JP7837720B2 - Additives and methods for using them, mineral binder compositions, methods for accelerating the hardening of mineral binder compositions, and methods for producing fluid mineral binder compositions. - Google Patents

Description

This invention relates to an additive for accelerating the hardening of a mineral binder composition. Furthermore, this invention relates to a mineral binder composition comprising at least an accelerating additive and a mineral binder. Further aspects of this invention relate to a method for accelerating the hardening of a mineral binder composition with an additive and the use of the additive as a hardening accelerator in a mineral binder composition.

There are many applications requiring mineral binder compositions, such as mortar or concrete, that exhibit high initial strength, for disaster recovery, road and runway maintenance, and in the manufacture of precast components. This is necessary because precast components need to be removed from formwork, transported, stacked, or prestressed within a few hours, or because structures built for disaster recovery, roads, and runways need to be transportable or load-bearing within a short period of time.

In practice, to achieve this objective, high-performance concrete mixes with a low wt/c ratio, i.e., a high cement content, are used, as well as heat treatment or steam treatment. These treatments require large amounts of energy and additional equipment. Therefore, such treatments should be avoided, and alternative methods to accelerate the hardening process are needed.

Various additives can be used as alternatives to heat treatment or steam treatment, but satisfactory results are not always obtained from these additives. In fact, many substances exist that are known to accelerate the solidification and hardening of mineral binder compositions. Commonly used substances include, for example, highly alkaline substances such as alkali metal hydroxides, alkali metal carbonates, alkali metal silicates, alkali metal aluminates, and alkaline earth metal chlorides. However, in some cases, these substances reduce the ultimate strength and durable adhesion of concrete.

Patent Documents 1 and 2 disclose alkali-free solidification accelerators for hydraulic binders that are said to avoid these drawbacks. To accelerate the solidification and hardening of hydraulic binders, such as cement, lime, hydraulic lime, and gypsum, and furthermore, mortar and concrete produced therefrom, alkali-free solidification and hardening accelerators are added, and the accelerators include aluminum hydroxide and optionally aluminum salts and organic carboxylic acids.

While such known accelerators do indeed accelerate the hardening of mineral binder compositions, they often have drawbacks, such as relatively low initial strength (e.g., within the first few hours) or poor workability of the newly prepared mineral binder composition when large amounts of these accelerators are used.

To improve the workability of mineral binder compositions, dispersants are widely used as additives for mineral binder compositions. Patent Document 3 (Toho Chemical Industry Co., Ltd.) describes, for example, a cement dispersant containing a copolymer obtained by reacting three different components. This cement dispersant has particularly excellent water-reducing properties, thereby reducing the delay in solidification.

However, dispersants and accelerators often interact with each other in undesirable ways. Specifically, there is a strong demand to simultaneously achieve high initial strength and good workability in mineral binder compositions. Simply combining accelerators and dispersants usually does not yield the desired results.

Therefore, a new and improved solution that can overcome the aforementioned shortcomings as much as possible is still needed.

European Patent No. 0076927B1 European Patent No. 0946451B1 U.S. Patent Application Publication No. 2013/0018162A1

The object of the present invention is to provide a curing accelerator, particularly in the form of an additive, that accelerates the curing process of a mineral binder composition, while substantially maintaining its workability, thereby allowing the accelerated mixture to be processed further over a period of time. In particular, the curing accelerator should be capable of increasing the initial strength of the mineral binder composition, especially within 6 to 8 hours after mixing.

Surprisingly, it has been found that this objective can be achieved by the features of claim 1. Therefore, the core of the present invention is an additive for accelerating the curing of a mineral binder composition, comprising a copolymer component and an accelerator component,
The copolymer components are components (A), (B), and optionally (C):
(A) An ester compound, in a quantity of 1 mole of formula (1)
RO-(AO) _n -H (1)
(In the formula, R is a _C1-12 alkyl group, A is a _C2-4 alkylene group, and n is an integer from 0 to 7.)
The compound of formula (1) is obtained by adding 0 to 10 moles of _C2-4 alkylene oxide to at least one of the compounds, and then subjecting the resulting adduct to a reaction with an α,β-unsaturated carboxylic acid, wherein the compound of formula (1) contains a component compound having n of 3 or less in an amount of 5% by mass or less relative to the total mass of the compound of formula (1), and is an ester compound.
(B) comprising a further α,β-unsaturated carboxylic acid or a salt thereof, and (C) optionally comprising a copolymer obtained from the reaction of at least one further copolymerizable monomer or a salt thereof;
The stimulating ingredients are,
a) At least one thiocyanate, in particular sodium thiocyanate,
b) at least one nitrate, particularly calcium nitrate; and c) at least one alkanolamine, particularly methyldiethanolamine,
Regarding additives.

By using the additive of the present invention, which includes a combination of copolymer and accelerator components, a mineral binder composition with high initial compressive strength can be obtained within 6 to 8 hours after mixing. Surprisingly, despite the high curing-accelerating effect of the additive of the present invention, the slump and workability of the mineral binder composition can be maintained at a rather high level.

