KR102322648B1 - Reinforced concrete antirust composition and preparation method thereof - Google Patents

Abstract

The present invention relates to a composition for preventing rust in reinforced concrete and a method for manufacturing the same, and when a rust preventive composition containing phosphoric acid, triethanolamine and sodium nitrite is used in the manufacture of concrete, it has been confirmed that the rust preventive effect is superior to that of the existing rust preventive agent. .

Description

Reinforced concrete antirust composition and its manufacturing method {Reinforced concrete antirust composition and preparation method thereof}

The present invention relates to a rust preventive composition for reinforced concrete and a method for manufacturing the same, and more particularly, to a rust preventive composition comprising phosphoric acid, triethanolamine and sodium nitrite.

Recently, in the collection of aggregate for concrete, inland sand has become scarce, and supply and demand are being made in the sea, and the sea sand is washed and used as aggregate for concrete. In particular, sea sand contains 0.02 to 0.30% of salt, and when it is used as a fine aggregate for reinforced concrete, it corrodes the reinforcement in reinforced concrete and causes the destruction of concrete. To solve this problem, the Korean Society of Architecture, the Korean Society of Civil Engineers, and the Korean Concrete Society have placed a limit on the salt content of fine aggregate for concrete, and if it exceeds this limit, rust prevention of rebar is recommended.

As a generalized anti-rust method, a predetermined anti-rust admixture is used in the manufacture of concrete. Rust inhibitors for reinforced concrete are divided into organic and inorganic types, and there are anode-type and cathode-type rust preventive mechanisms.

In particular, calcium nitrite, a raw material mainly used for rust preventive admixtures, corresponds to the anode type, which is an anode inhibitor, and the anode type compound has the advantage of excellent rust prevention effect even when calcium is not present in the solution. There was a problem in that it could not completely cover the metal surface acting as the anode, causing front corrosion of the reinforcing bars.

And a more serious problem is that, as calcium nitrite is classified as a toxic substance according to the Chemicals Control Act announced by the Ministry of Environment in March 2018, it cannot be added more than 25%, so its use is limited, and it is used as a raw material for a rust preventive admixture for reinforced concrete. If the amount of admixture used is not sufficient, the anti-rust performance cannot be sufficiently exhibited.

In addition, in the case of calcium nitrite powder, there is a problem that the solubility of water is 0℃, 77 g / 100mL in water, and precipitates according to the temperature change, and there is a risk of fire and explosion during transport, storage and manufacturing with a flash point of 110℃.

In order to solve these problems, it is necessary to develop a raw material for a rust preventive admixture for reinforced concrete that is not limited in the content used, can be manufactured in high concentration, can secure stable rust prevention performance according to changes in usage, and has safety when used.

Accordingly, the present inventors have found that when a rust preventive composition containing phosphoric acid, triethanolamine, and sodium nitrite (sodium nitrite) is used in the manufacture of concrete, the rust preventive effect is significantly superior to that of the conventional rust preventive agent. It was confirmed that it was excellent.

Accordingly, an object of the present invention is to provide a composition for preventing rust in reinforced concrete comprising phosphoric acid, ethanolamine and nitrite.

Another object of the present invention is to provide a reinforced concrete containing 10 to 40% (w/w) of a composition for rust prevention of reinforced concrete containing phosphoric acid, ethanolamine and nitrite.

Another object of the present invention is to provide a method for preparing a composition for rust prevention in reinforced concrete comprising a mixing step of preparing a mixture by mixing phosphoric acid, ethanolamine and nitrite.

Another object of the present invention relates to the use of a mixture of phosphoric acid, ethanolamine and nitrite to prevent rust in reinforced concrete.

The present invention relates to a composition for preventing rust in reinforced concrete and a method for manufacturing the same, and the composition according to the present invention exhibits an excellent rust preventive effect compared to the existing rust preventive agent when used for manufacturing concrete.

The present inventors confirmed that the rust-preventing effect was significantly excellent when concrete was manufactured using the composition for anti-rust containing phosphoric acid, triethanolamine and sodium nitrite.

The organic/inorganic composite rust preventive admixture raw material composition for reinforced concrete of the present invention includes triethanolamine and phosphoric acid containing three primary alcohols, and nitrite ( It is characterized in that it contains a nitrite) compound.

The mechanism of fixation of chloride ions by the compound is characterized in that OH- and Cl-, which are alcohol groups at the ends of ethanolamine and phosphoric acid derivatives, meet to form R-NH-Cl or R-PO-CL and release OH- ions to the outside. It acts as a barrier to corrosion and maintains the passivation film. In addition, C3A (Tricalcium aluminate aluminate; Ca ₃ Al ₂ O ₆ ) in cement initially adsorbed chloride and then dissociated as carbonation proceeded, but the ethanolamine derivative was immobilized by Cl- ion affinity to maintain a stable state. do.

