WO2022248630A1

WO2022248630A1 - Dispersion composition comprising a cement-based sealing slurry and an additive mixture

Info

Publication number: WO2022248630A1
Application number: PCT/EP2022/064341
Authority: WO
Inventors: Christian Schmidtke; Joachim Dengler; Florian DESCHNER; Harald Grassl; Klaus Seip
Original assignee: Basf Se
Priority date: 2021-05-27
Filing date: 2022-05-25
Publication date: 2022-12-01
Also published as: EP4347529A1

Abstract

The present invention relates to a dispersion composition comprising a cement-based sealing slurry comprising a) a Portland cement comprising an aluminate phase and b) a polymer dispersion and an additive mixture and the use thereof.

Description

Dispersion composition comprising a cement-based sealing slurry and an additive mixture The present invention is directed to a dispersion composition comprising a cement-based sealing slurry comprising a) a Portland cement comprising an aluminate phase and b) a polymer dispersion and an additive mixture, as well as the use thereof. It is known in the art that additives may be added to aqueous slurries or powder dispersants or improving their workability, i.e. kneadability, spreadybility, sprayability, pumpability, or lowability. Such admixtures are capable of preventing the formation of solid agglomerates and of dispersing the particles already present and those newly formed by hydration and in this way improving the workability. This effect is utilized in the preparation of construction material compositions which contain e.g. hydraulic binders, such as cement, lime, gypsum, hemihydrate or anhydrite. For example, set control agents or retarders may be used as additives to delay the hydration reaction and improve the workability. The retarders delay the hydration on-set by inhibiting the dissolution of the reactive cement components, in particular aluminates, and/or by masking the calcium ions thereby slowing down the hydration reaction. DE 4217181 A1 discloses condensation products of melamine and glyoxylic acids as additives for hydraulic binders. For improving the flexibility and the waterproofness, polymer dispersions are being applied in cement-based sealing slurries. However, a high polymer content reduces the drying properties and the cement hydration of the cement-containing system. A slowed drying process delays the work flow (i.e. two layers applications and attaching tiles) unfavorably. Hence, there is an ongoing need to provide a suitable dispersion composition providing well- balanced drying properties of polymer-containing dispersion compositions. In light of the above, the object of the present invention was to provide a dispersion composition, which provides a suitably open time (time until initial setting) whilst having a good processability (workability) during said open time and a rapid setting. In this connection, the dispersion composition needs to provide a well-balanced drying period. It has further been an object of the present invention to provide flexible and waterproofed material. Further, it has been an object of the present invention to provide a convenient additive mixture, which can be applied in order to accelerate drying of a cement-based sealing slurry, in particular in the presence of polymer dispersion. It has surprisingly been found that at least one of these objects can be achieved by the dispersion composition as claimed. It has further been found that the dispersion composition and/or the additive mixture as defined hereinafter provides improved drying properties. In a first aspect, the present invention therefore relates to a dispersion composition comprising A) a cement-based sealing slurry comprising a) a Portland cement comprising an aluminate phase, wherein the amount of alumina in form of Al₂O₃ is at least 2 wt.-% of the total mass of the aluminate-containing cement as determined by means of X-ray fluorescence (XRF), b) a polymer dispersion comprising a (co)polymer selected from the group consisting of acrylic acid ester polymer, acrylic-styrene copolymer, styrene-butadiene-based copolymer, vinyl acetate polymer, and ethylene-vinyl acetate copolymer; and B) an additive mixture comprising i) a polyol having the structure R⁵-(CHOH)_o-R⁴, wherein R⁴ and R⁵ are independently C₁-C₆- hydroxyalkyl, C₂-C₆-hydroxyalkenyl, C₁-C₆-aminoalkyl, -OH, C₁-C₅-alkyl, wherein o is an integerrom 0-5, and/or ii) NR¹R²R³, wherein R¹ is C₁-C₆-hydroxyalkyl, C₂-C₆-hydroxyalkenyl, C₁-C₆-aminoalkyl, (CH₂O)_n-OH, (CH₂CH₂O)_n- OH, or (CH₂CH₂CH₂O)_n-OH; R² and R³ are independently C₁-C₆-hydroxyalkyl, C₂-C₆-hydroxyalkenyl, C₁-C₆-aminoalkyl, (CH₂O)_n-OH, (CH₂CH₂O)_n-OH, or (CH₂CH₂CH₂O)_n-OH; or together with the nitrogen to whichhey are bonded form a 5- or 6-membered saturated, partially or fully unsaturated, or aromatic heterocyclic ring, wherein said heterocyclic ring comprises one or more, same of different heteroatoms selected from O, N, or S, wherein said N- and/or S-atoms are independently oxidized or non-oxidized, and wherein each substitutable carbon or heteroatom in the heterocyclic ring is independently unsubstituted or substituted with one or more, same or different substituents R^M; R^M is halogen, CN, NO₂, NH₂, OH, C₁-C₂-alkyl, C₁-C₂-alkoxy, C(=O)R^X, or two R^M form =O; R^X is H, C₁-C₂-alkyl, phenyl, or benzyl; and n is an integer from 1 to 10, and iii) a polycondensate of glyoxylic acid or a sulfite addition product of glyoxylic acid, and iv) a carbonate source, and v) optionally a salt of

wherein R1 is OH; R2 is H, OH, C₁-C₆ alkoxy, -SO₂X, -SO₃X, -OSO₃X, -PO, -PO₃X₂, -OPO₃X₂, -Z-COOX or - CH(OH)-SO₃X; R3 is H, COOX, C₃-C₆ alkyl which may be substituted by 1 to 5 OH or C₁-C₆ alkoxy; m is 0 or 1; or R1 and R2 taken together with the carbon atom to which they are attached form a carbonyl group provided m is 0; R4 is COOY or SO₃X; X is selected from H or a cation equivalent K_a wherein K is selected from an alkali metal, alkaline earth metal, zinc, iron, ammonium or phosphonium cation and a is 1/n wherein n is the valency of the cation; Y = is selected from X, C₁-C₆ alkyl or phenyl; and Z is CH₂ or CH(OH), provided that if R2 is SO₃X and m is 0 that R4 is not COOH. In the following, preferred embodiments of the components of the dispersion composition are described in further detail. It is to be understood that each preferred embodiment is relevant on its own as well as in combination with other preferred embodiments. In a preferred embodiment A1 of the first aspect, the Portland cement is an ordinary Portland cement comprising at least 3 wt.-% of aluminate types selected from the group consisting of C3A, C4AF, and mixtures thereof, and/or ess than 5 wt.-% of aluminate type CAC in form of CA, C2AS, CA2, and C12A7, and/or at least 3 wt.-% of CaSO₄·x H₂O, wherein x is selected from 0 to 1.5, and/or CaSO₄·x H₂O, wherein x is selected from 0 to 1.5, and Al₂O₃ and wherein the weight ratio of the CaSO₄·x H₂O to the amount of Al₂O₃ is from 1:3 to 4:1, preferably from 1:2 to 3:1. In a preferred embodiment A2 of the first aspect, the cement-based sealing slurry consists of the Portland cement and the polymer dispersion and comprises from 10 to 50 wt.-%, preferably from 20 to 45 wt.-%, of the polymer dispersion, based on the total weight of the cement-based sealing slurry. In a preferred embodiment A3 of the first aspect, the polymer dispersion is an aqueous polymer dispersion, preferably having a solid polymer content, determined according to DIN EN ISO 3251, from 20 to 70 wt.-%, more preferably from 30 to 65 wt.-%, and in particular from 40 to 60 wt.-%, based on the total weight of the aqueous polymer dispersion or a powder dispersion, preferably having a (co)polymer content from 60 to 95 wt.-%, more preferably from 70 to 90 wt.- %, based on the total weight of the powder dispersion. In a preferred embodiment A4 of the first aspect, the (co)polymer of the polymer dispersion has a Tg, calculated using the Fox equation , of -60 to 0 °C, preferably of -30 to -5 °C and/or the polymer dispersion comprises an acrylic-styrene copolymer. In a preferred embodiment A5 of the first aspect, the polyol has a molecular weight of less than 200 g/mol, preferably of less than 150 g/mol, more preferably of less than 100 g/mol and/or a C/O ratio of from less than 2 to more than 0.72, preferably from 1.5 to 0.8, in particular wherein the polyol is glycerol. In a preferred embodiment A6 of the first aspect, in NR¹R²R³, R¹ to R³ are independently C₁- C₆-hydroxyalkyl and/or R¹ to R³ are the same, preferably hydroxyethyl. In a preferred embodiment A7 of the first aspect, the polycondensate of glyoxylic acid is an amine-glyoxylic acid condensate, preferably wherein the amine-glyoxylic acid condensate is selected from the group consisting of a melamine-glyoxylic acid condensate, a urea-glyoxylic acid condensate, a melamine-urea-glyoxylic acid condensate, and a polyacrylamide-glyoxylic acid condensate, more preferably urea-glyoxylic acid condensate. In a preferred embodiment A8 of the first aspect, the carbonate source is selected from a group consisting of limestone, dolomite, calcium-magnesium carbonate, siderite, sodium carbonate, potassium carbonate, hydrogen carbonate, lithium carbonate, guanidinium carbonate, and calcium carbonate and/or wherein the carbonate source has a solubility in water of more than 0.08 g/l at 25 °C. In a preferred embodiment A9 of the first aspect, the salt of

is present in the additive mixture and wherein R2 is H, R3 is C₃-C₆ alkyl which may be substituted by 1 to 5 OH, and R4 is COOY, and Y is X being an alkali metal, preferably wherein the salt is sodium gluconate. In a preferred embodiment A10 of the first aspect, the weight ratio of the (co)polymer of the polymer dispersion to the Portland cement is from 2:1 to 1:2, preferably from 1.5:1 to 1:1.4, more preferably from 1.3:1 to 1: 1.2 and/or the weight ratio of water to the Portland cement is from 2:1 to 1:2, preferably from 1.5:1 to 1:1.4, more preferably from 1.3:1 to 1:1.2 and/or the weight ratio of the polymer dispersion to the Portland cement is from 4:1 to 1:1.3, preferably from 3:1 to 1:1, more preferably from 2.5:1 to 1: 1.1. In a preferred embodiment A11 of the first aspect, the dispersion composition further comprises C) calcium sulfate. In a second aspect, the present invention relates to the use of the dispersion composition according to the first aspect for improving flexibilisation or for providing waterproofness. In a third aspect, the present invention relates to the use of an additive mixture (AM-a) comprising i) a polyol having the structure R⁵-(CHOH)_o-R⁴, wherein R⁴ and R⁵ are independently C₁-C₆-hydroxyalkyl, C₂-C₆-hydroxyalkenyl, C₁-C₆-aminoalkyl, -OH, C₁-C₅-alkyl, wherein o is an integer from 0-5, and/or ii) NR¹R²R³, wherein R¹ is C₁-C₆-hydroxyalkyl, C₂-C₆-hydroxyalkenyl, C₁-C₆-aminoalkyl, (CH₂O)_n-OH, (CH₂CH₂O)_n-OH, or (CH₂CH₂CH₂O)_n-OH; R² and R³ are independently C₁-C₆-hydroxyalkyl, C₂-C₆-hydroxyalkenyl, C₁-C₆- aminoalkyl, (CH₂O)_n-OH, (CH₂CH₂O)_n-OH, or (CH₂CH₂CH₂O)_n-OH; or together with the nitrogen to which they are bonded form a 5- or 6-membered saturated, partially or fully unsaturated, or aromatic heterocyclic ring, wherein said heterocyclic ring comprises one or more, same of different heteroatoms selected from O, N, or S, wherein said N- and/or S-atoms are independently oxidized or non-oxidized, and wherein each substitutable carbon or heteroatom in the heterocyclic ring is independently unsubstituted or substituted with one or more, same or different substituents R^M; R^M is halogen, CN, NO₂, NH₂, OH, C₁-C₂-alkyl, C₁-C₂-alkoxy, C(=O)R^X, or two R^M form =O; R^X is H, C₁-C₂-alkyl, phenyl, or benzyl; and n is an integer from 1 to 10, and iii) a polycondensate or a sulfite addition product of at least one monomer with an aldehyde group, and v) optionally a salt of

