CORROSION INHIBITION OF METAL REINFORCEMENT PRESENT IN A HARDENED CONCRETE CONSTRUCTION HAVING ONE OR MORE SURFACES THAT ARE EXPOSED TO CHLORIDE INTRUSION

Abstract

A method for the corrosion inhibition, and optionally rehabilitation, of metal reinforcements present in a hardened concrete construction having one or more surfaces that are exposed to chloride intrusion, wherein the method comprises the step of applying an aqueous alkali metal nitrate solution, an aqueous alkaline earth metal nitrate solution, an aqueous zinc nitrate solution, an aqueous aluminium nitrate solution, an aqueous ammonium nitrate solution or a mixture thereof on one or more of the surfaces. The present disclosure also relates to the use of an aqueous alkali metal nitrate solution, an aqueous alkaline earth metal nitrate solution, an aqueous zinc nitrate solution, an aqueous aluminium nitrate solution, an aqueous ammonium nitrate solution or a mixture thereof as a corrosion inhibitor by applying it on one or more surfaces of hardened concrete construction comprising metal reinforcements that are exposed to chloride intrusion. Furthermore, the present disclosure relates to a corrosion inhibiting composition for inhibition of corrosion of metal reinforcements present in a hardened concrete construction having one or more surfaces that are exposed to chloride intrusion.

Claims

1. A method for the corrosion inhibition of metal reinforcements present in a hardened concrete construction having one or more surfaces that are exposed to chloride intrusion, wherein the method comprises the step of applying an aqueous alkali metal nitrate solution, an aqueous alkaline earth metal nitrate solution, an aqueous zinc nitrate solution, an aqueous aluminium nitrate solution, an aqueous ammonium nitrate solution or a mixture thereof on the one or more surfaces, wherein said aqueous nitrate solution further comprises an organic solvent selected from the group consisting of glycol ethers comprising ethylene substituted mono-ethyl, -methyl, -propyl, and -butyl glycol ethers.

2. The method according to claim 1, wherein the aqueous alkali metal nitrate solution is an aqueous calcium nitrate solution comprising between 10 weight % and 20 weight % of calcium nitrate dissolved in deionized water.

3. The method according to claim 1, wherein the aqueous solution further comprises between 0.1 weight % to 5.0 weight % of a penetration enhancing agent selected from the group consisting of: ethoxylated linear alcohols, ethoxylated octyl-, nonyl- and dodecyl-phenols with a degree of ethoxylation ranging from 12 to 20, secondary alcohol ethoxylates, ethoxylated thiols, glycerol mono and diesters, acetylenic alcohols and diols and alkoxylated acetylenic alcohols and diols, N-(alkyloxycarbonyl) alanine, N-alkylated pyrrolidinones, alkyl esters of sulfosuccinic acid, and N-acyl sarcosinates.

4. A method according to claim 1, wherein the aqueous solution comprises between 0.1 weight % to 5.0 weight of organic solvent selected from the group consisting of glycol ethers comprising ethylene substituted mono-ethyl, -methyl, -propyl, and -butyl glycol ethers.

5. (canceled)

6. (canceled)

7. (canceled)

8. (canceled)

9. A corrosion inhibiting composition for inhibition of corrosion of metal reinforcements present in a hardened concrete construction having one or more surfaces that are exposed to chloride intrusion, comprising: between 10 weight % and 20 weight % of calcium nitrate dissolved in deionized water; between 0.1 weight % to 5.0 weight % of a penetration enhancing agent selected from the group consisting of ethoxylated linear alcohols, ethoxylated octyl-, nonyl- and dodecyl-phenols with a degree of ethoxylation ranging from 12 to 20, secondary alcohol ethoxylates, ethoxylated thiols with a degree of ethoxylation ranging from 8 to 10, glycerol mono and diesters, acetylenic alcohols and diols, alkoxylated acetylenic alcohols and diols, N-(alkyloxycarbonyl) alanine, N-alkylated pyrrolidinones, alkyl esters of sulfosuccinic acid and N-acyl sarcosinates, and between 0.1 weight % to 5.0 weight % of organic solvent selected from the group consisting of glycol ethers comprising ethylene substituted mono-ethyl, -methyl, -propyl, and -butyl glycol ethers.