Hereinafter, the present invention will be described in more detail.

One aspect of the present invention is a composition for preventing rust in reinforced concrete comprising phosphoric acid, ethanolamine and nitrite.

If the content of phosphoric acid is high, it becomes acidic and has an adverse effect on corrosion prevention. When the content of ethanolamine used for neutralization of phosphoric acid is high, the rust prevention effect is lowered.

The phosphoric acid and ethanolamine are 1:1 to 1:5, 1:1 to 1:4.5, 1:1 to 1:4, 1:1 to 1:3.5, 1:1 to 1:3, 1:1.5 to 1:5, 1:1.5 to 1:4.5, 1:1.5 to 1:4, 1:1.5 to 1:3.5, 1:1.5 to 1:3, 1:2 to 1:5, 1:2 to 1: 4.5, 1:2 to 1:4, 1:2 to 1:3.5, 1:2 to 1:3, 1:2.5 to 1:5, 1:2.5 to 1:4.5, 1:2.5 to 1:4 or 1:2.5 to 1:3.5, for example, it may be a weight ratio of 1:2.5 to 1:3, but is not limited thereto.

The ethanolamine may be at least one selected from the group consisting of triethanolamine, diethanolamine, and monoethanolamine.

The phosphoric acid and nitrite are 1:0.2 to 1:0.8, 1:0.2 to 1:0.7, 1:0.2 to 1:0.6, 1:0.2 to 1:0.5, 1:0.2 to 1:0.4, 1:0.3 to 1 :0.8, 1:0.3 to 1:0.7, 1:0.3 to 1:0.6 or 1:0.3 to 1:0.5, for example, may be a weight ratio of 1:0.3 to 1:0.4, but is not limited thereto .

The nitrite may be at least one selected from the group consisting of alkali metal salts, earth metal salts, chromates and hypophosphites of nitrite, for example, sodium nitrite (Sodium nitrite) may be one, but limited thereto it is not If the content is high, it causes precipitation, and if it is low, the rust prevention effect is deteriorated.

The composition may include 15 to 40% by weight of phosphoric acid, 50 to 80% by weight of ethanolamine, and 5 to 20% by weight of nitrite.

The composition comprises 15 to 35% by weight, 15 to 30% by weight, 15 to 25% by weight, 18 to 40% by weight, 18 to 35% by weight, 18 to 30% by weight, 18 to 25% by weight, 20 to 40% by weight of phosphoric acid %, 20 to 35% by weight, 20 to 30% by weight, 20 to 25% by weight, 22 to 40% by weight, 22 to 35% by weight or 22 to 30% by weight, for example 22 to 25% by weight may be, but is not limited thereto.

The composition comprises 50 to 75 wt%, 50 to 70 wt%, 55 to 80 wt%, 55 to 75 wt%, 55 to 70 wt%, 60 to 80 wt% or 60 to 75 wt%, 60 to 75 wt% of ethanolamine 70% by weight, 65 to 80% by weight or 65 to 75% by weight, for example, 65 to 70% by weight may be included, but is not limited thereto.

The composition comprises 5 to 18 wt%, 5 to 15 wt%, 5 to 12 wt%, 5 to 10 wt%, 8 to 20 wt%, 8 to 18 wt%, 8 to 15 wt% or 8 to 12 wt% of nitrite. Weight%, for example, may be 8 to 10% by weight, but is not limited thereto.

In one embodiment of the present invention, phosphoric acid has a low pH and may interfere with the initial hydration reaction of cement, so it was buffered by neutralizing the acid using triethanolamine, which is alkaline, and adjusting the pH. If sodium nitrite is mixed at the same time without neutralizing phosphoric acid with triethanolamine, strong heat and gas are generated due to the neutralization reaction. Buffering the collision of acid and salt as much as possible helps to secure product quality and productivity in the future.

Another aspect of the present invention is a reinforced concrete containing 10 to 40% (w/w) of a composition for rust prevention of reinforced concrete containing phosphoric acid, ethanolamine and nitrite.

The reinforced concrete contains the composition for rust prevention 10 to 35% (w/w), 10 to 30% (w/w), 10 to 25% (w/w), 10 to 20% (w/w), 10 to 15% (w/w), 12-40% (w/w), 15-40% (w/w), 18-40% (w/w), 20-40% (w/w) or 25- 40% (w/w), for example, 30 to 40% (w/w) may be contained, but is not limited thereto.