wherein R1 is OH; R2 is H, OH, C₁-C₆ alkoxy, -SO₂X, -SO₃X, -OSO₃X, -PO, -PO₃X₂, -OPO₃X₂, -Z-COOX or -CH(OH)-SO₃X; R3 is H, COOX, C₃-C₆ alkyl which may be substituted by 1 to 5 OH or C₁-C₆ alkoxy; m is 0 or 1; or R1 and R2 taken together with the carbon atom to which they are attached form a carbonyl group provided m is 0; R4 is COOY or SO₃X; X is selected from H or a cation equivalent K_a wherein K is selected from an alkali metal, alkaline earth metal, zinc, iron, ammonium or phosphonium cation and a is 1/n wherein n is the valency of the cation; Y = is selected from X, C₁-C₆ alkyl or phenyl; and Z is CH₂ or CH(OH), provided that if R2 is SO₃X and m is 0 that R4 is not COOH, and of a carbonate source, for providing fast drying of a cement-based sealing slurry. In a preferred embodiment C1 of the third aspect, the carbonate source is comprised in the additive mixture (AM-a). In a fourth aspect, the present invention relates to a flexible water-proofing membrane obtained from a dispersion composition according to the first aspect. In a fifth aspect, the present invention relates to method of sealing a concrete or masonry structure comprising applying to the concrete or masonry structure the dispersion composition according to the first aspect. Detailed Description Before describing in detail exemplary embodiments of the present invention, definitions important for understanding the present invention are given. As used in this specification and in the appended claims, the singular forms of "a" and "an" also include the respective plurals unless the context clearly dictates otherwise. In the context of the present invention, the terms "about" and "approximately" denote an interval of accuracy that a person skilled in the art will understand to still ensure the technical effect of the feature in question. The term typically indicates a deviation from the indicated numerical value of ±20 %, preferably ±15 %, more preferably ±10 %, and even more preferably ±5 %. It is to be understood that the term "comprising" is not limiting. For the purposes of the present invention the term "consisting of" is considered to be a preferred embodiment of the term "comprising of". If hereinafter a group is defined to comprise at least a certain number of embodiments, this is meant to also encompass a group which preferably consists of these embodiments only. Furthermore, the terms "first", "second", "third" or "(a)", "(b)", "(c)", "(d)" etc. and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein. In case the terms "first", "second", "third" or "(a)", "(b)", "(c)", "(d)", "i", "ii" etc. relate to steps of a method or use or assay there is no time or time interval coherence between the steps, i.e. the steps may be carried out simultaneously or there may be time intervals of seconds, minutes, hours, days, weeks, months or even years between such steps, unless otherwise indicated in the application as set forth herein above or below. It is to be understood that this invention is not limited to the particular methodology, protocols, reagents etc. described herein as these may vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention that will be limited only by the appended claims. Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art. The term "substituted", as used herein, means that a hydrogen atom bonded to a designated atom is replaced with a specified substituent, provided that the substitution results in a stable or chemically feasible compound. Unless otherwise indicated, a substituted atom may have one or more substituents and each substituent is independently selected. The term "substitutable", when used in reference to a designated atom, means that attached to the atom is a hydrogen, which can be replaced with a suitable substituent. When it is referred to certain atoms or moieties being substituted with “one or more” substituents, the term “one or more” is intended to cover at least one substituent, e.g.1 to 10 substituents, preferably 1, 2, 3, 4, or 5 substituents, more preferably 1, 2, or 3 substituents, most preferably 1, or 2 substituents. When neither the term “unsubstituted” nor “substituted” is explicitly mentioned concerning a moiety, said moiety is to be considered as unsubstituted. The organic moieties mentioned in the above definitions of the variables are - like the term halogen - collective terms for individual listings of the individual group members. The prefix C_n- C_m indicates in each case the possible number of carbon atoms in the group. The term “halogen” denotes in each case fluorine, bromine, chlorine or iodine, in particularluorine, chlorine, or bromine. The term "alkyl" as used herein denotes in each case a straight-chain or branched alkyl group having usually from 1 to 6 carbon atoms, preferably 1 to 5 or 1 to 4 carbon atoms, more preferably 1 to 3 or 1 or 2 carbon atoms. Examples of an alkyl group are methyl, ethyl, n-propyl,so-propyl, n-butyl, 2-butyl, iso-butyl, tert-butyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 2,2-dimethylpropyl, 1-ethylpropyl, n-hexyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,1-dimethylbutyl, 1,2- dimethylbutyl, 1,3-dimethylbutyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 3,3-dimethylbutyl, 1- ethylbutyl, 2-ethylbutyl, 1,1,2-trimethylpropyl, 1,2,2-trimethylpropyl, 1-ethyl-1-methylpropyl, and 1-ethyl-2-methylpropyl. The term "alkoxy" as used herein denotes in each case a straight-chain or branched alkyl group which is bonded via an oxygen atom and has usually from 1 to 6 carbon atoms, preferably 1 to 2 carbon atoms, more preferably 1 carbon atom. Examples of an alkoxy group are methoxy, ethoxy, n-propoxy, iso-propoxy, n-butyloxy, 2-butyloxy, iso-butyloxy, tert.-butyloxy, and the like. The term “hydroxyalkyl” as used herein denotes in each case a straight-chain or branched alkyl group having usually from 1 to 6 carbon atoms and being further substituted with 1 to 5, preferably with 1 to 2 hydroxy groups, in particular with 1 hydroxy group. Preferably, the one hydroxy group is terminating the straight-chain or branched alkyl group so that the hydroxy group is bonded to an alkyl bridge, which is bonded to the remainder of the molecule. Examples of an hydroxyalkyl group are hydroxymethyl, hydroxyethyl, n-hydroxypropyl, 2-hydroxypropyl, n- hydroxybutyl, 2-hydroxybutyl, 2-hydroxy-2-methylpropyl, n-hydroxypentyl, and n-hydroxyhexyl. Hydroxymethyl, hydroxyethyl, hydroxypropyl, and hydroxybutyl, are preferred, in particular hydroxyethyl. The term “hydroxyalkenyl” as used herein denotes in each case an unsaturated hydrocarbon group having usually 2 to 6, preferably 2 to 4 carbon atoms comprising at least one carbon- carbon double bond in any position and being further substituted with 1 to 5, preferably with 1 to 2 hydroxy groups, in particular with 1 hydroxy group. Preferably, the one hydroxy group iserminating the unsaturated hydrocarbon group so that the hydroxy group is bonded to an alkenyl bridge, which is bonded to the remainder of the molecule. Examples of an hydroxyalkenyl are hydroxyvinyl, hydroxyallyl, hydroxymethallyl, hydroxybuten-1-yl, 2-hydroxy- 2-penten-1-yl, 1-hydroxy-3-penten-1-yl and the like. If geometric isomers are possible with regard to the double bond, the present invention relates to both, the E- and Z-isomers. The term “aminoalkyl” as used herein denotes in each case a straight-chain or branched alkyl group having usually from 1 to 6 carbon atoms and being further substituted with 1 to 5, preferably with 1 to 2 amino groups, in particular 1 amino group. Preferably, the one amino group is terminating the straight-chain or branched alkyl group so that the amino group is bonded to an alkyl bridge, which is bonded to the remainder of the molecule. Examples of an aminoalkyl group are aminomethyl, aminoethyl, n-aminopropyl, 2-aminopropyl, n-aminobutyl, 2- aminobutyl, 2-amino-2-methylpropyl, n-aminopentyl, and n-aminohexyl. Aminomethyl, aminoethyl, aminopropyl, and aminobutyl, are preferred, in particular aminoethyl. The term “heterocyclic” or “heterocyclyl” includes, unless otherwise indicated, in general a 5- or 6-membered, in particular 6-membered monocyclic ring. The heterocycle may be saturated, partially or fully unsaturated, or aromatic, wherein saturated means that only single bonds are present, and partially or fully unsaturated means that one or more double bonds may be present in suitable positions, while the Hückel rule for aromaticity is not fulfilled, whereas aromatic means that the Hückel (4n + 2) rule is fulfilled. The heterocycle typically comprises one or more, e.g.1, 2, 3, or 4, preferably 1, 2, or 3 heteroatoms selected from N, O and S as ring members, where S-atoms as ring members may be present as S, SO or SO₂. The remaining ring members are carbon atoms. In a preferred embodiment, the heterocycle is an aromatic heterocycle, preferably a 5- or 6-membered aromatic heterocycle comprising one or more, e.g.1, 2, 3, or 4, preferably 1, 2, or 3 heteroatoms selected from N, O and S as ring members, where S-atoms as ring members may be present as S, SO or SO₂. Examples of aromatic heterocycles are provided below in connection with the definition of “hetaryl”. “Hetaryls” or “heteroaryls” are covered by the term “heterocycles”. The saturated or partially or fully unsaturated heterocycles usually comprise 1, 2, 3, 4 or 5, preferably 1, 2 or 3 heteroatoms selected from N, O and S as ring members, where S-atoms as ring members may be present as S, SO or SO₂. The skilled person is aware that S, SO or SO₂ is to be understood as follows:

When referring to compositions and the weight percent of the therein comprised ingredients it is to be understood that according to the present invention the overall amount of ingredients does not exceed 100% (± 1% due to rounding). Preferred embodiment regarding the dispersion composition as well as the use thereof for improving flexibilisation or for providing waterproofness, a flexible water-proofing membrane obtained from said dispersion composition and a method of sealing a concrete or masonry structure are described hereinafter. Further, the use of a herein described specific additive mixture for providing fast drying of a cement-based sealing slurry is described hereinafter. It is to be understood that the preferred embodiments of the invention are preferred alone or in combination with each other. As indicated above, the present invention relates in one embodiment to a dispersion composition comprising A) a cement-based sealing slurry comprising a) a Portland cement comprising an aluminate phase, wherein the amount of alumina in form of Al₂O₃ is at least 2 wt.-% of the total mass of the aluminate-containing cement as determined by means of X-ray fluorescence (XRF), b) a polymer dispersion comprising a (co)polymer selected from the group consisting of acrylic acid ester polymer, acrylic-styrene copolymer, styrene-butadiene-based copolymer, vinyl acetate polymer, and ethylene-vinyl acetate copolymer; and B) an additive mixture comprising i) a polyol having the structure R⁵-(CHOH)_o-R⁴, wherein R⁴ and R⁵ are independently C₁-C₆- hydroxyalkyl, C₂-C₆-hydroxyalkenyl, C₁-C₆-aminoalkyl, -OH, C₁-C₅-alkyl, wherein o is an integer from 0-5, and/or ii) NR¹R²R³, wherein R¹ is C₁-C₆-hydroxyalkyl, C₂-C₆-hydroxyalkenyl, C₁-C₆-aminoalkyl, (CH₂O)_n-OH, (CH₂CH₂O)_n- OH, or (CH₂CH₂CH₂O)_n-OH; R² and R³ are independently C₁-C₆-hydroxyalkyl, C₂-C₆-hydroxyalkenyl, C₁-C₆-aminoalkyl, (CH₂O)_n-OH, (CH₂CH₂O)_n-OH, or (CH₂CH₂CH₂O)_n-OH; or together with the nitrogen to which they are bonded form a 5- or 6-membered saturated, partially or fully unsaturated, or aromatic heterocyclic ring, wherein said heterocyclic ring comprises one or more, same of different heteroatoms selected from O, N, or S, wherein said N- and/or S-atoms are independently oxidized or non-oxidized, and wherein each substitutable carbon or heteroatom in the heterocyclic ring is independently unsubstituted or substituted with one or more, same or different substituents R^M; R^M is halogen, CN, NO₂, NH₂, OH, C₁-C₂-alkyl, C₁-C₂-alkoxy, C(=O)R^X, or two R^M form =O; R^X is H, C₁-C₂-alkyl, phenyl, or benzyl; and n is an integer from 1 to 10, and iii) a polycondensate of glyoxylic acid or a sulfite addition product of glyoxylic acid, and iv) a carbonate source, and v) optionally a salt of

