Method to reduce the shrinkage of a mineral binder composition

Abstract

The present invention relates to a method to reduce the shrinkage of a mineral binder composition comprising a step of intergrinding and / or intermixing the mineral binder composition with a phenol resin-based polymer.

Description

[0001] METHOD TO REDUCE THE SHRINKAGE OF A MINERAL BINDER COMPOSITION

[0002] Technical Field

[0003] This invention relates to a method to reduce the shrinkage of a mineral binder composition.

[0004] Background of the invention

[0005] It is well known that compositions based on mineral binders, for example concrete, shrink during hardening. Known shrinkage mechanisms can be classified as plastic shrinkage, drying shrinkage, autogenous shrinkage, and carbonation shrinkage. Especially drying shrinkage frequently is a problem, because it induces internal stress in the hardened material and, if the stress is higher than the tensile strength of the material, leads to cracking.

[0006] Various ways are known from the prior art to mitigate the drying shrinkage of mineral binder compositions (for example “A critical review on drying shrinkage mitigation strategies in cement-based materials” by N. Tran et al. in Journal of Building Engineering, 38, 2021, 102210).

[0007] There is, however, still a need for further and improved methods to reduce the shrinkage of mineral binder compositions, especially where there is a high replacement level of Portland cement by supplementary cementitious materials such as pozzolanic and / or latent hydraulic materials.

[0008] Summary of the invention

[0009] It is an object if the present invention to provide methods to reduce the shrinkage, in particular the autogenous shrinkage, of a mineral binder composition. Especially, it is an object of the present invention to provide methods to reduce the shrinkage, in particular the autogenous shrinkage, of mineral binder compositions comprising a mineral binder having a high content of supplementary cementitious materials. Very particularly, it is an object of the present invention to provide methods to reduce theshrinkage, in particular the autogenous shrinkage, of mineral binder compositions comprising Portland cement and slag.

[0010] Surprisingly, it was found that the use of dispersants comprising or consisting of certain phenol resin-based polymer are effective in reducing the shrinkage, in particular the autogenous shrinkage, of mineral binder compositions.

[0011] Phenol resin-based polymers are known from the prior art to improve the workability of mineral binder compositions. For example, JP2008-517080A discloses that phenol resin-based polymers can improve the slump and slump flow of mineral binder compositions. However, such phenol resin-based polymers are hitherto unknown to have an effect on the shrinkage of mineral binder compositions.

[0012] Therefore, the objectives of the present invention are solved by a method as claimed in claim 1.

[0013] Further aspects of the present are the subject matter of independent claims.

[0014] Preferred embodiments are the subject matter of dependent claims.

[0015] Detailed Ways

[0016] The present invention relates to a method to reduce the shrinkage of a mineral binder composition, said method comprising the steps of

[0017] a) providing a dispersant,

[0018] b) providing a mineral binder composition,

[0019] c) intergrinding and / or intermixing the dispersant provided in step a) with the mineral binder composition provided in step b),

[0020] characterized in that the dispersant comprises or consists of a phenol resin-based polymer obtained from the polycondensation of the following monomers (i) to (v): (i) a mol% of monomers of formula (I)

[0021] <

[0022]

[0023] (ii) b mol% of monomers of formula (II)

[0024]

[0025] (iii) c mol% of monomers of formula (III)

[0026]

[0027] (v) e mol% of monomers selected from aldehydes, preferably formaldehyde, metaformaldehyde, paraformaldehyde, formalin, or mixtures thereof, wherein in formulas (I) to (IV)

[0028] R1is H or a C1 - C4 alkyl group, or a C2 - C5 acyl group,

[0029] R2is H, an alkali metal or an alkaline earth metal ion, or a moiety of structure

[0030]

[0031] R3is H or is O-R2,

[0032] R4is H, a C1 - C4 alkyl group, or a phosphate ester group,

[0033] R5is H, a C1 - C18 alkyl group, a polyisobutylene, or a sulfonic acid moiety, Ai and A2 independently of one another are CxH2x group with x = 2 to 5, n = 1 - 350, m = 2 - 300, and