Without being constrained by theory, the copolymer according to the present invention, unlike other copolymers, possesses a specific structure and a specially tuned molecular weight distribution, which is considered to have a far less adverse effect on the accelerator component. Therefore, the delay in the strength development of the mineral binder composition is significantly reduced. Furthermore, the accelerator components, based on three different classes of accelerators, appear to act synergistically with each other and in combination with the copolymer components.

In particular, the additives of the present invention are especially effective in mineral binder compositions containing Type III cement as defined in Standard ASTM C150, i.e., high initial strength cement.

Therefore, the additives of the present invention are particularly advantageous for producing mineral binder compositions, such as concrete compositions, that have high initial compressive strength and good workability without requiring steam curing or other special curing conditions. Such types of mineral binder compositions are of great interest for use in disaster recovery, road and runway maintenance, and the manufacture of precast components.

Further aspects of the present invention are the subject of further independent claims. Particularly preferred embodiments are outlined throughout the description and dependent claims.

A first aspect of the present invention is an additive for accelerating the curing of a mineral binder composition, comprising a copolymer component and an accelerator component.
The copolymer components are components (A), (B), and optionally (C):
(A) An ester compound, in a quantity of 1 mole of formula (1)
RO-(AO) _n -H (1)
(In the formula, R is a _C1-12 alkyl group, A is a _C2-4 alkylene group, and n is an integer from 0 to 7);
The compound of formula (1) is obtained by adding 0 to 10 moles of _C2-4 alkylene oxide to at least one of the compounds, and then subjecting the resulting adduct to a reaction with an α,β-unsaturated carboxylic acid, wherein the compound of formula (1) contains a component compound having n of 3 or less in an amount of 5% by mass or less relative to the total mass of the compound of formula (1), and is an ester compound.
(B) comprising a further α,β-unsaturated carboxylic acid or a salt thereof, and (C) optionally comprising a copolymer obtained from the reaction of at least one further copolymerizable monomer or a salt thereof;
The stimulating ingredients are,
d) At least one thiocyanate, in particular sodium thiocyanate,
e) at least one nitrate, particularly calcium nitrate; and f) at least one alkanolamine, particularly methyldiethanolamine,
This focuses on additives.

The copolymer component contains a polyalkylene glycol alkyl ether containing a small proportion of alkylene oxide (3 moles or less) and an ester compound derived from an α,β-unsaturated carboxylic acid.

In this invention, the compound of formula (1) contains only a small proportion of components having n 3 or less, that is, a compound containing a component compound having 3 or less moles of alkylene oxide, in an amount of 5% by mass or less relative to the total mass of the compound of formula (1). In a special embodiment, the compound of formula (1) does not contain a certain proportion of components having n 3 or less.

In formula (1), R is preferably a _C1-8 alkyl group, more preferably a _C1-4 alkyl group. Specific examples include a methyl group, an ethyl group, a propyl group, an n-butyl group, a sec-butyl group, and/or a tert-butyl group.

Specific examples of AO include ethyleneoxy groups, propyleneoxy groups, butyleneoxy groups, or mixtures thereof.

In the compound of formula (1), the average number of moles of alkylene oxide added is preferably 4 to 6, more preferably 4 to 5. Therefore, in this case, the distribution of the number of added moles is narrow. This proved particularly advantageous for achieving the advantages of the present invention.

Ether compounds containing a smaller proportion of short-chain polyalkylene glycol chains can be obtained, for example, by adding about 4 moles of _C2-4 alkylene oxide to 1 mole of _C1-12 monohydric alcohol in the presence of an alkaline catalyst, and then separating the portion of the product having 3 moles or less of alkylene oxide by distillation or a similar separation operation.

Ether compounds containing a smaller proportion of short-chain polyalkylene glycol chains can also be obtained directly without distillation or similar separation operations, i.e., by adding alkylene oxides to _C1-12 monohydric alcohols in the presence of an acid catalyst.

Where appropriate, the polyalkylene glycol alkyl ether may be further supplemented with 0 to 10 moles of _C2-4 alkylene oxide.

Ester compound (A) can be obtained by reacting an α,β-unsaturated carboxylic acid with a polyalkylene glycol alkyl ether obtained by the above-described method or a similar method, either as is or in combination with multiple polyalkylene glycol alkyl ethers having various polyalkylene glycol chain lengths.

Examples of α,β-unsaturated carboxylic acids suitable for producing ester compound (A) include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, half-esters of maleic acid, and half-esters of fumaric acid. The most preferred are acrylic acid and/or methacrylic acid. These α,β-unsaturated carboxylic acids were found to be the most preferred from both a technical and economic standpoint.

In a highly preferred embodiment, the ester compound (A) of the present invention is of formula (2):
The ester compound is at least one ester compound, wherein the ester compound contains a component compound having an m of 3 or less in an amount of 5% by mass or less relative to the total mass of the compound, and has an average m of 4.0 to 8.5.

