Cement compositions and methods of preparation thereof

A method of cementing a wellbore comprising:

• preparing a wellbore cementing composition comprising:
• 100 parts by weight of a cement,
• 0.01-20 parts by weight of a modified styrenic block copolymer having:
• at least one monoalkenyl arene polymer block A,
• at least one conjugated diene polymer block B, and
• at least an epoxy functional group or derivative thereof;
• wherein:
• the modified styrenic block copolymer has a degree of functionalization of 10-90% in the block B,
• the modified styrenic block copolymer is characterized as having an absorption rate of at least 0.05% upon exposure to water for at least 7 days;
• a mass ratio of an aqueous fluid to cement of 1:3 to 3:4;
• placing the wellbore cementing composition in the wellbore;
• and
• allowing the cementing composition to set.