Claims
- 1. A process of maintaining the slump of a cement mix, comprising adding to a cement mix 0.001 to 0.01% by weight of cement of a water-soluble poly(alkylene oxide) of molecular weight from 100,000-8,000,000 0.03 to 0.5% by weight of cement of and a plasticizer or superplasticizer selected from the group consisting of lignosulphonates, melamine sulfonate-formaldehyde condensates, carboxylates and styrene-maleic anhydride copolymers in free acid or salt form, said styrene-maleic anhydride copolymer selected from ##STR3## in which R is a C.sub.2-6 alkylene radical
- R.sub.1 is a C.sub.1-20 alkyl-, C.sub.6-9 cycloalkyl- or phenyl group,
- x, y, and z are numbers from 0.01 to 100
- m is a number from 1 to 100 and
- n is a number from 10 to 100
- with the provisos that
- i) the ratio of x to (y+z) is from 1:10 and 10:1 inclusive,
- ii) the ratio of z:y is from 3:1 to 100:1 and
- iii) m+n=15-100
- and ##STR4## in which M is hydrogen or the residue of a hydrophobic polyalkylene glycol or polysiloxane,
- R, R.sub.1, m and n are as hereinabove defined,
- a, b, and c are numbers from 1 to 100
- with the provisos that
- i) the ratio of a to (b+c) is from 1:10 to 10:1 inclusive,
- ii) the ratio of c:b is from 5:1 to 100:1 and
- iii) m+n=15-100.
- 2. A process for reducing the slump of a cement mix comprising the steps of adding to a cement mix as a first addition, one of either a water-soluble poly(alkylene oxide) having a molecular weight of from 100,000 to 8,000,000 or a .beta.-naphthalene sulfonate-formaldehyde condensate;
- adding, as a later addition, the other of said water-soluble poly(alkylene oxide) or .beta.-naphthalene sulfonate-formaldehyde condensate just prior to end-use of the cement mix; and
- adding, prior to said later addition, at least one plasticizer or superplasticizer selected from the group consisting of lignosulphonates, melamine sulfonate-formaldehyde condensates, carboxylates and styrene-maleic anhydride-based copolymers in free acid or salt form, said styrene-maleic anhydride-based copolymer selected from ##STR5## in which R is a C.sub.2-6 alkylene radical
- R.sub.1 is a C.sub.1-20 alkyl-, C.sub.6-9 cycloalkyl- or phenyl group,
- x, y, and z are numbers from 0.01 to 100
- m is a number from 1 to 100 and
- n is a number from 10 to 100
- with the provisos that
- i) the ratio of x to (y+z) is from 1:10 and 10:1 inclusive,
- ii) the ratio of z:y is from 3:1 to 100:1 and
- iii) m+n=15-100
- and ##STR6## in which M is hydrogen or the residue of a hydrophobic polyalkylene glycol or polysiloxane,
- R, R.sub.1, m and n are as hereinabove defined,
- a, b, and c are numbers from 1 to 100
- with the provisos that
- i) the ratio of a to (b+c) is from 1:10 to 10:1 inclusive,
- ii) the ratio of c:b is from 5:1 to 100:1 and
- iii) m+n=15-100,
- said water-soluble poly(alkylene oxide) being added in an amount of 0.001 to 0.01% by weight of cement, said .beta.-naphthalenesulfonate formaldehyde condensate being added in an amount of 0.1 to 1.5% by weight of cement and said plasticizer or superplasticizer being added in an amount of 0.03 to 0.5% by weight of cement.
- 3. A process according to claim 2 wherein the water-soluble poly(alkylene oxide) is added into the cement mix as said first addition and the .beta.-naphthalene sulphonate-formaldehyde condensate is added to the cement mix as said later addition.
- 4. A process according to claim 2, in which the water-soluble poly(alkylene oxide) is partially replaced by a (hydroxy)alkyl cellulose.
- 5. A process according to claim 2, in which the plasticizer or superplasticizer is a styrene-maleic anhydride copolymer.
- 6. A process according to claim 2 in which the poly(alkylene oxide) is a poly(ethylene oxide) having a molecular weight of 1,000,000-5,000,000.
- 7. A process according to claim 2, in which the .beta.-naphthalene sulphonate-formaldehyde condensate is added as an aqueous solution containing 40% by weight of a sodium salt of said .beta.-naphthalene sulphonate-formaldehyde condensate.
Priority Claims (2)
Number |
Date |
Country |
Kind |
9215600 |
Jul 1992 |
GBX |
|
9226411 |
Dec 1992 |
GBX |
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Parent Case Info
This is a continuation of application Ser. No. 08/095,125, filed Jul. 20, 1993, now U.S. Pat. No. 5,494,516.
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Continuations (1)
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Number |
Date |
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Parent |
95125 |
Jul 1993 |
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