Cement-based material additives

Abstract

A cementitious material is disclosed that includes an additive composition comprising about 5% to about 100% by weight halloysite and about 95% to about 0% by weight kaolinite. A method for controlling the rheology of a cementitious material and a method for controlling the early strength of a cementitious material are also disclosed.

Description

[Technical field]

[0001] Priority document This application claims priority to Australian Provisional Patent Application No. 2022900116 entitled "CEMENTITIOUS MATERIAL ADDITIVE" filed on January 21, 2022, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure generally relates to additives for modifying one or more properties of cement-based materials. In a particular aspect, the present disclosure relates to rheology modifiers and / or early strength enhancers for cement-based compositions such as concrete or mortar. [Background technology]

[0003] Cement-based materials such as concrete, mortar, and grout are widely used as building materials and engineering structures. In this regard, cement-based materials include one or more cement binders, one or more aggregates, optionally one or more additives, optionally one or more reinforcing materials, and water. Upon addition of water, the cement binder is activated and forms a paste that binds the aggregates together. If the aggregate has a fine particle size, the product is mortar. If the aggregate contains fine particle size materials and coarse stone materials, the product is concrete.

[0004] An additive is a component of a cementitious material, other than cement, water, and aggregate, that is added to the mixture just before or during mixing. In general, additives interact chemically with the other components of the cementitious material to modify one or more properties or characteristics of the fresh or hardened cementitious material.

[0005] Freshly mixed (i.e., fresh) concrete is a heterogeneous multiphase material whose rheological properties can significantly affect the workability of fresh concrete. Important rheological properties include yield stress and plastic viscosity. The workability of fresh concrete is traditionally quantified by "slump", which is a measurement of the rheology of concrete. Rheology modifiers are typically used to modify one or more rheological properties of a concrete mixture. Known rheology modifiers include water, polycarboxylate water reducers, naphthalene sulfonate / formaldehyde condensate water reducers, melamine sulfonate / formaldehyde condensate water reducers, lignosulfonate water reducers, cellulose derivatives or mixtures thereof.

[0006] In many applications, such as pavement repair, concrete and mortar with high early strength are required. Agents that increase the early strength of the concrete or mortar can be added to the concrete or mortar to achieve the desired strength sooner 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 fume, metakaolin, rice husk ash, and superplasticizers or high plasticizers such as polycarboxylate ethers.

[0007] 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 additionally, there is a need for replacements for known additives that can be used to modify one or more properties of cementitious compositions such as concrete or mortar. Summary of the Invention

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

[0009] In some embodiments, the additive composition modifies the rheology of the cement-based material.

[0010] In some embodiments, the additive composition enhances the early strength of concrete or mortar products 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% to about 1% by weight.

[0013] In some embodiments of the second aspect, the concrete composition comprises about 10% to about 15% by weight of a hydratable cementitious binder material, about 60% to about 75% by weight of coarse aggregate, and about 15% to about 20% by weight of 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 about 1% to about 10% by weight.

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

[0017] According to a fifth aspect, there is provided a concrete or mortar early strength improving composition comprising about 5% to about 100% by weight halloysite and 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 comprising adding to the cementitious material an effective amount of the concrete or mortar rheology modifying composition of the fourth aspect.

[0019] According to a seventh aspect, there is provided a method of controlling early-age strength of a cement-based material, the method comprising adding to the cement-based material an effective amount of the concrete or mortar early-age strength enhancing composition of the fifth aspect.

[0020] Embodiments of the present disclosure will now be described with reference to the accompanying drawings. [Brief description of the drawings]

[0021] [Figure 1] 1 is a plot of load (thin line, left axis) and energy (thick line, right axis) versus displacement for 50 MPa mining shotcrete formed according to an embodiment of the present disclosure. The flexural toughness of HRM#110 was tested according to ASTM C-1550.

[0022] [Diagram 2] FIG. 2 is a plot of compressive strength (MPa) versus age for two 40 MPa self-compacting concrete (SCC) 650 mm spread samples and three samples of 40 MPa self-compacting concrete (SCC) 650 mm spread formed according to embodiments of the present disclosure.

[0023] [Diagram 3] FIG. 3 is a plot of bleed reduction (mL) versus halloysite-kaolin (kaolinite) content for a control 40 MPa self-compacting concrete (SCC) 650 mm spread and for three samples of 40 MPa self-compacting concrete (SCC) 650 mm spread formed according to embodiments of the present disclosure.

[0024] [Figure 4]FIG. 4 is a plot of MPA versus age for a control 40 MPa SCC 80 mm slump and three samples of 40 MPa SCC 80 mm slump formed according to embodiments of the present disclosure.

