KR20090103476A - Corrosion inhibiting effect improved corrosion inhibitor and cement composition using same of - Google Patents

Abstract

PURPOSE: A corrosion inhibitor and a cement composition containing the same are provided to inhibit the corrosion of a reinforcing bar and to prevent the changes in the applicability and durability. CONSTITUTION: A cement composition comprises cement and corrosion inhibitor. The corrosion inhibitor comprises calcium nitrite, gluconic-based compound, and water. The calcium nitrite is added to the cement in a ratio of 1.2-2.0 to 100 by weight. The gluconic-based compound is added to the cement in a ratio of 0.04-0.052 to 100 by weight.

Description

Corrosion inhibiting effect improved corrosion inhibitor and cement composition using same of}

The present invention relates to a rust preventive agent and a cement composition using the same, and more particularly, to an anticorrosive agent capable of controlling the coagulation of a cement composition with excellent anti-corrosive effect and a cement composition using the same.

 Cement compositions are widely used in building structures and civil structures in the form of cement paste, mortar, concrete and the like. In particular, reinforced concrete including reinforcing bars is a structure excellent in shock resistance, fire resistance, and durability, and is widely used in civil engineering structures such as dams, bridges, airports, and breakwaters, as well as construction structures such as apartments, houses, schools, and hospitals. Reinforced concrete is used by mixing limestone, aggregates such as sand, iron ore, etc., and it is economically superior to other structural materials, so it can be used semi-permanently unless the steel is corroded.

However, recently, due to the lack of aggregates, sand collected from the sea as well as sand taken from the river is used as reinforced concrete aggregate. Sand collected from the sea contains chlorides such as sodium chloride (NaCl) and magnesium chloride (MgCl 2), and the chloride may corrode the steel contained in the reinforced concrete, thereby reducing the durability of the reinforced concrete.

In order to prevent corrosion of the reinforced concrete, a rust preventive agent is added to the reinforced concrete, and as the use of aggregates containing a large amount of chlorides such as sea sand in the concrete increases, more rust preventive agents are added to the concrete. However, when a large amount of chemicals such as rust inhibitors are added, condensation of concrete may occur more rapidly than when no rust inhibitor is added, resulting in poor workability.

The problem to be solved by the present invention is to provide a cement composition with improved durability or workability.

Another problem to be solved by the present invention is to provide a rust preventive agent having an increased rust prevention effect by containing a large amount of rust preventive ingredients while controlling the setting time of the cement composition.

Problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

Cement composition according to the embodiments of the present invention for solving the above problems include a rust inhibitor including cement and calcium nitrite, gluconic acid compound and water, calcium nitrite is 1.2 parts by weight or more based on 100 parts by weight of cement It is 2.0 weight part or less, and a gluconic acid type compound is 0.04 weight part or more and 0.052 weight part or less with respect to 100 weight part of cement.

The rust preventive agent according to the embodiments of the present invention for solving the above another problem is 39.2% by weight or more, 39.4% by weight or less calcium nitrite, 0.6% by weight or more, 0.8% by weight or less gluconic acid compound and 60% by weight of water Includes include.

Other specific details of the present invention are included in the following detailed description of the invention.

The cement composition may not only prevent corrosion of reinforcing steel by adding a rust preventive agent, but also prevent deterioration of workability or durability due to a change in the setting rate of the cement composition due to the addition of the rust preventive agent. In addition, by using a relatively inexpensive rust preventive agent, it is possible to provide a cost-competitive cement composition.

1 is a graph showing the setting rate of the cement composition according to the composition ratio of calcium nitrite in the cement composition.

2A, 2B and 2C are graphs showing the setting speed of the cement composition when 0.04 parts by weight, 0.052 parts by weight and 0.06 parts by weight of sodium gluconate were added to the cement composition, respectively.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the present embodiments are intended to complete the disclosure of the present invention, and the general knowledge in the art to which the present invention pertains. It is provided to fully convey the scope of the invention to those skilled in the art, and the present invention is defined only by the scope of the claims.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Unless otherwise defined, all terms (including technical and scientific terms) used in the present specification may be used in a sense that can be commonly understood by those skilled in the art. In addition, the terms defined in the commonly used dictionaries are not ideally or excessively interpreted unless they are specifically defined clearly.