wherein R1 is OH; R2 is H, OH, C₁-C₆ alkoxy, -SO₂X, -SO₃X, -OSO₃X, -PO, -PO₃X₂, -OPO₃X₂, -Z-COOX or - CH(OH)-SO₃X; R3 is H, COOX, C₃-C₆ alkyl which may be substituted by 1 to 5 OH or C₁-C₆ alkoxy; m is 0 or 1; or R1 and R2 taken together with the carbon atom to which they are attached form a carbonyl group provided m is 0; R4 is COOY or SO₃X; X is selected from H or a cation equivalent K_a wherein K is selected from an alkali metal, alkaline earth metal, zinc, iron, ammonium or phosphonium cation and a is 1/n wherein n is the valency of the cation; Y = is selected from X, C₁-C₆ alkyl or phenyl; and Z is CH₂ or CH(OH), provided that if R2 is SO₃X and m is 0 that R4 is not COOH. Surprisingly, it was found that the dispersion compositions according to the present invention especially benefit from specific advantageous in term of drying properties. Without being bound to any theory, it is assumed that the herein disclosed additive mixture provides a controlled aluminate reaction, which results in a faster drying of the cement-based sealing slurry due to hydration. In the following, preferred embodiments of the dispersion composition, which are relevant for all aspects of the invention, are described in further detail hereinafter. It is to be understood that each preferred embodiment is relevant on its own as well as in combination with other preferred embodiments. The mineralogical phases are indicated by their usual name followed by their cement notation. The primary compounds are represented in the cement notation by the oxide varieties: C for CaO, S for SiO₂, A for Al₂O₃, $ for SO₃, H for H₂O; this notation is used throughout. The term "Portland cement" generally denotes any cement compound containing Portland clinker, especially CEM I, II, III, IV and V within the meaning of standard EN 197-1, paragraph 5.2. A preferred cement is ordinary Portland cement (OPC) according to DIN EN 197-1 which may either contain calcium sulfate (< 7% by weight) or is essentially free of calcium sulfate (<1% by weight). Calcium aluminate cement (also referred to as CAC or high aluminate cement) means a cement containing calcium aluminate phases. The term "aluminate phase" denotes any mineralogical phase resulting from the combination of aluminate (of chemical formula Al₂O₃, or "A" in cement notation), with other mineral species. The amount of alumina (in form of Al₂O₃) is at least 2 wt.-%, preferably at least 3 wt.-%, and more preferably at least 4 wt.-%, of the total mass of the aluminate-containing cement as determined by means of X-ray fluorescence (XRF). More precisely, said mineralogical phase of aluminate type comprises e.g. tricalcium aluminate (C₃A), monocalcium aluminate (CA), calcium-di-aluminate (CA2), mayenite (C₁₂A₇), gehlenite (C2AS), tetracalcium aluminoferrite (C₄AF), or a combination of several of these phases. Sulfoaluminate cement has a content of yeelimite (of chemical formula 4CaO.3Al₂O₃.SO₃ or C₄A₃$ in cement notation) of greater than 15% by weight. Mineralogical phases in cement are typically determined using quantitative X-ray diffraction (XRD). Preferably, the Portland cement is an ordinary Portland cement. Preferably, the ordinary Portland cement comprises aluminate types selected from the group consisting of C3A, C4AF, and mixtures thereof. In a preferred embodiment, the ordinary Portland cement comprises at least 1 wt.-%, more preferably at least 2 wt.-%, and even more preferably at least 3 wt.-%, of aluminate types selected from the group consisting of C3A, C4AF, and mixtures thereof. In a preferred embodiment, the ordinary Portland cement comprises less than 5 wt.-%, more preferably less than 4 wt.-%, and even more preferably less than 3 wt.-%, of aluminate type CAC in form of CA, C2AS, CA2, and C12A7. The ordinary Portland cement according to the present invention contains an aluminate phase and may additionally contain at least one sulfate source, preferably calcium sulfate source. The calcium sulfate source may be selected from calcium sulfate dihydrate, anhydrite, α- and β-hemihydrate, i.e. α-bassanite and β-bassanite, or mixtures thereof. Preferably the calcium sulfate is α-bassanite and/or β-bassanite. In a preferred embodiment, the ordinary Portland cement comprises at least 3 wt.-%, more preferably at least 4 wt.-%, and even more preferably at least 5 wt.-%, of CaSO₄·x H₂O, wherein x is selected from 0 to 1.5. It is further preferred, that the ordinary Portland cement comprises from at least 3 to less than 7 wt.-%, more preferably from at least 4 to 6 wt.-%, and even more preferably 4.5. to 5.5 wt.-%, of CaSO₄·x H₂O, wherein x is selected from 0 to 1.5. Preferably, the C3A, C4AF, CA, C2AS, CA2, C12A7, and CaSO₄·x H₂O are determined using quantitative X-ray diffraction (XRD). In this connection it is preferred to perform Rietveld refinement for the analysis. In a preferred embodiment, the ordinary Portland cement comprises at least 5 wt.-%, more preferably at least 10 wt.-%, and even more preferably at least 15 wt.-%, of sulfoaluminate types such as yeelimite having the chemical formula 4CaO.3Al₂O₃.SO₃ or C₄A₃$ in cement notation. In a preferred embodiment, the ordinary Portland cement comprises CaSO₄·x H₂O, wherein x is selected from 0 to 1.5, and Al₂O₃ and wherein the weight ratio of the CaSO₄·x H₂O to the amount of Al₂O₃ is from 1:3 to 4:1, preferably from 1:2 to 3:1. In a preferred embodiment, the cement-based sealing slurry consists of the Portland cement and the polymer dispersion. In this connection it is preferred that the cement-based sealing slurry comprises from 10 to 50 wt.-%, preferably from 15 to 48 wt.-%, and more preferably from 20 to 45 wt.-%, of the polymer dispersion, based on the total weight of the cement-based sealing slurry. It is further preferred that the cement-based sealing slurry comprises from 50 to 90 wt.-%, preferably from 52 to 85 wt.-%, and more preferably from 55 to 80 wt.-%, of the Portland cement, based on the total weight of the cement-based sealing slurry. The polymer dispersion comprising a (co)polymer selected from the group consisting of acrylic acid ester polymer, acrylic-styrene copolymer, styrene-butadiene-based copolymer, vinyl acetate polymer, and ethylene-vinyl acetate copolymer, preferably selected from the group consisting of acrylic acid ester polymer and acrylic-styrene copolymer. In a preferred embodiment, the polymer dispersion is an aqueous polymer dispersion. The (co)polymer of the polymer dispersion is preferably made up of ethylenically unsaturated compounds in polymerized form. The preparation of these polyaddition compounds is generally carried out by metal complex-catalyzed, anionically catalyzed, cationically catalyzed and particularly preferably free-radically catalyzed polymerization, as is familiar to a person skilled in the art, of ethylenically unsaturated compounds. The free-radically catalyzed polymerization of ethylenically unsaturated compounds will be familiar to a person skilled in the art and is, in particular, carried out by the method of free- radical bulk, emulsion, solution, precipitation, or suspension polymerization, with free-radically initiated aqueous emulsion polymerization being particularly preferred. Carrying out free-radically initiated emulsion polymerization of ethylenically unsaturated compounds (monomers) in an aqueous medium is known [cf. Emulsion polymerization in Encyclopedia of Polymer Science and Engineering, Vol.8, pages 659 ff. (1987); D. C. Blackley, in High Polymer Latices, Vol.1, pages 35 ff. (1966); H. Warson, The Applications of Synthetic Resin Emulsions, chapter 5, pages 246 ff. (1972); D. Diederich, Chemie in unserer Zeit 24, pages 135 to 142 (1990); Emulsion Polymerisation, Interscience Publishers, New York (1965); DE-A 4003422 and Dispersionen synthetischer Hochpolymerer, F. Hölscher, Springer-Verlag, Berlin (1969)]. Free-radically initiated aqueous emulsion polymerization is usually carried out by dispersing the monomers, generally with concomitant use of dispersants such as emulsifiers and/or protective colloids, in an aqueous medium and polymerizing them by means of at least one water-soluble free-radical polymerization initiator. Frequently, the residual contents of unreacted monomers in the aqueous polymer dispersions obtained are decreased by chemical and/or physical after-treatment, the polymer solids content is set to a desired value by dilution or concentration or further customary additives, for example foam- or viscosity-modifying additives, are added to the aqueous polymer dispersion. Possible monomers are, in particular, monomers which can be free-radically polymerized in a simple manner, for example ethylene, vinylaromatic monomers such as styrene, α- methylstyrene, or o-chlorostyrene, vinyl acetate, acrylic acid, esters of acrylic acid and methacrylic acid with alkanols, which generally have from 1 to 12, preferably from 1 to 8 and in particular from 1 to 4, carbon atoms, especially methyl, ethyl, n-butyl, isobutyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl (e.g. hydroxyethyl methacrylate), esters of acrylic acid and methacrylic acid with alkanes, which generally have from 1 to 12, preferably from 1 to 10, and in particular from 1 to 8, carbon atoms (e.g. ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, 2- propylheptyl acrylate), and 1,3-butadiene. When preparing a polymer dispersion, the monomers mentioned generally form the main monomers which, based on the amount of all ethylenically unsaturated compounds used for preparing the polymer dispersion (total amount of monomers), add up to a proportion of ≥ 50% by weight, preferably ≥ 80% by weight and particularly preferably ≥ 90% by weight. In general, these monomers have only a moderate to low solubility in water under standard conditions [20°C, 1 atm (= 1.013 bar absolute)]. In a preferred embodiment, the polymer dispersion comprises an acrylic-styrene copolymer. Suitably, the acrylic-styrene copolymer is obtainable by free-radical polymerization of styrene and/or methylstyrene, in particular styrene, with acrylates selected from the group consisting of methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, hydroxyethylmethacrylate, 2-propylheptyl acrylate, and mixtures thereof, in particular selected from the group consisting of 2-ethylhexyl acrylate, hydroxyethylmethacrylate, butyl acrylate, and mixtures thereof. In this connection, it is to be understood that methylstyrene refers to alpha-methylstyrene, beta- methylstyrene, 2-methylstyrene, 3-methylstyrene, and 4-methylstyrene, preferably to alpha- methylstyrene. Preferably, the acrylic-styrene copolymer is obtainable by free-radical polymerization of 15 to 50 wt.-%, more preferably 20 to 45 wt.-%, and in particular 25 to 40 wt.-%, of styrene and/or methylstyrene with 50 to 85 wt.-%, more preferably 55 to 80 wt.-%, and in particular 60 to 75 wt.-%, of at least one acrylate. In this connection it is preferred that styrene is polymerized with the at least one acrylate selected from the group consisting of methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, hydroxyethylmethacrylate, 2-propylheptyl acrylate, and mixtures thereof, in particular selected from the group consisting of 2-ethylhexyl acrylate, hydroxyethylmethacrylate, butyl acrylate, and mixtures thereof. In a preferred embodiment, the polymer dispersion comprises a styrene-butadiene-based copolymer. In a preferred embodiment, the polymer dispersion comprises a vinyl acetate polymer. In a preferred embodiment, the polymer dispersion further comprises a terpolymer. Suitable erpolymers are addition products of vinyl acetate, ethylene and vinyl ester. Preferably, the vinyl esters are those of carboxylic acids having 1 to 15 carbon atoms. Preference is given to vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, vinyl laurate, 1-methylvinyl acetate, vinyl pivalate, and vinyl esters of α-branched monocarboxylic acids having 9 to 11 carbon atoms, an example being VeoVa^TM 9 or VeoVa^TM 10. Vinyl acetate is particularly preferred. In a preferred embodiment, the polymer dispersion is an aqueous polymer dispersion, preferably having a solid polymer content, determined according to DIN EN ISO 3251, from 20 to 70 wt.-%, more preferably from 25 to 72 wt.-%, even more preferably from 30 to 65 wt.-%, and in particular from 40 to 60 wt.-%, based on the total weight of the aqueous polymer dispersion. In another preferred embodiment, the polymer dispersion is a powder dispersion, preferably having a (co)polymer content from 60 to 95 wt.-%, more preferably from 65 to 92 wt.-%, even more preferably from 70 to 90 wt.-%, based on the total weight of the powder dispersion. In a preferred embodiment, the (co)polymer of the polymer dispersion has a Tg, calculated using the Fox equation, of -60 to 0 °C, preferably of -50 to -4 °C, more preferably of -40 to -2 °C, even more preferably of -30 to -5 °C. According to Fox (cf. T.G. Fox, Bull. Am. Phys. Soc. (Ser II) 1, 123, [1956] and Ullmanns Enzyklopädie der technischen Chemie, Weinheim (1980), S.17, 18) the following equation is a suitable approximation for the Tg of polymer dispersions:

