WO2023030666A1 - Concrete admixtures - Google Patents

Concrete admixtures Download PDF

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Publication number
WO2023030666A1
WO2023030666A1 PCT/EP2021/074550 EP2021074550W WO2023030666A1 WO 2023030666 A1 WO2023030666 A1 WO 2023030666A1 EP 2021074550 W EP2021074550 W EP 2021074550W WO 2023030666 A1 WO2023030666 A1 WO 2023030666A1
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WO
WIPO (PCT)
Prior art keywords
water
sodium
concrete admixture
calcium
metabisulphite
Prior art date
Application number
PCT/EP2021/074550
Other languages
French (fr)
Inventor
Arman BILGE
Ugur Semih AYTAC
Ahmet ERDAL
Original Assignee
Fosroc Yapi Kimyasallari Sanayi Ve Ticaret Anonim Sirketi
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from TR2021/013627 external-priority patent/TR2021013627A2/en
Application filed by Fosroc Yapi Kimyasallari Sanayi Ve Ticaret Anonim Sirketi filed Critical Fosroc Yapi Kimyasallari Sanayi Ve Ticaret Anonim Sirketi
Priority to AU2021463061A priority Critical patent/AU2021463061A1/en
Priority to CN202180101913.0A priority patent/CN118019720A/en
Priority to KR1020247010255A priority patent/KR20240060621A/en
Publication of WO2023030666A1 publication Critical patent/WO2023030666A1/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B22/00—Use of inorganic materials as active ingredients for mortars, concrete or artificial stone, e.g. accelerators, shrinkage compensating agents
    • C04B22/08—Acids or salts thereof
    • C04B22/14—Acids or salts thereof containing sulfur in the anion, e.g. sulfides
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B22/00—Use of inorganic materials as active ingredients for mortars, concrete or artificial stone, e.g. accelerators, shrinkage compensating agents
    • C04B22/08—Acids or salts thereof
    • C04B22/085—Acids or salts thereof containing nitrogen in the anion, e.g. nitrites
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B24/00—Use of organic materials as active ingredients for mortars, concrete or artificial stone, e.g. plasticisers
    • C04B24/16—Sulfur-containing compounds
    • C04B24/20—Sulfonated aromatic compounds
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
    • C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
    • C04B40/0028—Aspects relating to the mixing step of the mortar preparation
    • C04B40/0039—Premixtures of ingredients
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2103/00—Function or property of ingredients for mortars, concrete or artificial stone
    • C04B2103/30—Water reducers, plasticisers, air-entrainers, flow improvers
    • C04B2103/302—Water reducers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
    • Y02W30/50—Reuse, recycling or recovery technologies
    • Y02W30/91—Use of waste materials as fillers for mortars or concrete

Definitions

  • the present invention relates to admixtures for use in concrete.
  • Concrete is a construction material formed from a mixture of cement, aggregates (sand and stone) and water.
  • the water used in concrete activates the cement, which acts as the binding agent.
  • the aggregates (coarse and fine) in the mix are bound together by the cement as it sets and cures to produce a hardened concrete.
  • Mixes that use larger aggregates tend to be stronger than those with finer aggregates. Importantly, the less water that is added to a concrete mixture, the stronger that mixture will be.
  • the cement may commonly be hydraulic cement, such as Portland cement.
  • Portland cement also known as Ordinary Portland Cement or OPC
  • OPC Ordinary Portland Cement
  • Portland cement is prepared by heating a mixture of raw components (including calcium carbonate, aluminium silicate, silicon dioxide and miscellaneous iron oxides) to a sintering temperature (usually about 1450°C), resulting in the formation of clinker.
  • Portland cement clinker is formed by the reaction of calcium oxide with acidic components to give primarily tricalcium silicate, dicalcium silicate, tricalcium aluminate, and a ferrite phase “C4AF” (tetracalcium aluminoferrite).
  • This clinker is ground with calcium sulphate (usually in the form of gypsum) in a grinding mill to provide the cement in the form of a fine, homogeneous powder.
  • Other additives or cement replacements can be incorporated before or after the milling process. These include fillers and OPC replacements, such as calcium carbonate and other minerals, ground granulated blast furnace slag, natural pozzolans and pulverised fuel ash (PFA).
  • the components that form the cement powder (clinker, calcium sulphate, and optional additives such as fillers and cement replacements) may be referred to as the cement composition.
  • the strength of concrete is important, because it is used to make articles that need to have this property. For example, roads, pavements, bridges, walls, buildings and foundations are often made from concrete.
  • Concrete admixtures are commonly added during mixing of the cement, aggregates and water, to enhance specific properties of the fresh or hardened concrete, e.g. workability, durability, or early and/or final strength.
  • Concrete admixtures may include one or more water-reducing agent.
  • Water-reducing agents are additives that can reduce the amount of water that needs to be used for mixing, and that can increase the strength of concrete without adversely impacting concrete workability.
  • a concrete admixture that includes one or more water-reducing agent may be referenced as a water-reducing concrete admixture.
  • sulfonated melamine resin salts Conventionally, sulfonated melamine resin salts, polycarboxylates, salts of highly condensed naphthalene sulfonic acid formaldehyde, lignin sulfonates (lignosulfonates) and the like have been used as water reducing agents.
  • the aim of the present invention is to provide alternatives to lignosulphonate-based admixtures, whereby said alternatives are more cost-effective but possess a waterreducing capability equal to or greater than that of lignosulphonate admixtures.
  • the present invention provides, in a first aspect, the use of one or more agent selected from sodium metabisulphite, sodium nitrate, sodium naphthalene, calcium metabisulphite, calcium nitrate, calcium naphthalene and combinations thereof, as a water-reducing additive for concrete.
  • the one or more agent may be used to partly or fully replace lignosulfonate material in a concrete admixture.
  • lignosulfonate material such as sodium lignosulfonate, is commonly used as a water-reducing additive for concrete.
  • the present invention has provided new options for reducing the amount of water used for mixing. These new options can increase the strength of concrete without adversely impacting concrete workability.
  • sodium naphthalene When sodium naphthalene is present, it is preferably in the form of sodium naphthalene sulfonate.
  • calcium naphthalene When calcium naphthalene is present, it is preferably in the form of calcium naphthalene sulfonate.
  • each of these agents can be effectively and successfully used to partly or fully replace lignosulfonate material in a water-reducing concrete admixture.
  • the present invention provides, in a second aspect, a water-reducing concrete admixture comprising: a) one or more agent selected from sodium metabisulphite, sodium nitrate, sodium naphthalene, calcium metabisulphite, calcium nitrate, calcium naphthalene and combinations thereof; and b) lignosulfonate material.
  • the lignosulfonate material may, for example, be selected from sodium lignosulfonate, calcium lignosulfonate, magnesium lignosulfonate, potassium lignosulfonate, and combinations thereof.
  • the lignosulfonate material comprises or is sodium lignosulfonate.
  • each of the above agents and in particular sodium metabisulphite, can be effectively and successfully used in combination with polymeric material which is vinyl copolymer (especially vinyl acetate copolymer) and/or polycarboxylate and/or polycarboxylate ether, to fully replace lignosulfonate material in a water-reducing concrete admixture.
  • polymeric material which is vinyl copolymer (especially vinyl acetate copolymer) and/or polycarboxylate and/or polycarboxylate ether, to fully replace lignosulfonate material in a water-reducing concrete admixture.