10. The method of claim 1 wherein the organic solvent is ethylene glycol monobutyl ether.

11. The method of claim 2 wherein the aqueous calcium nitrate solution comprises between 15 weight % and 20 weight % of calcium nitrate dissolved in deionized water.

12. The method of claim 3 wherein the concentration of the penetration enhancing agent in the aqueous solution is between 0.5 weight % and 3.0 weight %.

13. The method of claim 3 wherein the ethoxylated linear alcohols are ethoxylated fatty alcohols with a degree of ethoxylation of more than 10.

14. The method of claim 13 wherein ethoxylate linear alcohol is a tridecyl alcohol ethoxylate.

15. The method of claim 3 wherein the ethoxylated thiols is a terdodecyl mercaptan with a degree of ethoxylation ranging from 8 to 10.

16. The method of claim 3 wherein the N-(alkyloxycarbonyl) alanine is at least one of N-octyl alanine, N-dodecyl alanine, N-hexadecyl alanine and N-octadecyl alanine.

17. The method of claim 3 wherein the N-alkylated pyrrolidinones are selected from 1-(C8-C12-alkyl)-2-pyrrolidinones.

18. The method of claim 17 wherein the N-alkylated pyrrolidinones are 1-octyl-2-pyrrolidinone or 1-dodecyl-2-pyrrolidinone.

19. The method of claim 3 wherein the N-acyl sarcosinate is selected from at least one of N-oleyl sarcosine, N-lauroyl sarcosine, N-myristoyl sarcosine, N-cocoyl sarcosine and sodium salts thereof.

20. The method of claim 4 wherein the organic solvent is present in the aqueous solution from 1.0 weight % to 2.0 weight %.

21. The method of claim 4 wherein the organic solvent is ethylene glycol monobutyl ether.

22. The composition of claim 9 wherein between 15 weight % and 20 weight % of calcium nitrate is dissolved in the deionized water.

23. The composition of claim 9 wherein penetration enhancing agent is present in an amount of 0.5 weight % to 3.0 weight %.

24. The composition of claim 9 wherein the ethoxylated linear alcohols is an ethoxylated fatty alcohol with a degree of ethoxylation of more than 10.

25. The composition of claim 24 wherein the ethoxylated linear alcohols are tridecyl alcohol ethoxylates.

26. The composition of claim 9 wherein the ethoxylated thiol is a terdodecyl mercaptan.

27. The composition of claim 9 wherein the N-(alkyloxycarbonyl) alanine is selected from N-octyl alanine, N-dodecyl alanine, N-hexadecyl alanine and N-octadecyl alanine.

28. The composition of claim 9 wherein the N-alkylated pyrrolidinones is 1-(C8-C12 alkyl)-2-pyrrolidinone.

29. The composition of claim 28 wherein N-alkylated pyrrolidinones are 1-octyl-2-pyrrolidinone or 1-dodecyl-2-pyrrolidinone.

30. The composition of claim 9 wherein the alkyl esters of sulfosuccinic acid are C14-C18 sulfosuccinate diesters.

31. The composition of claim 9 wherein the N-acyl sarcosinates are selected from at least one of N-oleyl sarcosine, N-lauroyl sarcosine, N-myristoyl sarcosine, N-cocoyl sarcosine and sodium salts thereof.

32. The composition of claim 9 wherein the organic solvent is present in an amount from 1.0 weight % to 2.0 weight %.

33. The composition of claim 9 wherein the organic solvent is an ethylene glycol monobutyl ether.

Description

DESCRIPTION OF THE FIGURES

[0059] FIG. 1 shows a graph representing the mean values of the half-cell potentials (in μV), versus the time (in days) of concrete specimens with a water/cement ratio of 0.5 (comprising 5 kg/m.sup.3 of mix NaCl) that were treated with (corrosion inhibition) composition 1, (corrosion inhibition) composition 2, and the comparative corrosion inhibiting products Grace Postrite and Sika® FerroGard®-903+ and a reference without surface treatment;

