| 摘要 |
The purpose of the present invention is to provide a cement additive that can exert sufficient water-reducing performance and improve the dispersion retaining ability of a cement even at a lower addition level than conventional lignin derivatives. The cement additive, which comprises a lignin derivative essentially having a lignin moiety and a polyalkylene glycol moiety, is characterized in that, in the lignin derivative: the average addition mole number of an alkylene oxide constituting the polyalkylene glycol moiety exceeds 10; the molar ratio of the polyalkylene glycol moiety to the lignin moiety is 0.1-20; the number-average molecular weight is 6,000-200,000; and the molecular weight distribution is 1.0-3.5. |