The ethanolamine may be at least one selected from the group consisting of triethanolamine, diethanolamine, and monoethanolamine.

The nitrite may be at least one selected from the group consisting of alkali metal salts, earth metal salts, chromates and hypophosphites of nitrite, for example, but may be sodium nitrite, but is not limited thereto.

Another aspect of the present invention is a method for preparing a composition for rust prevention in reinforced concrete comprising a mixing step of preparing a mixture by mixing phosphoric acid, ethanolamine and nitrite.

The mixing step is a manufacturing method comprising the following steps:

A first mixing step of preparing a mixture by adding ethanolamine in an amount of 1 to 5 times the weight of phosphoric acid to phosphoric acid; and

A second mixing step of preparing a mixture by adding nitrite in an amount of 0.2 to 0.8 times the weight of phosphoric acid to the mixture of the first mixing step.

The ethanolamine may be at least one selected from the group consisting of triethanolamine, diethanolamine, and monoethanolamine.

The nitrite may be at least one selected from the group consisting of alkali metal salts, earth metal salts, chromates and hypophosphites of nitrite, for example, but may be sodium nitrite, but is not limited thereto.

The first mixing step is 1 to 4.5 times, 1 to 4 times, 1 to 3.5 times, 1 to 3 times, 1.5 to 5 times, 1.5 to 4.5 times, 1.5 to 4 times, 1.5 to 3.5 times, 1.5 to 3.5 times compared to phosphoric acid. multiples of 3, multiples of 2 to 5, multiples of 2 to 4.5, multiples of 2 to 4, multiples of 2 to 3.5, multiples of 2 to 3, multiples of 2.5 to 5, multiples of 2.5 to 4.5, multiples of 2.5 to multiples of 4 or multiples of 2.5 to 3.5, e.g. For example, 2.5 to 3 times the weight of ethanolamine may be added, but is not limited thereto.

The second mixing step is 0.2 to 0.7 times, 0.2 to 0.6 times, 0.2 to 0.5 times, 0.2 to 0.4 times, 0.3 to 0.8 times, 0.3 to 0.7 times, 0.3 to 0.6 times, or 0.3 to 0.5 times, for example, compared to phosphoric acid. For example, 0.3 to 0.4 times the weight of nitrite may be added, but is not limited thereto.

The second mixing step may be a step of preparing a mixture comprising 15 to 40 wt% of phosphoric acid, 50 to 80 wt% of ethanolamine, and 5 to 20 wt% of nitrite.

The composition comprises 15 to 35% by weight, 15 to 30% by weight, 15 to 25% by weight, 18 to 40% by weight, 18 to 35% by weight, 18 to 30% by weight, 18 to 25% by weight, 20 to 40% by weight of phosphoric acid %, 20 to 35% by weight, 20 to 30% by weight, 20 to 25% by weight, 22 to 40% by weight, 22 to 35% by weight or 22 to 30% by weight, for example 22 to 25% by weight may be, but is not limited thereto.

The composition comprises 50 to 75 wt%, 50 to 70 wt%, 55 to 80 wt%, 55 to 75 wt%, 55 to 70 wt%, 60 to 80 wt% or 60 to 75 wt%, 60 to 75 wt% of ethanolamine 70% by weight, 65 to 80% by weight or 65 to 75% by weight, for example, 65 to 70% by weight may be included, but is not limited thereto.

The composition comprises 5 to 18 wt%, 5 to 15 wt%, 5 to 12 wt%, 5 to 10 wt%, 8 to 20 wt%, 8 to 18 wt%, 8 to 15 wt% or 8 to 12 wt% of nitrite. Weight%, for example, may be 8 to 10% by weight, but is not limited thereto.

The nitrite may be at least one selected from the group consisting of alkali metal salts, earth metal salts, chromates and hypophosphites of nitrite, for example, but may be sodium nitrite, but is not limited thereto.

In one embodiment of the present invention, as a result of preparing a rust-preventing composition comprising 23 wt% of phosphoric acid, 68 wt% of triethanolamine, and 9 wt% of sodium nitrite, and using the composition for concrete composition using the same, the anti-rust efficiency was very excellent.

The present invention relates to a composition for preventing rust in reinforced concrete and a method for manufacturing the same, and when a rust preventive composition containing phosphoric acid, triethanolamine and sodium nitrite is used in the manufacture of concrete, it has been confirmed that the rust preventive effect is superior to that of the existing rust preventive agent. .

1 is a graph showing the rust preventive effect of the rust preventive composition according to an embodiment of the present invention compared to the reference concrete for each concentration.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, these examples are only for illustrating the present invention, and the scope of the present invention is not limited by these examples.

