be refined by a wet or dry process. For example, refining and purification of the halloysite component can be achieved by selectively engineering the particle size distribution of the halloysite - kaolinite hybrid using a wet process.

[0028] Canadian patent application No. 3042894 discloses a highly specialised liquid grout product that is used for wellbore sealing applications. The product includes a range of ‘fibres’ which are surface treated and functionalised with polymers to give synthetic ‘nanocomposites’. Halloysite nanotubes functionalised with a polysaccharide are suggested as one possible type of fibre amongst a list of other possible additives. The additives are used to give stability under thermal cycling and there is no discussion of improving rheology. Indeed, the functionalised nanocomposites disclosed actually cause rheology problems, namely very high viscosity.

[0029] The cementitious material may be a mortar composition or a concrete composition.

[0030] The mortar composition can be any composition comprising cement, fine aggregate (e.g. sand), water, the additive composition and, optionally, one or more further additive. Mortar compositions are sometimes alternatively referred to as grout compositions. As used herein, the term “mortar” refers to a cement or cementitious mixture with fine gravel such as sand and the terms “mortar” and “grout” may be used interchangeably throughout this specification.

[0031] The concrete composition can be any concrete composition containing cement, fine aggregate (e.g. sand), coarse aggregate (e.g. stone material), water, the additive composition and, optionally, one or more further additive. As used herein the term “concrete” means mortar that also contains coarse stone material like crushed stone or pebbles.

[0032] The cement used in the concrete or mortar composition will typically comprise a hydratable cementitious binder material, such as Portland cement and / or cement substitute, which, when mixed with water, serves as a binder to hold a mixture together to form building materials and engineering structures.Cementitious materials that are considered “hydratable” or hydraulic are those that harden by chemical reaction with water. Suitable cementitious materials include, but are not limited to Portland cement, siliceous fly ash, calcareous fly ash, blast furnace slag, quartz dust, limestone, oil shale, natural pozzolan, and natural calcined pozzolan, any of which have hydrating properties or can be combined with Portland cement to form additive hydraulic cements.

[0033] In some embodiments, the cement is present in the composition in an amount ranging from 0.5% to 75% by dry weight of the composition.

[0034] The concrete or mortar composition comprises water. Water, when mixed with the cement, forms a paste that binds the aggregate together. An amount of water is added to the 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 mortar or 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 cement 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.

[0035] The concrete or mortar composition also comprises one or more aggregate. Aggregates are mostly chemically inert, solid bodies held together by the cement or hardened cement paste or hardened mortar. Aggregates come in various shapes, sizes, and materials ranging from fine particles, such as sand, to large particles, such as coarse rocks. The selection of an aggregate is determined, in part, by the desired characteristics of the cement mix. For example, the density of 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 aggregates are usually washed to remove any dust, silt, clay, organic matter, or other impurities that would interfere with the bonding reaction with the cement paste.

[0036] The aggregates may be fine or coarse aggregates. In some embodiments, the one or more aggregate is chosen from gravel, crushed rock, and sand. In some embodiments, the crushed rock is chosen from limestone and granite. In some embodiments, the one or more aggregate is chosen from vermiculite, ceramic spheres, perlite, expanded clay, shale, slate, crushed brick, crushed limestone, sand, river gravel, crushed recycled concrete, steel shot, iron shot, steel pellets, and iron pellets.

[0037] The amount of cement, stone material, water and additives can be readily determined by the person skilled in the art based on existing knowledge of concrete compositions and properties. For example, the concrete composition may comprise from about 10 wt% to about 15 wt% cement, fromabout 60 wt% to about 75 wt% stone material and from about 15 wt% to about 20 wt% water. The amount of additive in the composition will depend on the type of additive and the desired properties.

[0038] In some embodiments, the concrete composition is suitable for applications such as selfconsolidating concrete, precast concrete, shotcrete, slip-form pavements, deep foundations (antiwashout), lightweight concretes, dry cast block, pipe, hollowcore, Putze, plasters, swimming pool shell and pilings. In some embodiments, the composition has a form suitable for applications in need or desire of high-strength concrete, stamped concrete, high-performance concrete, ultra-high-performance concrete, self-consolidating concretes, rollcrete, class concrete, cork-cement composites, cellular concrete, asphalt concrete, rubberized concrete, and polymer concrete.

