Ultrarapid hardening cement composition and dispersant for ultrarapid hardening cement composition

A method of using an ultrarapid hardening cement composition wherein the method comprises a step of kneading and placing the ultrarapid hardening cement composition at an ambient temperature of 15° C. or less, wherein the ultrarapid cement hardening composition comprises:

• an ultrarapid hardening cement (A) comprising a calcium aluminate;
• and a cement dispersant (B),
• wherein the cement dispersant (B) comprises a copolymer having:
• a repeating unit derived from a monomer represented by the following formula (1):
• in the formula, R1 being the same or different and each representing a hydrogen atom or an alkyl group containing 1 to 18 carbon atoms;
• n representing an average molar number of addition and being a number of 10 to 300;
• and
• a repeating unit derived from a monomer represented by the following formula (2):
• in the formula, M representing a hydrogen atom, a monovalent metal atom, a divalent metal atom, an ammonium group, or an organic amine group;
• wherein the ultrarapid hardening cement composition is produced by being kneaded at a water/the ultrarapid hardening cement (A) ratio of 35% by mass or less and wherein the mass ratio of the cement dispersant (B) to the ultrarapid hardening cement (A) is 0.01:100 to 8.0:100.