[0034] a molar ratio of a : b : c : d is 0.1 - 2.0 : 0.1 - 6.0 : 0.0 - 2.0 : 0.0 - 0.5, and molar ratio of (a + b + c + d) : e is from 1 : 10 to 10 : 1.A reduction of shrinkage, within the present context, relates to the difference of shrinkage, in particular measured according to standard JCI-SAS2-2, of a mineral binder composition comprising a phenol resin-based polymer as described above, as compared to the same mineral binder composition not comprising the phenol resinbased polymer. A reduction of shrinkage means that the shrinkage, in particular measured according to standard JCI-SAS2-2, after a given time of curing is lower for a mineral binder composition comprising a phenol resin-based polymer as described above as compared to the same mineral binder composition not comprising a phenol resin-based polymer and cured for the same time.

[0035] In particular, the reduction of shrinkage is a reduction of the autogenous shrinkage measured according to standard JCI-SAS2-2.

[0036] A mineral binder composition is a composition comprising at least one mineral binder. A mineral binder composition may additionally comprise aggregates, fillers, admixtures different from the dispersant comprising or consisting of the phenol resinbased polymer, and / or water. A mineral binder composition can, in particular, be a cement, concrete, or a mortar composition.

[0037] A mineral binder preferably comprises Portland cement and at least one supplementary cementitious material. Additionally, gypsum and / or cements different from Portland cement, such as calcium sulfoaluminate cements or high-alumina cements, may be present.

[0038] According to embodiments, in a method of the present invention the mineral binder composition comprises a mineral binder having a content of supplementary cementitious material of at least 21 w%, preferably at least 36 w%, more preferably at least 66 w%, still more preferably at least 81 w%, especially at least 96 w%, relative to the total dry weight of the mineral binder. Preferably, Portland cement is additionally present.

[0039] Supplementary cementitious materials preferably are pozzolanic and / or latent hydraulic materials.

[0040] According to embodiments, in a method of the present invention, the supplementary cementitious material is selected from the group consisting of slag, fly ash, calcined clay, silica fume, biomass ashes, natural pozzolanes such as pumice, trass, oil shale, and mixtures thereof.According to embodiments, in a method of the present invention, the slag is selected from the group consisting of ground granulated blast furnace slag, basic oxygen furnace slag, electric arc furnace slag, ladle slag, or mixtures thereof.

[0041] According to preferred embodiments, in a method of the present invention, the mineral binder composition comprises a mineral binder, said mineral binder comprising at least 21 w%, preferably at least 36 w%, more preferably at least 66 w%, still more preferably at least 81 w%, especially at least 96 w%, relative to the total dry weight of the mineral binder, of ground granulated blast furnace slag, basic oxygen furnace slag, ladle slag, and / or fly ash, and the remainder to 100 w% Portland cement.

[0042] Especially, the slag is ground granulated blast furnace slag according to standard JIS A 6206:2013.

[0043] Aggregates, fillers, and / or admixtures typically used in the production of concrete or dry mortars can be additionally present in a mineral binder composition of the present invention.

[0044] For example, a mineral binder composition of the present invention may include (in each case relative to the total dry weight of the composition:

[0045] (i) 280 - 600 kg / m3of mineral binder,

[0046] (ii) 500 - 950 kg / m3of fine aggregate, preferably sand,

[0047] (iii) 750 - 1100 kg / m3of coarse aggregate, preferably gravel, and

[0048] (iv) optionally 0.1 - 10 w% of at last one admixture, preferably of a superplasticizer, relative to the total dry weight of the mineral binder.

[0049] Water may additionally be present in an amount to yield a weight ratio of mineral binder to water of 0.1 to 0.6, preferably 0.2 to 0.5, especially 0.25 to 0.35.

[0050] The dispersant of the present invention comprises or consists of a phenol resinbased polymer. The dispersant may additionally comprise other components, in particular solvents, defoamers, plasticizers, thickeners, pigments, and / or biocides. According to embodiments, in a method of the present invention, the dispersant is an aqueous preparation of the phenol resin-based polymer having a solids content of 25 - 50 w%. In particular, the aqueous preparation is a dispersion or a solution.According to embodiments, in a method of the present invention, the dispersant is interground and / or intermixed in step c) in an amount so that a ratio of 0.1 - 10 w%, preferably 0.1 - 5 w%, more preferably 0.5 - 1 w%, of the phenol resin-based polymer relative to the total dry weight of the mineral binder results.