In formula (2), ^R1 is a _C1-12 alkyl group, ^R2 is a hydrogen atom or a methyl group, A is a _C2-4 alkylene group, and m is an integer from 0 to 15, representing the number of moles of alkylene oxide added. Preferred ^R1 and A are the same groups as those previously defined for R and A in relation to the compounds of formula (1).

Examples of suitable further α,β-unsaturated carboxylic acids or their salts (B) include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, half-esters of maleic acid and/or half-esters of fumaric acid. Suitable salts include: alkali metal salts, e.g., salts of lithium, sodium and/or potassium; alkaline earth metal salts, e.g., salts of calcium and/or magnesium; ammonium salts, e.g., ammonium salts and/or tetraoctylammonium salts; and organic amines, e.g., alkanolamines, polyalkylene polyamines and/or their derivatives, e.g., alkylates, alkylene oxide ducts and/or their lower alkylamine salts; and combinations thereof.

Among these, preferred are acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, or combinations of two or more of these acids. In specific embodiments, alkali metal salts, alkaline earth metal salts, and ammonium salts of these acids are used.

In this invention, if appropriate, other copolymerizable monomers (C) may be used in copolymerization in addition to components (A) and (B).

Other copolymerizable monomers are compounds commonly used in polycarboxylic acid-based cement dispersants, i.e., monomers, and may be polyalkylene glycol monoalkenyl ethers, (meth)allyl sulfonic acid (salt), styrene sulfonic acid (salt), alkyl (meth)acrylate esters, styrene, or (meth)acrylamide. Other copolymerizable monomers are not particularly limited, as long as they are monomers capable of copolymerizing with components (A) and (B).

The usable component (C) is, for example, an ester compound of a polyalkylene glycol alkyl ether having the same structure as the ester compound of component (A), except that the length of the alkyl chain and the number of moles of alkylene oxide added differ from those defined for the compound of formula (A). For example, the number of moles of compound (C) added is 20 to 50.

Examples of polyalkylene glycol monoalkenyl ethers include alkenyl ethers formed from polyalkylene glycol and _C3-8 alkenyl ethers. Specific examples include adducts of 3-methyl-3-buten-1-ol and alkylene oxide, and adducts of 2-propen-1-ol (allyl alcohol) and alkylene oxide, as well as their ethers.

Component (C) used in the present invention can also be obtained by condensing monomers, namely compound a (polyalkylene polyamine); compound b (a dibasic acid or an ester of a dibasic acid with a _C1-4 lower alcohol); and compound c (acrylic acid, methacrylic acid, or an ester of acrylic acid or methacrylic acid with a _C1-4 lower alcohol) in a certain proportion to obtain a polyimide polyamine, adding a certain amount of alkylene oxide of compound d, and then copolymerizing the resulting compound.

Non-limiting examples of compound a include: polyalkylene polyamines, e.g., diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, dipropylenetriamine, tripropylenetetramine, and/or tetrapropylenepentamine.

Examples of compound b are as follows: dibasic acids and their _C1-C4 lower alcohol esters, such as loaronic acid, succinic acid, fumaric acid, maleic acid, glutaric acid, adipic acid, pimelic acid, phthalic acid, azelaic acid, and sebacic acid, and esters of these with C1 _-C4 lower alcohols, such as methanol, ethanol, propanol, butanol, and their various isomers. Of these, adipic acid is most preferred from the viewpoint of effectiveness and economy.

Examples of compound c are as follows: acrylic acid or methacrylic acid and its _C1-C4 lower alcohol esters, e.g., acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate and butyl methacrylate.

Polyamide polyamines containing these three components, namely compounds a, b, and c, can be easily obtained by known condensation polymerization techniques. The _C2-4 alkylene oxide of compound d, which is added to the amino residue of the polyamide polyamine, is ethylene oxide, propylene oxide, butylene oxide, or a mixture thereof.

The production of polyamide polyamines, in other words, the condensation polymerization reaction of compounds a, b, and c, can be carried out by a two-step reaction method, for example, by subjecting only compounds a and b to condensation polymerization, then adding a monobasic acid as compound c, and continuing the condensation polymerization; or by a one-step reaction method, where compounds a, b, and c are mixed at once and condensation polymerization is carried out; or by a similar method.

These methods are all considered to yield the same result, because the condensation polymerization reaction (which is an amidation reaction) proceeds according to an amide exchange reaction, and therefore the acrylic acid residue or methacrylic acid residue resulting from compound c ultimately becomes the end of the polyamide chain.