[0060] FIG. 2 shows a graph representing the mean values of the half-cell potentials (in μV), versus the time (in days) of concrete specimens with a water/cement ratio of 0.65 (comprising 5 kg/m.sup.3 of mix NaCl) that were treated with composition 1, composition 2, and the comparative corrosion inhibiting products Grace Postrite and Sika® FerroGarde-903+ and a reference without surface treatment;

[0061] FIG. 3 shows a graph representing the mean values of the polarization resistance (in Ω) versus the time (in days) of concrete specimens with a water/cement ratio of 0.5 (comprising 5 kg/m.sup.3 of mix NaCl) that were treated with composition 1, composition 2, and the comparative corrosion inhibiting products Grace Postrite and Sika® FerroGarde-903+ and a reference without surface treatment;

[0062] FIG. 4 shows a graph representing the mean values of the polarization resistance (in Ω) versus the time (in days) of concrete specimens with a water/cement ratio of 0.65 (comprising 5 kg/m.sup.3 of mix NaCl) that were treated with composition 1, composition 2, and the comparative corrosion inhibiting products Grace Postrite and Sika® FerroGarde-903+ and a reference without surface treatment;

[0063] FIG. 5 shows a graph representing the mean values of total integrated current, i.e. total corrosion (in coulomb) versus time (in days) according to the ASTM G-109 for composition 1, composition, and the comparative corrosion inhibiting products Grace Postrite and Sika® FerroGarde-903+, Grace DCI-S and a reference without surface treatment.

DETAILED DESCRIPTION

[0064] The present disclosure relates to a method for the corrosion inhibition of metal reinforcements present in a hardened concrete construction having one or more (outer) surfaces that are exposed to chloride intrusion. Corrosion inhibition is the minimization or prevention of corrosion with a chemical substance (a corrosion inhibitor) when added in small concentrations to an environment. There can however also be an additional effect of rehabilitation of already corroded metal reinforcements.

[0065] In this method, an aqueous alkali metal nitrate solution, an aqueous alkaline earth metal nitrate solution, an aqueous zinc nitrate solution, an aqueous aluminum nitrate solution, an aqueous ammonium nitrate solution or a mixture of two or more of these solutions are applied on one or more of the surfaces of the hardened concrete construction that is exposed with chloride intrusion.

[0066] More in particular, an aqueous calcium nitrate solution is applied on one or more of these surfaces. The aqueous calcium nitrate solution in particular comprises between 10 weight % and 20 weight % of calcium nitrate dissolved in deionized water. More in particular, between 15 weight % and 20 weight %, and most in particular around 15 weight %. calcium nitrate is dissolved in deionized water.

[0067] The aqueous solution can furthermore comprise one or more penetration enhancing agents, also called surfactants and/or co-solvents selected from the group comprising: [0068] ethoxylated linear alcohols, more in particular ethoxylated fatty alcohols with a degree of ethoxylation of more than 10, and more in particular tridecyl alcohol ethoxylates, [0069] ethoxylated octyl-, nonyl- and dodecyl-phenols with a degree of ethoxylation ranging from 12 to 20, [0070] secondary alcohol ethoxylates, [0071] ethoxylated thiols, in particular terdodecyl mercaptan with a degree of ethoxylation ranging from 8 to 10, [0072] glycerol mono and diesters, [0073] acetylenic alcohols and diols and alkoxylated acetylenic alcohols and diols, [0074] N-(alkyloxycarbonyl) alanine, more in particular N-octyl alanine, N-dodecyl alanine, N-hexadecyl alanine and/or N-octadecyl alanine, [0075] N-alkylated pyrrolidinones, more in particular 1-(C8-C12-alkyl)-2-pyrrolidinone, more in particular 1-octyl-2-pyrrolidinone, 1-dodecyl-2-pyrrolidinone, [0076] alkyl esters of sulfosuccinic acid, more in particular C14-C18 sulfosuccinate diesters, [0077] N-acyl sarcosinates, more in particular N-oleyl sarcosine, N-lauroyl sarcosine, N-myristoyl sarcosine and/or N-cocoyl sarcosine, and/or sodium salts thereof.

