(57) The present invention relates to a cement composition which comprises a cement, cellulose nanofibers, and water, wherein the mass ratio of the water to the cement is 0.4 or less. Preferred as the cement is Portland cement. It is preferable that the Portland cement be high-early-strength Portland cement and that the mass ratio of a fine aggregate to the high-early-strength Portland cement be 2.0 or less. It is preferable that the amount of the cellulose nanofibers in the cement composition per unit volume be 0.1-15 kg/m3. The present invention further relates to a cured object obtained from the cement composition, the cement composition giving a cured object sample aged in water and a cured object sample aged in air, the ratio of the splitting tensile strength of the latter sample as measured at a material age of 91 days in accordance with JIS-A-1113 (2006) to that of the former sample as measured likewise being 0.90-1.10.
(71) Daio Seishi KK (JP); Sumitomo Mitsui Construction Co Ltd (JP)