Next, the reaction molar ratios of these three components constituting the polyamide polyamine will be explained. 1.0 mole of compound a (polyalkylene polyamine) is subjected to a reaction with 0.5 to 0.95 moles of compound b (dibasic acid or its ester). The condensation polymerization reaction product obtained by the reaction of compound a and compound b within this molar range—in other words, a condensation polymerization product derived from polyalkylene polyamine and dibasic acid in an average ratio of 2 moles:1 mole to 20 moles:19 moles—is obtained using a polyamide with a certain range of chain length, resulting in a dispersant with high water-reducing performance and maintained slump fluidity. If the chain length of the polyamide is shorter than the above range (when the reaction ratio is lower than 0.5 moles), the desired polyamide polyamine structure cannot be obtained. A chain length longer than the above range (when the reaction ratio is higher than 0.95 moles) is undesirable because the resulting water-reducing performance is significantly reduced.

The amount of alkylene oxide added to the polyamide polyamine is 0 to 8 moles per equivalent of amino residues of the polyamide polyamine. If the amount exceeds 8 moles, the molecular weight of compound A increases, leading to a decrease in the cation equivalent, and therefore, the amphoteric polymer of the present invention will not be sufficiently effective. In the present invention, the addition of alkylene oxide is preferred, and the amount is preferably 0.5 to 6.0 moles, and particularly preferably 1.0 to 5.5 moles, per equivalent of amino residues of the polyamide polyamine.

The ratio of components (A) to (C) involved in copolymerization is preferably (A):(B):(C) = 50-95:5-50:0-40 by mass. More preferably, the ratio of (A):(B):(C) is 70-90:10-30:0-20 by mass.

The method for producing the copolymer of the present invention is not particularly limited and may be a known polymerization method, such as solution polymerization or bulk polymerization using a polymerization initiator.

Solution polymerization can be carried out in either batch or continuous manner. Examples of solvents used include: water and alcohols, e.g., methanol, ethanol, and isopropanol; aromatic or aliphatic hydrocarbons, e.g., benzene, toluene, xylene, cyclohexane, and n-hexane; ester or ketone compounds, e.g., ethyl acetate, acetone, and methyl ethyl ketone; and cyclic ether compounds, e.g., tetrahydrofuran and dioxane. From the viewpoint of the solubility of the monomers used as raw materials and the resulting copolymers, the solvent used is preferably water and at least one chemical species selected from the group consisting of C1 _-C4 lower alcohols, more preferably water.

When polymerization is carried out in aqueous solution, the radical polymerization initiators used are water-soluble polymerization initiators, such as: persulfates, e.g., ammonium persulfate, sodium persulfate, and potassium persulfate; hydrogen peroxide; azoamidine compounds, e.g., 2,2'-azobis-2-methylpropionamidine hydrochloride; cyclic azoamidine compounds, e.g., 2,2'-azobis-2-(2-imidazolin-2-yl)propane hydrochloride; and water-soluble azo compounds, e.g., azonitrile compounds, e.g., 2-carbamoylazoisobutyronitrile.

In parallel with this, accelerators can also be used, including the following: alkali metal sulfites, e.g., sodium bisulfite, metabisulfite, sodium hypophosphite, iron(II) salts, e.g., Mohr's salt, sodium hydroxymethanesulfonate dihydrate, hydroxylamine salts, thiourea, L-ascorbic acid (salt), and erythorbic acid (salt).

Radical polymerization initiators used in solution polymerization using lower alcohols, aromatic hydrocarbons, aliphatic hydrocarbons, ester compounds, or ketone compounds as solvents include: peroxides, e.g., benzoyl peroxide, lauroyl peroxide, and sodium peroxide; hydroperoxides, e.g., t-butyl hydroperoxide and cumene hydroperoxide; or azo compounds, e.g., azobisisobutyronitrile. It is also possible to use accelerators such as amine compounds in parallel with these. When using a mixed solvent of water and lower alcohols, radical polymerization initiators or combinations of radical polymerization initiators and accelerators can be selected and used as needed from the various radical polymerization initiators and accelerators exemplified above.

Radical polymerization initiators used in bulk polymerization include: peroxides, e.g., benzoyl peroxide, lauroyl peroxide, and sodium peroxide; hydroperoxides, e.g., t-butyl hydroperoxide and cumene hydroperoxide; or azo compounds, e.g., azobisisobutyronitrile.

The reaction temperature during copolymerization is not particularly limited; for example, when using a persulfate as an initiator, a suitable reaction temperature range is 30–95°C.

In copolymerization, chain transfer agents can also be used. Examples of usable chain transfer agents include: thiol chain transfer agents, such as mercaptoethanol, thiofrieserol, thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, thiomalic acid, octyl thioglycolate, octyl 3-mercaptopropionic acid, and/or 2-mercaptoethanesulfonic acid. Two or more chain transfer agents can be used in parallel.

The polymerization time is not particularly limited, and its range is, for example, appropriately 0.5 to 10 hours, preferably 0.5 to 8 hours, and more preferably 0.5 to 6 hours. Polymerization times shorter or longer than these ranges are undesirable because they result in a decrease in polymerization rate or productivity.

