Cement additive, cement composition, and cement additive raw material

A cement additive, comprising:

• a polycarboxylic acid-based copolymer (A) having a structural unit (I) derived from an unsaturated polyalkylene glycol-based monomer (a) represented by the general formula (1) and a structural unit (II) derived from an unsaturated carboxylic acid-based monomer (b) represented by the general formula (2);
• and
• an alkanolamine compound (B),
• wherein a content of the structural unit (II) with respect to a total amount of the structural unit (I) and the structural unit (II) is 60 mol % or less:
• in the general formula (1), R1 and R2 are identical to or different from each other, and each represent a hydrogen atom or a methyl group, R3 represents a hydrogen atom or a hydrocarbon group having 1 to 30 carbon atoms, AO represents an oxyalkylene group having 2 to 18 carbon atoms, n represents an average number of moles added of oxyalkylene groups each represented by AO, and n represents from 1 to 90, and x represents an integer of from 0 to 2;
• in the general formula (2), R4 to R6 are identical to or different from one another, and each represent a hydrogen atom, a methyl group, or a —(CH2)zCOOM group, and the —(CH2)zCOOM group optionally forms an anhydride with a —COOX group or any other —(CH2)zCOOM group, z represents an integer of from 0 to 2, M represents a hydrogen atom, an alkali metal, an alkaline earth metal, an ammonium group, an organic ammonium group, or an organic amine group, and X represents a hydrogen atom, an alkali metal, an alkaline earth metal, an ammonium group, an organic ammonium group, or an organic amine group,
• wherein the alkanolamine compound (B) is selected from the group consisting of monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, methyl ethanolamine, methylisopropanolamine, methyldiisopropanolamine, diethanolisopropanolamine, diisopropanolethanolamine, tetrahydroxyethylethylenediamine, N,N-bis(2-hydroxyethyl)2-propanolamine, N,N-bis(2-hydroxypropyl)-N-(hydroxyethyl)amine, N,N-bis(2-hydroxyethyl)-N-(2-hydroxypropyl)amine, N,N,N′,N′-tetra(2-hydroxypropyl)ethylenediamine, N,N,N′,N″,N″-pentakis(2-hydroxypropyl)di ethylenetriamine, and tris(2-hydroxybutyl)amine.