wherein X¹, ^X2, ..., Xⁿ are the mass fractions 1, 2, ..., n and Tg¹, Tg^2,, …, Tgⁿ are the glass ransition temperatures, in kelvins, of homopolymers of each of the monomers 1, 2, …, n. The individual Tgs are known, for example, from Ullmann's Encyclopedia of Industrial Chemistry, VCH, Weinheim, Vol. A 21 (1992) p.169 and from J. Brandrup, E. H. Immergut, Polymer Handbook 3^rd ed., J. Wiley, New York 1989. The (co)polymers of the polymer dispersion are preferably present in the form of particles having an average particle diameter of from 10 to 1000 nm, more preferably from 30 to 600 nm, and in particular from 50 to 400 nm, measured by the pseudoelastic light scattering method (ISO standard 13321; cumulant z-average). The aqueous polymer dispersion may additionally comprises at least one surface active compound. The surface active compound serves to stabilize the aqueous dispersion of the polymer by keeping the particles of the polymer dispersed. The surface active compound may be an emulsifier, a protective colloid or a mixture of both of them. The emulsifier and the protective colloid are distinct from each other by their weight-average molar mass Mw. An emulsifier has typically a weight average molar mass Mw in general below 2000, while the weight-average molar mass Mw of the protective colloid may be up to 50000, in particular from above 2000 to up to 50000. Typically, the amount of the surface active compound is in the range from 0.1 to 10% by weight, in particular in the range from 0.5 to 5% by weight, based on the total amount of polymer in the aqueous polymer dispersion. Preferably, the surface active compound comprises one or more emulsifiers. The emulsifier is non-ionic, anionic, or cationic. In case of employing a mixture of emulsifiers, their compatibility has to assured, which can be evaluated in case of doubt by preliminary tests. Typically, an anionic emulsifier is compatible with another anionic emulsifier or a non-ionic emulsifier. Similarly, a cationic emulsifier is typically compatible with another cationic emulsifier or a non- ionic emulsifier. Preferably, the emulsifier is an anionic emulsifier, a combination of two or more anionic emulsifier or a combination of at least one anionic emulsifier and at least one non-ionic emulsifier. Non-ionic emulsifier are, for example, ethoxylated C₈-C₃₆ fatty alcohols having a degree of ethoxylation of from 3 to 50 (= ethylene oxide units [EO]: 3-50) and ethoxylated mono-, di- and tri-C₄-C₁₂ alkylphenols having a degree of ethoxylation of from 3 to 50. Examples of customary nonionic emulsifiers are the Emulgin B grades (cetyl/stearyl alcohol ethoxylates, RTM BASF), Dehydrol LS grades (fatty alcohol ethoxylates, EO units: 1-10, RTM BASF), Lutensol A grades (C₁₂C₁₄-fatty alcohol ethoxylates, EO units: 3-8, RTM BASF), Lutensol AO grades (C₁₃C₁₅-oxo alcohol ethoxylates, EO units: 3-30), Lutensol AT grades (C₁₆C₁₈-fatty alcohol ethoxylates, EO units: 11-80), Lutensol ON grades (C10-oxo alcohol ethoxylates, EO units: 3-11) and Lutensol TO grades (C₁₃-oxo alcohol ethoxylates, EO units: 3-20). Here and in the following the phrase “EO units” means the number average of ethylene oxide repeating units in the emulsifier. Anionic emulsifiers include for example the alkali metal salts of dialkyl esters of sulfosuccinic acid, the alkali metal salts and the ammonium salt of C₈-C₁₂ alkyl sulfates, the alkali metal salts and the ammonium salts of C₁₂-C₁₈ alkylsulfonic acids, the alkali metal salts and the ammonium salts of C₉-C₁₈ alkylarylsulfonic acid, the alkali metal salts and the ammonium salts of sulfuric acid monoesters of ethoxylated C₁₂-C₁₈ alkanols (EO units: 4-30) or a sulfuric acid monoester of an ethoxylated (C₄-C₁₂ alkyl)phenol (EO units: 3-50). Further anionic emulsifiers are fatty alcohol phosphates, alkylphenol phosphates, alkyl polyglycol ether phosphates, alkyl polyalkylene oxide phosphates, and fatty alcohol ether phosphates and the salts thereof, in particular the alkalimetal salts and ammonium salts thereof, with particular preference given to the alkalimetal salts such as sodium salts. A comprehensive description of suitable emulsifiers may be found in Houben-Weyl, Methoden der organischen Chemie, volume XIV/1, Makromolekulare Stoffe, Georg-Thieme-Verlag, Stuttgart, 1961, pages 192 to 208. Like the aforementioned emulsifiers, suitable protective colloids may be non-ionic, anionic or cationic. Examples of protective colloids are poly(vinyl alcohols), poly(alkylene glycols), poly(acrylic acids) and the alkali metal salt thereof, poly(methacrylic acids) and the alkali metal salt thereof and gelatin derivatives. Anionic protective colloid can also be a copolymer, containing a suitable amount of at least one anionic monomer, such as acrylic acid, methacrylic acid, maleic acid, 2-acrylamido-2-methylpropane sulfonic acid, para-vinylphenyl sulfonic acid or salt forms thereof, preferably alkali metal salts thereof, in polymerized form. Examples of cationic protective colloids are homo polymers and copolymers containing a sufficient amount of cationic monomers, in particular monoethylenically unsaturated monomers having one or more amino groups, which are N-protonated or N-alkylated. Examples include N-protonated and N- alkylated derivatives of homopolymers or copolymers of N-vinylformamide in their at least partly hydrolyzed form, homopolymers or copolymers of N-vinylacetamide in their at least partly hydrolyzed form, N-protonated and N-alkylated derivatives of homopolymers or copolymers of N-vinylcarbazole, N-protonated and N-alkylated derivatives of homopolymers or copolymers of 1-vinylimidazole, N-protonated and N-alkylated derivatives of homopolymers or copolymers of 2-vinylimidazole, N-protonated and N-alkylated derivatives of homopolymers or copolymers of 2-vinylpyridine, N-protonated and N-alkylated derivatives of homopolymers or copolymers of 4- vinylpyridine, N-protonated and N-alkylated derivatives of homopolymers or copolymers of amine-group-bearing acrylates, N-protonated and N-alkylated derivatives of homopolymers or copolymers of aminegroup-bearing methacrylates, wherein the nitrogen of the amine-group is protonated at a pH below 7 or is permanently positively charged, for example by alkylation. Further comonomers in such cationic protective colloids may be acrylamide, methacrylamide and N-vinyl pyrrolidone. The protective colloids are distinct from the polymers dispersed in the aqueous polymer dispersion as they are water-soluble or water dispersible. The term “water-soluble or water dispersible” is understood that the corresponding protective colloid can be dissolved or dispersed in deionized water at 20°C and 1013 mbar in an amount of at least 10 g/L polymer such that the resulting aqueous solution has either no measurable particle size or a particle size of at most 20 nm as determined by dynamic light scattering in accordance with DIN 22412:2008. A comprehensive description of suitable protective colloids may be found in Houben-Weyl, Methoden der organischen Chemie, volume XIV/1, Makromolekulare Stoffe, Georg-Thieme- Verlag, Stuttgart, 1961, pages 411 to 420. In a preferred embodiment, the polyol has the structure R⁵-(CHOH)_o-R⁴, wherein R⁴ and R⁵ are independently C₁-C₃-hydroxyalkyl, C₂-C₃-hydroxyalkenyl, C₁-C₃-aminoalkyl, -OH, C₁-C₃-alkyl, wherein o is an integer from 0-5, more preferably R⁵-(CHOH)_o-R⁴, wherein R⁴ and R⁵ are independently C₁-C₂-hydroxyalkyl, or -OH, wherein o is an integer from 0-5. In a preferred embodiment, the polyol has a molecular weight of less than 200 g/mol, preferably of less than 150 g/mol, and more preferably of less than 100 g/mol. It is further preferred that the polyol has a molecular weight of 80 to less than 200 g/mol, preferably of 83 to less than 150 g/mol, and more preferably of 85 to less than 100 g/mol. In a preferred embodiment, the polyol has a C/O ratio of from less than 2 to more than 0.72, preferably from 1.5 to 0.8 and more preferably from 1.1 to 0.9. In a preferred embodiment, the polyol is selected from the group consisting of ethylene glycol, glycerol, pentaerythritol, and C₄-C₇ sugar alcohols such as erythritol, threitol, arabitol, xylitol, ribitol, mannitol, sorbitol, galactitol, fucitol, iditol, inositol, and volemitol, in particular wherein the polyol is glycerol. In a preferred embodiment, in NR¹R²R³, R¹ to R³ are independently C₁-C₆-hydroxyalkyl, C₂-C₆- hydroxyalkenyl, C₁-C₆-aminoalkyl, (CH₂O)_n-OH, (CH₂CH₂O)_n-OH, or (CH₂CH₂CH₂O)_n-OH, wherein n is an integer from 1 to 10, preferably from 1 to 5, more preferably from 1 to 3. In a preferred embodiment, in NR¹R²R³, R¹ to R³ are independently C₁-C₆-hydroxyalkyl, C₂-C₆- hydroxyalkenyl, (CH₂O)_n-OH, (CH₂CH₂O)_n-OH, or (CH₂CH₂CH₂O)_n-OH, wherein n is an integer from 1 to 10, preferably from 1 to 5, more preferably from 1 to 3. In a preferred embodiment, in NR¹R²R³, R¹ to R³ are independently C₁-C₆-hydroxyalkyl. In a preferred embodiment, in NR¹R²R³, R¹ to R³ are the same. In a preferred embodiment, in NR¹R²R³, R¹ to R³ are independently selected from the group consisting of hydroxymethyl, hydroxyethyl, n-hydroxypropyl, 2-hydroxypropyl, n-hydroxybutyl, 2- hydroxybutyl, 2-hydroxy-2-methylpropyl, n-hydroxypentyl, and n-hydroxyhexyl, preferably selected from the group consisting of hydroxymethyl, hydroxyethyl, hydroxypropyl, and hydroxybutyl, in particular hydroxyethyl. Glyoxylic acid has the following structure:

As used herein, addition products of glyoxylic acid refer to products, which are obtainable by reacting a nucleophilic compound with the α-carbonyl group of glyoxylic acid, so as to obtain α- substituted α-hydroxy- acetic acid or a salt thereof as an adduct. As used herein, condensation products of glyoxylic acid refer to condensation products obtainable by reacting a compound containing at least one amino or amido group with the α- carbonyl group of glyoxylic acid, such that water is set free. Examples of compounds containing at least one amino or amido group include urea, thiourea, melamine, guanidine, acetoguanamine, benzoguanamine and other acylguanamines, polyvinylamine and polyacrylamide. In a preferred embodiment, the dispersion composition comprises the polycondensate of glyoxylic acid. In a preferred embodiment, the polycondensate of glyoxylic acid is an amine-glyoxylic acid condensate. The term “amine-glyoxylic acid condensate” as used herein is intended to mean a condensate of glyoxylic acid with a compound containing amino or amido groups reactive with aldehydes. Examples of compounds containing aldehyde-reactive amino or amido groups include urea, thiourea, melamine, guanidine, acetoguanamine, benzoguanamine and other acylguanamines and polyacrylamide. In a preferred embodiment, the amine-glyoxylic acid condensate is selected from the group consisting of a melamine-glyoxylic acid condensate, a urea-glyoxylic acid condensate, a melamine-urea-glyoxylic acid condensate, and a polyacrylamide-glyoxylic acid condensate, more preferably urea-glyoxylic acid condensate. The amine-glyoxylic acid condensates are obtainable by reacting glyoxylic acid with a compound containing aldehyde-reactive amino or amido groups. The glyoxylic acid can be used as an aqueous solution or as glyoxylic acid salts, preferably glyoxylic acid alkaline metal salts. Likewise, the amine compound can be used as salt, for example as guanidinium salts. In general, the amine compound and the glyoxylic acid are reacted in a molar ratio of 0.5 to 2 equivalents, preferably 1 to 1.3 equivalents, of glyoxylic acid per aldehyde-reactive amino or amido group. The reaction is carried out at a temperature of 0 to 120 °C, preferably 25 to 105 °C, most preferably 50 to 105 °C. The pH value is preferably from 0 to 8. The viscous products obtained in the reaction can be used as such, adjusted to a desired solids content by dilution or concentration or evaporated to dryness by, e.g., spray-drying, drum-drying, or flash-drying. In general, the amine-glyoxylic acid condensates have molecular weights in the range of from 500 to 25000 g/mol, preferably 1000 to 10000 g/mol, particularly preferred 1000 to 5000 g/mol. The molecular weight is measured by the gel permeation chromatography method (GPC) as indicated in detail in the experimental part. In a preferred embodiment, the dispersion composition comprises the sulfite addition product of glyoxylic acid. Preferably, the sulfite addition product has the following formula:

