JPH04275960A - Mixture for suppessing corrosion of steel in concrete - Google Patents

Abstract

PURPOSE: To provide a composition for prohibiting corrosion of concrete reinforcing steel material having an excellent effect.

CONSTITUTION: This admixture for prohibiting corrosion of concrete reinforcing steel in concrete contains an O/W emulsion wherein (a) the oil phase comprises an unsaturated fatty acid ester of 10 to 55%, an ethoxylated 6-12C alkylphenol and the ester of an aliphatic carboxylic acid with a mono-, di- or trihydric alcohol of 1 to 5% and (b) the water phase comprises a saturated 12-30C fatty acid of 0.1 to 5.0%, an amphoteric compound of 0.1 to 1.0% including at least one amino group and at least one acid group, a glycol of 2 to 10% and a soap of 0.1 to 2% (all of the percentages are expressed by the ratio to the weight of total emulsion).

COPYRIGHT: (C)1992,JPO

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION This invention relates to corrosion inhibition of reinforcing steel in concrete. Specifically, the present invention provides emulsified mixture compositions and methods for inhibiting corrosion of steel in concrete.

BACKGROUND OF THE INVENTION Reinforcing steel in concrete is usually protected from corrosion by a highly alkaline concrete medium. However, corrosion of steel can occur as a result of external application of anti-icing chemicals or contact with chlorides that have entered the concrete matrix from seawater. This corrosion process can be accelerated by the growth of cracks in the concrete, which directly exposes the steel to the corrosive effects of chlorides. This corrosive action ultimately leads to a decrease in the strength of the concrete structure. This structural weakening of concrete is a common occurrence at various sites. Therefore, there is a need for new corrosion inhibiting compositions that protect reinforcing steel from the effects of corrosive chloride chemicals.

0002

SUMMARY OF THE INVENTION Accordingly, the present invention provides that (a) the oil phase comprises 10-55% unsaturated fatty acid ester, 1-15% ethoxylated C6-C12 alkylphenol and 1% unsaturated fatty acid ester;
-5% of an ester of a monohydric, dihydric or trihydric alcohol and an aliphatic carboxylic acid; (b) the aqueous phase contains 0.1-5%;
0% saturated C12-30 fatty acids, 0.1-1.0% amphoteric compounds containing at least one amine group and at least one acid group, 2-10% glycols and 0.1-1.0% amphoteric compounds containing at least one amine group and at least one acid group.
An oil-in-water emulsion containing 1-2% soap (all percentages are by weight of the total emulsion);
A mixture for inhibiting corrosion of reinforcing steel in concrete is provided.

In a preferred embodiment of the invention, the mixture comprises: (a) the oil phase comprises 10-55% C4-15 alkyl or C4-15 alkylene glycol oleate;
3-5% of ethoxylated nonylphenols containing 2-4 oxyethylene molecular units, and 2-5% of monovalent, divalent or trivalent phenols with a total number of carbon atoms in the ester of 8-46. (b) the aqueous phase contains 0.1-5.0% by weight of saturated C12-30 esters of aliphatic carboxylic acids with alcohols;
fatty acids, 0.1 to 1.0% of amphoteric compounds containing at least one amine group and at least one acid group, 2-
Contains an oil-in-water emulsion containing 10% glycol and 0.1-2% soap.

Preferably C4-15 alkyl or C4
The unsaturated fatty acid ester, which is -15 alkylene glycol oleate, is preferably 15 to 3 of the emulsion.
Exist in the 0% range. It is of course permissible to use more than one such compound and to mix two types of compounds. Representative examples of preferred compounds are n-butyl oleate and propylene glycol oleate.

Ethoxylated nonylphenol, preferably containing 2-4 oxyethylene molecular units, is preferably present in the range 3 to 10%. A wide variety of such compounds are available in the art, any of which are suitable for use in the compositions of this invention. Additionally, one or more such compounds can be used, as can all other compounds used in this invention described herein.

The ester preferably contains 10-38, more preferably 12-30 carbon atoms. The alcohol is preferably glycerin. Representative examples of preferred esters are lard monoglyceride, acetylated lard monoglyceride and ethoxylated castrol glyceride.