[0051] Monomers (i) to (v) for obtaining phenolic resin-based dispersants by polycondensation are described in detail in the following.

[0052] Monomer (i) is represented by formula (I):

[0053]

[0054] In Formula (I),

[0055] R1is H or a C1-C4 alkyl group, or a C2-C5 acyl group,

[0056] R5is H, C1-C18 alkyl group, polyisobutylene, or sulfonic acid moiety,

[0057] Ai is a CXH2X group, where x = 2 to 5,

[0058] n = 1 to 350.

[0059] Monomer (i) is a compound where an alkylene oxide with 2 to 5 carbon atoms has been added to phenol or its derivatives, and also includes derivatives (alkyl esters or fatty acid esters) of such alkylene oxide adducts.

[0060] The C1-C4 alkyl groups in R1may be selected from the group consisting of methyl, ethyl, propyl, and butyl groups, which can be branched (e.g., isopropyl, isobutyl, secbutyl, tert-butyl) and / or cyclic (e.g., cyclopropyl, isobutyl, sec-butyl, tert-butyl) structures. For example, cyclopropyl group, cyclobutyl group).

[0061] C1-C5 acyl groups in R1may be selected from the group consisting of saturated or unsaturated acyl groups (R'(CO)- group, where R' is a hydrocarbon group with 1 to 4 carbon atoms). Acetic acid, propionic acid, butanoic acid, and pentanoic acid are examples of saturated acyl groups with 2 to 4 carbon atoms.C1-C18 alkyl groups in R5 may be selected from the group consisting of methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl (lauryl), tetradecyl (myristyl), hexadecyl (palmityl), octadecyl. These can be branched (e.g., isopropyl, isobutyl, sec-butyl, tert-butyl, neopentyl, etc.) and / or cyclic (e.g., cyclopropyl, cyclopentyl, cyclohexyl, 1-adamantyl group, etc.

[0062] Alkylene oxide (-A1O-) has an alkylene group (CxH2x group, x = 2-5). Thus, the alkylene oxide may be selected from the group consisting of ethylene oxide, propylene oxide, butylene oxide, and pentene oxide, which may be single or mixed additions. When two or more alkylene oxides are added, they may be arranged in block-wise or randomly.

[0063] According to embodiments, at least some of the alkylene groups (CxH2x groups) of the alkylene oxide (-A1O-), such as more than 20 mol%, 25 mol%, or 30 mol%, have 3 to 5 carbons (x = 3 to 5). This percentage may be less than 100 mol%, less than 90 mol%, less than 80 mol%, less than 70 mol%, less than 60 mol%, less than 50 mol%, or less than 40 mol%. When at least some of the alkylene groups (CxH2x groups) have 3 to 5 carbons, the resulting phenolic resin-based dispersant can be made relatively hydrophobic, thereby enabling the use of slag in the mineral binder.

[0064] According to other embodiments, the alkylene groups (CxH2x groups) of the alkylene oxide (-A1O-) may all have 2 carbons (x=2), i.e. , all may be ethylene.

[0065] n is the average number of moles of alkylene oxide added, and is a number from 1 to 350, preferably 2 to 300, more preferably 3 to 150.

[0066] One monomer (i) of formula (I) can be used alone or in combination with two or more different monomers of formula (I).

[0067] Monomer (ii) is represented by formula (II):

[0068]

[0069] In formula (II),R2is H, alkali metal ion, alkaline earth metal ion, or a portion of the following structure:

[0070]

[0071] R3is H, or O-R2,

[0072] R5is H, C1-C18 alkyl group, polyisobutylene, or sulfonic acid moiety,

[0073] A1 is a CXH2X group, where x = 2 to 5,

[0074] n = 1 to 350.

[0075] Monomer (ii) is a phosphate ester derivative of a compound where an alkylene oxide with 2 to 5 carbon atoms has been added to phenol or its substituent.

[0076] Preferably, R2is selected from the group of ions of lithium, sodium, potassium, calcium, or magnesium.