wherein X is in each case independently selected from H or a cation equivalent K_a, wherein K is an alkali metal, alkaline earth metal, zinc, iron, aluminum, ammonium, or a phosphonium cat ion, and wherein a is 1/n, wherein n is the valence of the cation. More preferably, X is H or Ka, wherein K is an alkali metal. Even more preferably K is lithium, sodium or potassium. It is to be understood that also mixed salts are possible. In a particularly preferred embodiment X is independently sodium or potassium or a mixture thereof. The carbonate source may be an inorganic carbonate having an aqueous solubility of 0.1 g/l or more. The aqueous solubility of the inorganic carbonate is determined in water (starting at pH 7) at 25 °C. These characteristics are well known to those skilled in the art. The inorganic carbonate may be selected from alkaline metal carbonates such as potassium carbonate, sodium carbonate or lithium carbonate, and alkaline earth metal carbonates satisfying the required aqueous solubility, such as magnesium carbonate. It is also possible to use guanidine carbonate as an inorganic carbonate, as well as sodium hydrogencarbonate and potassium hydrogencarbonate. Alternatively, the carbonate source is selected from organic carbonates. "Organic carbonate" denotes an ester of carbonic acid. The organic carbonate is hydrolyzed in the presence of the cementitious system to release carbonate ions. In an embodiment, the organic carbonate is selected from ethylene carbonate, propylene carbonate, glycerol carbonate, dimethyl carbonate, di(hydroxyethyl)carbonate or a mixture thereof, preferably ethylene carbonate, propylene carbonate, and glycerol carbonate or a mixture thereof, and in particular ethylene carbonate and/or propylene carbonate. Mixtures of inorganic carbonates and organic carbonates can as well be used. In a preferred embodiment, the carbonate source is selected from a group consisting of limestone, dolomite, calcium-magnesium carbonate, siderite, sodium carbonate, potassium carbonate, hydrogen carbonate, lithium carbonate, guanidinium carbonate, and calcium carbonate. In a preferred embodiment, the carbonate source has a solubility in water of more than 0.08 g/l, more preferably of more than 0.09 g/l, and in particular of more than 0.1 g/l, at 25 °C. In a preferred embodiment, the salt of

s present in the additive mixture and wherein R2 is H, R3 is C₃-C₆ alkyl which may be substituted by 1 to 5 OH, and R4 is COOY, and Y is X being an alkali metal, preferably potassium or sodium. In a preferred embodiment, the salt is sodium gluconate. n a preferred embodiment, the additive mixture comprising i) a polyol having the structure R⁵-(CHOH)_o-R⁴, wherein R⁴ and R⁵ are independently C₁-C₆- hydroxyalkyl, C₂-C₆-hydroxyalkenyl, C₁-C₆-aminoalkyl, -OH, C₁-C₅-alkyl, wherein o is an integer rom 0-5 and ii) NR¹R²R³, wherein R¹ is C₁-C₆-hydroxyalkyl, C₂-C₆-hydroxyalkenyl, C₁-C₆-aminoalkyl, (CH₂O)_n-OH, (CH₂CH₂O)_n- OH, or (CH₂CH₂CH₂O)_n-OH; R² and R³ are independently C₁-C₆-hydroxyalkyl, C₂-C₆-hydroxyalkenyl, C₁-C₆-aminoalkyl, (CH₂O)_n-OH, (CH₂CH₂O)_n-OH, or (CH₂CH₂CH₂O)_n-OH; or together with the nitrogen to which they are bonded form a 5- or 6-membered saturated, partially or fully unsaturated, or aromatic heterocyclic ring, wherein said heterocyclic ring comprises one or more, same of different heteroatoms selected from O, N, or S, wherein said N- and/or S-atoms are independently oxidized or non-oxidized, and wherein each substitutable carbon or heteroatom in the heterocyclic ring is independently unsubstituted or substituted with one or more, same or different substituents R^M; R^M is halogen, CN, NO₂, NH₂, OH, C₁-C₂-alkyl, C₁-C₂-alkoxy, C(=O)R^X, or two R^M form =O; R^X is H, C₁-C₂-alkyl, phenyl, or benzyl; and n is an integer from 1 to 10. Hence, it is preferred if the additive mixture comprises components i) to iv). In a preferred embodiment, the weight ratio of the (co)polymer of the polymer dispersion to the Portland cement is from 2:1 to 1:2, preferably from 1.5:1 to 1:1.4, more preferably from 1.3:1 to 1: 1.2. In a preferred embodiment, the weight ratio of water to the Portland cement is from 2:1 to 1:2, preferably from 1.5:1 to 1:1.4, more preferably from 1.3:1 to 1:1.2. In a preferred embodiment, the weight ratio of the polymer dispersion to the Portland cement is from 4:1 to 1:1.3, preferably from 3:1 to 1:1, more preferably from 2.5:1 to 1: 1.1. In a preferred embodiment, the dispersion composition comprises the cement-based sealing slurry from 50 to 99 wt.-%, more preferably from 70 to 99 wt.-%, and in particular from 80 to 99 wt.-%, and the additive mixture from 1 to 50 wt.-%, more preferably from 1 to 30 wt.-%, and in particular from 1 to 20 wt.-%, each based on the total amount of the dispersion composition. In a preferred embodiment, the dispersion composition further comprises C) calcium sulfate. In a preferred embodiment, the dispersion composition further comprises D) at least one additional retarder. The at least one additional retarder may be selected from the group consisting of: -The bisulfite adduct as synthesized according to WO2017/212045A1: additive 1, page 26; the resulting suspension can be used directly or can be present as a powder which is obtainable, e.g., by drum-drying, spray drying, or flash-drying; -Fruit acids (citric acid, tartaric acid, gluconic acid) or salts thereof; -α-hydroxy carboxylic acids or salts thereof; and -Organic phosphates, phosphonoalkylcarboxylic acids, phosphonates (such as ATMP, BHMTMP, DTPMP, EDTMP, HDTMP, HEDP, HEMPA, and PBTC as provided by Zschimmer & Schwarz). In a preferred embodiment, the dispersion composition further comprises E) at least one additional accelerator. The at least one additional accelerator may be selected from the group consisting of: -Water-soluble organic carbonates such as ethylene carbonate, propylene carbonate, trimethylene carbonate, glycerol carbonate, dimethyl carbonate, or di(hydroxyethyl)carbonate, inorganic carbonates, such as alkali metal carbonates, like sodium carbonate; -Calcium-silicate-hydrate nanocrystals in suspension or as powders as described in WO2010/026155A1, EP14198721, WO2014/114784 or WO2014/114782; -Amorphous aluminum hydroxide (e.g. Geloxal), calcium oxide, calcium hydroxide; and -Lithium salts such as lithium sulfate. In a preferred embodiment, the dispersion composition further comprises F) at least one dispersant. The dispersant is preferably a polymeric dispersant, which has anionic and/or anionogenic groups and polyether side chains, which preferably comprise polyalkylene glycol side chains. The anionic and/or anionogenic groups and the polyether side chains are preferably attached to the backbone of the polymeric dispersant. The dispersants are in this case more preferably selected from the group of polycarboxylate ethers (PCEs), the anionic group being in the case of PCEs carboxylic groups and/or carboxylate groups, and phosphorylated polycondensates. Most preferable are the polycarboxylate ethers (PCEs).

The PCE is preferably produced by the radical copolymerization of a polyether macromonomer and an acid monomer in a way that at least 45 mol-%, preferably at least 80 mol-% of all structural units of the copolymer were formed by copolymerization of the polyether macromonomer and the acid monomer. The term acid monomer means in particular a monomer comprising anionic and/or anionogenic groups. The term polyether macromonomer means in particular a monomer comprising at least two ether groups, preferably at least two alkylene glycol groups.

The polymeric dispersant preferably comprises as anionic and/or anionogenic group at least one structural unit of the general formulae (la), (lb), (lc) and/or (Id):

(la)

in which

R¹ is H or an unbranched or branched C₁-C₄ alkyl group, CH₂COOH or CH₂CO-X-R³;

X is NH-(C_nH_2n) or O-(C_nH_2n) with n = 1 , 2, 3 or 4, or is a chemical bond, where the nitrogen atom or the oxygen atom is bonded to the CO group;

R² is OM, PO₃M₂, or O-PO₃M₂; with the proviso that X is a chemical bond if R² is OM; R³ is PO₃M₂, or O-PO₃M₂;

(lb)

in which

R³ is H or an unbranched or branched C₁-C₄ alkyl group; n is 0, 1, 2, 3 or 4;

R⁴ is PO₃M₂, or O-PO₃M₂; (lc)

in which

R⁵ is H or an unbranched or branched C₁-C₄ alkyl group;

Z is O or NR⁷;

R⁷ is H, (C_nH_2n)-OH, (C_nH_2n)-PO₃M₂, (C_nH_2n)-OPO₃M₂, (C₆H₄)-PO₃M₂, or (C₆H₄)-OPO₃M₂, and n is 1 , 2, 3 or 4;

(Id)

in which

R⁶ is H or an unbranched or branched C₁-C₄ alkyl group;

Q is NR⁷ or O;

R⁷ is H, (C_nH_2n)-OH, (C_nH_2n)-PO₃M₂, (C_nH_2n)-OPO₃M₂, (C₆H₄)-PO₃M₂, or (C₆H₄)-OPO₃M₂; n is 1 , 2, 3 or 4; and where each M in the above formulae independently of any other is H or a cation equivalent.

Preferable is a composition where the polymeric dispersant comprises as polyether side chain at least one structural unit of the general formulae (I la), (lib), (lie) and/or (lid):

(Ila)

in which R¹⁰, R¹¹ and R¹² independently of one another are H or an unbranched or branched C₁-C₄ alkyl group; Z is O or S; E is an unbranched or branched C₁-C₆ alkylene group, a cyclohexylene group, CH₂- C₆H₁₀, 1,2-phenylene, 1,3-phenylene or 1,4-phenylene; G is O, NH or CO-NH; or E and G together are a chemical bond; A is an unbranched or branched alkylene with 2, 3, 4 or 5 carbon atoms or CH₂CH(C₆H₅); n is 0, 1, 2, 3, 4 or 5; a is an integer from 2 to 350; R¹³ is H, an unbranched or branched C₁-C₄ alkyl group, CO-NH₂ or COCH₃; (IIb)

in which R¹⁶, R¹⁷ and R¹⁸ independently of one another are H or an unbranched or branched C₁-C₄ alkyl group; E is an unbranched or branched C₁-C₆ alkylene group, a cyclohexylene group, CH₂- C₆H₁₀, 1,2-phenylene, 1,3-phenylene, or 1,4-phenylene, or is a chemical bond; A is an unbranched or branched alkylene with 2, 3, 4 or 5 carbon atoms or CH₂CH(C₆H₅); n is 0, 1, 2, 3, 4 and/or 5; L is C_xH_2x with x = 2, 3, 4 or 5, or is CH₂CH(C₆H₅); a is an integer from 2 to 350; d is an integer from 1 to 350; R¹⁹ is H or an unbranched or branched C₁-C₄ alkyl group; R²⁰ is H or an unbranched C₁-C₄ alkyl group; and n is 0, 1, 2, 3, 4 or 5; (IIc)

in which R²¹, R²² and R²³ independently of one another are H or an unbranched or branched C₁-C₄ alkyl group; W is O, NR²⁵, or is N; V is 1 if W = O or NR²⁵, and is 2 if W = N; A is an unbranched or branched alkylene with 2 to 5 carbon atoms or CH₂CH(C₆H₅); a is an integer from 2 to 350; R²⁴ is H or an unbranched or branched C₁-C₄ alkyl group; R²⁵ is H or an unbranched or branched C₁-C₄ alkyl group; (IId)

in which R⁶ is H or an unbranched or branched C₁-C₄ alkyl group; Q is NR¹⁰, N or O; V is 1 if W = O or NR¹⁰ and is 2 if W = N; R¹⁰ is H or an unbranched or branched C₁-C₄ alkyl group; A is an unbranched or branched alkylene with 2 to 5 carbon atoms or CH₂CH(C₆H₅); and a is an integer from 2 to 350. In an embodiment, the polymeric dispersant is a phosphorylated polycondensation product comprising structural units (III) and (IV): (III)

in which T is a substituted or unsubstituted phenyl or naphthyl radical or a substituted or unsubstituted heteroaromatic radical having 5 to 10 ring atoms, of which 1 or 2 atoms are heteroatoms selected from N, O and S; n is 1 or 2; B is N, NH or O, with the proviso that n is 2 if B is N and with the proviso that n is 1 if B is NH or O; A is an unbranched or branched alkylene with 2 to 5 carbon atoms or CH₂CH(C₆H₅); a is an integer from 1 to 300; R²⁵ is H, a branched or unbranched C₁ to C₁₀ alkyl radical, C₅ to C₈ cycloalkyl radical, aryl radical, or heteroaryl radical having 5 to 10 ring atoms, of which 1 or 2 atoms are heteroatoms selected from N, O and S; where the structural unit (IV) is selected from the structural units (IVa) and (IVb):