[0025] [Diagram 5] FIG. 5 is a plot of shear strain (%) versus shear stress (Pa) performed on a 20 wt % solids slurry of an additive composition according to an embodiment of the present disclosure to demonstrate the rheological effect. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Disclosed herein is a cement-based material containing an additive composition, the additive composition comprising about 5% to about 100% by weight halloysite and about 95% to about 0% by weight kaolinite.

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

[0028] Canadian Patent Application No. 3042894 discloses a highly specialized liquid grout product used for wellbore sealing applications. The product comprises a series of "fibers" that are surface treated and functionalized with polymers to give a synthetic "nanocomposite". Halloysite nanotubes functionalized with polysaccharides are suggested as one possible type of fiber, among a list of other possible additives. The additives are used to provide stability under thermal cycling and arguably improve rheology. In fact, the functionalized nanocomposite disclosed does indeed cause rheological problems, namely very high viscosity.

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

[0030] The mortar composition may be any composition comprising cement, fine aggregate (e.g., sand), water, an additive composition, and optionally one or more additional additives. The mortar composition may alternatively be referred to as a grout composition. As used herein, the term "mortar" refers to a cement or cementitious mixture that includes fine gravel, such as sand, and the terms "mortar" and "grout" may be used interchangeably throughout this specification.

[0031] The concrete composition may be any concrete composition containing cement, fine aggregate (e.g., sand), coarse aggregate (e.g., stone), water, an additive composition, and optionally one or more additional additives. As used herein, the term "concrete" refers to mortar that also contains coarse stone materials such as crushed stone or pebbles.

[0032] The cement used in concrete or mortar compositions typically includes hydratable cementitious binder materials, such as Portland cement and / or cement substitutes, which when mixed with water, act as a binder that holds the mixture together to form building materials and engineered structures. Cementitious materials 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 pozzolans, and natural calcined pozzolans, any of which have hydrating properties or can be combined with Portland cement to form additional 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] A concrete or mortar composition includes water. When mixed with cement, water forms a paste that binds the aggregates together. An amount of water is added to the concrete such that the concrete is workable so that it can be consolidated and molded into a desired shape. Too much water reduces the concrete strength, and too little water makes the mortar or concrete unworkable. The amount of water is defined as the W / C ratio, where W is the mass of the water and C is the mass of one or more cement binders. In some embodiments, the W / C ratio is in the range of 0.20 to 0.70. In some embodiments, the W / C ratio is in the range of 0.35 to 0.60 or 0.40 to 0.50. In some embodiments, the W / C ratio is in the range of 0.35 to 0.45 or 0.20 to 0.30.

[0035] Concrete or mortar compositions also contain one or more aggregates. Aggregates are mostly chemically inert solids that are held together by the cement or hardened cement paste or hardened mortar. Aggregates come in a variety of shapes, sizes and materials, ranging from fine particles such as sand to larger particles such as coarse rock. The choice of aggregate is determined, in part, by the desired attributes of the cementitious mixture. For example, the density of concrete is affected by the density of the aggregate. Soft, porous aggregates can result in weak concrete with low abrasion resistance, while the use of hard aggregates can create strong concrete with high abrasion resistance. Aggregates are usually washed to remove dust, silt, clay, organic matter or other impurities that would interfere with the bonding reaction with the cement paste.

[0036] The aggregate may be fine or coarse aggregate. In some embodiments, the one or more aggregates are selected from gravel, crushed rock, and sand. In some embodiments, the crushed rock is selected from limestone and granite. In some embodiments, the one or more aggregates are selected 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 amounts of cement, stone, water and additives can be readily determined by one of ordinary skill in the art based on existing knowledge of concrete compositions and properties. For example, a concrete composition may include about 10% to about 15% by weight cement, about 60% to about 75% by weight stone, and about 15% to about 20% by weight water. The amount of additives in the composition depends on the type of additive and the desired properties.

[0038] In some embodiments, the concrete composition is suitable for applications such as self-compacting concrete, precast concrete, shotcrete, slipform paving, caisson piling (non-segregating), lightweight concrete, dry cast block, pipe, hollow core, plasterwork, stucco, swimming pool exteriors, and piling. In some embodiments, the composition has a form suitable for applications where there is a need or desire for high strength concrete, stamped concrete, high performance concrete, ultra high performance concrete, self-compacting concrete, rolled crete, 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 concrete or mortar compositions. The term "rheology" refers to the flow dynamics of liquids and the deformation of solids. The rheological properties of heterogeneous dispersions such as mortar and concrete are complex and cannot be represented by a single parameter. Rheological properties of fresh cementitious materials that can be monitored and controlled include slump and yield stress. Prior art rheology modifiers known to modify the rheological properties of fresh cementitious materials include water, chemical contaminants (e.g., polycarboxylate water reducers, naphthalene sulfonate / formaldehyde condensate water reducers, melamine sulfonate / formaldehyde condensate water reducers, lignosulfonate water reducers, etc.), or hydrocolloid viscosity modifying contaminants such as cellulose derivatives, or mixtures thereof. The inventors have surprisingly found that the addition of an additive composition comprising about 5% to about 100% halloysite and about 95% to about 0% kaolinite, about 0.01% to about 1% by weight, to a concrete composition provides one or more rheological benefits including reduced bleeding, reduced aggregate separation, optimized spreading and slump characteristics, improved slump retention and pumping / flow. Furthermore, the addition of an additive composition comprising about 5% to about 100% halloysite and about 95% to about 0% kaolinite, about 1% to about 10% by weight, to a concrete composition provides one or more rheological benefits including improved pumping and flow characteristics resulting from reduced separation of components under shear. The latter attribute is particularly suitable when the mortar is used as a subsurface backfill grout mixture.