[0078] Examples of such surfactants are 1,4-dimethyl-1,4-bis-(2-methylpropyl-)-2-butyne-1,4-diol ether, polymerized with oxirane, methyl terminated (Surfynol® 2502 from Evonik), 2,4,7,9-tetramethyl-1,5-decyne-4,7-diol (Surfynol® 104 from Evonik), Poly(oxy-1,2-ethanediyl), alpha-[3,5-dimethyl-1-(2-methylpropyl)hexyl]-ω-hydroxy (Tergitol TMN-6 from Croda), Sodium N-Oleyl Sarcosinate (Crodasinic OS35 from Croda).

[0079] These surfactants are in particular present between 0.1 weight % to 5.0 weight %, more in particular between 0.5 weight % and 3.0 weight %.

[0080] The aqueous solution can furthermore comprise an organic solvent selected from the group consisting of glycol ethers comprising ethylene substituted mono-ethyl, -methyl, -propyl, and -butyl glycol ethers, more in particular ethylene glycol monobutyl ether. Of these, ethylene glycol monobutyl ether is preferred. An example thereof is Butyl Cellosolve Solvent from Dow Chemical.

[0081] The organic solvent is in particular present between 0.1 weight % to 5.0 weight %, more in particular between 1.0 weight % and 2.0 weight %.

[0082] The present disclosure further relates to the use of an aqueous alkali metal nitrate solution, an aqueous alkaline earth metal nitrate solution, an aqueous zinc nitrate solution, an aqueous aluminum nitrate solution, an aqueous ammonium nitrate solution of a mixture of two or more thereof as a corrosion inhibitor by applying it on one or more surfaces of a hardened concrete construction comprising metal reinforcements that are exposed to chloride intrusion.

[0083] The solution can thus be used as a corrosion inhibitor, but can also serve as a corrosion rehabilitator.

[0084] In particular, an aqueous calcium nitrate solution is applied. This aqueous calcium nitrate solution comprises between 10 weight % to 20 weight %, more in particular between 15 weight % and 20 weight % and most in particular around 15 weight % of calcium nitrate that is dissolved in deionized water.

[0085] The aqueous solution can comprise between 0.1 weight % to 5.0 weight %, more in particular between 0.5 weight % and 3.0 weight % of a penetration enhancing agent selected from the group consisting of [0086] ethoxylated linear alcohols, more in particular ethoxylated fatty alcohols with a degree of ethoxylation of more than 10, and more in particular tridecyl alcohol ethoxylates, [0087] ethoxylated octyl-, nonyl- and dodecyl-phenols with a degree of ethoxylation ranging from 12 to 20, [0088] secondary alcohol ethoxylates, [0089] ethoxylated thiols, in particular terdodecyl mercaptan with a degree of ethoxylation ranging from 8 to 10, [0090] glycerol mono and diesters, [0091] acetylenic alcohols and diols and alkoxylated acetylenic alcohols and diols, [0092] N-(alkyloxycarbonyl) alanine, more in particular N-octyl alanine, N-dodecyl alanine, N-hexadecyl alanine and/or N-octadecyl alanine, [0093] N-alkylated pyrrolidinones, more in particular 1-(C8-C12-alkyl)-2-pyrrolidinone, more in particular 1-octyl-2-pyrrolidinone, 1-dodecyl-2-pyrrolidinone, [0094] alkyl esters of sulfosuccinic acid, more in particular C14-C18 sulfosuccinate diesters, [0095] N-acyl sarcosinates, more in particular N-oleyl sarcosine, N-lauroyl sarcosine, N-myristoyl sarcosine and/or N-cocoyl sarcosine, and/or sodium salts thereof.

[0096] The aqueous solution can furthermore comprise between 0.1 weight % to 5.0 weight %, more in particular between 1.0 weight % and 2.0 weight % of organic solvent selected from the group consisting of glycol ethers comprising ethylene substituted mono-ethyl, -methyl, -propyl, and -butyl glycol ethers, more in particular ethylene glycol monobutyl ether.