in which D is a substituted or unsubstituted phenyl or naphthyl radical or a substituted or unsubstituted heteroaromatic radical having 5 to 10 ring atoms, of which 1 or 2 atoms are heteroatoms selected from N, O and S; E is N, NH or O, with the proviso that m is 2 if E is N and with the proviso that m is 1 if E is NH or O; A is an unbranched or branched alkylene with 2 to 5 carbon atoms or CH₂CH(C₆H₅); b is an integer from 0 to 300; M independently at each occurrence is H or a cation equivalent;

in which V is a substituted or unsubstituted phenyl or naphthyl radical and is optionally substituted by 1 or two radicals selected from R⁸, OH, OR⁸, (CO)R⁸, COOM, COOR⁸, SO₃R⁸ and NO₂; R⁷ is COOM, OCH₂COOM, SO₃M or OPO₃M₂; M is H or a cation equivalent; and R⁸ is C₁-C₄ alkyl, phenyl, naphthyl, phenyl-C₁-C₄ alkyl or C₁-C₄ alkylphenyl. The polymeric dispersants comprising structural units (I) and (II) can be prepared by conventional methods, for example by free radical polymerization. The preparation of the dispersants is, for example, described in EP0894811, EP1851256, EP2463314, and EP0753488. In a preferred embodiment, the dispersant is a polymer comprising a sulfonic acid and/or sulfonate group. In an embodiment, the polymeric dispersant comprising sulfonic acids and/or sulfonates and is selected from the group consisting of lignosulfonates (LGS), melamine formaldehyde sulfonate condensates (MFS), β-naphthalene sulfonic acid condensates (BNS), sulfonated ketone-formaldehyde-condensates, and copolymers comprising sulfo group containing units and/or sulfonate group-containing units and carboxylic acid and/or carboxylate group-containing units. The lignosulfonates used as polymeric sulfonated dispersants are products, which are obtained as by-products of the paper industry. Such products are described in Ullmann's Encyclopedia of Industrial Chemistry, 5th Ed., Vol. A8, pages 586, 587. They comprise units of the strongly simplified and idealized formula

wherein n is usually 5 to 500. Lignosulfonates have usually molecular weights between 2.000 and 100.000 g/mol. Generally, they are present in the form of their sodium-, calcium-, and/or magnesium salts. Examples for suitable lignosulfonates are the products marketed under the trade name Borresperse of the Norwegian company Borregaard LignoTech. The melamine-formaldehyde-sulfonate condensates (also called MFS-resins) and their preparation are for example described in CA 2172004 A1, DE 4411797 A1, US 4,430,469, US 6,555,683 and CH 686186, as well as in "Ullmann's Encyclopedia of Industrial Chemistry, 5th Ed., Vol. A2, page 131" and "Concrete Admixtures Handbook –Properties, Science and Technology, 2nd Ed., pages 411, 412". Preferred melamine-formaldehyde-sulfonate condensates comprise (strongly simplified and idealized) units of the formula

Melamine formaldehyde sulfite (PMS) wherein n is typically a number from 10 to 300. The molecular weight is preferably in the region from 2.500 to 80.000 g/mol. An example for melamine-formaldehyde-sulfonate condensates are products marketed by the company BASF Construction Additives GmbH under the trade name Melment^®. In addition to the sulfonated melamine units additional monomers can be co-condensated. In particular urea is suitable. Furthermore aromatic building units like gallic acid, aminobenzene sulfonic acid, sulfanilic acid, phenol sulfonic acid, aniline, ammonium benzoic acid, dialkoxybenzene sulfonic acid, dialkoxybenzoic acid, pyridine, pyridine monosulfonic acid, pyridine disulfonic acid, pyridine carboxylic acid and pyridine dicarboxylic acid can be co- condensated into the melamine-formaldehyde-sulfonate condensates. The sulfonated ketone-formaldehyde are products in which as ketone component a mono- or diketone is used. Preferably acetone, butanone, pentanone, hexanone or cyclohexanone are built into the polymer. Such condensates are known and for example described in WO 2009/103579. Preferable are sulfonated acetone-formaldehyde-condensates. They comprise typically units of the formula (according to J. Plank et al., J. Appl. Poly. Sci.2009, 2018 – 2024):

wherein m and n are typically an integer from 10 to 250, M is an alkali metall ion, for example Na⁺, and the ratio of m:n is generally in the region from about 3:1 to about 1:3, in particular from about 1,2:1 to about 1:1,2. Examples for suitable acetone-formaldehyde-condensates are products, which are marketed by the company BASF Construction Solutions GmbH under the trade name Melcret^® K1L. Furthermore aromatic building units like gallic acid, aminobenzene sulfonic acid, sulfanilic acid, phenol sulfonic acid, aniline, ammonium benzoic acid, dialkoxybenzene sulfonic acid, dialkoxybenzoic acid, pyridine, pyridine monosulfonic acid, pyridine disulfonic acid, pyridine carboxylic acid and pyridine dicarboxylic acid can be co-condensated. The β-naphthaline-formaldehyde-condensates (BNS) are products, which are obtained by a sulfonation of naphthaline followed by a polycondensation with formaldehyde. Such products are described amongst others in "Concrete Admixtures Handbook –Properties, Science and Technology, 2nd Ed., pages 411-413" and "Ullmann's Encyclopedia of Industrial Chemistry, 5th Ed., Vol. A8, pages 587, 588". They comprise units of the formula

Typically the molecular weight (M_w) is from 1.000 to 50.000 g/mol. Examples for suitable β-naphthaline-formaldehyde-condensates are the products marketed byhe company BASF Construction Additives GmbH under the trade name Melcret^® 500 L. Furthermore aromatic building units like gallic acid, aminobenzene sulfonic acid, sulfanilic acid, phenol sulfonic acid, aniline, ammonium benzoic acid, dialkoxybenzene sulfonic acid, dialkoxybenzoic acid, pyridine, pyridine monosulfonic acid, pyridine disulfonic acid, pyridine carboxylic acid and pyridine dicarboxylic acid can be co-condensated. As outlined above, the present invention relates in a second aspect to the use of the dispersion composition according to the first aspect (including all preferred embodiments) formproving flexibilisation or for providing waterproofness of particularly membranes. As outlined above, the present invention relates in a third aspect to the use of an additive mixture (AM-a) comprising i) a polyol having the structure R⁵-(CHOH)_o-R⁴, wherein R⁴ and R⁵ are independently C₁-C₆-hydroxyalkyl, C₂-C₆-hydroxyalkenyl, C₁-C₆-aminoalkyl, -OH, C₁-C₅-alkyl, wherein o is an integer from 0-5, and/or ii) NR¹R²R³, wherein R¹ is C₁-C₆-hydroxyalkyl, C₂-C₆-hydroxyalkenyl, C₁-C₆-aminoalkyl, (CH₂O)_n-OH, (CH₂CH₂O)_n-OH, or (CH₂CH₂CH₂O)_n-OH; R² and R³ are independently C₁-C₆-hydroxyalkyl, C₂-C₆-hydroxyalkenyl, C₁-C₆- aminoalkyl, (CH₂O)_n-OH, (CH₂CH₂O)_n-OH, or (CH₂CH₂CH₂O)_n-OH; or together with the nitrogen to which they are bonded form a 5- or 6-membered saturated, partially or fully unsaturated, or aromatic heterocyclic ring, wherein said heterocyclic ring comprises one or more, same of different heteroatoms selected from O, N, or S, wherein said N- and/or S-atoms are independently oxidized or non-oxidized, and wherein each substitutable carbon or heteroatom in the heterocyclic ring is independently unsubstituted or substituted with one or more, same or different substituents R^M; R^M is halogen, CN, NO₂, NH₂, OH, C₁-C₂-alkyl, C₁-C₂-alkoxy, C(=O)R^X, or two R^M form =O; R^X is H, C₁-C₂-alkyl, phenyl, or benzyl; and n is an integer from 1 to 10, and iii) a polycondensate or a sulfite addition product of at least one monomer with an aldehyde group, and v) optionally a salt of

wherein R1 is OH; R2 is H, OH, C₁-C₆ alkoxy, -SO₂X, -SO₃X, -OSO₃X, -PO, -PO₃X₂, -OPO₃X₂, -Z-COOX or -CH(OH)-SO₃X; R3 is H, COOX, C₃-C₆ alkyl which may be substituted by 1 to 5 OH or C₁-C₆ alkoxy; m is 0 or 1; or R1 and R2 taken together with the carbon atom to which they are attached form a carbonyl group provided m is 0; R4 is COOY or SO₃X; X is selected from H or a cation equivalent K_a wherein K is selected from an alkali metal, alkaline earth metal, zinc, iron, ammonium or phosphonium cation and a is 1/n wherein n is the valency of the cation; Y = is selected from X, C₁-C₆ alkyl or phenyl; and Z is CH₂ or CH(OH), provided that if R2 is SO₃X and m is 0 that R4 is not COOH, and of a carbonate source, or providing fast drying of a cement-based sealing slurry. Preferably, the cement-based sealing slurry comprises a polymer dispersion. Preferably, the cement-based sealing slurry comprises a Portland cement. Preferably, the additive mixture (AM-a) comprises components i) to iii). Regarding further preferred embodiments of the cement-based sealing slurry and the additive components i) to v), the same preferred embodiments as for the first aspect apply. Preferably, the carbonate source is comprised in the additive mixture (AM-a). Thus, in a preferred embodiment the additive mixture comprising i) a polyol having the structure R⁵-(CHOH)_o-R⁴, wherein R⁴ and R⁵ are independently C₁-C₆-hydroxyalkyl, C₂-C₆-hydroxyalkenyl, C₁-C₆-aminoalkyl, -OH, C₁-C₅-alkyl, wherein o is an integer from 0-5, and/or ii) NR¹R²R³, wherein R¹ is C₁-C₆-hydroxyalkyl, C₂-C₆-hydroxyalkenyl, C₁-C₆-aminoalkyl, (CH₂O)_n-OH, (CH₂CH₂O)_n-OH, or (CH₂CH₂CH₂O)_n-OH; R² and R³ are independently C₁-C₆-hydroxyalkyl, C₂-C₆-hydroxyalkenyl, C₁-C₆- aminoalkyl, (CH₂O)_n-OH, (CH₂CH₂O)_n-OH, or (CH₂CH₂CH₂O)_n-OH; or together with the nitrogen to which they are bonded form a 5- or 6-membered saturated, partially or fully unsaturated, or aromatic heterocyclic ring, wherein said heterocyclic ring comprises one or more, same of different heteroatoms selected from O, N, or S, wherein said N- and/or S-atoms are independently oxidized or non-oxidized, and wherein each substitutable carbon or heteroatom in the heterocyclic ring is independently unsubstituted or substituted with one or more, same or different substituents R^M; R^M is halogen, CN, NO₂, NH₂, OH, C₁-C₂-alkyl, C₁-C₂-alkoxy, C(=O)R^X, or two R^M form =O; R^X is H, C₁-C₂-alkyl, phenyl, or benzyl; and n is an integer from 1 to 10, and iii) a polycondensate or a sulfite addition product of at least one monomer with an aldehyde group, and iv) a carbonate source, and v) optionally a salt of

wherein R1 is OH; R2 is H, OH, C₁-C₆ alkoxy, -SO₂X, -SO₃X, -OSO₃X, -PO, -PO₃X₂, -OPO₃X₂, -Z-COOX or -CH(OH)-SO₃X; R3 is H, COOX, C₃-C₆ alkyl which may be substituted by 1 to 5 OH or C₁-C₆ alkoxy; m is 0 or 1; or R1 and R2 taken together with the carbon atom to which they are attached form a carbonyl group provided m is 0; R4 is COOY or SO₃X; X is selected from H or a cation equivalent K_a wherein K is selected from an alkali metal, alkaline earth metal, zinc, iron, ammonium or phosphonium cation and a is 1/n wherein n is the valency of the cation; Y = is selected from X, C₁-C₆ alkyl or phenyl; and Z is CH₂ or CH(OH), provided that if R2 is SO₃X and m is 0 that R4 is not COOH, for providing fast drying of a cement-based sealing slurry. It is in particular preferred that the additive mixture comprises components i) to iv). In a preferred embodiment, the additive mixture comprises i) the polyol in an amount of 5 to 30 wt.-%, ii) the NR¹R²R³ in an amount of 2 to 25 wt.-%, iii) the polycondensate or a sulfite addition product in an amount of 1 to 30 wt.-%, iv) the carbonate source in an amount of 4 to 45 wt.-%, and v) the salt of

in an amount of 0 to 15 wt.-%, each based on the total weight of the additive mixture. In a preferred embodiment, the additive mixture comprises i) the polyol in an amount of 10 to 30 wt.-%, ii) the NR¹R²R³ in an amount of 5 to 20 wt.-%, iii) the polycondensate or a sulfite addition product in an amount of 10 to 30 wt.-%, iv) the carbonate source in an amount of 25 to 45 wt.-%, and v) the salt of