[0007] The saturated fatty acid preferably has a content of 0.1 to 5.
It is present in the aqueous phase in a weight percent relative to the emulsion ranging from 0%, more preferably from 0.5 to 2.0%. Preferred acids are lauric acid, myristic acid, palmitic acid and stearic acid, with stearic acid being particularly preferred.

[0008] The total amount of saturated fatty acids + soap is 0.2-7.
0%, preferably in the range 0.6-4.0%. Any soap can be used, but calcium stearate and stearic acid are most preferred.

The amphoteric compound may be any of the types described above in this specification. Preferred amphoteric compounds are reaction products of alkyl acetic acids or alkyl formic acids and C8-22 aliphatic amines. A particularly preferred type of amphoteric compound is cocoalkyl β-amino-propionic acid (coco: long chain derived from coconut oil).

"Glycol" includes any polyglycol having no more than 5 glycols, glycol ethers or ether groups. A preferred glycol is propylene glycol, but glycerin, ethylene glycol, butyl glycol, diethylene glycol,
Propylene glycol methyl ether and preferred members of the "Cellsolve"(TM) family of materials may also be used.

The emulsion may further contain materials other than those described herein in the aqueous phase or the oil phase or both in art-recognized amounts.

The oil phase of the emulsion may comprise from about 15% to about 65%, preferably from about 20% to about 35%, of the total weight of the emulsion.

The weight of water in the total emulsion ranges from about 20% to about 8%.
0%, preferably about 50% to about 75%.

The emulsion mixture of the present invention is produced in a conventional manner. They may be present in a single dose of cement formulation in an amount of about 0.3% to about 6.4%, preferably about 1% by weight of the cement.
．． It is added to concrete in doses of 3% to about 2.6%.

[0015] Reinforcing steels used in combination with concrete compositions containing the mixture emulsions described herein are subject to less chloride-induced corrosion than similar reinforcing steels in the same circumstances. I understand. therefore,
The present invention also provides concrete compositions suitable for use in combination with reinforcing steel, comprising a mixture emulsion as described herein. A method is also provided for protecting reinforcing steel placed in concrete from corrosion, comprising adding a mixture emulsion as described herein before the concrete is poured around the reinforcement and set.

The emulsion mixture of the invention is very stable under common temperature fluctuations. high p of concrete
It is believed that upon contact with the H environment, the emulsion disintegrates, bringing the activator into contact with the reinforcing steel rod, but this is not intended to limit the scope of the invention. The emulsion distributes the active agent uniformly in the concrete, which promotes uniform corrosion protection.

The invention will be further described with reference to the following examples. Emulsion mixture formulation A of the invention below is used in the examples. Emulsion mixture preparation A
component
Weight percent of total emulsion ingredients Cocoalkyl β-amino-propionic acid
0.3 N-butyl oleate
21 Propylene glycol dioleate
8 poly(2) ethoxylated nonylphenol
1.5 poly(4) ethoxylated nonylphenol
1.5 stearic acid

0.6 lard monoglyceride

0.5 acetylated lard monoglyceride
2.5 propylene glycol

8.0 Calcium stearate
0
．． 15 water

55.95 The mixing method of the concrete of Examples 1 and 2 is as follows: Type 1 cement

217kg fine mixed material

700kg coarse mixed material (max. 1.9
cm size mixture) 866 kg water (0
．． 48 water/cement)
105kg slump

5.1cm air content rate

2.5% unit weight

2403kg/cu. M.

[0018]
The test method used in Example 1 described in this specification was the time versus corrosion method (“Protective System for New PS Concrete”).
NewPrestressed and Su
U.S. Department of Transportation, Bureau of Highway Administration, Report FHWA/RD-86/1
93, April 1987, p. 126). This method was developed to closely approximate the concrete installation site. This method quantifies the corrosion effects in reinforced concrete exposed to long-term chloride attack. The test consisted of a mat with two reinforcing steel bars 1 inch (2.5 cm) below the surface and 4 reinforcing steel bars 4 inches (10 cm) below the initial position, each for the treatment being tested. 2 pieces, 12 inches x 12 inches x 7 inches (
It consists of a concrete specimen with dimensions (30.5 cm x 30.5 cm x 17.8 cm). The mat is electrically connected to a resistor and the resulting slope of the cathode (lower mat) to the anode (upper mat) surface is made to promote the corrosion process. The test measures the macrocell corrosion current between the top and bottom of the bar, the sample anode half-cell potential, and the mat-to-mat resistance between the reinforcing layers, storing sodium chloride and then air drying. Including repeating things.