[0097] The present disclosure also relates to a corrosion inhibiting composition for inhibition of corrosion of metal reinforcements present in a hardened concrete construction having one or more surfaces that are exposed to chloride intrusion. This corrosion inhibiting composition in particular comprises: [0098] between 10 weight % and 20 weight %, more in particular between 15 weight % and 20 weight %, and most in particular 15 weight % of calcium nitrate dissolved in deionized water; [0099] between 0.1 weight % to 5.0 weight %, more in particular between 0.5 weight % and 3.0 weight % of a penetration enhancing agent selected from the group consisting of [0100] ethoxylated linear alcohols, more in particular ethoxylated fatty alcohols with a degree of ethoxylation of more than 10, and more in particular tridecyl alcohol ethoxylates, [0101] ethoxylated octyl-, nonyl- and dodecyl-phenols with a degree of ethoxylation ranging from 12 to 20, [0102] secondary alcohol ethoxylates, [0103] ethoxylated thiols, in particular terdodecyl mercaptan with a degree of ethoxylation ranging from 8 to 10, [0104] glycerol mono and diesters, [0105] acetylenic alcohols and diols, [0106] alkoxylated acetylenic alcohols and diols, [0107] N-(alkyloxycarbonyl) alanine, more in particular N-octyl alanine, N-dodecyl alanine, N-hexadecyl alanine and/or N-octadecyl alanine, [0108] N-alkylated pyrrolidinones, more in particular 1-(C8-C12-alkyl)-2-pyrrolidinone, more in particular 1-octyl-2-pyrrolidinone, 1-dodecyl-2-pyrrolidinone, [0109] alkyl esters of sulfosuccinic acid, more in particular C14-C18 sulfosuccinate diesters, [0110] N-acyl sarcosinates, more in particular N-oleyl sarcosine, N-lauroyl sarcosine, N-myristoyl sarcosine and/or N-cocoyl sarcosine, and/or sodium salts thereof, and [0111] between 0.1 weight % to 5.0 weight %, more in particular between 1.0 weight % and 2.0 weight % of organic solvent selected from the group consisting of glycol ethers comprising ethylene substituted mono-ethyl, -methyl, -propyl, and -butyl glycol ethers, more in particular ethylene glycol monobutyl ether.

[0112] The composition serves as a corrosion inhibiting composition, but can also serve as a corrosion rehabilitation composition.

Experiments

[0113] Three hardened steel reinforced concrete specimens with a composition as represented in Table 1 were prepared for every water/cement ratio (0.5 and 0.65) and for every different corrosion inhibitor tested, meaning a total of 6 specimens for every composition. The cement/sand ratio was the same for all specimens, i.e. ⅓. Two different water/cement ratios were tested (i.e. 0.50 and 0.65). 5 kg/m.sup.3 of NaCl was added in the water of the concrete mix to enhance corrosion activity. The concrete mix was then casted in cubic molds with a dimension of 100 mm×100 mm×100 mm. 4 rebars were placed in each mould at equal distances from the centre of the specimen. The specimens were fully cured, i.e. they were cured for 3 days at standard conditions (22° C., 50% RH), were then demoulded and cured for further 25 days in water (22° C., 100% RH). The reinforced concrete specimens were properly prepared for the electrochemical measurements and the rebars were insulated with epoxy sealing.

TABLE-US-00001 TABLE 1 Mix designs of the concrete specimens MATERIAL kg/m.sup.3 kg/m.sup.3 Cement II 42.5N 525.0 525.0 (Lafarge-Holcim) Sand (EN 12620) 1575.0 1575.0 Water 262.5 341.25 NaCl 5.0 5.0 Concrete Mix Characteristics Water/Cement ratio 0.5 0.65 Compressive Strength 16.2 MPa 15.0 MPa
The specimens were treated 3 times by applying 0.3 l/m.sup.2 of two different corrosion inhibiting compositions (composition 1 and composition 2) as shown in tables 2 and 3 below on one of the surfaces of the specimens.

