Use of a rheological additive, in a process of manufacture by vibro-compaction of a formulation containing water and at least one hydraulic binder, characterized in that the said additive is an emulsion of at least one non-cross-linked copolymer, consisting of: a) (meth)acrylic acid, b) alkyl (meth)acrylate having 1 to 25 carbon atoms, preferentially 1 to 4 carbon atoms, in which this alkyl methacrylate is preferentially ethyl (meth)acrylate, c) a monomer of formula R 1 -(R 2 O) m -R 3, in which: - R 1 designates a radical containing an unsaturated polymerizable function, belonging to the group of vinylics, as well as to the group of acrylic, methacrylic, maleic esters, as well as to the group of unsaturated urethanes such as acrylurethane, methacrylurethane, α-α' dimethyl-isopropenyl-benzylurethane, allylurethane, as well as to the group of allylic or vinylic ethers, whether or not substituted, or again to the group of ethylenically unsaturated amides or imides, or again to the group constituted by acrylamide and methacrylamide, and preferentially methacrylic, - R 2 O designates an alkylene oxide group having 1 to 6 carbon atoms, preferentially an ethylene oxide and propylene oxide group, very preferentially an ethylene oxide group, - m is an integer comprised between 20 and 30, preferentially between 23 and 27, and is very preferentially equal to 25, - R 3 designates a linear or branched alkyl chain having 28 to 33 carbon atoms, preferentially 30 to 33 carbon atoms, and having very preferentially 32 carbon atoms. a) (meth)acrylic acid, b) alkyl (meth)acrylate having 1 to 25 carbon atoms, preferentially 1 to 4 carbon atoms, in which this alkyl methacrylate is preferentially ethyl (meth)acrylate, c) a monomer of formula R 1 -(R 2 O) m -R 3, in which: - R 1 designates a radical containing an unsaturated polymerizable function, belonging to the group of vinylics, as well as to the group of acrylic, methacrylic, maleic esters, as well as to the group of unsaturated urethanes such as acrylurethane, methacrylurethane, α-α' dimethyl-isopropenyl-benzylurethane, allylurethane, as well as to the group of allylic or vinylic ethers, whether or not substituted, or again to the group of ethylenically unsaturated amides or imides, or again to the group constituted by acrylamide and methacrylamide, and preferentially methacrylic, - R 2 O designates an alkylene oxide group having 1 to 6 carbon atoms, preferentially an ethylene oxide and propylene oxide group, very preferentially an ethylene oxide group, - m is an integer comprised between 20 and 30, preferentially between 23 and 27, and is very preferentially equal to 25, - R 3 designates a linear or branched alkyl chain having 28 to 33 carbon atoms, preferentially 30 to 33 carbon atoms, and having very preferentially 32 carbon atoms. - R 1 designates a radical containing an unsaturated polymerizable function, belonging to the group of vinylics, as well as to the group of acrylic, methacrylic, maleic esters, as well as to the group of unsaturated urethanes such as acrylurethane, methacrylurethane, α-α' dimethyl-isopropenyl-benzylurethane, allylurethane, as well as to the group of allylic or vinylic ethers, whether or not substituted, or again to the group of ethylenically unsaturated amides or imides, or again to the group constituted by acrylamide and methacrylamide, and preferentially methacrylic, - R 2 O designates an alkylene oxide group having 1 to 6 carbon atoms, preferentially an ethylene oxide and propylene oxide group, very preferentially an ethylene oxide group, - m is an integer comprised between 20 and 30, preferentially between 23 and 27, and is very preferentially equal to 25, - R 3 designates a linear or branched alkyl chain having 28 to 33 carbon atoms, preferentially 30 to 33 carbon atoms, and having very preferentially 32 carbon atoms.