US 5,634,966 AGranted

Nitrite-based corrosion inhibitors with improved anodic and cathodic inhibiting performance

AssigneeW.R. Grace & Co.-Conn.

InventorsNeal S. Berke, Maria C. Hicks

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Abstract

Mixed anodic/cathodic corrosion inhibitors for use in hydraulic cement, comprising a) a first component consisting of an amount of alkali or alkaline earth metal nitrite sufficient to inhibit anodic corrosion; and b) a second component comprising an agent that acts to increases the anodic corrosion performance of the first component; wherein said first and second components are present in a weight ratio of from about 1:0.1 to 1:1. Optionally an EO/PO superplasticizer can be incorporated where the weight ratio of the first component, i.e., nitrite, to EO/PO superplasticizer is from about 1:0.005 to 1:0.25, with the surprising benefit of increased protection against cathodic corrosion without harming the level of anodic corrosion inhibition.

Claims23

Dependent claims

A corrosion-inhibiting admixture, which, when added to hydraulic cement, imparts enhanced anodic and cathodic corrosion inhibition, said admixture comprising:

a) a first component consisting of an amount of alkali or alkaline earth metal nitrite effective to inhibit anodic corrosion;
b) a second component comprising an agent operative to enhance said corrosion inhibition effectiveness of said first component, said second component comprising a material selected from the group consisting of an ether and an alkylene glycol, said ether having the formula R.sub.1 O(AO).sub.n H wherein A is at least one C.sub.2 -C.sub.4 alkylene group, n is 1-10, and R.sub.1 is an alkyl or cycloalkyl group having 1 to 10 carbon atoms;
and said alkylene glycol having the formula HOBOH, wherein B is a C.sub.3 -C.sub.10 alkylene group;
and said first and second components are present in a weight ratio of from about 1:0.1 to 1:1;
and
c) a third component consisting of an EO/PO superplasticizer in a weight ratio to said first component of from about 1:0.005 to 1:0.25, said superplasticizer comprising (i) a polymeric backbone moiety and (ii) polymeric side chain moieties, wherein one of said (i) and (ii) polymeric moieties is a polyether moiety and the other is a non-polyether moiety formed by polymerization of ethylenically-unsaturated monomers.

3 more elements

A hardened cement composition comprising embedded steel, hydraulic cement binder, and an admixture composition comprising:

a) a first component consisting of an amount of alkali or alkaline earth metal nitrite effective to inhibit anodic corrosion;
b) a second component comprising an agent operative to enhance said anodic corrosion inhibition effectiveness of said first component, said second component comprising a material selected from the group consisting of an ether and an alkylene glycol, said ether having the formula R.sub.1 O(AO).sub.n H wherein A is at least one C.sub.2 -C.sub.4 alkylene group, n is 1-10, and R.sub.1 is an alkyl or cycloalkyl group having 1 to 10 carbon atoms;
and said alkylene glycol having the formula HOBOH, wherein B is a C.sub.3 -C.sub.10 alkylene group;
and said first and second components are present in a weight ratio of from about 1:0.1 to 1:1;
and
c) an EO/PO superplasticizer in a weight ratio to said first component of from about 1:0.005 to 1:0.25, said superplasticizer comprising (i) a polymeric backbone moiety and (ii) polymeric side chain moieties, wherein one of said (i) and (ii) polymeric moieties is a polyether moiety and the other is a non-polyether moiety formed by polymerization of ethylenically-unsaturated monomers;
wherein said hardened cement composition has enhanced anodic and cathodic corrosion inhibition.

4 more elements

A method of producing a cement composition having enhanced anodic and cathodic corrosion resistance, comprising adding to a hydraulic cement binder

a) a first component consisting of an amount of alkali or alkaline earth metal nitrite effective sufficient to inhibit anodic corrosion;
b) a second component comprising an agent operative to enhance said anodic corrosion inhibition effectiveness of the first component, said second component comprising a material selected from the group consisting of an ether and an alkylene glycol, said ether having the formula R.sub.1 O(AO).sub.n H wherein A is at least one C.sub.2 -C.sub.4 alkylene group, n is 1-10, and R.sub.1 is an alkyl or cycloalkyl group having 1 to 10 carbon atoms;
and said alkylene glycol having the formula HOBOH, wherein B is a C.sub.3 -C.sub.10 alkylene group;
and said first and second components are present in a weight ratio of from about 1:0.1 to 1:1;
and c) an EO/PO superplasticizer in a weight ratio to said first component of from about 1:0.005 to 1:0.25, said superplasticizer comprising (i) a polymeric backbone moiety and (ii) polymeric side chain moieties, wherein one of said (i) and (ii) polymeric moieties is a polyether moiety and the other is a non-polyether moiety formed by polymerization of ethylenically-unsaturated monomers;
wherein enhanced anodic and cathodic corrosion resistance is imparted to said cement composition.

3 more elements

Dependencies are inferred from the claim text.