[0077] Preferred embodiments of R5, A1 , and n, are as described above.

[0078] One monomer (ii) of formula (II) can be used alone or in combination with two or more different monomers of formula (II).

[0079] Monomer (iii) is represented by the following formula (III):

[0080]

[0081] In formula (III),

[0082] R4is H, C1-C4 alkyl group, or phosphate group,

[0083] Ai and A2 are independently of each other CxH2x groups, where x = 2 to 5, n = 1 to 350, m = 2 to 300.Monomer (iii) is a compound where an alkylene oxide is added to two hydroxy groups of hydroxyethylphenol, and also includes derivatives of alkylene oxide adducts, in particular phosphate esters.

[0084] Hydroxyethylphenol can be o-hydroxyethyl-phenol, m-hydroxyethyl-phenol, or p-hydroxyethylphenol.

[0085] Monomer (iii) is preferably a compound in which an alkylene oxide with 2 to 5 carbon atoms is added to o-hydroxyethyl-phenol.

[0086] Very preferably, R4is a phosphate ester derivative.

[0087] Preferred embodiments of the C1-C4 alkyl group of R4, Ai and A2, and n are as described above, m is the average number of moles of alkylene oxide added, and is a number from 2 to 300, preferably from 5 to 250, more preferably from 5 to 200. One monomer (iii) of formula (III) can be used alone or in combination with two or more different monomers of formula (III).

[0088] Monomer (iv) is represented by the following formula (IV):

[0089]

[0090] In formula (IV),

[0091] R5is H, C1-C18 alkyl group, polyisobutylene, or sulfonic acid moiety.

[0092] Preferred embodiments of R5, are as described above.

[0093] Monomer (v) is an aldehyde, preferably formaldehyde, meta-formaldehyde, paraformaldehyde, formalin, or a mixture thereof. Monomer (v) can be used alone or in combination of two or more monomers.

[0094] The molar ratio of monomers (i) to (iv), i.e. , a:b:c:d, may be 0.1 to 2.0 : 0.1 to 6.0 : 0.0 to 2.0 : 0.0 to 0.5. In other words, monomers (iii) and (iv) are not essential components, and these monomers may also be absent. The molar ratio of a: b: c: dpreferably is 0.5 to 1.5 : 0.5 to 6.0 : 0.0 to 1.0 : 0.0 to 0.5, more preferably 0.5 to 1.5 : 0.5 to 6.0 : 0.0 to 1.0 : 0.0, still more preferably 0.1 to 2.0 : 0.1 to 6.0 : 0.1 to 2.0 : 0.0. The molar ratio of monomer (v) to the sum of monomers (i)-(iv), i.e. (a+b+c+d):e may be 1 :10 to 10:1 , preferably 2:10 to 10:2, more preferably 3:10 to 10:3.

[0095] The polymerization method for obtaining the above phenolic resin-based dispersant by polycondensation of the above monomers is not particularly limited.

[0096] In polycondensation, the order and method of addition of each monomer are not particularly limited. For example, it is possible to add all the monomers to be reacted in one batch before the polycondensation reaction, to add a portion of the monomers to be used before the polycondensation reaction and then add the remaining monomers dropwise, or to add a portion of the monomers to be used before the polycondensation reaction and add the remaining monomers after a certain reaction time elapses. After a certain reaction time, the remaining monomers can be added additionally.

[0097] Polycondensates are obtained, for example, by polycondensation of the monomers used in the presence of a dehydration catalyst, either solvent-free or under solvent, at a reaction temperature of 80°C to 150°C and under normal pressure to pressurized conditions, for example, 0.001 to 1 MPa (gauge pressure).

