Patent ID: 8177905

Claim:
A method of imparting flow to a cementitious composition, comprising the addition thereto of an admixture comprising: (1) 2-phosphonobutane-1,2,4-tricarboxylic acid; (2) optionally, citric acid or citric acid monohydrate; and (3) at least one polymer derived from ethylenically-unsaturated mono- or dicarboxylic acids, and characterised in that the polymer comprises: a) 51-95 mole % of moieties of formula 1a and/or 1b and/or 1c wherein R 1 =hydrogen or a C 1-20 aliphatic hydrocarbon residue; X=O a M, —O—(C m H 2m O) n —R 2 , —NH—(C m H 2m O) n —R 2 , M=hydrogen, a mono- or divalent metal cation, an ammonium ion or an organic amine residue; a=0.5 or 1; R 2 =hydrogen, C 1-20 aliphatic hydrocarbon, C 5-8 cycloaliphatic hydrocarbon or optionally substituted C 6-14 aryl residue; Y=O, NR 2 ; m=2-4; and n=0-200; b) 1-48.9 mole % of moieties of the general formula II wherein R 3 =hydrogen or C 1-5 aliphatic hydrocarbon; p=0-3; and R 2 has the meaning given previously; c) 0.1-5 mole % of moieties of Formulae IIIa or IIIb wherein S=H, —COO a M, —COOR 5 —W—R 7 —CO—[NH—(CH 2 ) 3 ] s —W—R 7 —CO—O—(CH 2 ) z —W—R 7 —(CH 2 ) z —V—(CH 2 ) z —CH═CH—R 2 —COOR 5 when S is —COOR 5 or COO a M U 1 =—CO—NH—, —O—, —CH 2 O— U 2 =—NH—CO—, —O—, —OCH 2 — V=—O—CO—C 6 H 4 —CO—O— or —W— R 4 =H, CH 3 R 5 =a C 3-20 aliphatic hydrocarbon residue, a C 5 -C 8 cycloaliphatic hydrocarbon residue or a C 6-14 aryl residue; wherein r=2-100 s=1, 2 z=0-4 x=1-150 y=0-15; and d) 0-47.9 mole % of moieties of the general formula IVa and/or IV b: wherein a, M, X and Y have the meanings defined above.