  • the present invention therefore also provides, in a third aspect, a water-reducing concrete admixture comprising: a) one or more agent selected from sodium metabisulphite, sodium nitrate, sodium naphthalene, calcium metabisulphite, calcium nitrate, calcium naphthalene, and combinations thereof; and b) polymeric material which is selected from vinyl copolymers (especially vinyl acetate copolymer), polycarboxylate, polycarboxylate ether, and combinations thereof.
  • a water-reducing concrete admixture comprising: a) one or more agent selected from sodium metabisulphite, sodium nitrate, sodium naphthalene, calcium metabisulphite, calcium nitrate, calcium naphthalene, and combinations thereof; and b) polymeric material which is selected from vinyl copolymers (especially vinyl acetate copolymer), polycarboxylate, polycarboxylate ether, and combinations thereof.
  • the agent a) comprises or is sodium metabisulphite.
  • each of the above agents can be effectively and successfully used in combination with a blend of modified sugars to fully replace lignosulfonate material in a water-reducing concrete admixture.
  • the present invention therefore further provides, in a fourth aspect, a water-reducing concrete admixture comprising: a) one or more agent selected from sodium metabisulphite, sodium nitrate, sodium naphthalene, calcium metabisulphite, calcium nitrate, calcium naphthalene and combinations thereof; and b) a blend of modified sugars comprising two or more (e.g. three or more) of: sodium gluconate, potassium gluconate, glucose syrup, molasses, vinasse and dextrins (e.g. yellow dextrin and/or maltodextrin).
  • This has the benefit that no lignosulfonate needs to be used to achieve good results and the admixture is more cost-effective than lignosulfonate-based admixtures.
  • the blend of modified sugars comprises both glucose syrup and molasses; in one preferred embodiment the glucose syrup and molasses are included in a weight ratio of 0.75: 1 or more, preferably 1 : 1 or more or 1.1 : 1 or more or 1.2: 1 or more. Having at least as much glucose syrup as molasses, by weight in the blend may be beneficial.
  • the blend of modified sugars comprises both glucose syrup and sodium gluconate; in one preferred embodiment the glucose syrup and sodium gluconate are included in a weight ratio of 0.5: 1 or more, preferably 0.6: 1 or more or 0.7: 1 or more. Having at least half as much glucose syrup as sodium gluconate, by weight in the blend may be beneficial.
  • the agent a) is selected from sodium nitrate and sodium naphthalene and combinations thereof.
  • the water-reducing concrete admixture does not comprise formaldehyde.
  • the water-reducing concrete admixture does not comprise triisobutyl phosphate.
  • the present invention further provides, in a fifth aspect, a method of producing concrete, the method comprising: mixing cement, aggregates and water together with a water-reducing concrete admixture as defined in any one of the second to fourth aspects.
  • the water-reducing concrete admixture is added at an addition level of from 0.5 to 5wt%, e.g. from 1 to 3wt% or from 1 to 2wt% (with respect to the total weight of the mixture).
  • the cement may be hydraulic cement, such as Portland cement.
  • one or more agent selected from sodium metabisulphite, sodium nitrate, sodium naphthalene, calcium metabisulphite, calcium nitrate, calcium naphthalene and combinations thereof is used as a water-reducing additive for concrete.
  • agents have been identified as cost-effective replacements for lignosulfonate material and they can replace some or all of the lignosulfonate material used in a waterreducing concrete admixture.
  • sodium naphthalene When sodium naphthalene is present, it is preferably in the form of sodium naphthalene sulfonate.
  • calcium naphthalene When calcium naphthalene is present, it is preferably in the form of calcium naphthalene sulfonate.
  • the agent is selected from sodium metabisulphite, sodium nitrate and sodium naphthalene.
  • the ligno sulfonate material that is fully or partly replaced may, in particular, be sodium lignosulfonate. However, it could alternatively or additionally be other lignosulfonate material, such as calcium lignosulfonate or magnesium lignosulfonate or potassium lignosulfonate.
  • a water-reducing concrete admixture comprises (a) one or more lignosulfonate- replacement agent selected from sodium metabisulphite, sodium nitrate, sodium naphthalene, calcium metabisulphite, calcium nitrate, calcium naphthalene and combinations thereof and (b) lignosulfonate material. It may be that the weight ratio of lignosulfonate-replacement agent to lignosulfonate material is from 1 :50 to 50: 1, such as from 1 :40 to 40: 1, preferably from 1 :30 to 30: 1, e.g.
  • the weight ratio of lignosulfonate-replacement agent to lignosulfonate material is from 1 : 10 to 10: 1, such as from 1 :7 to 7: 1, preferably from 1 :5 to 5: 1.
  • the weight ratio of lignosulfonate-replacement agent to lignosulfonate material is from 4: 1 to 50: 1, such as from 4: 1 to 10: 1 or from 4: 1 to 9: 1. In one embodiment the weight ratio of lignosulfonate-replacement agent to lignosulfonate material is from 2: 1 to 50: 1, such as from 2: 1 to 10: 1 or from 2: 1 to 9: 1. In one embodiment the weight ratio of lignosulfonate-replacement agent to lignosulfonate material is from 1 : 1 to 50: 1, such as from 1 : 1 to 10: 1 or from 1 : 1 to 9: 1.
  • lignosulfonate-replacement agent as lignosulfonate material, e.g. at least three times as much.
  • the majority of the water-reducing concrete admixture is lignosulfonate-replacement agent and lignosulfonate material (e.g. 60wt% or more, or 70wt% or more, or 80wt% or more, such as 90wt% or more of the water-reducing concrete admixture).
  • the water-reducing concrete admixture consists essentially of lignosulfonate-replacement agent and lignosulfonate material or consists only of lignosulfonate-replacement agent and lignosulfonate material.
  • additives may be present in the water-reducing concrete admixture, e.g. in amounts of 15wt% or less, such as 10wt% or less, e.g. from 0.5 to 10wt% or from 1 to 8wt%.
  • additives may be materials known in the art for use in concrete admixtures, e.g. surfactants (air entraining agents and/or defoamers) and/or amines (known for use as strength enhancers and/or set accelerators) and/or defoamers and/or biocides.
  • Amines such as triethanolamine and tri-isopropanolamine and diethanol isopropanolamine are, in particular, known for use in concrete and may optionally be present.
  • Specific examples of additives that may be present in the present invention include sodium lauryl ether sulphate, triethanolamine and tri-isopropanolamine.
  • Triisobutylphosphate and formaldehyde are also examples of other additives that can, in embodiments, be present.
  • melamine and/or sulfonated melamine resin salts are included as additives, e.g. in amounts of 15wt% or less, such as 10wt% or less or 5wt% or less, e.g. from 0.5 to 10wt% or from 1 to 8wt%.
  • additives e.g. in amounts of 15wt% or less, such as 10wt% or less or 5wt% or less, e.g. from 0.5 to 10wt% or from 1 to 8wt%.
  • the lignosulfonate-replacement agent comprises sodium metabisulphite, and in particular it may be that the lignosulfonate-replacement agent is sodium metabisulphite.
  • the sodium metabisulphite may be provided in the form of a powder or in the form of a solution, especially an aqueous solution, e.g. as a 30-60 or 30-50% wt/wt solution in water, such as a 35-45% wt/wt solution in water.
  • the sodium metabisulphite may be provided in a non-food grade form, as this is more cost-effective.
  • there may, for example, be ppm level impurities of metal ions such as Fe ions.