The method of adding materials dropwise during copolymerization is not particularly limited. Examples include: adding some or all of the monomers to the reaction vessel, followed by dropwise addition of initiators, etc.; adding one or more monomers to the reaction vessel, followed by dropwise addition of other monomers, initiators, chain transfer agents, etc.; adding a monomer mixture, a radical polymerization initiator, and a chain transfer agent dropwise; and adding a mixture of monomers and chain transfer agents, along with a radical polymerization initiator, dropwise. Generally, the timing of their addition is carefully considered, taking into account the reactivity of each monomer.

The copolymer obtained by the method described above can be used as a copolymer component of the additive of the present invention in its acidic state. However, from the viewpoint of preventing acid hydrolysis of the ester, it is preferable to neutralize it with an alkali to obtain the salt form. Examples of alkalis include: hydroxides of alkali metals and alkaline earth metals, ammonia, mono-, di- and tri-alkylamines (containing 2 to 8 carbon atoms), and mono-, di- and tri-alkanolamines (containing 2 to 8 carbon atoms).

The preferred copolymers of the present invention, used as copolymer components in the additives of the present invention, are partially or completely neutralized. A copolymer salt refers to a salt obtained by partially or completely neutralizing an acidic copolymer.

The weight-average molecular weight of the copolymer of the present invention (determined by gel permeation chromatography (hereinafter referred to as "GPC method") in relation to polyethylene glycol) is preferably in the range of 1,000 to 100,000. If the weight-average molecular weight falls outside this range, the resulting water-reducing performance deteriorates significantly, or the desired slump loss reduction effect cannot be obtained. For better water-reducing performance, a weight-average molecular weight in the range of 5,000 to 30,000 is more preferable. The molecular weight can be controlled by adjusting the type and/or amount of radical polymerization initiators, etc., in aqueous solution polymerization. The molecular weight distribution can also be controlled by using chain transfer agents, etc., in combination.

Specific examples of copolymers suitable for use in the copolymer component of the additive of the present invention are described in paragraphs 0103-0139 of Patent Document 3, which is incorporated herein by reference.

The copolymer component particularly includes the copolymer obtained from the reaction of components (A), (B), and optionally (C) in proportions of 10-90% by weight, especially 20-80% by weight, specifically 30-70% by weight, for example 40-60% by weight.

The copolymer component is preferably an aqueous solution. In particular, the copolymer component contains 10 to 90% by weight, especially 20 to 80% by weight, specifically 30 to 70% by weight, for example, 40 to 60% by weight of water.

When preparing a mineral binder composition, such a solution can be easily mixed into the mineral binder composition along with the water mixture.

At least one thiocyanate is selected from alkaline thiocyanates and/or alkaline earth thiocyanates. In particular, at least one thiocyanate is an alkaline thiocyanate. Most preferably, at least one thiocyanate contains or consists of sodium thiocyanate.

At least one nitrate is selected from alkaline nitrates and/or alkaline earth nitrates. In particular, at least one nitrate is an alkaline earth nitrate. Most preferably, at least one nitrate contains or consists of calcium nitrate.

At least one alkanolamine can be selected from, for example, the following: N-ethyldiethanolamine (EDEA), N-butyldiethanolamine (BDEA), triethanolamine (TEA), 2-(diisopropylamino)ethanol, 2-(2-aminoethylamino)ethanol, N,N,N'-trimethylaminoethylethanolamine, N,N'-bis-(2-hydroxyethyl)ethylenediamine, N-methyldiethanolamine (MDEA), diethanol Amines (DEA), 2-amino-2-methyl-1,3-propanediol (AMPD), tris(hydroxymethyl)aminomethane (TRIS), 3-amino-1,2-propanediol (APD), 2-(2-aminoethoxy)ethanol, diisopropanolamine (DiPA), triisopropanolamine (TiPA), N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine (THPED) and/or N-methyldiisopropanolamine (MDiPA). However, other amino alcohols may also be used.

In particular, at least one alkanolamine is a tertiary alkanolamine. Most preferably, at least one alkanolamine includes or consists of N-methyldiethanolamine.

Specifically, the weight ratio of at least one thiocyanate to at least one nitrate is 1:2 to 1:12, particularly 1:3 to 1:10, preferably 1:5 to 1:7, and the weight ratio of at least one thiocyanate to at least one alkanolamine is 1:0.8 to 1:5, particularly 1:1 to 1:3, specifically 1:1.2 to 1:1.8. The advantages of the present invention become particularly apparent with such ratios.

The accelerator component is preferably an aqueous solution or dispersion. In this case, at least one nitrate, at least one thiocyanate, at least one alkanolamine, and various further optional components are dissolved and/or dispersed in water.

In particular, the proportion of water in the accelerator component is 5 to 50% by weight, especially 10 to 40% by weight, specifically 15 to 25% by weight, relative to the weight of the accelerator component.

In a further preferred embodiment, the accelerator component further comprises at least one organic acid. The addition of an organic acid can further improve the accelerator effect of the additive.