[0098] The above dehydration catalysts include hydrochloric acid, perchloric acid, nitric acid, formic acid, methanesulfonic acid, octyl sulfonic acid, dodecyl sulfonic acid, vinyl sulfonic acid, allylsulfonic acid, phenol sulfonic acid, acetic acid, sulfuric acid, diethyl sulfate, dimethyl sulfate, phosphoric acid, oxalic acid, boric acid, benzoic acid, phthalic acid, Salicylic acid, pyruvic acid, maleic acid, malonic acid, nitrobenzoic acid, nitrosalicylic acid, paratoluenesulfonic acid, benzenesulfonic acid, dodecylbenzenesulfonic acid, trifluoromethanesulfonic acid, fluoroacetic acid, thioglycolic acid, mercaptopropionic acid, activated white earth, and others are listed, One or more of these dehydration catalysts can be used alone or in combination. When the polycondensation reaction is carried out under solvent conditions, water, glycol ether compounds such as propylene glycol monomethyl ether (PGME), aromatic compounds such as toluene and xylene, cyclic aliphatic compounds such as methylcyclohexane can be used as solvents. Acetic acid, for example, can also be used as a solvent.The reaction can preferably be carried out at a temperature of 95°C to 130°C, and the polycondensation reaction can be completed by reacting for 3 to 25 hours.

[0099] The polycondensation reaction preferably is carried out under acidic conditions. Preferably the pH of the reaction system is 4 or less.

[0100] After completion of the polycondensation reaction, various known methods can be employed to reduce the content of unreacted monomer (v) in the reaction system. For example, the pH of the reaction system can be made alkaline and / or the reaction system can be heat-treated to 60 to 140°C. Additionally or alternatively, the reaction system can be depressurized (e.g., gauge pressure of -0.1 to -0.001 MPa) to volatilize and remove unreacted monomer (v).

[0101] The dehydration catalyst used in the reaction can be neutralized after completion of the reaction and removed by filtration as a salt. But even if the catalyst is not removed, the performance of the dispersant is not impaired. In addition to the above filtration, other methods of catalyst removal include phase separation, dialysis, ultrafiltration, and the use of ion exchangers can be employed.

[0102] By neutralizing and diluting the polycondensate with water, the useability including weighing and other operations for use as a dispersant is improved. Alkaline hydroxides such as sodium hydroxide and potassium hydroxide, alkaline earth hydroxides such as calcium hydroxide, ammonia, organic amines such as monoethanolamine, diethanolamine, and triethanolamine are examples of basic compounds used for neutralization.

[0103] The phenolic resin-based dispersant finally obtained has a molecular weight Mw in the range of 5000 to 100000, preferably 10000 to 80000, more preferably 15000 to 35000 measured by gel permeation chromatography method (hereinafter referred to as “GPC”) against a polyethylene glycol equivalent standard.

[0104] In a method of the present invention, further admixtures that differ chemically from the phenol resin-based polymer, especially selected from plasticizers, superplasticizers, grinding aids, accelerators, and / or retarders, may be intermixed or interground with the mineral binder composition together with dispersant of the present invention.According to embodiments, in a method of the present invention, the method further comprises intergrinding and / or intermixing at least one polycarboxylate ether and / or at least one alkanolamine with the mineral binder composition.

[0105] According to embodiments, in a method of the present invention, in step c) the dispersant is interground with the mineral binder composition on a ball mill or on a vertical roller mill.

[0106] In case where the dispersant is interground with the mineral binder composition in step c), it is possible to add the dispersant to the mineral binder composition before and / or during the grinding.

[0107] In particular, in case where the dispersant is interground with the mineral binder composition in step c) of a method of the present invention, the mineral binder composition is Portland clinker or a supplementary cementitious material.

[0108] The terms grinding and milling are used interchangeably within the present context. It is of particular advantage that the phenol resin-based polymer is stable to heat and therefore is not affected by the heat developing during grinding of mineral binder composition.

[0109] In case where the dispersant is intermixed with the mineral binder composition in step c), it is possible to mix the dispersant with the mineral binder composition I the dry state, for example to produce a dry mortar. It is likewise possible to mix the dispersant with the mineral binder composition in the wet state, in particular to produce concrete. Mixing in the wet state refers to the mixing of the dispersant with the mineral binder composition together with the mixing water. For example, the dispersant can be added together with the mixing water to the dry mineral binder composition. Mixers and mix protocols are not particularly limited and are known to the skilled person.

[0110] The shrinkage, especially the autogenous shrinkage, of a mineral binder composition is reduced by a method of the present invention.