Hereinafter, a cement composition according to embodiments of the present invention may include a cement paste in which cement and water are mixed; Mortars in which small aggregates such as cement, water and sand are mixed; And it may be concrete mixed with aggregates such as cement, water and sand, gravel.

The cement composition having improved durability according to embodiments of the present invention includes cement, water, and a cement admixture.

The cement may be, for example, light cement or hydraulic cement such as lime, blast furnace lime or the like. The hydraulic cement may be portland cement and blast furnace slag cement, fly ash cement, mixed cement, such as Portland pozzolane cement, and the like, and preferably Portland cement.

Cement admixtures serve to impart certain properties to the cement composition, such as preventing corrosion of the reinforcing bars, and include rust inhibitors and other cement composition additives.

The rust preventive agent serves to prevent corrosion of the reinforcing bar in the cement composition including the bar. Specifically, the rust preventive agent serves to prevent corrosion of the surface of the rebar by chlorides such as sodium chloride and magnesium chloride (eg, chlorine ions (Cl-)) contained in aggregate such as sand, particularly sea sand.

The rust preventive agent includes calcium nitrite (Ca (NO 2) 2), a gluconic acid compound, and water.

Calcium nitrite chemically reacts with chlorides to prevent corrosion of steel bars. The rust inhibitor including calcium nitrite according to embodiments of the present invention may have a similar rust preventive effect as a rust inhibitor including lithium nitrite (LiNO 2) and the like, and may be inexpensive. However, as can be seen in Experimental Example 1 to be described later, when calcium nitrite is mixed in the cement composition in order to increase the rust-preventing effect, for example, when the calcium composition contains 1.2 parts by weight or more of calcium nitrite, the condensation rate of the cement composition is increased. As a result, the workability and durability of the cement composition may be degraded. However, in the embodiments of the present invention, even if a large amount of calcium nitrite is mixed, the anti-corrosive agent can control the setting rate by the gluconic acid compound, thereby providing a cement composition having improved workability and durability. This will be described later in detail while explaining the gluconic acid compound.

40 wt% of calcium nitrite may be about 1.2 parts by weight or more and 2.0 parts by weight or less based on 100 parts by weight of cement. When calcium nitrite is less than about 1.2 parts by weight with respect to 100 parts by weight of cement, the rust preventive effect may be reduced, and reinforcing steel may deteriorate durability of the cement composition. On the other hand, when the calcium nitrite is more than about 2.0 parts by weight based on 100 parts by weight of cement, the cementation rate of the cement composition may be too high, resulting in poor workability and durability of the cement composition.

Preferably, the content of calcium nitrite may be about 39.2% by weight or more and about 39.4% by weight or less based on the total rust inhibitor. When the content of calcium nitrite is less than about 39.2% by weight, the rust preventive effect of the rust preventive agent may be deteriorated, and when the content of the calcium nitrite is greater than about 39.4% by weight, the setting rate of the cement composition may be increased.

Gluconic acid-based compounds, preferably sodium gluconate, serve to slow the rate at which cement compositions congeal. Specifically, the gluconate-based compound prevents the cement composition from condensing quickly above a predetermined setting rate by calcium nitrite and other cement composition additives included in the rust preventive agent, and prevents the workability and durability of the cement composition from deteriorating. Do it.

The gluconic acid compound may be about 0.04 parts by weight or more and about 0.052 parts by weight or less, preferably about 0.04 parts by weight, based on 100 parts by weight of cement. If the gluconic acid-based compound is less than about 0.04 parts by weight, the cement composition may quickly set, resulting in poor workability and durability of the cement composition. In addition, when the gluconic acid-based compound is more than about 0.052 parts by weight, the condensation of the cement composition may be delayed, thereby decreasing the workability and durability.

Preferably, the content of the gluconic acid compound may be 0.6 wt% or more and 0.8 wt% or less with respect to the whole rust preventive agent. If the content of the gluconic acid-based compound is less than 0.6% by weight, the cement composition may be quickly condensed. If it is more than 0.8% by weight, the condensation of the cement composition may be delayed.

Other cement composition additives may optionally include an air entraing agent (AE agent), a water reducing agent, an expanding agent, and the like, depending on the use of the cement composition.