[0040] Advantageously, the additive composition can be used to replace a portion of the Portland cement in a concrete composition, so that the additive composition can be used to produce green cement or green concrete.

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

[0042] In addition to the additive compositions described herein, the concrete or mortar composition may also contain an effective amount of one or more additional additives as needed. The one or more additional additives that may be used include, but are not limited to, plasticizers, viscosity modifiers, corrosion inhibitors, shrinkage reducing agents, set accelerators, set retarders, air trapping agents, air entraining agents, deaeration agents, pigments, colorants, mineral admixtures, corrosion inhibitors, and fibers for plastic shrinkage control or structural reinforcement. As used herein, the term "effective amount" of an additive refers to the amount per cubic meter of hardened mortar or concrete to impart an improvement or modification of one or more properties of the wet or hardened mortar or concrete composition.

[0043] Suitable air entraining agents, when used, contain a sufficient amount of surfactant to improve durability, improve processability, reduce bleeding, or reduce freeze / thaw problems.

[0044] Suitable plasticizers, when used, include lignosulfonates, sulfonated naphthalene formaldehyde condensates, sulfonated melamine formaldehyde condensates, acetone formaldehyde condensates or polycarboxylic acid ethers in amounts sufficient to reduce the water required for workable concrete.

[0045] Suitable retarders, if used, include sugar, sucrose, sodium gluconate, glucose, citric acid or tartaric acid in an amount sufficient to retard setting time, add long term strength or offset adverse hot weather conditions.

[0046] Suitable accelerators, when used, include calcium chloride, calcium dinitrate or sodium nitrate in an amount sufficient to accelerate setting time, achieve early strength or offset adverse cold weather conditions.

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

[0048] Suitable pigments, when used, contain a sufficient amount of metal oxide to impart color.

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

[0050] The concrete or mortar composition may also contain one or more reinforcing materials such as steel rebar, steel fibers, glass fibers, and plastic fibers.

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

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

[0053] A control 50 MPa mining shotcrete composition and a 50 MPa mining shotcrete composition formed in accordance with one embodiment of the present disclosure were formed using the following ingredients and standard procedures. This composition was selected because it is a typical 220 mm to 240 mm slump shotcrete or fibercrete composition.

[0054] [Table 1]

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

[0056] The HRM compositions performed very well compared to the control, which was a standard mining shotcrete design without any rheology modifier. The properties displayed would be highly desirable in this application. These compositions begin to separate at high slump, but the HRM was able to control this separation and minimize visible bleed water. The HRM performed at a minimum of 1 kg / m 3 and 2 kg / m2 if processing costs are acceptable. 3 It can be administered at .

[0057] The data obtained was as follows: [Table 2]

[0058] The flexural toughness of HRM#110 was tested according to ASTM C-1550 and the results are shown in FIG.

[0059] Example 2 - Trial #7, 40MPa self-compacting concrete (SCC) 650mm spread

[0060] A control 40 MPa SCC 650 mm diffusion (self-compacting concrete, self-consolidating concrete or ultraworkable concrete) and three 40 MPa SCC 650 mm diffusion compositions were formed according to one embodiment of the present disclosure using the following ingredients and standard procedures.

[0061] [Table 3]

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

[0063] The results showed a very clear increase in strength or performance with increasing HRM levels. Compressive strength also increased at all ages. See Figure 2. This increase was not as pronounced in the lower slump designs, but with the addition of HRWR and the open microstructural design, HRM appears to provide more benefit, in some cases helping to separate or disperse cement particles at a micro level to improve hydration. The HRM product performed very well compared to the control without the rheology modifier. To confirm, the control was also replicated at a slightly different w / c ratio (see Figure 2, Control #2). There was a visible increase in paste and the slump did not return like with other rheology modifiers on the market. The measurements below show excellent performance and that HRM is very fit for purpose. HRM could add value to this application, the properties described pump well and allow for higher coarse aggregate content compared to typical SCC designs. HMR can improve workability, pumpability and finishability in these applications.