[0039] In some embodiments, the additive composition is used to modify the rheology of the concrete or mortar composition. The term “rheology” describes the flow dynamics of liquids and the deformation of solids. Rheological properties of heterogeneous dispersions such as mortar and concrete are complex and cannot be expressed in a single parameter. Rheological properties of fresh cementitious materials that can be monitored and controlled include slump and yield stress. Prior art rheology modifiers that are known to modify rheological properties of fresh cementitious materials include water, chemical contaminants (eg, polycarboxylate water reducing agents, naphthalene sulfonate / formaldehyde condensate water reducing agents, melamine sulfonate / formaldehyde condensate water reducing agents, lignosulfonate water reducing agents, etc) or hydrocolloid viscosity modifying contaminants such as cellulose derivatives, or mixtures thereof. The present inventors have surprisingly found that the addition of from about 0.01 wt% to about 1 wt% of the additive composition comprising from about 5% to about 100% by weight halloysite and from about 95% to about 0% by weight kaolinite to a concrete composition provides one or more rheology benefit including reduced bleeding, reduced segregation of aggregate, optimised spread and slump characteristics, slump retention and pumping / flow improvements. Furthermore, addition of from about 1 wt% to about 10 wt% of the additive composition comprising from about 5% to about 100% by weight halloysite and from about 95% to about 0% by weight kaolinite to a concrete composition provides one or more rheology benefit including improved pumping and flow characteristics brought about by a reduction in the segregation of components under shear. The latter characteristics are particularly suitable when the mortar is used as an underground backfill grout mix.

[0040] Advantageously, the additive composition can be used to produce green cement or concrete because the additive composition can be used to supplement some of the Portland cement in a concrete composition.

[0041] In some embodiments, the additive composition is used to enhance early strength of a concrete or mortar product formed using the concrete or mortar composition.

[0042] In addition to the additive composition described herein, the concrete or mortar composition can also contain an effective amount of one or more further additive as required. The one or more further additive that could be used includes, but is not limited to, plasticisers, viscosity modifiers, corrosion inhibitors, shrinkage reducing agents, solidification accelerators, solidification retarders, air scavengers, air entraining agents, de-airing agents, pigments, colorants, mineral admixtures, corrosion inhibitors, and fibres for plastic shrinkage inhibition or structural reinforcement, etc. As used herein, the term “effective amount” of an additive means a quantity per cubic metre of hardened mortar or concrete to impart an improvement or modification of one or more property of the wet or cured mortar or concrete composition.

[0043] Suitable air entraining agents, if used, include detergents in an amount sufficient to improve durability, to improve workability, to reduce bleeding, or to reduce freezing / thawing problems.

[0044] Suitable plasticisers, if used, include lignosulfonate, sulfonated naphthalene formaldehyde condensate, sulfonated melamine formaldehyde condensate, acetone formaldehyde condensate or polycarboxylate ethers in an amount sufficient to decrease water needed for workable concrete.

[0045] Suitable retarding agents, if used, include sugar, sucrose, sodium gluconate, glucose, citric acid or tartaric acid in an amount sufficient to delay setting time, to add long term strength, or to offset adverse high temperature weather.

[0046] Suitable accelerating agents, if used, include calcium chloride, calcium dinitrate or sodium nitrate in an amount sufficient to speed up the setting time, to achieve an early strength, or to offset adverse low temperature weather.

[0047] Suitable mineral admixtures, if used, include fly ash or silica fume in an amount sufficient to improve workability, plasticity, or strength.

[0048] Suitable pigments, if used, include metal oxides in an amount sufficient to impart colour.

[0049] The cementitious material can be prepared by any suitable method such as by mixing the ingredients.

[0050] The concrete or mortar composition may also contain one or more reinforcement material such as steel reinforcing bars, steel fibres, glass fibres, and plastic fibres.