Throughout this specification, "%" used to indicate the concentration of a specific substance is (weight/weight)% solid/solid, (weight/volume)%, and (weight/volume)% for solid/solid, and Liquid/liquid is (vol/vol) %.

Example 1: Preparation of test water

Based on the test method for immersion in salt water for rebar according to the regulations of KS F 2561, a salt solution was prepared as shown in Table 1 below so that 1 L of aqueous solution was obtained using water as a solvent.

drug name Weight (g) Sodium Chloride (NaCl) 24.5 Magnesium chloride (MgCl ₂ .6H ₂ O) 11.1 Sodium sulfate (Na ₂ SO ₄ ) 4.1 Calcium Chloride (CaCl ₂ ) 1.2 Potassium Chloride (KCl) 0.7 Sum 41.6

Using a measuring vessel, 250 mL of water was added, 203 mL of the salt solution prepared according to Table 1 was added, and then 3.0 g of calcium hydroxide was added and stirred to prepare test water.

Example 2: Preparation of composition for rust prevention

Phosphoric acid was mixed with 2 to 4 times the weight of triethanolamine compared to phosphoric acid, and the pH was adjusted to between 6 and 10. Thereafter, sodium nitrite (sodium nitrite) of 0.3 to 0.7 times the weight of phosphoric acid was added to prepare concrete rebar rust inhibitor raw materials of 4 compositions corresponding to A to D as shown in Table 2 below, each having a total amount of 280 g. .

Furtherance A B C D E triethanolamine 170.8 g
(61% by weight) 190.4 g
(68% by weight) 198.8 g
(71% by weight) 168.0 g
(60% by weight) Ca(NO ₂ ) ₂
24% (w/w) aqueous solution phosphoric acid 84.0 g
(30% by weight) 64.4 g
(23% by weight) 50.4 g
(18% by weight) 84.0 g
(30% by weight) Sodium nitrite 25.2 g
(9% by weight) 25.2 g
(9% by weight) 30.8 g
(11% by weight) 28.0 g
(10% by weight) water 12% (w/w) aqueous solution was prepared by adding water to the composition ratio

Compositions A to D were prepared and used in the form of a 12% (w/w) aqueous solution by adding water.

Test Example 1: Comparison of corrosion area of rebar (1)

To 500 ml of test water, add 2.8 g of each of the aqueous solutions of the rust preventive raw material compositions A to D and the 24% (w/w) calcium nitrite solution prepared at 12% (w/w) in 500 ml of test water, add water again while stirring, and add water for a total amount of 500 mL A test solution was prepared so that

In order to compare the corrosion area of reinforcing bars, a reinforcing bar with a circular shape of 10 mm specified in KS D 3561 with the material specified in SGD 3 of KS D 3526, with a length of about 100 mm and one end of which is processed into a hemispherical shape, is used. 50 mm was immersed in the test water. After that, the corrosion reaction was carried out under the conditions of 30 °C for 7 days in a sealed state in which the rebar was flooded.

The measured value of the corrosion area of the rebar surface was calculated with respect to the ratio to the total area. Specifically, a 24% (w/w) _{aqueous solution of calcium nitrite (Ca(NO 2} ) ₂ ) and a 12% (w/w) aqueous solution of the composition were equally applied to 500 ml of test water by 2.8 g each. According to KS F 2561, the corrosion area of rebar was compared and shown in Table 3.

Furtherance A B C D E Corrosion area (%) 27 22 46 33 77

As can be seen in Table 3, each corrosion area was 35.1% in composition A, 28.6% in B, 59.7% in C, and 42.9% in D, based on the corrosion area of rebar in 24% calcium nitrite aqueous solution. It was confirmed that the corrosion area of the reinforcing bar was remarkably small compared to the same amount used even at a concentration 50% lower than that of calcium nitrite.

Test Example 2: Comparison of corrosion area of rebar (2)

In Test Example 1, a 30% (w/w) aqueous solution with a higher concentration was prepared by selecting composition B, which had the smallest corrosion area of rebar, and dissolving calcium nitrite powder corresponding to composition E in water to prepare a 30% aqueous solution. It was selected as a control group. 2.8 g, 5.6 g, 8.3 g, and 11.1 g of the aqueous solutions of the compositions B and E prepared in 500 ml of test water were added, respectively, and water was added again while stirring to prepare a test solution so that the total amount was 500 mL.

The corrosion reaction of the reinforcing bar was induced in the same way as in Test Example 1. As a result, the corrosion area is measured by calculating the measured value of the corrosion area of the rebar surface as a ratio to the total area, and after deriving the corrosion area (%) from it, the rust prevention rate (100 - corrosion area, %) was calculated.