  • a water-reducing concrete admixture comprises one or more lignosulfonate-replacement agent selected from sodium metabisulphite, sodium nitrate, sodium naphthalene, calcium metabisulphite, calcium nitrate, calcium naphthalene and combinations thereof and comprises no lignosulfonate material.
  • the lignosulfonate-replacement agent may suitably be used in combination with a supplemental active agent.
  • the supplemental active agent may be (i) polymeric material which is selected from vinyl copolymers (especially vinyl acetate copolymer), polycarboxylate, polycarboxylate ether, and combinations thereof, or it may be (ii) a blend of modified sugars comprising two or more (e.g. three or more) of: sodium gluconate, potassium gluconate, glucose syrup, molasses, vinasse and dextrins (e.g. yellow dextrin and/or maltodextrin), or it may be (i) and (ii).
  • the water-reducing concrete admixture comprises: a) one or more lignosulfonate-replacement agent selected from sodium metabisulphite, sodium nitrate, sodium naphthalene, calcium metabisulphite, calcium nitrate, calcium naphthalene and combinations thereof; and b) a supplemental active agent which comprises polymeric material which is selected from vinyl copolymers (especially vinyl acetate copolymer), polycarboxylate, polycarboxylate ether, and combinations thereof.
  • lignosulfonate-replacement agent selected from sodium metabisulphite, sodium nitrate, sodium naphthalene, calcium metabisulphite, calcium nitrate, calcium naphthalene and combinations thereof
  • a supplemental active agent which comprises polymeric material which is selected from vinyl copolymers (especially vinyl acetate copolymer), polycarboxylate, polycarboxylate ether, and combinations thereof.
  • the supplemental active agent is vinyl acetate copolymer.
  • the vinyl acetate copolymer may be provided in liquid form.
  • the supplemental active agent is vinyl acetate copolymer together with a blend of modified sugars comprising two or more (e.g. three or more) of: sodium gluconate, potassium gluconate, glucose syrup, molasses, vinasse and dextrins (e.g. yellow dextrin and/or maltodextrin); for example, the blend may comprise sodium or potassium gluconate together with glucose syrup and molasses.
  • the blend of modified sugars comprises both glucose syrup and molasses; in one preferred embodiment the glucose syrup and molasses are included in a weight ratio of 0.5: 1 or more, especially 0.75: 1 or more, preferably 1 : 1 or more, e.g. 1.1 : 1 or more, or 1.2: 1 or more. Having at least as much glucose syrup as molasses, by weight in the blend may be beneficial.
  • the blend of modified sugars comprises both glucose syrup and sodium gluconate; in one preferred embodiment the glucose syrup and sodium gluconate are included in a weight ratio of 0.3: 1 or more, especially 0.5: 1 or more, preferably 0.6: 1 or more or 0.7: 1 or more. Having at least half as much glucose syrup as sodium gluconate, by weight in the blend may be beneficial. In some embodiments, it may be that the sodium gluconate is replaced, partly or fully, by potassium gluconate.
  • the weight ratio of lignosulfonate-replacement agent to the polymeric material is from 1 :50 to 50: 1, such as from 1 :40 to 40: 1, preferably from 1 :30 to 30: 1, e.g. it may be from 1 :25 to 25: 1 or from 1 : 20 to 20: 1 or from 1 : 15 to 15: 1.
  • the weight ratio of lignosulfonate-replacement agent to the polymeric material e.g. vinyl acetate copolymer
  • the weight ratio of lignosulfonate-replacement agent to the polymeric material is from 1:10 to 10:1, such as from 1:7 to 7:1, preferably from 1:5 to 5:1 or from 1:3 to 3:1 or from 1:2 to 2:1.
  • the weight ratio of lignosulfonate-replacement agent to the polymeric material is from 1:1 to 10:1, such as from 1:1 to 7:1, preferably from 1:1 to 5:1 or from 1:1 to 3:1 or from 1:1 to 2:1.
  • the weight ratio of lignosulfonate-replacement agent to the blend of modified sugars is from 1:50 to 50:1, such as from 1:40 to 40:1, preferably from 1:30 to 30:1, e.g. it may be from 1:25 to 25:1 or from 1 : 20 to 20: 1 or from 1:15 to 15:1. In one preferred embodiment it may be that the weight ratio of lignosulfonate-replacement agent to the blend of modified sugars is from 1:10 to 10:1, such as from 1:7 to 7:1, preferably from 1:5 to 5:1 or from 1 :3 to 3: 1 or from 1 :2 to 2: 1.
  • the weight ratio of lignosulfonate-replacement agent to the blend of modified sugars is from 1:10 to 1:1, such as from 1:7 to 1:1, preferably from 1:5 to 1:1 or from 1 : 3 to 1 : 1 or from 1 : 2 to 1:1.
  • the majority of the water-reducing concrete admixture is lignosulfonate-replacement agent and supplemental active agent (e.g. 60wt% or more, or 70wt% or more, or 80wt% or more, such as 90wt% or more of the water-reducing concrete admixture).
  • supplemental active agent e.g. 60wt% or more, or 70wt% or more, or 80wt% or more, such as 90wt% or more of the water-reducing concrete admixture.
  • the water-reducing concrete admixture consists essentially of lignosulfonate-replacement agent and supplemental active agent or consists only of lignosulfonate-replacement agent and supplemental active agent.
  • additives may be present in the water-reducing concrete admixture, e.g. in amounts of 15wt% or less, such as I0wt% or less, e.g. from 0.5 to 10wt% or from 1 to 8wt%.
  • these other additives may be materials known in the art for use in concrete admixtures, e.g. surfactants (air entraining agents and/or defoamers) and/or amines (known for use as strength enhancers and/or set accelerators) and/or defoamers and/or biocides.
  • Amines such as triethanolamine and tri-isopropanolamine and diethanol isopropanolamine are, in particular, known for use in concrete and may optionally be present.
  • Specific examples of additives that may be present in the present invention include sodium lauryl ether sulphate, triethanolamine and tri-isopropanolamine.
  • Triisobutylphosphate and formaldehyde are also examples of other additives that can, in embodiments, be present.
  • melamine and/or sulfonated melamine resin salts are included as additives, e.g. in amounts of 15wt% or less, such as 10wt% or less or 5wt% or less, e.g. from 0.5 to 10wt% or from 1 to 8wt%.
  • additives e.g. in amounts of 15wt% or less, such as 10wt% or less or 5wt% or less, e.g. from 0.5 to 10wt% or from 1 to 8wt%.
  • the water-reducing concrete admixture may optionally be provided in combination with a solvent. This may be useful in relation to the ease of addition of the admixture when mixing the concrete.
  • the solvent may, in one embodiment, be water.
  • the lignosulfonate-replacement agent comprises sodium metabisulphite, and in particular it may be that the lignosulfonate-replacement agent is sodium metabisulphite.
  • the sodium metabisulphite may be provided in the form of a powder or in the form of a solution, especially an aqueous solution, e.g. as a 30-60 or 30-50% wt/wt solution in water, such as a 35-45% wt/wt solution in water.
  • the sodium metabisulphite may be provided in a non-food grade form, as this is more cost-effective.
  • there may, for example, be ppm level impurities of metal ions such as Fe ions.
  • the water-reducing concrete admixture comprises: a) one or more lignosulfonate-replacement agent selected from sodium metabisulphite, sodium nitrate, sodium naphthalene, calcium metabisulphite, calcium nitrate, calcium naphthalene and combinations thereof; and b) a supplemental active agent which comprises a blend of modified sugars comprising two or more (e.g. three or more) of: sodium gluconate, potassium gluconate, glucose syrup, molasses, vinasse and dextrins (e.g. yellow dextrin and/or maltodextrin).