[0111] According to embodiments, in a method of the present invention, the shrinkage, in particular the autogenous shrinkage, is reduced by at least 30%, preferably at least 50%, as compared to a mineral binder composition without the dispersant, when measured according to standard JCI-SAS2-2 after a curing time of 7d or more. The reduction of shrinkage is always measured in comparison to a mineral bindercomposition of the same composition but without the dispersant of the present invention intermixed or interground.

[0112] In another aspect, the present invention relates to a mineral binder composition obtained by a method as described above.

[0113] All features and embodiments as described above also apply to this aspect.

[0114] For example, a mineral binder composition obtained by a method of the present invention comprises (in each case relative to the total dry weight of the composition:

[0115] (i) 280 - 600 kg / m3of mineral binder,

[0116] (ii) 500 - 950 kg / m3of fine aggregate, preferably sand,

[0117] (iii) 750 - 1100 kg / m3of coarse aggregate, preferably gravel,

[0118] (iv) optionally 0.1 - 10 w% of at last one admixture, preferably of a superplasticizer, relative to the total dry weight of the mineral binder, and (v) 0.1 - 10 w%, preferably 0.1 - 5 w%, more preferably 0.5 - 1 w%, of the phenol resin-based polymer relative to the total dry weight of the mineral binder.

[0119] A preferred mineral binder composition obtained by a method of the present invention comprises (in each case relative to the total dry weight of the composition:

[0120] (i) 280 - 600 kg / m3of a mineral binder comprising at least 21 w%, preferably at least 36 w%, more preferably at least 66 w%, still more preferably at least 81 w%, especially at least 96 w%, of at least one supplementary cementitious material and the remainder to 100 w% of Portland cement, in each case relative to the total dry weight of the mineral binder, (ii) 500 - 950 kg / m3of fine aggregate, preferably sand,

[0121] (iii) 750 - 1100 kg / m3of coarse aggregate, preferably gravel,

[0122] (iv) optionally 0.1 - 10 w% of at last one admixture, preferably of a superplasticizer, relative to the total dry weight of the mineral binder, and (v) 0.1 - 10 w%, preferably 0.1 - 5 w%, more preferably 0.5 - 1 w%, of the phenol resin-based polymer relative to the total dry weight of the mineral binder.In another aspect, the present invention relates to the use of the mineral binder composition as described above for the production of concrete, cementitious tile adhesive, grouting mortar, repair mortar, masonry mortar, waterproofing mortar, anchoring mortar, thin joint mortar render, screed, underlayment, overlayment, or wall levelling compound.

[0123] All features and embodiments as described above also apply to this aspect.

[0124] Examples

[0125]

[0126] 1.1 Preparation of monomer of Formula (I)

[0127] In a stainless steel high-pressure reactor equipped with a thermometer, stirrer, pressure gauge, and nitrogen inlet pipe, 80 parts of diethylene glycol monophenyl ether (Hysolve DPH manufactured by Toho Chemical Industry Co., Ltd.) and 0.2 parts of 96% potassium hydroxide were charged. The air in the reaction vessel was replaced with nitrogen and heated to 150°C under nitrogen atmosphere. Then, while maintaining 150°C, 1700 parts of ethylene oxide were introduced into the reactor over the course of 10 hours. The temperature was maintained for 2 hours to complete the alkylene oxide addition reaction. Polyethylene glycol monophenyl ether (90 mol of EO added per mol of diethylene glycol monophenyl ether) was obtained as monomer (i).

[0128] 1.2 Preparation of monomer of Formula (II)

[0129] Using p-tert-butylphenol (DIC Corporation, PTBP) as a starting material, an alkylene oxide adduct was obtained by an alkylene oxide addition reaction following the preparation method for the monomer of formula (I). The number of mol of ethylene oxide added per mole of p-tert-butylphenol was 6. Three mol of the obtained EO adduct of p-tert-butylphenol were introduced into a glass reaction vessel equipped with a stirrer, thermometer, and nitrogen inlet tube, and reacted with 1 mol of anhydrous phosphoric acid at 50°C for 4 hours under a stream of nitrogen.