TABLE-US-00002 TABLE 2 Corrosion Inhibiting Composition 1 (composition 1) MATERIAL % by weight Calcium Nitrate 15.0 Alcoxylated Acetylenic Diol  0.5 Ethylene Glycol Mono-Butyl Ether  1.5 Deionized Water 83.0

TABLE-US-00003 TABLE 3 Corrosion Inhibiting Composition 2 (composition 2) MATERIAL % by weight Calcium Nitrate 15.0 Acetylenic Diol  1.0 Ethylene Glycol Mono-Buyl Ether  1.5 Deionized Water 82.5

[0114] In a first test, the ability of the composition to diffuse into the concrete matrix after their surface treatment with composition 1 and composition 2 (or in other words, the depth of penetration) was tested. Each fully cured specimen (as described above) was treated 3 times, once every 6 hours, with 0.3 l/m.sup.2 of the respective composition. Afterwards, the treated concrete specimens were stored for one week at standard conditions (22° C., 50% RH). In table 4, the measurements of the penetration depth of the nitrates in the treated concrete specimens are shown. These measurements are based on the detection of nitrates in dust samples collected from concrete specimens at different depths. The detection was based on colour reactions of the extracted samples with sulfanilic acid and a-naphthylamine. The final solution absorbs intensively at λ=520 nm and the NaNO.sub.2 is evaluated through spectrophotometry. Spectroquant NOVA 60 spectrophotometer was utilized. The results are represented in table 4 below.

TABLE-US-00004 TABLE 4 Measurement of nitrates in the treated concrete specimens Depth Composition1 Composition 2 (cm) (nitrates measured in mg/l) (nitrates measured in mg/l) 0-1 3.70 4.40 1-3 0.98 2.20 3-4 0.38 0.77 4-5 0.09 0.18
Out of the measurements as shown in table 4, it could be concluded that [0115] both composition 1 and composition 2 penetrate the hardened steel reinforced concrete sufficiently to reach the steel reinforcement, i.e. to a depth of 1-3 cm and 3-4 cm, in this way being able to protect the steel reinforcements against corrosion caused by intrusion of chloride; [0116] composition 2 achieved a higher penetration than composition 1, especially in the areas where the steel reinforcements are present.

[0117] In a second test, the half-cell potentials of concrete specimens treated with the same composition 1 and composition 2 using the electrochemical measurements according to ASTM C876-09 (Standard test method for corrosion potentials of uncoated reinforcing steel in concrete) were measured. This test method covers the estimation of the electrical corrosion potential of uncoated reinforcing steel in field and laboratory concrete, for the purpose of determining the corrosion activity of the reinforcing steel. In FIG. 1, the mean values of the half-cell potentials (in μV), while in FIG. 3, the mean values of the polarization resistance (in Ω) versus the time (in days) of concrete specimens with a water/cement ratio of 0.5 (comprising 5 kg/m.sup.3 of mix NaCl) that were treated with composition 1, composition 2, the comparative corrosion inhibiting products Grace Postrite® and Sika® FerroGarde-903+ and the reference without surface treatment are shown. Postrite® is a liquid containing 15 wt. % calcium nitrite and is available from W. R. Grace Construction Products of Cambridge, Mass. It is applied as an admixture in the fresh concrete. Sika® FerroGarde-903+ is a surface applied mixed corrosion inhibitor, designed for use as an impregnation of steel reinforced concrete. FerroGarde-903+ is based on organic compounds, i.e. amino-alcohols and salts of amino-alcohols. Out of FIG. 1, it could be concluded that composition 2 exhibits similar performance with Sika® FerroGarde-903+. FIG. 3 confirms the conclusion of FIG. 1, while it shows that composition 2 and Grace Postrite® perform similarly. According to FIG. 3, composition 1 actively protects the steel reinforcement, especially during the first 12 months of the test. In FIG. 2, the mean values of the half-cell potentials (in μV), while in FIG. 4, the mean values of the polarization resistance (in Ω) versus the time (in days) of concrete specimens with a water/cement ratio of 0.65 (comprising 5 kg/m.sup.3 of mix NaCl) that were treated with composition 1, composition 2, the comparative corrosion inhibiting products Grace Postrite® and Sika® FerroGarde-903+ and the reference without surface treatment are shown. In FIG. 2, it is shown that all the applied corrosion inhibitors perform similarly. composition 2 exhibits similar performance with Sika® FerroGarde-903+ and Grace Postrite®. FIG. 4 confirms the conclusions as made out of FIG. 2.