  • the supplemental active agent is a blend of modified sugars comprising sodium or potassium gluconate together with glucose syrup and molasses.
  • dextrin e.g. yellow dextrin, may also be present.
  • the supplemental active agent is a blend of modified sugars comprising sodium gluconate, glucose syrup and molasses.
  • dextrin e.g. yellow dextrin, may also be present.
  • the gluconate may be provided in powder form or may be provided in the form of a solution, e.g. an aqueous solution.
  • the glucose syrup and molasses may be provided in liquid form.
  • this may suitably be yellow dextrin in powder form; this can, for example, be added to the liquid components after they have been mixed.
  • the blend of modified sugars comprises glucose syrup and molasses in a weight ratio of 0.5: 1 or more, especially 0.75: 1 or more, preferably 1 : 1 or more, e.g. 1.1 : 1 or more, or 1.2: 1 or more. Having at least as much glucose syrup as molasses, by weight in the blend may be beneficial.
  • the blend of modified sugars comprises glucose syrup and sodium gluconate in a weight ratio of 0.3: 1 or more, especially 0.5 : 1 or more, preferably 0.6: 1 or more or 0.7: 1 or more. Having at least half as much glucose syrup as sodium gluconate, by weight in the blend may be beneficial. In some embodiments, it may be that the sodium gluconate is replaced, partly or fully, by potassium gluconate.
  • the weight ratio of lignosulfonate-replacement agent to the blend of modified sugars is from 1 :50 to 50: 1, such as from 1 :40 to 40: 1, preferably from 1 :30 to 30: 1, e.g. it may be from 1 :25 to 25: 1 or from 1 : 20 to 20: 1 or from 1 : 15 to 15: 1. In one preferred embodiment it may be that the weight ratio of lignosulfonate-replacement agent to the blend of modified sugars is from 1 : 10 to 10: 1, such as from 1 :7 to 7: 1, preferably from 1 :5 to 5: 1 or from 1 :3 to 3: 1.
  • the weight ratio of lignosulfonate-replacement agent to the blend of modified sugars is from 1 :5 to 10: 1, such as from 1 :3 to 7: 1, preferably from 1 :2 to 5: 1 or from 1 :2 to 3: 1.
  • the majority of the water-reducing concrete admixture is lignosulfonate-replacement agent and supplemental active agent (e.g. 60wt% or more, or 70wt% or more, or 80wt% or more, such as 90wt% or more of the water-reducing concrete admixture).
  • supplemental active agent e.g. 60wt% or more, or 70wt% or more, or 80wt% or more, such as 90wt% or more of the water-reducing concrete admixture.
  • the water-reducing concrete admixture consists essentially of lignosulfonate-replacement agent and supplemental active agent or consists only of lignosulfonate-replacement agent and supplemental active agent.
  • additives may be present in the water-reducing concrete admixture, e.g. in amounts of 15wt% or less, such as 10wt% or less, e.g. from 0.5 to 10wt% or from 1 to 8wt%.
  • additives may be materials known in the art for use in concrete admixtures, e.g. surfactants (air entraining agents and/or defoamers) and/or amines (known for use as strength enhancers and/or set accelerators) and/or defoamers and/or biocides.
  • Amines such as triethanolamine and tri-isopropanolamine and diethanol isopropanolamine are, in particular, known for use in concrete and may optionally be present.
  • Triisobutylphosphate and formaldehyde are also examples of other additives that can, in embodiments, be present.
  • melamine and/or sulfonated melamine resin salts are included as additives, e.g. in amounts of 15wt% or less, such as 10wt% or less or 5wt% or less, e.g. from 0.5 to 10wt% or from 1 to 8wt%.
  • additives e.g. in amounts of 15wt% or less, such as 10wt% or less or 5wt% or less, e.g. from 0.5 to 10wt% or from 1 to 8wt%.
  • the water-reducing concrete admixture does not comprise formaldehyde. Likewise, in one embodiment, the water-reducing concrete admixture does not comprise tri-isobutyl phosphate. It may be that neither formaldehyde nor triisobutyl phosphate is present.
  • the water-reducing concrete admixture may optionally be provided in combination with a solvent. This may be useful in relation to the ease of addition of the admixture when mixing the concrete.
  • the solvent may, in one embodiment, be water.
  • the lignosulfonate-replacement agent comprises sodium metabisulphite, and it may be that the lignosulfonate-replacement agent is sodium metabisulphite.
  • the sodium metabisulphite may be provided in the form of a powder or in the form of a solution, especially an aqueous solution, e.g. as a 30-60 or 30-50% wt/wt solution in water, such as a 35-45% wt/wt solution in water.
  • the sodium metabisulphite may be provided in a non-food grade form, as this is more cost-effective.
  • there may, for example, be ppm level impurities of metal ions such as Fe ions.
  • the lignosulfonate-replacement agent is not sodium metabisulphite.
  • the lignosulfonate-replacement agent comprises sodium nitrate and it may be that the lignosulfonate-replacement agent is sodium nitrate.
  • the sodium nitrate may be provided in the form of a solution, especially an aqueous solution, e.g. as a 30-60% wt/wt solution in water.
  • the lignosulfonate-replacement agent comprises sodium naphthalene, and it may be that the lignosulfonate-replacement agent is sodium naphthalene.
  • the sodium naphthalene may be provided in the form of a solution, especially an aqueous solution, e.g. as a 30-60% wt/wt solution in water.
  • the admixtures of the present invention may suitably be mixed with concrete at addition levels of from 0.5 to 5wt%, e.g. from 1 to 3wt%.
  • the trial concretes were prepared using a pan type mixer, with 10 dm 3 volume mixes being prepared for testing.
  • the admixtures according to the invention provide cost-effective alternatives to the currently used sodium lignosulfonate-based admixtures.

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Abstract

The present invention provides the use of one or more agent selected from sodium metabisulphite, sodium nitrate, sodium naphthalene, calcium metabisulphite, calcium nitrate, calcium naphthalene and combinations thereof, as a water-reducing additive for concrete. The one or more agent may be used to partly or fully replace lignosulfonate material in a concrete admixture.

Description

CONCRETE ADMIXTURES
Field of the Invention
The present invention relates to admixtures for use in concrete.
Background to the Invention
Concrete is a construction material formed from a mixture of cement, aggregates (sand and stone) and water. The water used in concrete activates the cement, which acts as the binding agent. The aggregates (coarse and fine) in the mix are bound together by the cement as it sets and cures to produce a hardened concrete. Mixes that use larger aggregates tend to be stronger than those with finer aggregates. Importantly, the less water that is added to a concrete mixture, the stronger that mixture will be.
The cement may commonly be hydraulic cement, such as Portland cement. Portland cement (also known as Ordinary Portland Cement or OPC) may be defined as a cementitious material meeting the requirements of ASTM Cl 50 or the requirements of European Standard EN 197-1.
Portland cement is prepared by heating a mixture of raw components (including calcium carbonate, aluminium silicate, silicon dioxide and miscellaneous iron oxides) to a sintering temperature (usually about 1450°C), resulting in the formation of clinker. Portland cement clinker is formed by the reaction of calcium oxide with acidic components to give primarily tricalcium silicate, dicalcium silicate, tricalcium aluminate, and a ferrite phase “C4AF” (tetracalcium aluminoferrite).