[0051] The concrete or mortar composition may be a dry composition, a wet composition, an intermediate composition or a cured composition.EXAMPLES

[0052] Example 1 - Trial #2, 50MPa Mining Shot-Crete

[0053] Control 50MPa mining shot-crete and 50MPa mining shot-crete compositions formed according to an embodiment of the present disclosure were formed using the following components and standard procedures. This composition was chosen because it is a typical 220mm - 240mm slump Shot-Crete or Fibrecrete composition.

[0055] The HRM rheology modifier (HRM) comprised approximately 30% halloysite and 70% fine kaolinite.

[0056] The HRM composition performed very well relative to the control which was a standard mining shot-crete design with no rheology modifier. The properties displayed would be very desirable in this application. These compositions start to segregate at high slump, but HRM was able to control this segregation and minimise the visible bleed water. HRM could be dosed at a minimum of 1kg per m3and if treated costs allow, dosed at 2kg per m3.

[0057] The data obtained was as follows:

[0058] The flexural toughness of HRM#110 was tested in accordance with ASTM C-1550 and the results are shown in Figure 1.

[0059] Example 2 - Trial #7, 40MPa Self-Compacting Concrete (SCC) 650mm spread

[0060] Control 40MPa SCC 650mm spread (self-compacting concrete, self-consolidating concrete or super-workable concrete) and three 40MPa SCC 650mm spread compositions formed according to an embodiment of the present disclosure were formed using the following components and standard procedures.

[0061]

[0062] The HRM rheology modifier (HRM) comprised approximately 30% halloysite and 70% fine kaolinite.

[0063] The results showed a very clear increase in strength or performance with increased HRM levels. There was also an increase in compressive strengths at every age. See Figure 2. This increase was not noticeable in lower slump designs, but with the addition of HRWR and a design where the microstructure had been opened up, the HRM seemed to provide more benefits, possibly assisting in separating or dispersing cement particles at the micro level to allow improved hydration. The HRM products performed very well relative to the no rheology modifier control. The control was also duplicated with a slightly different w / c ratio to confirm (see Control # 2, Figure 2). There was an increase in visible paste and the slump did not revert like other rheology modifiers on the market. The measured results below show outstanding performance and that HRM is very fit for purpose. HRM has potential to add value to this application, the properties noted would pump well and allow for higher coarse aggregate contents vs typical SCC designs. HMR may improve workability, pumpability and finishability in these applications.

[0064] The data obtained was as follows:

[0065] Example 3 - Trial #6, 40MPa Self-Compacting Concrete (SCC) 80mm slump

[0066] Control 40MPa SCC 80mm slump (self-compacting concrete, self-consolidating concrete or super-workable concrete) and three 40MPa SCC 80mm slump compositions formed according to an embodiment of the present disclosure were formed using the following components and standard procedures.

[0067]

[0068] The HRM rheology modifier (HRM) comprised approximately 30% halloysite and 70% fine kaolinite.

[0069] The results showed an increase in strength gain or improved performance with increased HRM levels, but only very minimal (see Figure 4). HRM at 1kg, 2kg and 4kg is not detrimental to this grade of concrete. HRM performed very well vs the no rheology modifier (RM) control. There was an increase in visible paste and the slump did not revert like other rheology modifiers on the market. The measured results below indicate that the plastic properties were very desirable and fit for purpose. HRM has potential to add value to this application, the properties noted would pump well and allow for higher coarse aggregate contents. HMR may improve workability, pumpability and finishability in these applications.

[0070] The data obtained was as follows:

[0071] Example 4 - Trial #5, Continuous flight auger (CFA) pilings

[0072] Control concrete for CFA pilings and a CFA piling concrete composition formed according to an embodiment of the present disclosure were formed using the following components and standard procedures.

[0073]

[0074] The HRM rheology modifier (HRM) comprised approximately 30% halloysite and 70% fine kaolinite.

[0075] HRM performed very well relative to a natural mineral rheology modifier in the control. The measured results below are quite different, but the plastic properties in the HRM design were also very desirable and fit for purpose. HRM has potential to add value to this application for multiple reasons, including:1. Workability / softness was the same as the expensive imported RM in the control.2. Bleed under pressure was the same as the control.3. Workability reduction over time was clearly superior vs the control that reduced in spread / slump very fast.