It is preferable to use a carboxylic acid, more preferably formic acid and/or acetic acid, as the organic acid. However, generally, all monobasic or polybasic carboxylic acids can be used. It is most preferable that at least one organic acid contains or consists of formic acid.

The weight ratio of at least one thiocyanate to at least one organic acid is preferably 1:0.1 to 1:3, particularly 1:0.3 to 1:2, and specifically 1:0.5 to 1:1.

In a highly preferred embodiment, the accelerator component is
a) 1 to 10% by weight, particularly 2 to 8% by weight, specifically 3 to 6% by weight of at least one thiocyanate, in particular sodium thiocyanate;
b) 30–80% by weight, particularly 40–75% by weight, specifically 55–75% by weight, at least one nitrate, in particular calcium nitrate;
c) 1 to 10% by weight, particularly 3 to 9% by weight, specifically 5 to 8% by weight, of at least one alkanolamine, particularly N-methyldiethanolamine;
d) Optionally, 1 to 10% by weight of at least one carboxylic acid, particularly formic acid;
e) Containing 5-50% by weight, particularly 10-40% by weight, specifically 15-25% by weight of water,
These proportions are given relative to the total weight of the accelerator component.

In one possible embodiment, the additive is a two-component composition comprising a copolymer component in a first container and an accelerator component separated from the first component in a second container. This allows these components to be mixed individually with the mineral binder composition. This facilitates the customization of each additive to meet the specific needs of the mineral binder composition.

In another possible embodiment, the additive is a one-component composition containing a copolymer component and an accelerator component mixed together. This fixes the ratio of the copolymer component to the accelerator component, reducing measurement errors during use.

In particular, the weight ratio of the copolymer component to the total weight of all promoting substances in the promoting agent component is 0.1 to 2, specifically 0.2 to 1, and especially 0.3 to 0.5.

Preferably, the weight ratio of the copolymer component to the accelerator component in the additive is 0.1 to 2, specifically 0.2 to 1, and particularly 0.3 to 0.5.

Further aspects of the present invention relate to a mineral binder composition comprising at least the additives and mineral binders described above. In this composition, the proportion of the additives is preferably 0.01 to 20% by weight, and more particularly 0.1 to 10% by weight, relative to the mineral binder.

The term "mineral binder" refers to a binder that reacts in the presence of water through hydration to form a solid hydrate or hydrate phase. Examples of such binders include: hydraulic binders (e.g., cement or hydraulic lime), latent hydraulic binders (e.g., slag), pozzolanic binders (e.g., fly ash), or non-hydraulic binders (e.g., gypsum or calcium lime).

For example, the mineral binder or binder composition contains a hydraulic binder, such as cement. For example, the cement is of type I, II, III, IV, or V (according to standard ASTM C150). Cement having a proportion of 35% by weight or more of cement clinker may also be used. The proportion of hydraulic binder in the total mineral binder may be at least 5% by weight, for example, at least 20% by weight, for example, at least 35% by weight, for example, at least 65% by weight. In further exemplary embodiments, the mineral binder contains at least 95% by weight of hydraulic binder, such as cement clinker.

If the mineral binder contains other binders in addition to or instead of the hydraulic binder, this may also be desirable. These include, for example, potential hydraulic binders and/or pozzolanic binders. Suitable potential hydraulic binders and/or pozzolanic binders include, for example, slag, fly ash, and/or silica dust. Similarly, the mineral binder composition may contain inert substances, such as coarse limestone powder, coarse quartz powder, and/or pigments. In exemplary embodiments, the mineral binder contains 5 to 95% by weight, for example, 5 to 65% by weight, or for example, 15 to 35% by weight, of potential hydraulic and/or pozzolanic binders.

The mineral binder is most preferably a type III cement (according to standard ASTM C150). The additives of the present invention are particularly suitable for mineral binder compositions based on this type of cement.

In further exemplary embodiments, the mineral binder composition further contains solid aggregates, particularly fine particles, sand particles, and/or gravel. Such binder compositions can be used, for example, as mortar mixtures or concrete mixtures.

For example, the mineral binder composition also contains water, where the weight ratio of water to mineral binder may be in the range of 0.25 to 0.8, for example, 0.3 to 0.6, or for example, 0.35 to 0.5. Such a mineral binder composition can be directly processed as a mortar mixture or concrete mixture.

Another aspect of the present invention relates to a method for accelerating the curing of a mineral binder composition, comprising the steps of adding the additive of the present invention described above to the mineral binder composition and mixing the mineral binder composition with water. In this method, the proportion of the additive is preferably 0.01 to 20% by weight, particularly 0.1 to 10% by weight, relative to the mineral binder.

In this method, the mineral binder composition is preferably defined as described above.

For example, the additive of the present invention can be mixed with water and then added to a mineral binder composition. However, in another embodiment, the mineral binder composition can be mixed with water first, and then the additive of the present invention can be mixed into it.