This clinker is ground with calcium sulphate (usually in the form of gypsum) in a grinding mill to provide the cement in the form of a fine, homogeneous powder. Other additives or cement replacements can be incorporated before or after the milling process. These include fillers and OPC replacements, such as calcium carbonate and other minerals, ground granulated blast furnace slag, natural pozzolans and pulverised fuel ash (PFA). The components that form the cement powder (clinker, calcium sulphate, and optional additives such as fillers and cement replacements) may be referred to as the cement composition. The strength of concrete is important, because it is used to make articles that need to have this property. For example, roads, pavements, bridges, walls, buildings and foundations are often made from concrete.
Concrete admixtures are commonly added during mixing of the cement, aggregates and water, to enhance specific properties of the fresh or hardened concrete, e.g. workability, durability, or early and/or final strength.
Concrete admixtures may include one or more water-reducing agent. Water-reducing agents are additives that can reduce the amount of water that needs to be used for mixing, and that can increase the strength of concrete without adversely impacting concrete workability. A concrete admixture that includes one or more water-reducing agent may be referenced as a water-reducing concrete admixture.
Conventionally, sulfonated melamine resin salts, polycarboxylates, salts of highly condensed naphthalene sulfonic acid formaldehyde, lignin sulfonates (lignosulfonates) and the like have been used as water reducing agents.
The aim of the present invention is to provide alternatives to lignosulphonate-based admixtures, whereby said alternatives are more cost-effective but possess a waterreducing capability equal to or greater than that of lignosulphonate admixtures.
Summary of the Invention
The present invention provides, in a first aspect, the use of one or more agent selected from sodium metabisulphite, sodium nitrate, sodium naphthalene, calcium metabisulphite, calcium nitrate, calcium naphthalene and combinations thereof, as a water-reducing additive for concrete.
In particular, the one or more agent may be used to partly or fully replace lignosulfonate material in a concrete admixture. As discussed above, lignosulfonate material, such as sodium lignosulfonate, is commonly used as a water-reducing additive for concrete.
Being able to use less lignosulfonate material has the technical benefit of providing a cheaper water-reducing concrete admixture whilst still achieving good results. In general, the present invention has provided new options for reducing the amount of water used for mixing. These new options can increase the strength of concrete without adversely impacting concrete workability.
These new options involve the use of the following agents: sodium metabisulphite, sodium nitrate, sodium naphthalene, calcium metabisulphite, calcium nitrate, or calcium naphthalene.
When sodium naphthalene is present, it is preferably in the form of sodium naphthalene sulfonate.
When calcium naphthalene is present, it is preferably in the form of calcium naphthalene sulfonate.
The skilled person will appreciate that, provided there are no compatibility issues, more than one of these agents can be used together in combination, but it is not necessary to use more than one. In one embodiment, only one of these agents is used. In another embodiment, a combination of two or more of these agents is used.
In particular, it has been identified by the inventors that each of these agents can be effectively and successfully used to partly or fully replace lignosulfonate material in a water-reducing concrete admixture.
Thus, the present invention provides, in a second aspect, a water-reducing concrete admixture comprising: a) one or more agent selected from sodium metabisulphite, sodium nitrate, sodium naphthalene, calcium metabisulphite, calcium nitrate, calcium naphthalene and combinations thereof; and b) lignosulfonate material.
This has the benefit that less lignosulfonate material can be used, thereby reducing costs, whilst still achieving good results.
The lignosulfonate material may, for example, be selected from sodium lignosulfonate, calcium lignosulfonate, magnesium lignosulfonate, potassium lignosulfonate, and combinations thereof. In one embodiment, the lignosulfonate material comprises or is sodium lignosulfonate.
It has also been identified by the inventors that each of the above agents, and in particular sodium metabisulphite, can be effectively and successfully used in combination with polymeric material which is vinyl copolymer (especially vinyl acetate copolymer) and/or polycarboxylate and/or polycarboxylate ether, to fully replace lignosulfonate material in a water-reducing concrete admixture.
The present invention therefore also provides, in a third aspect, a water-reducing concrete admixture comprising: a) one or more agent selected from sodium metabisulphite, sodium nitrate, sodium naphthalene, calcium metabisulphite, calcium nitrate, calcium naphthalene, and combinations thereof; and b) polymeric material which is selected from vinyl copolymers (especially vinyl acetate copolymer), polycarboxylate, polycarboxylate ether, and combinations thereof.
This has the benefit that no lignosulfonate material needs to be used to achieve good results and the admixture is more cost-effective than lignosulfonate-based admixtures.
In one embodiment, the agent a) comprises or is sodium metabisulphite.
It has further been identified by the inventors that each of the above agents can be effectively and successfully used in combination with a blend of modified sugars to fully replace lignosulfonate material in a water-reducing concrete admixture.
The present invention therefore further provides, in a fourth aspect, a water-reducing concrete admixture comprising: a) one or more agent selected from sodium metabisulphite, sodium nitrate, sodium naphthalene, calcium metabisulphite, calcium nitrate, calcium naphthalene and combinations thereof; and b) a blend of modified sugars comprising two or more (e.g. three or more) of: sodium gluconate, potassium gluconate, glucose syrup, molasses, vinasse and dextrins (e.g. yellow dextrin and/or maltodextrin). This has the benefit that no lignosulfonate needs to be used to achieve good results and the admixture is more cost-effective than lignosulfonate-based admixtures.
In one embodiment, the blend of modified sugars comprises both glucose syrup and molasses; in one preferred embodiment the glucose syrup and molasses are included in a weight ratio of 0.75: 1 or more, preferably 1 : 1 or more or 1.1 : 1 or more or 1.2: 1 or more. Having at least as much glucose syrup as molasses, by weight in the blend may be beneficial.
In one embodiment, the blend of modified sugars comprises both glucose syrup and sodium gluconate; in one preferred embodiment the glucose syrup and sodium gluconate are included in a weight ratio of 0.5: 1 or more, preferably 0.6: 1 or more or 0.7: 1 or more. Having at least half as much glucose syrup as sodium gluconate, by weight in the blend may be beneficial.
In one embodiment, the agent a) is selected from sodium nitrate and sodium naphthalene and combinations thereof.
In one embodiment, the water-reducing concrete admixture does not comprise formaldehyde.
In one embodiment, the water-reducing concrete admixture does not comprise triisobutyl phosphate.
The present invention further provides, in a fifth aspect, a method of producing concrete, the method comprising: mixing cement, aggregates and water together with a water-reducing concrete admixture as defined in any one of the second to fourth aspects.
In one embodiment, the water-reducing concrete admixture is added at an addition level of from 0.5 to 5wt%, e.g. from 1 to 3wt% or from 1 to 2wt% (with respect to the total weight of the mixture).
The cement may be hydraulic cement, such as Portland cement. Detailed Description of the Invention
In the present invention, one or more agent selected from sodium metabisulphite, sodium nitrate, sodium naphthalene, calcium metabisulphite, calcium nitrate, calcium naphthalene and combinations thereof, is used as a water-reducing additive for concrete. These agents have been identified as cost-effective replacements for lignosulfonate material and they can replace some or all of the lignosulfonate material used in a waterreducing concrete admixture.
When sodium naphthalene is present, it is preferably in the form of sodium naphthalene sulfonate.
When calcium naphthalene is present, it is preferably in the form of calcium naphthalene sulfonate.
The skilled person will appreciate that, provided there are no compatibility issues, more than one of these agents can be used together in combination, but it is not necessary to use more than one. In one embodiment, only one of these agents is used. In another embodiment, a combination of two or more of these agents is used.