The air entrainer serves to entrain air inside the cement composition, improving workability and increasing resistance to freeze thaw. For example, the air entrainer may be anionic air entrainer such as resin soap, ester air entrainer, sulfonate air entrainer; Cationic air entrainers such as alkyl betaine type and alkylamide betaine type air entrainers; It may include an ether-based air entrainer having a hydrophilic group such as a hydroxyl group, ethylene oxide group, nonionic air entrainer such as ester-based air entrainer.

The sensitizer serves to uniformly disperse the cement in the cement composition, and may include, for example, clay dispersants, lignosulfonates, hydroxylated carboxylates, carbohydrates and the like.

In addition, the swelling agent serves to prevent the cement composition from shrinking after condensation or to provide swellability to the cement composition, and may include, for example, ethrin guide, calcium hydroxide, and the like.

Hereinafter, the present invention will be described in more detail through experimental examples, but the present invention is not limited to the following experimental examples. Percentages and mixing ratios in the following experimental examples are based on weight unless otherwise indicated. In addition, the contents not described herein are omitted because they are sufficiently technically inferred by those skilled in the art.

Experimental Example 1 Condensation Rate of Calcium Nitrite and Mortar

Production of the test body

A cement composition having a composition ratio according to Table 1 (hereinafter referred to as "mortar") was prepared according to the following method according to Korean Industrial Standard (KS L 5109). In Table 1 below, the calcium nitrite aqueous solution is a 40 wt% aqueous solution, and the weight part of calcium nitrite is a weight ratio of calcium nitrite to 100 parts by weight of cement. In addition, water is mixed water used in the process of mixing cement, sand, and calcium nitrite aqueous solution.

Iii) The entire volume of water was placed in the mixture vessel.

Ii) Cement was placed in water and the mixer was started to orbit the paddle at 62 rpm and mixed for 30 seconds while rotating at 140 ± 5 rpm.

Viii) The whole amount of sand (standard yarn) was slowly added while mixing at the first speed.

Iii) The mixer was stopped and the rotation speed was reduced, ie, the paddles were orbited at 125 rpm and mixed for 30 seconds while rotating at 285 ± 10 rpm.

Iii) The mixer was stopped and the mortar left for 90 seconds. During the first 15 seconds of this period, all of the mortar attached to the sides of the container was scraped into the container with a scraper and the container was capped for the rest of this period.

Iii) mixing was completed after 1 minute of mixing at the second rate.

Table 1

Cement (g) Sand (g) water Calcium Nitrite Aqueous Solution Mass (g) Parts by weight Mass (g) Calcium nitrite parts by weight A 3000 7350 1350 45 - - B 3000 7350 1332 44 30 0.4 C 3000 7350 1296 43 90 1.2 D 3000 7350 1260 42 150 2.0 E 3000 7350 1224 41 210 2.8

Condensation rate measurement

Each mortar specimen was measured by the following method in accordance with the Korean Industrial Standards (KS F 2436). Here, the mortar initial time was measured when the mortar resistance value was 3.5 MPa, and the cement paste termination time was measured when the mortar resistance value was 28 MPa.

 V) Bleeding water was removed using a pipette or other suitable tool immediately before the penetration test.

Ii) According to the mortar hardening, a needle of appropriate size was attached to the penetration resistance mechanism, and the support surface of the needle was brought into contact with the mortar surface.

I) Slowly and evenly, the instrument was applied with a vertical force downward to penetrate the needle into the mortar to a depth of 25 ± 2 mm. The time required to penetrate to a depth of 25 mm was 10 ± 2 seconds.

최초) The first experiment was performed after 3 ~ 4 hours after the first contact of water and cement, and after that, it was measured every 30 minutes ~ 1 hour. Experiments were performed six times or more at the same time interval until the resistance measurement was 28 MPa or more.

The measurement result by this is shown in FIG.

1 is a graph showing the setting rate of the cement composition according to the composition ratio of calcium nitrite in the cement composition.

Referring to FIG. 1, mortar solidifies faster in B, C, D, and E to which 0.4 parts by weight, 1.2 parts by weight, 2.0 parts by weight, and 2.8 parts by weight of calcium nitrite are added, respectively, compared to A without addition of calcium nitrite. It can be seen that. Specifically, the mortar initial time is not significantly different from A without calcium nitrite and B with 0.4 parts by weight of calcium nitrite, but C, D containing 1.2 parts by weight, 2.0 parts by weight and 2.8 parts by weight of calcium nitrite It can be seen from E and E that mortar is formed faster. It can also be seen that mortar terminates faster in B, C, D and E containing calcium nitrite.