As can be seen in Table 4 and FIG. 1, according to the experimental results for each sample, it can be seen that the corrosion inhibitory effect is stably improved as the amount of the rust preventive composition increases. This can be interpreted that the advantageous effect on the anticorrosive performance is expressed even at a low amount of use due to the combined action of the anode and the cathode according to the organic/inorganic complex.

Usage (g/L) Anti-rust rate (%) Composition E (calcium nitrite)
30% (w/w) aqueous solution composition B
30% (w/w) aqueous solution 5.6 23 87 11.2 32 91 16.8 73 96 22.4 96 98

As can be seen in FIG. 1 , in the case of composition B, it was found that even when the concentration was relatively lowered, the performance was equivalent to or higher than that of calcium nitrite in the rust prevention rate. Therefore, it was confirmed that it was possible to manufacture at least twice or more highly concentrated depending on the amount used, and the advantage of being commercially available by applying different concentration levels as needed was confirmed.

Test Example 3: Concrete Compressive Strength Ratio Test

Test specimens were prepared as shown in Table 5 below with reference concrete for measuring compressive strength, test concrete to which 12% (w/w) aqueous solution of rust inhibitor composition B was added, and test concrete to which 24% (w/w) aqueous solution of calcium nitrite was added.

division water-cement ratio
(weight%) fine aggregate rate
(volume%) Unit material consumption (kg/m ³ ) cement water fine aggregate coarse aggregate rust inhibitor
Raw material reference concrete 61.0 44.0 300 180 832 1,067 0 Concrete with composition B added 61.0 44.0 300 176 832 1,067 3.9 Concrete with composition E added 61.0 44.0 300 176 832 1,067 3.9

Most sites in Korea apply the standard of 3.9 kg/m ³ for the use of rust preventives, so as shown in Table 5 above, 3.9 kg/m ³ as the amount of raw materials for rust preventives is applied to prevent rust in accordance with the regulations of KS F 2561 (rust inhibitor for reinforced concrete). It was evaluated based on the criteria for rate and compressive strength (compressive strength ratio of 90% or more).

The rust prevention rate test was performed according to the KS F 2561 rust inhibitor standard for reinforced concrete. Standard curing was performed on the prepared concrete for the compressive strength test, the compressive strength was measured at 7 days and 28 days of age, and the compressive strength of the test concrete was calculated as a percentage with respect to the compressive strength of the reference concrete, as shown in Table 6 below. The intensity ratio was calculated.

division Compressive strength ratio (%) reference concrete Concrete with composition B added Concrete with composition E added 7 days old 100 112 113 age 28 days 100 114 116

As can be seen in Table 6, it can be seen that a favorable effect in terms of compressive strength is expressed from the test concrete using the rust preventive material compared to the reference concrete without the rust preventive raw material. This is because some of the raw materials for rust preventives exist as free alkali ions in the mixed solution state, so C3A (Tricalcium silicate; alite) and C2S (Dicalcium silicate; belite) in cement By contributing to the hydration of the material, it is judged that the advantageous effect in terms of compressive strength is expressed compared to the case where the rust preventive material is not added.

Claims (9)

18 to 30% by weight of phosphoric acid, 60 to 75% by weight of triethanolamine, and 8 to 12% by weight of sodium nitrite (Sodium nitrite) Reinforced concrete rust prevention composition. delete delete According to claim 1, wherein the rust-preventive composition comprises 22 to 25% by weight of phosphoric acid, 65 to 70% by weight of triethanolamine and 8 to 10% by weight of sodium nitrite, reinforced concrete rust preventive composition. delete 18 to 30% by weight of phosphoric acid, 60 to 75% by weight of triethanolamine, and 8 to 12% by weight of sodium nitrite Reinforced concrete containing 10 to 40% (w / w) of the composition for rust prevention of reinforced concrete comprising 8 to 12% by weight. 18 to 30% by weight of phosphoric acid, 60 to 75% by weight of triethanolamine, and 8 to 12% by weight of sodium nitrite relative to the total weight of the mixture A method of manufacturing a composition for rust prevention in reinforced concrete comprising a mixing step of preparing a mixture . The method according to claim 7, wherein the mixing step comprises the following steps:
A first mixing step of preparing a mixture by adding triethanolamine to phosphoric acid; and
A second mixing step of preparing a mixture by adding sodium nitrite to the mixture of the first mixing step. The method according to claim 7, wherein the mixture comprises 22 to 25% by weight of phosphoric acid, 65 to 70% by weight of triethanolamine and 8 to 10% by weight of sodium nitrite.

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