[0130] Thereafter, the temperature was maintained at 100°C for 3 hours to terminate the phosphate esterification reaction. The phosphate ester of p-tert-butylphenol EO adduct (6 mol of EP per mol of p-tert-butylphenol) was obtained as monomer (ii).1.3 Preparation of monomer of Formula (III)

[0131] In a stainless steel high-pressure reactor equipped with a thermometer, stirrer, pressure gauge, and nitrogen inlet tube, 100 parts of ortho-hydroxyethylphenol (Aldrich reagent) and 0.3 parts of 96% potassium hydroxide were charged, the air in the reaction vessel was replaced with nitrogen and heated to 130°C under nitrogen atmosphere. Then, 190 parts of ethylene oxide were introduced into the reactor over the course of 4 hours while maintaining the temperature at 130°C. The temperature was then maintained for 2 hours to complete the alkylene oxide addition reaction. Ethoxylated ortho-hydroxyethylphenol (total of 6 mol of EO added per mol of ortho-hydroxyethylphenol) was obtained as the monomer (iii).

[0132] 1.4 Preparation of Phenol resin-based polymer

[0133] In a glass reaction vessel equipped with a stirrer, thermometer, and reflux cooler, each of the monomers (i), (ii), and (iii) obtained as described above were introduced in a molar ratio of 1 : 1 : 0.5. The temperature was raised to 70°C, and then 98% sulfuric acid was added at 1.0 mass% to the total mass of the monomers (i) to (iii). Next, formalin (equivalent of 5 mol formaldehyde) was added into the vessel as the monomer (v). The temperature was subsequently increased to 105°C. When 105°C was reached, the pH of the reactants was 2.1 (in a 1 % aqueous solution at 20°C). The temperature was maintained at 105°C for 6 hours, then the reaction was terminated by addition of 48% caustic soda to neutralize the reactants (the pH of the 1% aqueous solution of the reactants ranged from 5.0 to 7.5 after neutralization). Thereafter, an appropriate amount of water was added so that the solid content of the reaction product was 40 w%. Thus, the dispersant was obtained as an aqueous preparation of the phenol resin-based polymer having 30 w% solids content. The molecular weight Mw of the phenol resin-based polymer was determined by gel permeation chromatography (GPC) to be 28000 g / mol.

[0134] Concrete production

[0135] Concrete compositions were prepared in accordance with JIS A 1138 with 146 kg / m3of Ordinary Portland cement (from Taiheiyo Cement, density of 3.16 g / cm3), 437 kg / m3of ground granulated blast furnace slag (Cerament A, Blaine fineness 4000 cm2 / g), 693 kg / m3of sand (land sand, fineness modulus 2.88), and 870 kg / m3of gravel (crushed sandstone, fineness modulus 6.75). Water was added in a weightratio of 0.3 water to binder. Mixing was done in a twin-shaft forced mixer with a nominal capacity of 100 liters, and the volume of concrete produced in each batch was 50 liters. The respective amounts as indicated in below table 1 of the dispersant (aqueous preparation of the phenol resin-based polymer having 30 w% solids content) obtained as described above, of a polycarboxylate ether (PCE: Sika® ViscoCrete® 1100 NT; 21 w% solids content), and of organic SRA (polyalkylene glycol, EO / PO added to low molecular weight alcohol) were added together with the mixing water. Note that all ratios rel. to mineral binder are ratios relative to the sum of cement and ground granulated blast furnace slag.

[0136] The slump and slump flow of the concrete compositions were evaluated in accordance with standards JIS A 1101:2020 and JIS A 1150:2020 directly after mixing. Results are shown in the following table 1.

[0137] The air content of the concrete composition was evaluated in accordance with standard JIS A 1128:2019 directly after mixing. Results are shown in the following table 1.

[0138] The shrinkage was evaluated in accordance with standard JCI-SAS2-2 after the time autogenous indicated in the following table 1. Results are shown in the following table 1.Table 1: Concrete examples (C-1, C-2: comparative; E-1: inventive)

[0139]

[0140] ‘positive values: expansion, negative values : shrinkage

[0141] It is clear from the above results that the use of a dispersant of the present invention does lead to acceptable slump and slump flow which is comparable to the one achieved with a conventional PCE superplasticizer. At the same time, a dispersant of the present invention significantly reduces the shrinkage, specifically the autogenous shrinkage. It is to be noted that an expansion as measured in the above experiments is of no practical concern, because it does not constitute a risk for cracking of the hardening mineral binder composition. Such reduction in shrinkage is not achievable when using a PCE superplasticizer in combination with a conventional organic shrinkage reducing agent (SRA).