In one embodiment, the agent is selected from sodium metabisulphite, sodium nitrate and sodium naphthalene.
In all aspects of the invention, the ligno sulfonate material that is fully or partly replaced may, in particular, be sodium lignosulfonate. However, it could alternatively or additionally be other lignosulfonate material, such as calcium lignosulfonate or magnesium lignosulfonate or potassium lignosulfonate.
Partial replacement
In one embodiment, there is a partial replacement of the lignosulfonate material. Thus, a water-reducing concrete admixture comprises (a) one or more lignosulfonate- replacement agent selected from sodium metabisulphite, sodium nitrate, sodium naphthalene, calcium metabisulphite, calcium nitrate, calcium naphthalene and combinations thereof and (b) lignosulfonate material. It may be that the weight ratio of lignosulfonate-replacement agent to lignosulfonate material is from 1 :50 to 50: 1, such as from 1 :40 to 40: 1, preferably from 1 :30 to 30: 1, e.g. it may be from 1 :25 to 25: 1 or from 1 :20 to 20: 1 or from 1 : 15 to 15: 1. In one preferred embodiment it may be that the weight ratio of lignosulfonate-replacement agent to lignosulfonate material is from 1 : 10 to 10: 1, such as from 1 :7 to 7: 1, preferably from 1 :5 to 5: 1.
In one embodiment the weight ratio of lignosulfonate-replacement agent to lignosulfonate material is from 4: 1 to 50: 1, such as from 4: 1 to 10: 1 or from 4: 1 to 9: 1. In one embodiment the weight ratio of lignosulfonate-replacement agent to lignosulfonate material is from 2: 1 to 50: 1, such as from 2: 1 to 10: 1 or from 2: 1 to 9: 1. In one embodiment the weight ratio of lignosulfonate-replacement agent to lignosulfonate material is from 1 : 1 to 50: 1, such as from 1 : 1 to 10: 1 or from 1 : 1 to 9: 1.
In one embodiment there is at least twice as much lignosulfonate-replacement agent as lignosulfonate material, e.g. at least three times as much.
In one embodiment, the majority of the water-reducing concrete admixture is lignosulfonate-replacement agent and lignosulfonate material (e.g. 60wt% or more, or 70wt% or more, or 80wt% or more, such as 90wt% or more of the water-reducing concrete admixture). In one embodiment, it may be that the water-reducing concrete admixture consists essentially of lignosulfonate-replacement agent and lignosulfonate material or consists only of lignosulfonate-replacement agent and lignosulfonate material.
It may optionally be that other additives may be present in the water-reducing concrete admixture, e.g. in amounts of 15wt% or less, such as 10wt% or less, e.g. from 0.5 to 10wt% or from 1 to 8wt%. These other additives may be materials known in the art for use in concrete admixtures, e.g. surfactants (air entraining agents and/or defoamers) and/or amines (known for use as strength enhancers and/or set accelerators) and/or defoamers and/or biocides.
Amines such as triethanolamine and tri-isopropanolamine and diethanol isopropanolamine are, in particular, known for use in concrete and may optionally be present. Specific examples of additives that may be present in the present invention include sodium lauryl ether sulphate, triethanolamine and tri-isopropanolamine. Triisobutylphosphate and formaldehyde are also examples of other additives that can, in embodiments, be present.
It may optionally be that melamine and/or sulfonated melamine resin salts are included as additives, e.g. in amounts of 15wt% or less, such as 10wt% or less or 5wt% or less, e.g. from 0.5 to 10wt% or from 1 to 8wt%. These are known in the art as water-reducing agents, but in the present invention are used in lower amounts than is conventional.
In one embodiment, the lignosulfonate-replacement agent comprises sodium metabisulphite, and in particular it may be that the lignosulfonate-replacement agent is sodium metabisulphite.
The sodium metabisulphite may be provided in the form of a powder or in the form of a solution, especially an aqueous solution, e.g. as a 30-60 or 30-50% wt/wt solution in water, such as a 35-45% wt/wt solution in water. In embodiments, the sodium metabisulphite may be provided in a non-food grade form, as this is more cost-effective. Thus there may, for example, be ppm level impurities of metal ions such as Fe ions.
Full replacement
In another embodiment, there is full replacement of the lignosulfonate material. Thus a water-reducing concrete admixture comprises one or more lignosulfonate-replacement agent selected from sodium metabisulphite, sodium nitrate, sodium naphthalene, calcium metabisulphite, calcium nitrate, calcium naphthalene and combinations thereof and comprises no lignosulfonate material.
In such embodiments, the lignosulfonate-replacement agent may suitably be used in combination with a supplemental active agent. The supplemental active agent may be (i) polymeric material which is selected from vinyl copolymers (especially vinyl acetate copolymer), polycarboxylate, polycarboxylate ether, and combinations thereof, or it may be (ii) a blend of modified sugars comprising two or more (e.g. three or more) of: sodium gluconate, potassium gluconate, glucose syrup, molasses, vinasse and dextrins (e.g. yellow dextrin and/or maltodextrin), or it may be (i) and (ii). It may be that the water-reducing concrete admixture comprises: a) one or more lignosulfonate-replacement agent selected from sodium metabisulphite, sodium nitrate, sodium naphthalene, calcium metabisulphite, calcium nitrate, calcium naphthalene and combinations thereof; and b) a supplemental active agent which comprises polymeric material which is selected from vinyl copolymers (especially vinyl acetate copolymer), polycarboxylate, polycarboxylate ether, and combinations thereof.
In one embodiment, the supplemental active agent is vinyl acetate copolymer. The vinyl acetate copolymer may be provided in liquid form.
In another embodiment, the supplemental active agent is vinyl acetate copolymer together with a blend of modified sugars comprising two or more (e.g. three or more) of: sodium gluconate, potassium gluconate, glucose syrup, molasses, vinasse and dextrins (e.g. yellow dextrin and/or maltodextrin); for example, the blend may comprise sodium or potassium gluconate together with glucose syrup and molasses.
In one embodiment, the blend of modified sugars comprises both glucose syrup and molasses; in one preferred embodiment the glucose syrup and molasses are included in a weight ratio of 0.5: 1 or more, especially 0.75: 1 or more, preferably 1 : 1 or more, e.g. 1.1 : 1 or more, or 1.2: 1 or more. Having at least as much glucose syrup as molasses, by weight in the blend may be beneficial.
In one embodiment, the blend of modified sugars comprises both glucose syrup and sodium gluconate; in one preferred embodiment the glucose syrup and sodium gluconate are included in a weight ratio of 0.3: 1 or more, especially 0.5: 1 or more, preferably 0.6: 1 or more or 0.7: 1 or more. Having at least half as much glucose syrup as sodium gluconate, by weight in the blend may be beneficial. In some embodiments, it may be that the sodium gluconate is replaced, partly or fully, by potassium gluconate.
It may be that the weight ratio of lignosulfonate-replacement agent to the polymeric material (e.g. vinyl acetate copolymer) is from 1 :50 to 50: 1, such as from 1 :40 to 40: 1, preferably from 1 :30 to 30: 1, e.g. it may be from 1 :25 to 25: 1 or from 1 : 20 to 20: 1 or from 1 : 15 to 15: 1. In one preferred embodiment it may be that the weight ratio of lignosulfonate-replacement agent to the polymeric material (e.g. vinyl acetate copolymer)is from 1:10 to 10:1, such as from 1:7 to 7:1, preferably from 1:5 to 5:1 or from 1:3 to 3:1 or from 1:2 to 2:1. In one embodiment, the weight ratio of lignosulfonate-replacement agent to the polymeric material (e.g. vinyl acetate copolymer) is from 1:1 to 10:1, such as from 1:1 to 7:1, preferably from 1:1 to 5:1 or from 1:1 to 3:1 or from 1:1 to 2:1.