A further aspect of the present invention relates to a method for producing a fluid mineral binder composition, particularly a fluid concrete composition, wherein the above-mentioned additive is mixed with a mineral binder, aggregate, and water. Preferably, the proportion of the additive is 0.01 to 20% by weight, particularly 0.1 to 10% by weight, relative to the mineral binder.

In particular, a fluid mineral binder composition means that it is a mineral binder composition in a fluid state, ready to be flowed and placed in the intended location. Specifically, a fluid mineral binder composition is, for example, in a state that allows it to be cast into a formwork.

The order in which components are added to produce a fluid mineral binder composition can, in principle, be selected in any meaningful order. This allows the method of the present invention to be adapted to its intended use.

For example, in a highly preferred embodiment, a method for producing a fluid mineral binder composition includes the steps of adding a mineral binder, aggregate, water, and an additive for promoting the hardening of the mineral binder composition to a mixing unit all at once, and simultaneously mixing all of these components in the mixing unit to obtain a fluid mineral binder composition.

In other words, in this implementation, the fluid mineral binder composition is produced in a single mixing unit by simultaneously mixing all components. Since the fluid mineral binder composition can be obtained in a single process step, this is highly beneficial for precast applications. While not limited to theory, it is believed that this is possible through the use of the additives of the present invention. Specifically, such a single-step method stands in sharp contrast to established prior art methods, which typically rely on time-consuming and relatively complex stepwise approaches. Here, in the prior art method, for example, a cement paste is produced in the first step, and then further components are added stepwise thereafter.

According to another highly preferred embodiment, a method for producing a fluid mineral binder composition includes the following steps:
- The mineral binder, aggregate, water, and copolymer components of the additives of the present invention described above are added together to the mixing section, and all of these components are mixed simultaneously in the mixing section to obtain a premix composition;
- After a predetermined time, particularly after 0.5 to 10 hours, the accelerator component of the additive of the present invention as described above is added to a premix composition for obtaining a fluid mineral binder composition.

This particular embodiment is especially advantageous when the mineral binder composition is a ready-mixed concrete composition. The premixed composition can be stored and/or transported for a considerable period of time while maintaining its fluidity. Furthermore, when the mineral binder composition must be placed, it is sufficient to add the accelerator component of the additive of the present invention to obtain a mineral binder composition with fluidity that can be placed, for example, directly into a formwork.

A further aspect of the present invention relates to the use of the additive described above as a curing accelerator in a mineral binder composition. In this case, the proportion of the additive is preferably 0.01 to 20% by weight, particularly 0.1 to 10% by weight, relative to the mineral binder.

The mineral binder composition is preferably defined as described above.

Specifically, additives may be used to increase the initial compressive strength, particularly after 6 to 8 hours, and especially after 6 hours. Optionally, additives may also be used to simultaneously increase the workability, particularly the slump of the mineral binder composition.

Further advantageous embodiments of the present invention are also evident from the exemplary embodiments.

Preparation of curing accelerator additives: The accelerator component (AC) was prepared by mixing the substances shown in Table 1. All of these substances are available on the market.

The copolymer component (CC) according to the present invention is a copolymer having a methyl-terminated polyethylene glycol ester of methacrylic acid (averaging 4 ethylene oxide units) and methacrylic acid in a weight ratio of 4:1, and a molecular weight of Mw = 6800 g/mol (measured by GPC).

The accelerator component AC and the copolymer component CC were stored in separate containers. Therefore, this exemplary additive is a two-component additive.

Concrete Mixture Table 2 shows the concrete mixes used in this experiment.

Preparation and Testing of Concrete Specimens Fresh concrete was tested using the concrete mixes listed in Table 2. A premixture of additives (the accelerator component AC and copolymer component CC mentioned above; or comparative example additives (see Tables 3 and 4)) and mixed water were added to a dry mixture of aggregate (sand, gravel) and cement in a 55-liter twin-screw mixer, and the resulting mixture was kneaded for a predetermined time to obtain a usable concrete composition.

Next, immediately after removing the freshly prepared concrete, concrete testing was performed. Specifically, the following tests were conducted: slump test (according to JIS A 1101) and measurement of the air bubble content (according to JIS A 1128).

The compressive strength tests of the concrete composition were conducted in accordance with JIS A 1108, using test specimens prepared according to JIS A 1132.

During this process, columnar test specimens with a diameter of 100 mm and a length of 200 mm were prepared using freshly manufactured concrete. After curing for 6 hours, 8 hours, and 24 hours, the compressive strength of these specimens was measured.

Results: Table 3 shows the measurement results obtained using the additives listed in the table. The results in Table 3 were obtained for concrete manufactured at a relatively low temperature of 5°C.

As is clear from Table 3, the additive (I1) of the present invention is extremely excellent in both slump (an indicator of workability) and initial strength after 6 and 8 hours. Nevertheless, the strength after 24 hours is also at a considerably high level.