Experimental Example 2- Condensation Rate of Sodium Gluconate and Mortar

Production of the test body

A cement composition (hereinafter referred to as "mortar") test specimen having a composition ratio according to Table 2 was prepared according to the test article manufacturing method described in Experimental Example 1. In the following Table 2, the calcium nitrite aqueous solution and the sodium gluconate aqueous solution are 40 wt% aqueous solution, and the weight parts of calcium nitrite and sodium gluconate are weight ratios of calcium nitrite and sodium gluconate to 100 parts by weight of cement. In addition, weight percentage of calcium nitrite and sodium gluconate is a weight ratio with respect to the whole rust preventive agent, and water is mixed water used in the process of mixing cement, sand, and rust preventive agent.

TABLE 2

Cement (g) Sand (g) water Rust preventive 40 wt% calcium nitrite aqueous solution 40 wt% sodium gluconate aqueous solution Mass (g) Mass (g) Calcium nitrite parts by weight Calcium Nitrite Weight% Mass (g) Sodium Gluconate Sodium Gluconate F 3000 7350 1294.2 90 1.2 38.7 3 0041 1.3 G 3000 7350 1258.2 150 2.0 39.2 3 0.04 0.8 H 3000 7350 1222.2 210 2.8 39.4 3 0.04 0.6 I 3000 7350 1293.66 90 1.2 38.3 3.9 0.052 1.7 J 3000 7350 1257.66 150 2.0 39.0 3.9 0.0521 1.0 K 3000 7350 1221.66 210 2.8 39.3 3.9 0.052 0.7 L 3000 7350 1293.3 90 1.2 38.1 4.5 0.60 1.9 M 3000 7350 1257.3 150 2.0 38.8 4.5 0.60 1.2

Condensation rate measurement

Each mortar test specimen was measured by the method of measuring the mortar's setting rate of mortar described in Experimental Example 1, and the measurement results are shown in FIGS. 2A to 2C.

2A, 2B and 2C are graphs showing the setting speed of the cement composition when 0.04 parts by weight, 0.052 parts by weight and 0.06 parts by weight of sodium gluconate were added to the cement composition, respectively.

Referring to F, G, H and A of Figure 2a, when 0.04 parts by weight of sodium gluconate is added, even if calcium nitrite is added to the mortar, the mortar condensation rate is significantly faster than when calcium nitrite is not added to the mortar. You can see that it is not. In particular, referring to F, G, and A of FIG. 2A, when 0.04 parts by weight of sodium gluconate is added together with 1.2 parts by weight or 2.0 parts by weight of calcium nitrite, the rate of condensation of mortar and mortar is not increased. It can be seen that similar.

Similarly referring to FIGS. 2B and 2C, I to K and A, when 0.052 parts by weight of sodium gluconate is added, even though calcium nitrite is added to the mortar, it does not settle faster than the case where calcium nitrite is not added. Able to know.

Also, referring to A, G, H, and K of FIGS. 2A and 2B, the content of calcium nitrite in the dispersant is preferably 39.2 wt% or more and 39.4 wt% or less, and the content of sodium gluconate is 0.6 wt% or more. When it is 0.8 wt% or less, it can be seen that the mortar's setting rate is similar to that in which no dispersant containing potassium nitrite is added.

Although the embodiments of the present invention have been described above, it will be understood by those skilled in the art that the present invention may be implemented in other specific forms without changing the technical spirit or essential features thereof. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

Claims (4)

cement; And Anti-corrosive agent comprising calcium nitrite, gluconic acid compound and water, The calcium nitrite is 1.2 parts by weight or more and 2.0 parts by weight or less based on 100 parts by weight of the cement, The gluconic acid-based compound is 0.04 parts by weight or more and 0.052 parts by weight or less based on 100 parts by weight of the cement. The method of claim 1, The gluconate compound is a cement composition comprising sodium gluconate. Calcium nitrite at least 39.2% by weight and at most 39.4% by weight; 0.6% by weight or more and 0.8% by weight or less of the gluconic acid compound; And Antirust agent for cement compositions containing 60% by weight of water. The method of claim 3, wherein The gluconic acid-based compound is a rust inhibitor for cement composition containing sodium gluconate.