It may be that the weight ratio of lignosulfonate-replacement agent to the blend of modified sugars is from 1:50 to 50:1, such as from 1:40 to 40:1, preferably from 1:30 to 30:1, e.g. it may be from 1:25 to 25:1 or from 1 : 20 to 20: 1 or from 1:15 to 15:1. In one preferred embodiment it may be that the weight ratio of lignosulfonate-replacement agent to the blend of modified sugars is from 1:10 to 10:1, such as from 1:7 to 7:1, preferably from 1:5 to 5:1 or from 1 :3 to 3: 1 or from 1 :2 to 2: 1. In one embodiment, it may be that the weight ratio of lignosulfonate-replacement agent to the blend of modified sugars is from 1:10 to 1:1, such as from 1:7 to 1:1, preferably from 1:5 to 1:1 or from 1 : 3 to 1 : 1 or from 1 : 2 to 1:1.
In one embodiment, the majority of the water-reducing concrete admixture is lignosulfonate-replacement agent and supplemental active agent (e.g. 60wt% or more, or 70wt% or more, or 80wt% or more, such as 90wt% or more of the water-reducing concrete admixture). In one embodiment it may be that the water-reducing concrete admixture consists essentially of lignosulfonate-replacement agent and supplemental active agent or consists only of lignosulfonate-replacement agent and supplemental active agent.
It may optionally be that other additives may be present in the water-reducing concrete admixture, e.g. in amounts of 15wt% or less, such as I0wt% or less, e.g. from 0.5 to 10wt% or from 1 to 8wt%. These other additives may be materials known in the art for use in concrete admixtures, e.g. surfactants (air entraining agents and/or defoamers) and/or amines (known for use as strength enhancers and/or set accelerators) and/or defoamers and/or biocides.
Amines such as triethanolamine and tri-isopropanolamine and diethanol isopropanolamine are, in particular, known for use in concrete and may optionally be present. Specific examples of additives that may be present in the present invention include sodium lauryl ether sulphate, triethanolamine and tri-isopropanolamine. Triisobutylphosphate and formaldehyde are also examples of other additives that can, in embodiments, be present.
It may optionally be that melamine and/or sulfonated melamine resin salts are included as additives, e.g. in amounts of 15wt% or less, such as 10wt% or less or 5wt% or less, e.g. from 0.5 to 10wt% or from 1 to 8wt%. These are known in the art as water-reducing agents, but in the present invention are used in lower amounts than is conventional.
The water-reducing concrete admixture may optionally be provided in combination with a solvent. This may be useful in relation to the ease of addition of the admixture when mixing the concrete. The solvent may, in one embodiment, be water.
In one embodiment, the lignosulfonate-replacement agent comprises sodium metabisulphite, and in particular it may be that the lignosulfonate-replacement agent is sodium metabisulphite.
The sodium metabisulphite may be provided in the form of a powder or in the form of a solution, especially an aqueous solution, e.g. as a 30-60 or 30-50% wt/wt solution in water, such as a 35-45% wt/wt solution in water. In embodiments, the sodium metabisulphite may be provided in a non-food grade form, as this is more cost-effective. Thus there may, for example, be ppm level impurities of metal ions such as Fe ions.
It may be that the water-reducing concrete admixture comprises: a) one or more lignosulfonate-replacement agent selected from sodium metabisulphite, sodium nitrate, sodium naphthalene, calcium metabisulphite, calcium nitrate, calcium naphthalene and combinations thereof; and b) a supplemental active agent which comprises a blend of modified sugars comprising two or more (e.g. three or more) of: sodium gluconate, potassium gluconate, glucose syrup, molasses, vinasse and dextrins (e.g. yellow dextrin and/or maltodextrin). In some embodiments, the supplemental active agent is a blend of modified sugars comprising sodium or potassium gluconate together with glucose syrup and molasses. Optionally, dextrin, e.g. yellow dextrin, may also be present.
In one embodiment, the supplemental active agent is a blend of modified sugars comprising sodium gluconate, glucose syrup and molasses. Optionally, dextrin, e.g. yellow dextrin, may also be present.
The gluconate may be provided in powder form or may be provided in the form of a solution, e.g. an aqueous solution. The glucose syrup and molasses may be provided in liquid form. When dextrin is used, this may suitably be yellow dextrin in powder form; this can, for example, be added to the liquid components after they have been mixed.
In one embodiment, the blend of modified sugars comprises glucose syrup and molasses in a weight ratio of 0.5: 1 or more, especially 0.75: 1 or more, preferably 1 : 1 or more, e.g. 1.1 : 1 or more, or 1.2: 1 or more. Having at least as much glucose syrup as molasses, by weight in the blend may be beneficial.
In one embodiment, the blend of modified sugars comprises glucose syrup and sodium gluconate in a weight ratio of 0.3: 1 or more, especially 0.5 : 1 or more, preferably 0.6: 1 or more or 0.7: 1 or more. Having at least half as much glucose syrup as sodium gluconate, by weight in the blend may be beneficial. In some embodiments, it may be that the sodium gluconate is replaced, partly or fully, by potassium gluconate.
It may be that the weight ratio of lignosulfonate-replacement agent to the blend of modified sugars is from 1 :50 to 50: 1, such as from 1 :40 to 40: 1, preferably from 1 :30 to 30: 1, e.g. it may be from 1 :25 to 25: 1 or from 1 : 20 to 20: 1 or from 1 : 15 to 15: 1. In one preferred embodiment it may be that the weight ratio of lignosulfonate-replacement agent to the blend of modified sugars is from 1 : 10 to 10: 1, such as from 1 :7 to 7: 1, preferably from 1 :5 to 5: 1 or from 1 :3 to 3: 1. In one embodiment, it may be that the weight ratio of lignosulfonate-replacement agent to the blend of modified sugars is from 1 :5 to 10: 1, such as from 1 :3 to 7: 1, preferably from 1 :2 to 5: 1 or from 1 :2 to 3: 1.
In one embodiment, the majority of the water-reducing concrete admixture is lignosulfonate-replacement agent and supplemental active agent (e.g. 60wt% or more, or 70wt% or more, or 80wt% or more, such as 90wt% or more of the water-reducing concrete admixture). In one embodiment, it may be that the water-reducing concrete admixture consists essentially of lignosulfonate-replacement agent and supplemental active agent or consists only of lignosulfonate-replacement agent and supplemental active agent.
It may optionally be that other additives may be present in the water-reducing concrete admixture, e.g. in amounts of 15wt% or less, such as 10wt% or less, e.g. from 0.5 to 10wt% or from 1 to 8wt%. These other additives may be materials known in the art for use in concrete admixtures, e.g. surfactants (air entraining agents and/or defoamers) and/or amines (known for use as strength enhancers and/or set accelerators) and/or defoamers and/or biocides.
Amines such as triethanolamine and tri-isopropanolamine and diethanol isopropanolamine are, in particular, known for use in concrete and may optionally be present.
Specific examples of additives that may be present in the present invention include sodium lauryl ether sulphate, triethanolamine and tri-isopropanolamine. Triisobutylphosphate and formaldehyde are also examples of other additives that can, in embodiments, be present.