[0118] In a third test, a group of reinforced concrete specimens was prepared according to the ASTM G109-07 method (Standard test method for determining effects of chemical admixtures on corrosion of embedded steel reinforcement in concrete exposed to chloride environments). This test method covers a procedure for determining the effects of chemical admixtures on the corrosion of metals in concrete. This test method can be used to evaluate materials intended to inhibit chloride-induced corrosion of steel in concrete. The specimens were prepared properly according to the mix-design presented in table 1 with a water/cement ratio of 0.5. 5 kg of NaCl was added per cubic meter of concrete mix in the water to enhance corrosion activity.

In table 5a and 5b below, the corrosion test results according to ASTM G109-07 on reference sample without surface treatment and on samples treated with composition 1, composition 2 and the comparative corrosion inhibiting products Grace DCI®S, Grace Postrite® and Sika® FerroGarde-903+.

TABLE-US-00005 TABLE 5a Corrosion test results according to ASTM G109-07 on reference sample without surface treatment and treated samples with composition 1 and composition 2 Reference Composition 1 Composition 2 Total Total Total Time Current corrosion Current corrosion Current corrosion (days) (μA) (Coulomb) (μA) (Coulomb) (μA) (Coulomb) 0 0.0 0.0 0.0 0.0 0.0 0.0 157 0.2 1.4 0.0 0.0 0.0 0.0 192 1.2 3.5 0.5 0.8 0.2 0.3 227 1.9 8.2 0.8 2.7 0.6 1.5 262 2.6 15.0 1.4 6.0 0.8 3.6 297 3.5 24.2 1.9 11.0 1.0 6.4 343 3.7 38.5 2.0 18.8 1.3 10.9 376 3.9 49.3 2.2 24.8 1.3 14.6 400 4.0 57.5 2.2 29.3 1.2 17.2

TABLE-US-00006 TABLE 5b Corrosion test results according to ASTM G109-07 on treated samples with comparative corrosion inhibiting products Grace Postrite ®, Sika ® FerroGard ®-903+ and Grace DCI ®S Sika ® FerroGard ®- Grace Postrite ® 903+ Grace DCI ®S Total Total Total Time Current corrosion Current corrosion Current corrosion (days) (μA) (Coulomb) (μA) (Coulomb) (μA) (Coulomb) 0 0.0 0.0 0.0 0.0 0.0 0.0 157 0.0 0.0 0.0 0.0 0.0 0.0 192 0.2 0.3 0.1 0.2 0.2 0.3 227 0.6 1.5 0.4 0.9 0.6 1.5 262 0.9 3.8 0.5 2.3 1.0 3.9 297 1.4 7.3 0.7 4.1 1.7 8.0 343 1.4 12.8 0.9 7.3 1.6 14.6 376 1.3 16.7 1.0 10.0 1.7 19.3 400 1.3 19.4 1.0 12.0 1.5 22.6
In FIG. 5, the mean values of the total integrated current, i.e. total corrosion (in Coulomb) according to the ASTM G109-07 method are shown in view of the time (in days) for composition 1, composition 2, the comparative corrosion inhibiting products Grace DCI®S, Grace Postrite® and Sika® FerroGarde-903+ and the reference. Grace DCI®S is a liquid corrosion inhibitor that is added to concrete during the batching process. It contains a minimum of 30% calcium nitrite. The principle of the ASTM G109-07-test is “the lower the total integrated current, the less corrosion there is”. Out of FIG. 5, it can be concluded that composition 2 performs slightly better than Grace Postrite® and Grace DCI®S. It can furthermore be concluded that surface applied corrosion inhibiting composition 2 delays the onset of corrosion of the steel reinforcement embedded in reinforced concrete constructions more effectively than corrosion inhibiting compositions that are applied as admixtures in concrete mix during the batching process, e.g. Grace DCI®S.