in an amount of 2 to 15 wt.-%, each based on the total weight of the additive mixture. In a preferred embodiment, the additive mixture (AM-a) comprises i) the polyol in an amount of 25 to 35 wt.-%, ii) the NR¹R²R³ in an amount of 10 to 25 wt.-%, iii) the polycondensate or a sulfite addition product in an amount of 20 to 35 wt.-%, and v) the salt of

in an amount of 5 to 18 wt.-%, each based on the total weight of the additive mixture (AM-a). In a preferred embodiment, the additive mixture comprises i) the polyol in an amount of 5 to 27 wt.-%, ii) the NR¹R²R³ in an amount of 3 to 15 wt.-%, iii) the polycondensate or a sulfite addition product in an amount of 1 to 8 wt.-%, iv) the carbonate source in an amount of 4 to 17 wt.-%, and water in an amount of 50 to 80 wt.-%, each based on the total weight of the additive mixture. In a preferred embodiment, the additive mixture (AM-a) comprises i) the polyol in an amount of 5 to 27 wt.-%, ii) the NR¹R²R³ in an amount of 3 to 15 wt.-%, iii) the polycondensate or a sulfite addition product in an amount of 1 to 8 wt.-%, and water in an amount of 55 to 80 wt.-%, each based on the total weight of the additive mixture (AM-a). Preferably, the use of the additive mixture and of the additive mixture (AM-a) together with a carbonate source according to the present invention provides a pot life of the cement-based sealing slurry of 0.3 to 3 hours, more preferably of 0.4 to 2.5 hours, even more preferably of 0.5 to 2 hours, and in particular of 1 to 2 hours. In this connection it is to be understood that the pot life is the use period within which the polymer-modified building material in the made-up state has a viscosity and creaminess appropriate for processing, such that it can be applied to the application substrate with a suitable aid (brick trowel, squeegee, etc.). If this period is exceeded, the building material can no longer be spread smoothly on the application substrate. Faster systems are difficult to process and extremely slow systems having a pot life of more than 3 hours delay the next working steps. Preferably, the pot life according to the present invention is determined via a thin film of the material to be tested having a height of from 1.5 to 3.5 mm, a width of from 10.0 to 14.0 cm, and a length of from 15 to 30 cm on a Teflon foil. In a preferred embodiment, the use of the additive mixture and of the additive mixture (AM-a) together with a carbonate source provides a drying time of less than 4 hours, preferably of less than 3.5 hours, even more preferably of less than 3 hours, and in particular of less than 2 hours. In this connection, it is to be understood that the drying of the film is preferably evaluated by applying a pressure of approximately 10 to 20 g on the film, to check when the film can no longer be plastically deformed. As outlined above, the present invention relates in a fourth aspect to a flexible water-proofing membrane obtained from a dispersion composition according to the first aspect. Regarding the preferred embodiments of the components of the dispersion composition, the same preferred embodiments as for the first aspect apply. As outlined above, the present invention relates in a fifth aspect to a method of sealing a concrete or masonry structure comprising applying to the concrete or masonry structure the dispersion composition according to the first aspect. The term "concrete" denotes a mortar to which are added coarse granulates, i.e. granulates with a diameter of greater than 5 mm. The term "mortar" or "grout" denotes a cement paste to which are added fine granulates, i.e. granulates whose diameter is between 150 pm and 5 mm (for example sand), and optionally very fine granulates. A grout is a mixture of sufficiently low viscosity for filling in voids or gaps. Mortar viscosity is high enough to support not only the mortar's own weight but also that of masonry placed above it. The term "cement paste" denotes the inorganic binder composition admixed with water. The aggregate in this invention can be for example silica, quartz, sand, crushed marble, glass spheres, granite, limestone, sandstone, calcite, marble, serpentine, travertine, dolomite, feldspar, gneiss, alluvial sands, any other durable aggregate, and mixtures thereof. The aggregates are often also called fillers and in particular do not work as a binder. Preferably, the dispersion composition is applied on the concrete or masonry structure in a thickness from 0.5 mm to 5 mm, more preferably from 0.8 mm to 3 mm. It is to be understood that the thickness is measured directly after the application of the dispersion on the concrete or masonry structure, i.e. in wet condition. The dispersion may be applied once or multiple times. Regarding the preferred embodiments of the components of the dispersion composition, the same preferred embodiments as for the first aspect apply. The present invention is further illustrated by the following examples. Examples Starting materials For the examples and comparative examples, the following starting materials were used: Polymer dispersions Aqueous dispersions; Dispersion 1: In a 4 L glass vessel equipped with anchor stirrer, heating and cooling devices, and various feeds, 400.0 g of deionized water and 6.8 g of a polystyrene seed latex dispersion (with a solids content of 33% by weight; with a weight-average particle diameter of 28 nm) were heated to an internal temperature of 90 °C while stirring (140 rpm). After this temperature had been reached, 10% by weight of the starter solution were added in one portion and the mixture obtained was stirred for 5 minutes. Subsequently, starting at the same time, the total amount of the monomer emulsion was increased within 180 minutes and the remaining amount of starter solution is metered in continuously and with constant flow rates via spatially separate inlets over the course of 195 minutes. Starter solution: 8.4 g sodium peroxodisulfate 111.6 g of deionized water Monomer emulsion: 544.0 g deionized water 4.5 g of an aqueous solution containing 32% by weight of fatty alcohol polyglycol ether sulfate (Emulphor® FAS 30 from BASF SE) 36.2 g of an aqueous solution containing 20% by weight of fatty alcohol polyethoxylated (Lutensol® AT 18 of the company BASF SE) 5.0 g of an aqueous solution containing 15% by weight of sodium lauryl sulfate 90.0 g hydroxyethyl methacrylate 480.0 g styrene 30.0 g n-butyl acrylate and 815.0 g of 2-ethylhexyl acrylate The reaction mixture was then left to react for a further 15 minutes at the aforementioned temperature and the mixture was then cooled to 85 °C. Subsequently, starting at this temperature, 30 g of an aqueous solution containing 10% by weight of tert-butyl hydroperoxide and 34 g of an aqueous solution containing 13% by weight of acetone bisulfite (1:1 addition product of acetone and sodium hydrogen sulfite) were transferred to the reaction mixture over a period of 120 minutes and spatially separate feeds with continuously constant flow rates. The reaction mixture was then left to react for a further 15 minutes at the aforementioned temperature and the mixture was then cooled to room temperature. Afterwards, the aqueous polymer dispersion obtained was then adjusted to a pH of 7.5 with an aqueous sodium hydroxide solution. The polymer dispersion obtained had a solids content of 54.0% by weight, a number-average particle diameter of 250 nm and a glass transition temperature of -15°C. Re-dispersible dispersion powders; RDP 1: The re-dispersible dispersion powder (RDP 1) based on a styrene-acrylate dispersion which was produced by spray-drying as described in US 2020/0207671 A1: Example xiii in Table 1, page 11. Additives Polymer 1: Urea-glyoxylic acid condensate The urea-glyoxylic acid condensate was synthesized according to WO2019/077050A1: Synthetic procedure A, retarder 7 in table 1, page 24-26. The resulting suspension can be used directly or can be dried to a powder which is obtainable, e.g. by drum-drying, spray drying, or flash-drying. Accelerator powder 1 In a rotating drum 179.6 g spray dried urea-glyoxylic-acid condensate, 59.9 g sodium gluconate, 365.3 g sodium bicarbonate, and 110.7 g silica were filled. While the drum rotates, a mixture from 94.8 g triethanolamine (TEA) and 189.7 g glycerol were sprayed into the drum. Accelerator solution 1 2.868 g of an aqueous polymer 1 solution (s.c.52.3%), 6.157 Na₂CO₃, 5.575 g glycerol, 2.787 g TEA, and 30.812 g water were stirred, resulting in a suspension with a solids content of 33.23%. Accelerator solution 2 2.868 g of a 52.3% aqueous Polymer 1 solution, 3.079 g Na₂CO₃, 7.168 g glycerol, 3.584 g TEA, and 37.580 g water were stirred, resulting in a suspension with a solids content of 28.25%. Accelerator solution 3 2.868 g of a 52.3% aqueous Polymer 1 solution, 3.079 g Na2CO3, 7.168 g glycerol, and 17.190 g water were stirred, resulting in a suspension with a solids content of 38.76%. Accelerator solution 4 2.868 g of a 52.3% aqueous Polymer 1 solution, 7.168 g glycerol, 3.584 g TEA, and 10.3 g water were stirred, resulting in a suspension with a solids content of 39.76%. Accelerator solution 5 2.868 g of a 52.3% aqueous Polymer 1 solution, 3.079 g Na2CO3, and 17.190 g water were stirred, resulting in a suspension with a solids content of 19.79%. Application Tests The influence of the additives on hardening and drying of waterproofing membranes was investigated. Therefore, the building material composition was produced according to table 1.

Example 1: For a two-component application, 750 g of the dry compound from Table 1 was mixed with 7 g of powder 1 and 14 g CaSO₄ (anhydrite). Afterwards, 468.3 g of the dispersion 1 and 36 g water were added to the dry compound and stirred. The resulting dispersion-modified mineral building material mixture has a polymer dispersion / cement ratio (p/c) of 1.09 and a water / cement ratio (w/c) of 1.08. Example 2: For a two-component application, 750 g of the dry compound from table 1 was mixed with 14 g CaSO₄ (anhydrite). Separately, 468.3 g of the dispersion 1 were mixed with 41.5 g of accelerator solution 1. Afterwards, the resulting dispersion was added to the dry compound and stirred. Additional water was added until the resulting dispersion-modified mineral building material mixture has a polymer dispersion / cement ratio (p/c) of 1.09 and a water / cement ratio (w/c) of 1.08. Example 3: For a two-component application, 750 g of the dry compound from table 1 was mixed with 14 g CaSO₄ (anhydrite). Separately, 468.3 g of the dispersion 1 were mixed with 48.8 g of accelerator solution 2. Afterwards, the resulting dispersion was added to the dry compound and stirred. Additional water was added until the resulting dispersion-modified mineral building material mixture has a polymer dispersion / cement ratio (p/c) of 1.09 and a water / cement ratio (w/c) of 1.08. Example 4: For a one-component application where only water has to be added before usage, 750 g of the dry compound from table 1 was mixed with 7 g of powder 1, 14 g CaSO₄ (anhydrite), and 300 g RDP 1. Afterwards, water was added to the dry compound until the resulting dispersion- modified mineral building material mixture has a polymer dispersion / cement ratio (p/c) of 1.09 and a water / cement ratio (w/c) of 1.08. Example 5: For a two-component application, 750 g of the dry compound from table 1 was mixed with 14 g CaSO₄ (anhydrite). Separately, 468.3 g of the dispersion 1 were mixed with 26.8 g of accelerator solution 3. Afterwards, the resulting dispersion was added to the dry compound and stirred. Additional water was added until the resulting dispersion-modified mineral building material mixture has a polymer dispersion / cement ratio (p/c) of 1.09 and a water / cement ratio (w/c) of 1.08. Comparative example 1 For a two-component application, 750 g of the dry compound from table 1 was mixed with 468.3 g of the dispersion 1. Afterwards, additional water was added until the resulting dispersion-modified mineral building material mixture has a polymer dispersion / cement ratio (p/c) of 1.09 and a water / cement ratio (w/c) of 1.08. Comparative example 2 For a one-component application where only water has to be added before usage, 750 g of the dry compound from table 1 was mixed with 300 g RDP 1. Afterwards, water was added to the dry compound until the resulting dispersion-modified mineral building material mixture has a polymer dispersion / cement ratio (p/c) of 1.09 and a water / cement ratio (w/c) of 1.08. Comparative Example 3: For a two-component application, 750 g of the dry compound from table 1 was mixed with 14 g CaSO₄ (anhydrite). Separately, 468.3 g of the dispersion 1 were mixed with 28.8 g of accelerator solution 4. Afterwards, the resulting dispersion was added to the dry compound and stirred. Additional water was added until the resulting dispersion-modified mineral building material mixture has a polymer dispersion / cement ratio (p/c) of 1.09 and a water / cement ratio (w/c) of 1.08. Comparative Example 4: For a two-component application, 750 g of the dry compound from table 1 was mixed with 14 g CaSO₄ (anhydrite). Separately, 468.3 g of the dispersion 1 were mixed with 18.6 g of accelerator solution 5. Afterwards, the resulting dispersion was added to the dry compound and stirred. Additional water was added until the resulting dispersion-modified mineral building material mixture has a polymer dispersion / cement ratio (p/c) of 1.09 and a water / cement ratio (w/c) of 1.08. The influence of the additives on the setting and drying of the dispersion-modified mineral building material mixture was investigated by measuring the heat release using heat flow calorimetry. The addition of the hardening accelerator suspension accelerates the hardening (defined in H. F. W. Taylor (1997): Cement Chemistry, 2nd edition, p.212ft). Here, the cumulated amount of heat in joules per gram of cement that is released after 30 minutes within 2 and 5 hours was used. The effect is summarized in Table 2. The reference represents the heat flow without adding an additive according to the invention. Table 2: Cumulated heat of hydration, drying time, and pot life of the dispersion-modified mineral building material mixtures. The calorimetry measurements were performed at 20°C.

