Admixture for concrete

A method for improving the fluidity of a hydraulic composition which comprises adding a copolymer prepared by copolymerizing a monomer (a) represented by the following formula (A) with a monomer (b) selected from the group consisting of the compounds represented by the following formula (B) and those represented by the following formula (C) to a hydraulic composition:

• ##STR11## wherein R.sub.1 and R.sub.2 may be the same or different from each other and each represents a hydrogen atom or a methyl group;
• m1 is an integer of 0 to 2;
• AO represents an oxyalkylene group having 2 to 3 carbon atoms;
• n is a number of 110 to 300;
• and X represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, ##STR12## wherein R.sub.3, R.sub.4 and R.sub.5 may be the same or different from one another and each represents a hydrogen atom, a methyl group or a group represented by the formula:
• (CH.sub.2).sub.m2 COOM.sub.2 (wherein m2 is an integer of 0 to 2;
• and M.sub.2 represents a hydrogen atom, an alkali metal atom, 1/2 an alkaline earth metal atom, an ammonium group, an alkylammonium group or a substituted alkylammonium group);
• and M.sub.1 represents a hydrogen atom, an alkali metal atom, 1/2 an alkaline earth metal atom, an ammonium group, an alkylammonium group or a substituted alkylammonium group, and ##STR13## wherein R.sub.6 represents a hydrogen atom or a methyl group;
• and Y represents a hydrogen atom, an alkali metal atom, 1/2 an alkaline earth metal atom, an ammonium group, an alkylammonium group or a substituted alkylammonium group and having a molar ratio of monomer (a) to monomer (b) of from 0.1/100 to 100/100.

A hydraulic composition comprising a copolymer prepared by copolymerizing a monomer (a) represented by the following formula (A) with a monomer (b) selected from the group consisting of the compounds represented by the following formula (B) and those represented by the following formula (C), cement and water:

• ##STR14## wherein R.sub.1 and R.sub.2 may be the same or different from each other and each represents a hydrogen atom or a methyl group;
• m1 is an integer of 0 to 2;
• AO represents an oxyalkylene group having 2 to 3 carbon atoms;
• n is a number of 110 to 300;
• and X represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, ##STR15## wherein R.sub.3, R.sub.4 and R.sub.5 may be the same or different from one another and each represents a hydrogen atom, a methyl group or a group represented by the formula:
• (CH.sub.2).sub.m2 COOM.sub.2 (wherein m2 is an integer of 0 to 2;
• and M.sub.2 represents a hydrogen atom, an alkali metal atom, 1/2 an alkaline earth metal atom, an ammonium group, an alkylammonium group or a substituted alkylammonium group);
• and M.sub.1 represents a hydrogen atom, an alkali metal atom, 1/2 an alkaline earth metal atom, an ammonium group, an alkylammonium group or a substituted alkylammonium group, and ##STR16## wherein R.sub.6 represents a hydrogen atom or a methyl group;
• and Y represents a hydrogen atom, an alkali metal atom, 1/2 an alkaline earth metal atom, an ammonium group, an alkylammonium group or a substituted alkylammonium group and having a molar ratio of monomer (a) to monomer (b) of from 0.1/100 to 100/100.