[0064] The data obtained was as follows: [Table 4]

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

[0066] A control 40 MPa SCC 80 mm slump (self-compacting concrete, self-consolidating concrete or ultra-workable concrete) and three 40 MPa SCC 80 mm slump compositions were formed according to one embodiment of the present disclosure using the following ingredients and standard procedures:

[0067] [Table 5]

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

[0069] The results showed an increase in strength gain or improvement in performance with increasing HRM levels, but very minimal (see Figure 4). 1kg, 2kg and 4kg HRM are not detrimental to this grade of concrete. HRM performed very well against the control without rheology modifier (RM). There was a visible increase in paste and the slump did not return like other rheology modifiers on the market. The measurements below show that the plastic properties were very desirable and fit for purpose. HRM could add value to this application, the properties described are well pumped and allow for higher coarse aggregate content. HMR can improve workability, pumpability and finishability in these applications.

[0070] The data obtained was as follows: [Table 6]

[0071] Example 4 - Trial #5, Continuous Flight Auger (CFA) Stakeout

[0072] Control concrete for CFA piling and CFA piling concrete compositions formed according to embodiments of the present disclosure were formed using the following ingredients and standard procedures.

[0073] [Table 7]

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

[0075] The HRM performed very well compared to the natural mineral rheology modifier in the control. Although the measurements below were quite different, the plastic properties in the HRM design were also very desirable and fit for purpose. The HRM has the potential to add value to this application for several reasons, including: 1. The workability / softness was the same as the expensive imported RM in the control. 2. Bleed under pressure was the same as the control. 3. The decrease in workability over time was clearly superior to the control, which showed a very rapid decrease in diffusion / slump.

[0076] The compressive strength is slightly lower than the control but still exceptionally high. HRM can be used as a direct replacement or at 1kg-3kg / m 3 HRM is added at 100% and higher dosages give improved plastic performance. HRM added "body or fat" as well as flexibility and workability to the paste without excessively reducing slump. These properties allow for an increase in coarse aggregate without compromising workability, reducing the demand for sand and water.

[0077] The data obtained was as follows: [Table 8]

[0078] Example 5 - Trial #4, Plemmie Piling

[0079] Control concrete for tremie piling and tremie piling concrete compositions formed according to embodiments of the present disclosure were formed using the following ingredients and standard procedures.

[0080] [Table 9]

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

[0082] The HRM performed very well compared to the neutral or no rheology modifier control. The following measurements are similar, but again the plastic properties were very desirable and fit for purpose. Also the 24 hour compressive strength was 4MPa above the control at all data points, remaining at +2MPa. The 28 day shrinkage is much better (-60um). The HRM has the potential to add value to this application. It can be used as a direct replacement or, if processing costs are acceptable, at higher dosages, 1kg-3kg / m. 3 Improved results can be obtained by adding HRM at 100%. HRM added "body or fat", as well as flexibility and workability to the paste, without unduly reducing slump. These properties allow for an increase in coarse aggregate without compromising workability, reducing the demand for sand and water.

[0083] The data obtained was as follows: [Table 10]

[0084] Example 6 - Trial #3, 25MPa Pool Spray

[0085] A control spray mix and a spray mix concrete composition formed in accordance with one embodiment of the present disclosure were formed using the following ingredients and standard procedures.

[0086] [Table 11]

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

[0088] The HRM performed very well compared to the natural mineral rheology. The properties displayed are desirable in domestic and consumer applications. This design and RM was selected as it is a typical 70mm slump "spray mix" combination incorporating 25% fly ash. The measurements below are similar, but again the plastic properties were highly desirable and fit for purpose. The HRM can be used as a direct 1:1 replacement for currently used rheology modifiers, although improved results will also be obtained with higher dosages where processing costs are acceptable.

[0089] The data obtained was as follows: [Table 12]

[0090] It will be understood that the terms "comprise" and "include" and their derivatives (e.g., comprises, comprising, includes, including) as used herein are to be interpreted as including the features referred to by the term and are not meant to exclude the presence of additional features, unless specifically stated or implied.

[0091] The reference to any prior art in this specification is not, and should not be construed as, any form of admission that such prior art forms part of the common general knowledge.

[0092] It will be understood by those skilled in the art that the present disclosure is not limited in its use to the specific application or applications described. The present disclosure is not limited in its preferred embodiments with respect to the specific elements and / or features described or depicted herein. It will be understood that the present disclosure is not limited to the disclosed embodiment or embodiments, and that numerous rearrangements, modifications and substitutions are possible without departing from the scope described and defined by the following claims.

Claims

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

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

3. 10. The cementitious material of claim 1, wherein the additive composition enhances early-age strength of concrete or mortar products 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. 5. The concrete composition of claim 4, wherein the additive composition is present in an amount of from about 0.01% to about 1% by weight.

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

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

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

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

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

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