The pot life of the above-described dispersion-modified mineral building material mixture was assessed. The pot life is the use period within which the polymer-modified building material in the made-up state has a viscosity and creaminess appropriate for processing, such that it can be applied to the application substrate with a suitable aid (brick trowel, squeegee, etc.). If this period is exceeded, the building material can no longer be spread smoothly on the application substrate. A pot life of 0.5-2 h is desirable, whereas faster systems are difficult to process and extremely slow systems (pot life >3 h) delay the next working steps. The effect is summarized in Table 2. The dispersion-modified mineral building material mixture was used to produce a wet thin film (height: 2.5 mm, width 12.0 cm and length 20 to 25 cm) on a Teflon foil. The appearance of the dried building material was examined. All films were homogeneous (no separation), apparently smooth, and had no cracks. Furthermore, the drying of the film was evaluated. For this purpose, a pressure of approximately 10-20 g was exerted by placing a finger on the film, to check when the film could no longer be plastically deformed. A short drying time <3 h is desirable so that the next work steps are not delayed. These steps could be adding another layer of the film, applying tile adhesive, etc. The effect is summarized in Table 2. As can be seen from Table 2, the pot lives of comparative examples 3 and 4 are not sufficient.

Claims

Claims 1. A dispersion composition comprising A) a cement-based sealing slurry comprising a) a Portland cement comprising an aluminate phase, wherein the amount of alumina in form of Al₂O₃ is at least 2 wt.-% of the total mass of the aluminate-containing cement as determined by means of X-ray fluorescence (XRF), b) a polymer dispersion comprising a (co)polymer selected from the group consisting of acrylic acid ester polymer, acrylic-styrene copolymer, styrene-butadiene-based copolymer, vinyl acetate polymer, and ethylene-vinyl acetate copolymer; and B) an additive mixture comprising i) a polyol having the structure R⁵-(CHOH)_o-R⁴, wherein R⁴ and R⁵ are independently C₁-C₆-hydroxyalkyl, C₂-C₆-hydroxyalkenyl, C₁-C₆-aminoalkyl, -OH, C₁-C₅- alkyl, wherein o is an integer from 0-5, and/or ii) NR¹R²R³, wherein R¹ is C₁-C₆-hydroxyalkyl, C₂-C₆-hydroxyalkenyl, C₁-C₆-aminoalkyl, (CH₂O)_n-OH, (CH₂CH₂O)_n-OH, or (CH₂CH₂CH₂O)_n-OH; R² and R³ are independently C₁-C₆-hydroxyalkyl, C₂-C₆-hydroxyalkenyl, C₁-C₆- aminoalkyl, (CH₂O)_n-OH, (CH₂CH₂O)_n-OH, or (CH₂CH₂CH₂O)_n-OH; or together with the nitrogen to which they are bonded form a 5- or 6-membered saturated, partially or fully unsaturated, or aromatic heterocyclic ring, wherein said heterocyclic ring comprises one or more, same of different heteroatoms selected from O, N, or S, wherein said N- and/or S-atoms are independently oxidized or non-oxidized, and wherein each substitutable carbon or heteroatom in the heterocyclic ring is independently unsubstituted or substituted with one or more, same or different substituents R^M; R^M is halogen, CN, NO₂, NH₂, OH, C₁-C₂-alkyl, C₁-C₂-alkoxy, C(=O)R^X, or two R^M form =O; R^X is H, C₁-C₂-alkyl, phenyl, or benzyl; and n is an integer from 1 to 10, and iii) a polycondensate of glyoxylic acid or a sulfite addition product of glyoxylic acid, and iv) a carbonate source, and v) optionally a salt of

wherein R1 is OH; R2 is H, OH, C₁-C₆ alkoxy, -SO₂X, -SO₃X, -OSO₃X, -PO, -PO₃X₂, -OPO₃X₂, -Z-COOX or -CH(OH)-SO₃X; R3 is H, COOX, C₃-C₆ alkyl which may be substituted by 1 to 5 OH or C₁-C₆ alkoxy; m is 0 or 1; or R1 and R2 taken together with the carbon atom to which they are attached form a carbonyl group provided m is 0; R4 is COOY or SO₃X; X is selected from H or a cation equivalent K_a wherein K is selected from an alkali metal, alkaline earth metal, zinc, iron, ammonium or phosphonium cation and a is 1/n wherein n is the valency of the cation; Y = is selected from X, C₁-C₆ alkyl or phenyl; and Z is CH₂ or CH(OH), provided that if R2 is SO₃X and m is 0 that R4 is not COOH.

2. The dispersion composition according to claim 1, wherein the Portland cement is an ordinary Portland cement comprising at least 3 wt.-% of aluminate types selected from the group consisting of C3A, C4AF, and mixtures thereof, and/or less than 5 wt.-% of aluminate type CAC in form of CA, C2AS, CA2, and C12A7, and/or at least 3 wt.-% of CaSO₄·x H₂O, wherein x is selected from 0 to 1.5, and/or CaSO₄·x H₂O, wherein x is selected from 0 to 1.5, and Al₂O₃ and wherein the weight ratio of the CaSO₄·x H₂O to the amount of Al₂O₃ is from 1:3 to 4:1, preferably from 1:2 to 3:1.

3. The dispersion composition according to claim 1 or 2, wherein the cement-based sealing slurry consists of the Portland cement and the polymer dispersion and comprises from 10 to 50 wt.-%, preferably from 20 to 45 wt.-%, of the polymer dispersion, based on the total weight of the cement-based sealing slurry.

4. The dispersion composition according to any one of claims 1 to 3, wherein the polymer dispersion is an aqueous polymer dispersion, preferably having a solid polymer content, determined according to DIN EN ISO 3251, from 20 to 70 wt.-%, more preferably from 30 to 65 wt.-%, and in particular from 40 to 60 wt.-%, based on the total weight of the aqueous polymer dispersion or a powder dispersion, preferably having a (co)polymer content from 60 to 95 wt.-%, more preferably from 70 to 90 wt.-%, based on the total weight of the powder dispersion.

5. The dispersion composition according to any one of claims 1 to 4, wherein the (co)polymer of the polymer dispersion has a Tg, calculated using the Fox equation , of -60 to 0 °C, preferably of -30 to -5 °C and/or the polymer dispersion comprises an acrylic-styrene copolymer.

6. The dispersion composition according to any one of claims 1 to 5, wherein the polyol has a molecular weight of less than 200 g/mol, preferably of less than 150 g/mol, more preferably of less than 100 g/mol and/or a C/O ratio of from less than 2 to more than 0.72, preferably from 1.5 to 0.8, in particular wherein the polyol is glycerol.

7. The dispersion composition according to any one of claims 1 to 6, wherein in NR¹R²R³, R¹ to R³ are independently C₁-C₆-hydroxyalkyl and/or R¹ to R³ are the same, preferably hydroxyethyl.

8. The dispersion composition according to any one of claims 1 to 7, wherein the polycondensate of glyoxylic acid is an amine-glyoxylic acid condensate, preferably wherein the amine-glyoxylic acid condensate is selected from the group consisting of a melamine- glyoxylic acid condensate, a urea-glyoxylic acid condensate, a melamine-urea-glyoxylic acid condensate, and a polyacrylamide-glyoxylic acid condensate, more preferably urea-glyoxylic acid condensate.

9. The dispersion composition according to any one of claims 1 to 8, wherein the carbonate source is selected from a group consisting of limestone, dolomite, calcium- magnesium carbonate, siderite, sodium carbonate, potassium carbonate, hydrogen carbonate, lithium carbonate, guanidinium carbonate, and calcium carbonate and/or wherein the carbonate source has a solubility in water of more than 0.08 g/l at 25 °C.

10. The dispersion composition according to any one of claims 1 to 9, wherein the salt of

is present in the additive mixture and wherein R2 is H, R3 is C₃-C₆ alkyl which may be substituted by 1 to 5 OH, and R4 is COOY, and Y is X being an alkali metal, preferably wherein the salt is sodium gluconate.

11. The dispersion composition according of any one of claims 1 to 10, wherein the weight ratio of the (co)polymer of the polymer dispersion to the Portland cement is from 2:1 to 1:2, preferably from 1.5:1 to 1:1.4, more preferably from 1.3:1 to 1: 1.2 and/or the weight ratio of water to the Portland cement is from 2:1 to 1:2, preferably from 1.5:1 to 1:1.4, more preferably from 1.3:1 to 1:1.2 and/or the weight ratio of the polymer dispersion to the Portland cement is from 4:1 to 1:1.3, preferably from 3:1 to 1:1, more preferably from 2.5:1 to 1: 1.1.

12. The dispersion composition according of any one of claims 1 to 11, further comprising C) calcium sulfate.

13. Use of the dispersion composition according to any one of claim 1 to 12 for improvinglexibilisation or for providing waterproofness.

14. Use of an additive mixture (AM-a) comprising i) a polyol having the structure R⁵-(CHOH)_o-R⁴, wherein R⁴ and R⁵ are independently C₁-C₆-hydroxyalkyl, C₂-C₆-hydroxyalkenyl, C₁-C₆-aminoalkyl, -OH, C₁-C₅-alkyl, wherein o is an integer from 0-5, and/or ii) NR¹R²R³, wherein R¹ is C₁-C₆-hydroxyalkyl, C₂-C₆-hydroxyalkenyl, C₁-C₆-aminoalkyl, (CH₂O)_n-OH, (CH₂CH₂O)_n-OH, or (CH₂CH₂CH₂O)_n-OH; R² and R³ are independently C₁-C₆-hydroxyalkyl, C₂-C₆-hydroxyalkenyl, C₁-C₆- aminoalkyl, (CH₂O)_n-OH, (CH₂CH₂O)_n-OH, or (CH₂CH₂CH₂O)_n-OH; or together with the nitrogen to which they are bonded form a 5- or 6-membered saturated, partially or fully unsaturated, or aromatic heterocyclic ring, wherein said heterocyclic ring comprises one or more, same of different heteroatoms selected from O, N, or S, wherein said N- and/or S-atoms are independently oxidized or non-oxidized, and wherein each substitutable carbon or heteroatom in the heterocyclic ring is independently unsubstituted or substituted with one or more, same or different substituents R^M; R^M is halogen, CN, NO₂, NH₂, OH, C₁-C₂-alkyl, C₁-C₂-alkoxy, C(=O)R^X, or two R^M form =O; R^X is H, C₁-C₂-alkyl, phenyl, or benzyl; and n is an integer from 1 to 10, and iii) a polycondensate or a sulfite addition product of at least one monomer with an aldehyde group, and v) optionally a salt of

wherein R1 is OH; R2 is H, OH, C₁-C₆ alkoxy, -SO₂X, -SO₃X, -OSO₃X, -PO, -PO₃X₂, -OPO₃X₂, -Z-COOX or -CH(OH)-SO₃X; R3 is H, COOX, C₃-C₆ alkyl which may be substituted by 1 to 5 OH or C₁-C₆ alkoxy; m is 0 or 1; or R1 and R2 taken together with the carbon atom to which they are attached form a carbonyl group provided m is 0; R4 is COOY or SO₃X; X is selected from H or a cation equivalent K_a wherein K is selected from an alkali metal, alkaline earth metal, zinc, iron, ammonium or phosphonium cation and a is 1/n wherein n is the valency of the cation; Y = is selected from X, C₁-C₆ alkyl or phenyl; and Z is CH₂ or CH(OH), provided that if R2 is SO₃X and m is 0 that R4 is not COOH, and of a carbonate source, or providing fast drying of a cement-based sealing slurry.

15. The use according to claim 14, wherein the carbonate source is comprised in the additive mixture (AM-a).

16. A flexible water-proofing membrane obtained from a dispersion composition according to any one of claims 1 to 12.

17. A method of sealing a concrete or masonry structure comprising applying to the concrete or masonry structure the dispersion composition according to any one of claims 1 to 12.