A set control composition for cementitious systems comprises (a) an amine-glyoxylic acid condensate, and (b) at least one of (i) a borate source and (ii) a carbonate source. The carbonate source is selected from inorganic carbonates having an aqueous solubility of 0.1 gL.sup.−1 or more, and organic carbonates. The set control composition improves workability of cementitious systems for prolonged periods of time without compromising early compressive strength. Due to the retarding action of the set control composition, the dosage of dispersant(s) necessary to obtain a desired flowability of the cementitious system can be reduced.

The invention relates to an aqueous composition comprising a copolymer obtained by a specific polymerisation reaction using an anionic monomer comprising a polymerisable olefinic unsaturation and a carboxylic acid function and a monomer of formula (I):

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The invention also relates to said copolymer, to a method for the production thereof, and to the use of same as a superplasticizing agent.

A block copolymer for use as a dispersant for mineral binder compositions, containing an alkali activating agent. The block copolymer includes at least one first block A and at least one second block B, the first block A containing a monomeric unit M1 and the second block B containing a monomeric unit M2. A proportion of monomeric units M2, if any, in the first block A is less than 25 mol %, in particular less than or equal to 10 mol %, relative to all the monomeric units M1 in the first block A, and a proportion of monomeric units M1, if any, in the second block B is less than 25 mol %, in particular less than or equal to 10 mol %, relative to all the monomeric units M2 in the second block B.

A block copolymer for use as a dispersant for mineral binder compositions, containing an alkali activating agent. The block copolymer includes at least one first block A and at least one second block B, the first block A containing a monomeric unit M1 and the second block B containing a monomeric unit M2. A proportion of monomeric units M2, if any, in the first block A is less than 25 mol %, in particular less than or equal to 10 mol %, relative to all the monomeric units M1 in the first block A, and a proportion of monomeric units M1, if any, in the second block B is less than 25 mol %, in particular less than or equal to 10 mol %, relative to all the monomeric units M2 in the second block B.

A preparation method of a powdery polycarboxylate superplasticizer is provided, including: mixing a superplasticizer monomer with water to produce a mixture, heating and melting the mixture to produce a melt system; carrying out a bulk polymerization reaction by adding an initiator, a chain transfer agent and an unsaturated carboxylic acid into the melt system, forming a polycarboxylate superplasticizer precursor; and neutralizing and pulverizing the polycarboxylate superplasticizer precursor to produce a powdery polycarboxylate superplasticizer. Water is added in the bulk polymerization and reacts with the superplasticizer monomer and the unsaturated carboxylic acid. While the bulk polymerization reaction is guaranteed to be efficiently carried out and the solid polycarboxylate superplasticizer is formed, the viscosity of a bulk polymerization reaction system is reduced. The superplasticizer is suitable for dry-mixed mortar, high-efficiency concrete and other products.

A preparation method of a powdery polycarboxylate superplasticizer is provided, including: mixing a superplasticizer monomer with water to produce a mixture, heating and melting the mixture to produce a melt system; carrying out a bulk polymerization reaction by adding an initiator, a chain transfer agent and an unsaturated carboxylic acid into the melt system, forming a polycarboxylate superplasticizer precursor; and neutralizing and pulverizing the polycarboxylate superplasticizer precursor to produce a powdery polycarboxylate superplasticizer. Water is added in the bulk polymerization and reacts with the superplasticizer monomer and the unsaturated carboxylic acid. While the bulk polymerization reaction is guaranteed to be efficiently carried out and the solid polycarboxylate superplasticizer is formed, the viscosity of a bulk polymerization reaction system is reduced. The superplasticizer is suitable for dry-mixed mortar, high-efficiency concrete and other products.

A copolymer as dispersant in a binder composition comprising an alkaline activating agent, wherein the activating agent is especially suitable for activation of a latently hydraulic and/or pozzolanic binder, wherein the copolymer has a polymer backbone and side chains bonded thereto and comprises at least one ionizable monomer unit M1 and at least one side chain-bearing monomer unit M2, and wherein the copolymer has a gradient structure in at least one section A in a direction along the polymer backbone with regard to the ionizable monomer unit M1 and/or with regard to the side chain-bearing monomer unit M2.

A copolymer as dispersant in a binder composition comprising an alkaline activating agent, wherein the activating agent is especially suitable for activation of a latently hydraulic and/or pozzolanic binder, wherein the copolymer has a polymer backbone and side chains bonded thereto and comprises at least one ionizable monomer unit M1 and at least one side chain-bearing monomer unit M2, and wherein the copolymer has a gradient structure in at least one section A in a direction along the polymer backbone with regard to the ionizable monomer unit M1 and/or with regard to the side chain-bearing monomer unit M2.

The present invention relates to admixtures, especially a dispersant for solid particles, in particular a dispersant for mineral binder compositions, comprising: a) a superplasticizer and b) a copolymer having a polymer backbone and side chains bonded thereto, comprising at least one ionizable monomer unit M1 and at least one side chain-bearing monomer unit M2, wherein the copolymer has a nonrandom distribution of the monomer units M1 and/or the monomer units M2 in a direction along the polymer backbone, and wherein the superplasticizer and the copolymer differ from a chemical and/or structural point of view.

The present invention relates to admixtures, especially a dispersant for solid particles, in particular a dispersant for mineral binder compositions, comprising: a) a superplasticizer and b) a copolymer having a polymer backbone and side chains bonded thereto, comprising at least one ionizable monomer unit M1 and at least one side chain-bearing monomer unit M2, wherein the copolymer has a nonrandom distribution of the monomer units M1 and/or the monomer units M2 in a direction along the polymer backbone, and wherein the superplasticizer and the copolymer differ from a chemical and/or structural point of view.