[0076] The compressive strengths are slightly behind the control, but still exceptionally high. HRM could be used as a direct replacement, or is added at 1kg to 3kg per m3, the higher dose rate will return improved plastic performance. The HRM added “body or fat” to the paste as well as softness and workability without reducing the slump too much. These properties allow for an increase in coarse aggregate without compromising workability, which reduces sands and water demand.

[0077] The data obtained was as follows:

[0078] Example 5 - Trial #4, Tremie pilings

[0079] Control concrete for tremie pilings and a tremie piling concrete composition formed according to an embodiment of the present disclosure were formed using the following components and standard procedures.

[0080]

[0081] The HRM rheology modifier (HRM) comprised approximately 30% halloysite and 70% fine kaolinite.

[0082] HRM performed very well vs a neutral or no rheology modifier control. The measured results below are similar, but the plastic properties again were very desirable and fit for purpose. Also the 24 hour compressive strengths exceeded the control by 4MPa and maintained +2MPa at all data points. Shrinkage at 28 days is far superior (-60um). HRM has potential to add value to this application. HRM could be used as a direct replacement, or added at 1kg to 3kg per m3, higher dose rates if the treated costs allow will return improved results. The HRM added “body or fat” to the paste also softness and workability without reducing the slump too much. These properties allow for an increase in coarse aggregate without compromising workability, which will reduce sands and water demand.

[0083] The data obtained was as follows:

[0084] Example 6 - Trial #3, 25MPa pool spray

[0085] Control spray mix and a spray mix concrete composition formed according to an embodiment of the present disclosure were formed using the following components and standard procedures.

[0086]

[0087] The HRM rheology modifier (HRM) comprised approximately 30% halloysite and 70% fine kaolinite.

[0088] HRM performed very well relative to a natural mineral rheology. Properties displayed are desirable in domestic and civil applications. This design and RM was chosen because it is a typical 70mm slump "Spray mix" combination incorporating 25% fly ash. The measured results below are similar, but the plastic properties were also very desirable and fit for purpose. HRM could be used as a direct replacement, 1 for 1 with currently used rheology modifiers, but higher dose rates if the treated costs allow, will also return improved results.

[0089] The data obtained was as follows:

[0090] 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.

[0091] 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.

[0092] 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 itspreferred 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, but is capable of numerous rearrangements, modifications and substitutions without departing from the scope as set forth and defined by the following claims.

Claims

CLAIMS1. A cementitious material containing an additive composition comprising from about 5% to about 100% by weight halloysite and from about 95% to about 0% by weight kaolinite.

2. The cementitious material of claim 1, wherein the additive composition modifies the rheology of the cementitious material.

3. The cementitious material of either claim 1 or claim 2, wherein the additive composition enhances early strength of a concrete or mortar product formed using the cementitious material.

4. A concrete composition comprising a hydratable cementitious binder material, fine aggregate, coarse aggregate, water and the additive composition of any one of claims 1 to 3.

5. The concrete composition of claim 4, wherein the additive composition is present in an amount of from about 0.01 wt% to about 1 wt%.

6. The concrete composition of claim 5, comprising from about 10 wt% to about 15 wt% hydratable cementitious binder material, from about 60 wt% to about 75 wt% coarse aggregate and from about 15 wt% to about 20 wt% water.

7. A mortar composition comprising a hydratable cementitious binder material, fine aggregate, water and the additive composition of any one of claims 1 to 3.

8. The mortar composition of claim 7, wherein the additive composition is present in an amount of from about 1 wt% to about 10 wt%.

9. A concrete or mortar rheology modifying composition comprising from about 5% to about 100% by weight halloysite and from about 95% to about 0% by weight kaolinite.

10. A concrete or mortar early strength enhancing composition comprising from about 5% to about 100% by weight halloysite and from about 95% to about 0% by weight kaolinite.

11. A method of controlling the rheology of a cementitious material, the method comprising adding an effective amount of the concrete or mortar rheology modifying composition of claim 9 to the cementitious material.

12. A method of controlling the early strength of a cementitious material, the method comprising adding an effective amount of the concrete or mortar early strength enhancing composition of claim 10 to the cementitious material.

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