Cement dispersant, method for production thereof, and cement composition using the dispersant

A cement composition comprising a cement dispersant, water, cement, and sand, wherein a mortar prepared by kneading 400 parts of Portland cement, 800 parts of standard sand obtained from Toyoura, and 240 parts of water which contains 0.16% by weight of the cement dispersant to cement has a mortar flow value of not less than 100 mm and an amount of entrained air of not more than 10%, wherein said cement dispersant is a polycarboxylic acid type polymer (A) obtained by copolymerizing:

• 5 to 98% by weight of an (alkoxy)polyalkylene glycol mono(meth)acrylic ester monomer (a) represented by the following general formula (1):
• wherein R1 is a hydrogen atom or a methyl group, R2O is one species or a mixture of two or more species of an oxyalkylene group having 2 to 4 carbon atoms, wherein when R2O is a mixture of two or more species of oxyalkylene group having 2 to 4 carbon atoms, (R2O)m is a block or random copolymer, R3 is a hydrogen atom or an alkyl group of 1 to 5 carbon atoms, and m is the average addition mol number of oxyalkylene group;
• 95 to 2% by weight of a (meth)acrylic acid monomer (b) represented by the following general formula (2):
• wherein R4 is a hydrogen atom or a methyl group and M1 is a hydrogen atom, a monovalent metal atom, a divalent metal atom, an ammonium group, or an organic amine group;
• and
• 0 to 50% by weight of a monomer (c) which is different than (a) and (b), and which is copolymerizable with (a) and (b);
• wherein the total amount of (a), (b) and (c) is 100% by weight.

A cement composition comprising a polymer, cement, water, sand and coarse aggregate, wherein said polymer is contained in an amount of 0.15 to 0.29% by weight to the cement, water/cement ratio is 0.15 to 0.4, and slump flow value is 690 to 750 mm, wherein said cement composition is obtained by copolymerizing:

• 5 to 98% by weight of an (alkoxy)polyalkylene glycol mono(meth)acrylic ester monomer (a) represented by the following general formula (1):
• wherein R1 is a hydrogen atom or a methyl group, R2O is one species or a mixture of two or more species of an oxyalkylene group having 2 to 4 carbon atoms, wherein when R2O is a mixture of two or more species of oxyalkylene group having 2 to 4 carbon atoms, (R2O)m is a block or random copolymer, R3 is a hydrogen atom or an alkyl group of 1 to 5 carbon atoms, and m is the average addition mol number of oxyalkylene group;
• 95 to 2% by weight of a (meth)acrylic acid monomer (b) represented by the following general formula (2):
• wherein R4 is a hydrogen atom or a methyl group and M1 is a hydrogen atom, a monovalent metal atom, a divalent metal atom, an ammonium group, or an organic amine group;
• and
• 0 to 50% by weight of a monomer (c) which is different than (a) and (b), and which is copolymerizable with (a) and (b);
• wherein the total amount of (a), (b) and (c) is 100% by weight.

A cement dispersant which comprises as a main component a polycarboxylic acid type polymer (A) obtained by copolymerizing:

• 5 to 98% by weight of an (alkoxy)polyalkylene glycol mono(meth)acrylic ester monomer (a) represented by the following general formula (1):
• wherein R1 is a hydrogen atom or a methyl group, R2O is one species or a mixture of two or more species of an oxyalkylene group having 2 to 4 carbon atoms, wherein when R2O is a mixture of two or more species of oxyalkylene group having 2 to 4 carbon atoms, (R2O)m is a block or random copolymer, R3 is a hydrogen atom or an alkyl group of 1 to 5 carbon atoms, and m is the average addition mol number of oxyalkylene group;
• 95 to 2% by weight of a (meth)acrylic acid monomer (b) represented by the following general formula (2):
• wherein R4 is a hydrogen atom or a methyl group and M1 is a hydrogen atom, a monovalent metal atom, a divalent metal atom, an ammonium group, or an organic amine group;
• and
• 0 to 50% by weight of a monomer (c) which is different than (a) and (b), and which is copolymerizable with (a) and (b);
• wherein the total amount of (a), (b) and (c) is 100% by weight, or salt thereof, wherein said polymer (A) has a weight average molecular weight in the range of 10,000 to 500,000 in terms of polyethylene glycol determined by gel permeation chromatography, and has a value determined by subtracting the peak top molecular weight from the weight average molecular weight in the range of 0 to 8,000;
• wherein said polycarboxylic acid type polymer (A) is obtained by copolymerizing:
• 5 to 98% by weight of an (alkoxy)polyalkylene glycol mono(meth)acrylic ester monomer (a), 95 to 2% by weight of a (meth)acrylic acid monomer (b), and 0 to 50% by weight of a monomer (c) which is different than (a) and (b), and which is copolymerizable with (a) and (b);
• wherein the total amount of (a), (b) and (c) is 100% by weight.