It may optionally be that melamine and/or sulfonated melamine resin salts are included as additives, e.g. in amounts of 15wt% or less, such as 10wt% or less or 5wt% or less, e.g. from 0.5 to 10wt% or from 1 to 8wt%. These are known in the art as water-reducing agents, but in the present invention are used in lower amounts than is conventional.
In one embodiment, the water-reducing concrete admixture does not comprise formaldehyde. Likewise, in one embodiment, the water-reducing concrete admixture does not comprise tri-isobutyl phosphate. It may be that neither formaldehyde nor triisobutyl phosphate is present.
The water-reducing concrete admixture may optionally be provided in combination with a solvent. This may be useful in relation to the ease of addition of the admixture when mixing the concrete. The solvent may, in one embodiment, be water. In one embodiment, the lignosulfonate-replacement agent comprises sodium metabisulphite, and it may be that the lignosulfonate-replacement agent is sodium metabisulphite.
The sodium metabisulphite may be provided in the form of a powder or in the form of a solution, especially an aqueous solution, e.g. as a 30-60 or 30-50% wt/wt solution in water, such as a 35-45% wt/wt solution in water. In embodiments, the sodium metabisulphite may be provided in a non-food grade form, as this is more cost-effective. Thus there may, for example, be ppm level impurities of metal ions such as Fe ions.
However, in another embodiment, the lignosulfonate-replacement agent is not sodium metabisulphite.
In one embodiment, the lignosulfonate-replacement agent comprises sodium nitrate and it may be that the lignosulfonate-replacement agent is sodium nitrate. The sodium nitrate may be provided in the form of a solution, especially an aqueous solution, e.g. as a 30-60% wt/wt solution in water.
In one embodiment, the lignosulfonate-replacement agent comprises sodium naphthalene, and it may be that the lignosulfonate-replacement agent is sodium naphthalene.
The sodium naphthalene may be provided in the form of a solution, especially an aqueous solution, e.g. as a 30-60% wt/wt solution in water.
Use of the admixtures
The admixtures of the present invention may suitably be mixed with concrete at addition levels of from 0.5 to 5wt%, e.g. from 1 to 3wt%.
The admixtures of the present invention allow good water-reduction to be achieved and good strength characteristics to be achieved. The invention will now be further illustrated by reference to the following non-limiting worked examples.
Examples
Concrete admixture formulations were made by mechanically mixing together the components set out in Table la and Table lb below, at about room temperature (15- 35°C). The amounts given are parts by weight. The materials used in the examples were all obtained from commercial suppliers.
Figure imgf000017_0002
Table la- prepared formulations
Figure imgf000017_0001
Table lb - further prepared formulation
The prepared admixtures were then tested as follows:
Concrete was mixed using fine aggregate and coarse aggregate and cement from commercial suppliers.
The trial concretes were prepared using a pan type mixer, with 10 dm3 volume mixes being prepared for testing.
The tests carried out were all according to EN standards, in particular:
• EN 12350-2: Testing fresh concrete - Part 2 : Slump test
• EN 12350-6: Testing fresh concrete - Part 6 : Density
• EN 12350-7: Testing fresh concrete - Part 7 : Air content of fresh concrete - Pressure methods
• EN 12390-3: Testing hardened concrete - Part 3 : Compressive strength of test specimens
Each of the admixtures as prepared according to Table la and lb achieved good results for water-reduction and concrete strength.
Exemplary results are set out below:
Figure imgf000019_0001
Reference = 100% Na lignosulfonate
Figure imgf000020_0001
Table 3: water content and strength results for selected admixtures
Reference = 100% Na lignosulfonate
Figure imgf000021_0001
Table 4: - water content and strength results for DI admixture
Conclusion The admixtures according to the invention were all able to achieve water-reduction and strength characteristics comparable with or better than a sodium lignosulfonate reference.
Therefore, the admixtures according to the invention provide cost-effective alternatives to the currently used sodium lignosulfonate-based admixtures.

Claims

22 CLAIMS
1. The use of one or more agent selected from sodium metabisulphite, sodium nitrate, sodium naphthalene, calcium metabisulphite, calcium nitrate, calcium naphthalene and combinations thereof, as a water-reducing additive for concrete.
2. The use according to claim 1, wherein said agent is used to partly or fully replace lignosulfonate material in a concrete admixture.
3. A water-reducing concrete admixture comprising: a) one or more agent selected from sodium metabisulphite, sodium nitrate, sodium naphthalene, calcium metabisulphite, calcium nitrate, calcium naphthalene and combinations thereof; and b) lignosulfonate material.
4. A water-reducing concrete admixture comprising: a) one or more agent selected from sodium metabisulphite, sodium nitrate, sodium naphthalene, calcium metabisulphite, calcium nitrate, calcium naphthalene and combinations thereof; and b) polymeric material which is selected from vinyl copolymers (especially vinyl acetate copolymer), polycarboxylate, polycarboxylate ether, and combinations thereof.
5. The water-reducing concrete admixture according to claim 4, wherein the admixture further comprises a blend of modified sugars comprising, e.g. comprising sodium gluconate, glucose syrup and molasses.
6. The water-reducing concrete admixture according to claim 4 or claim 5, wherein the weight ratio of a) to b) is from 1 : 10 to 10: 1.
7. The water-reducing concrete admixture according to any one of claims 3 to 6, wherein the agent a) comprises sodium metabisulphite or is sodium metabisulphite.
8. A water-reducing concrete admixture comprising: a) one or more agent selected from sodium metabisulphite, sodium nitrate, sodium naphthalene, calcium metabisulphite, calcium nitrate, calcium naphthalene and combinations thereof; and b) a blend of modified sugars comprising two or more of: sodium gluconate, potassium gluconate, glucose syrup, molasses, vinasse and dextrins (e.g. yellow dextrin and/or maltodextrin), such as a blend comprising sodium gluconate, glucose syrup and molasses.
9. The water-reducing concrete admixture according to claim 8, wherein the blend of modified sugars comprises glucose syrup and molasses in a weight ratio of 0.75: 1 or more.
10. The water-reducing concrete admixture according to claim 9, wherein the blend of modified sugars comprises glucose syrup and molasses in a weight ratio of 1 : 1 or more.
11. The water-reducing concrete admixture according to any one of claims 8 to 10, wherein the blend of modified sugars comprises glucose syrup and sodium gluconate in a weight ratio of 0.5: 1 or more.
12. The water-reducing concrete admixture according to claim 11, wherein the blend of modified sugars comprises glucose syrup and sodium gluconate in a weight ratio of 0.6: 1 or more.
13. The water-reducing concrete admixture according to any one of claims 3 to 12, wherein any other additives that are present in the water-reducing concrete admixture are included in amounts of 15wt% or less.
14. The water-reducing concrete admixture according to any one of claims 3 to 13, wherein any other additives that are present in the water-reducing concrete admixture are selected from surfactants and amines.
15. The water-reducing concrete admixture according to any one of claims 3 to 14, wherein the admixture is provided in combination with a solvent, such as water.
16. The water-reducing concrete admixture according to any one of claims 3 to 15, wherein the admixture comprises sodium metabisulphite, sodium nitrate, or sodium naphthalene.
17. A method of producing concrete, the method comprising: mixing cement, aggregates and water together with a water-reducing concrete admixture as defined in any one of claims 3 to 16.
18. The method according to claim 17, wherein the water-reducing concrete admixture is added at an addition level of from 0.5 to 5wt%.
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