The test method for Example 2 is essentially the same, with the following differences: (a) The test specimen is 3 inches (thickness) x 4 inches (width) x 14 inches (length) (7.6 cm).
x 10.2 cm x 35.5 cm); and (b) 1 inch (2.5 cm) below the surface of the beam and two additional rods 0.5 inch (1.3 cm) from the bottom.
m). Example 1 Specimens of concrete with and without emulsion mixture formulation A are made with two mats of reinforcing steel. If an admixture is added, the proportion of 1.3% by weight of cement is 50%.
% and use. The mat, as mentioned above,
It is electrically connected to a 10 ohm electrical resistor so that corrosion activity can be measured directly by the corrosion versus time method. The surface of the specimen is exposed to concentrated (15%) sodium chloride solution for 4 days and dried for 3 days for a total of 48 cycles. Corrosion current is measured weekly. The performance of the specimens containing the mixture is considerably better than that of the specimens without the mixture. Example 2 Again, concrete beams are made of two mats of reinforcing steel, with and without admixture (undiluted in a proportion of 0.6% by weight of cement). The mat is electrically connected to a 10 ohm resistor to allow direct measurement of corrosion activity as described above. After normal concrete hardening, cracks perpendicular to the reinforcement axis appear between the surface of each beam and the upper layer of reinforcement steel. Next, the cracked surface of the concrete beam is continuously concentrated (
10%) sodium chloride solution. Measure corrosion current regularly. The performance of the beams containing the admixture is considerably better than that without the admixture.

Claims (10)

[Claims] Claim 1: (a) Oil phase is 10-55% unsaturated fatty acid ester, 1-15% ethoxylated C6-C1
(b) the aqueous phase contains 0.1-5.0% saturated C12-30;
fatty acids, 0.1-1.0% amphoteric compounds containing at least one amine group and at least one acid group, 2-10%
of glycol and 0.1-2% soap (all percentages are based on total emulsion weight)
A mixture containing an oil-in-water emulsion for inhibiting corrosion of reinforcing steel in concrete. 2. (a) The oil phase comprises 10-55% by weight of the emulsion of C4-15 alkyl or C4-15 alkylene glycol oleate, 3-15% of 2 to 4
Ethoxylated nonylphenol containing 6 oxyethylene molecular units and 2-5% aliphatic carboxylic acid ester with monohydric, dihydric or trihydric alcohol with a total number of carbon atoms in the ester from 8 to 46 (b) the aqueous phase comprises 0.1-5.0% by weight of the emulsion of a saturated C12-30 fatty acid, 0.1-1.0% of at least one amine group and at least one acid; Amphoteric compounds containing groups, 2-10% glycol and 0.1-2
Corrosion inhibiting mixture of reinforcing steel in concrete containing oil-in-water emulsion containing % soap. 3. A mixture according to claim 1 or claim 2, wherein the alkyl or alekylene glycol oleate ester is present in the range 15-30% by weight of the emulsion. 4. A mixture according to claim 1, wherein the ethoxylated nonylphenol is present in the range 5-10% by weight of the emulsion. [Claim 5] Saturated fatty acid + soap is 0.6-4 of the emulsion.
．． 5. A mixture according to any one of claims 1-4, comprising 0% by weight. 6. A mixture according to claim 1, wherein the amphoteric compound is cocoalkyl β-amino-propionic acid. 7. A mixture according to claim 1, wherein the oil phase comprises 15 to 65%, preferably 20 to 35%, by weight of the emulsion. 8. The weight of water in the total emulsion is 20-80%,
Mixture according to any one of claims 1-7, preferably 50-75%. 9. A concrete composition suitable for use with reinforcing steel, incorporating a mixture emulsion according to claim 1 or 2. 10. A method for preventing corrosion of reinforcing steel placed in concrete, comprising adding to the concrete a mixture emulsion according to claim 1 or claim 2 prior to pouring.