In contrast, in reference samples R1–R4, where nitrates, thiocyanates, alkanolamines, or nitrites were used as the sole promoting agent, the initial intensities at 6 and 8 hours were significantly lower (e.g., at best 0.9 MPa at R1).

Table 4 shows a comparison of the copolymer according to the present invention with other copolymers. The results in Table 4 were obtained for concrete produced at a temperature of approximately 20°C.

As is clear from Table 4, when using a standard polycarboxylic acid-based dispersant (which is not according to the present invention) (Experiment R5), the compressive strength obtained after 6 hours is significantly lower than when using the copolymer component of the present invention (Experiment I2). Furthermore, the plasticizing effect can be maintained at a higher level for a longer period of time.

It will be understood by those skilled in the art that the present invention can be implemented in other specific forms without departing from the spirit or substantial features of the invention. Therefore, the implementations and embodiments disclosed herein are in all respects illustrative and not limiting.

Claims (19)

An additive for accelerating the hardening of a mineral binder composition, comprising a copolymer component and an accelerator component,
The copolymer components include components (A), (B), and optionally (C):
(A) Ester compounds , which have formula (1)
RO-(AO) _n -H (1)
(In the formula, R is selected from a methyl group, an ethyl group, a propyl group, an n-butyl group, a sec-butyl group, and a tert-butyl group; A is a _C2-4 alkylene group; and n is an integer from 4 to 6. )
Ester compounds obtained by the reaction of at least one of the compounds with an α,β-unsaturated carboxylic acid,
(B) comprising a further α,β-unsaturated carboxylic acid or a salt thereof, and (C) optionally comprising a copolymer obtained from the reaction of at least one further copolymerizable monomer or a salt thereof;
The aforementioned accelerator component is
a ) Sodium thiocyanate,
b ) Calcium nitrate ; and c ) N -methyldiethanolamine,
Additives. The additive according to claim 1, wherein the copolymer component is an aqueous solution. The additive according to claim 1 or 2, wherein the copolymer component comprises the copolymer obtained from the reaction of components (A), (B), and optionally (C) in a proportion of 10 to 90% by weight. The copolymer component comprises 10 to 90 % by weight of water, as described in any one of claims 1 to 3. The additive according to any one of claims 1 to 4, wherein the ratio of components (A) to (C) involved in copolymerization is (A):(B):(C) = 50 to 95:5 to 50:0 to 40 by mass. The additive according to any one of claims 1 to 5 , wherein the weight ratio of sodium thiocyanate to calcium nitrate is 1:2 to 1:12, and the weight ratio of sodium thiocyanate to N-methyldiethanolamine is 1:0.8 to 1: 5 . The additive according to any one of claims 1 to 6, wherein the accelerator component is an aqueous solution. The additive according to any one of claims 1 to 7, wherein the accelerator component further comprises at least one carboxylic acid. The additive according to claim 8, wherein the weight ratio of sodium thiocyanate to at least one carboxylic acid is 1:0.1 to 1: 3 . The aforementioned accelerator component is, in relation to the total weight of the accelerator component,
f) 1 to 10 % by weight of sodium thiocyanate;
g) 30-80 % by weight of calcium nitrate;
h) 1 to 10 % by weight of N -methyldiethanolamine;
i) Optionally, 1 to 10% by weight of at least one of the carboxylic acids;
j) Contains 5-50 % by weight of water ,
The additive according to any one of claims 1 to 9. The additive according to any one of claims 1 to 10, comprising a two-component composition containing the copolymer component in a first container and the accelerator component separated from the copolymer component in a second container. The additive according to any one of claims 1 to 11, comprising a one-component composition containing the copolymer component and the accelerator component in a mixed state. A mineral binder composition comprising at least one additive and mineral binder according to any one of claims 1 to 12 . A method for accelerating the hardening of a mineral binder composition, comprising the steps of: adding an additive according to any one of claims 1 to 11 to the mineral binder composition; and mixing the mineral binder composition with water. A method for producing a fluid mineral binder composition, comprising mixing the additive described in any one of claims 1 to 12 with a mineral binder, aggregate, and water. The method according to claim 15, comprising the step of adding the mineral binder, the aggregate, the water, and the additive for promoting the effects of the mineral binder composition to a mixing section all at once, and mixing all of these components simultaneously to obtain the mineral binder composition having fluidity in the mixing section. - A step of adding the mineral binder, the aggregate, the water, and the copolymer component of the additive according to any one of claims 1 to 12 to a mixing unit, and simultaneously mixing all of the components in the mixing unit to obtain a premix composition;
- The method according to claim 15 , comprising the step of adding the accelerator component of the additive according to any one of claims 1 to 12 to the premix composition after a certain period of time in order to obtain the fluid mineral binder composition. A method of using the additive described in any one of claims 1 to 12 as a curing accelerator in a mineral binder composition. The method according to claim 18, wherein the additive is used to increase the initial compressive strength.