Claims

Claims1. A method to reduce the shrinkage of a mineral binder composition, said method comprising the steps ofa) providing a dispersant,b) providing a mineral binder composition,c) intergrinding and / or intermixing the dispersant provided in step a) with the mineral binder composition provided in step b),characterized in that the dispersant comprises or consists of a phenol resinbased polymer obtained from the polycondensation of the following monomers (i) to (v):(i) a mol% of monomers of formula (I)(ii) b mol% of monomers of formula (II)(iii) c mol% of monomers of formula (III)(III), and(iv) d mol% of monomers of formula (IV)(v) e mol% of monomers selected from aldehydes, preferably formaldehyde, metaformaldehyde, paraformaldehyde, formalin, or mixtures thereof, wherein in formulas (I) to (IV)R1is H or a C1 - C4 alkyl group, or a C2 - C5 acyl group,R2is H, an alkali metal or an alkaline earth metal ion, or a moiety of structureR3is H or is O-R2,R4is H, a C1 - C4 alkyl group, or a phosphate ester group,R5is H, a C1 - C18 alkyl group, a polyisobutylene, or a sulfonic acid moiety, Ai and A2 independently of one another are CxH2x group with x = 2 to 5, n = 1 - 350, m = 2 - 300, anda molar ratio of a : b : c : d is 0.1 - 2.0 : 0.1 - 6.0 : 0.0 - 2.0 : 0.0 - 0.5, and a molar ratio of (a + b + c + d) : e is from 1 : 10 to 10 : 1.

2. The method according to claim 1 , wherein the mineral binder composition comprises a mineral binder having a content of supplementary cementitious material of at least 21 w%, preferably at least 36 w%, more preferably at least 66 w%, still more preferably at least 81 w%, especially at least 96 w%, relative to the total dry weight of the mineral binder.

3. The method according to claim 2, wherein the supplementary cementitious material is selected from the group consisting of slag, fly ash, calcined clay, silica fume, biomass ashes, natural pozzolanes such as pumice, trass, oil shale, and mixtures thereof.

4. The method as claimed in claim 3, wherein the slag is selected from the group consisting of ground granulated blast furnace slag, basic oxygen furnace slag, electric arc furnace slag, ladle slag, or mixtures thereof.

5. The method as claimed in at least one of claims 1 - 4, wherein the dispersant is an aqueous preparation of the phenol resin-based polymer having a solids content of 25 - 50 w%.

6. The method as claimed in at least one of the claims 1 - 5, wherein the dispersant is interground and / or intermixed in step c) in an amount so that a ratio of 0.1 - 10 w%, preferably 0.1 - 5 w%, more preferably 0.5 - 1 w%, of the phenol resin-based polymer relative to the total dry weight of the mineral binder results.

7. The method as claimed in at least one of the claims 1 - 6, wherein in step c) the dispersant is interground with the mineral binder composition on a ball mill or on a vertical roller mill.

8. The method as claimed in at least one of the claims 1 - 7, wherein the method further comprises intergrinding and / or intermixing at least one polycarboxylate ether and / or at least one alkanolamine with the mineral binder composition.

9. The method as claimed in at least one of the claims 1 - 8, wherein the shrinkage, in particular the autogenous shrinkage, is reduced by at least 30%, preferably at least 50%, as compared to a mineral binder composition without the dispersant, when measured according to standard JCI-SAS2-2 after a curing time of 7d or more.

10. A mineral binder composition obtained by a method as claimed in at least one of claims 1 - 9.

11. Use of the mineral binder composition as claimed in claim 10 for the production of concrete, cementitious tile adhesive, grouting mortar, repair mortar, masonry mortar, waterproofing mortar, anchoring mortar, thin joint mortar render, screed, underlayment, overlayment, or wall levelling compound.

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