KR20170142452A - Freezing resistance admixture for high early strength cement in winter season - Google Patents

Abstract

The present invention relates to a cold-resistant admixture for early strength-type cement for use in winter time. Specifically, the cold-resistant admixture comprises: a first admixture to improve flowability and retention properties of cement; and a second admixture which is mixed with the first admixture prior to use to express and enhance early strength of cement, wherein the first admixture and the second admixture are combined with early strength-type cement and an anti-freezing agent prior to use. Accordingly, by combining a liquid admixture for improving flowability and retention properties of cement and a powder admixture for expressing and enhancing early strength of cement with early strength-type cement and an anti-freezing agent, the cold-resistant admixture of the present invention ensures early flowability and retention, and thus prevents slump loss and enhances early compressive strength.

Description

{FREEZING RESISTANCE ADMIXTURE FOR HIGH EARLY STRENGTH CEMENT IN WINTER SEASON FOR CROSS-

The present invention relates to a cold-resistant admixture for cement in winter season, and more particularly to a cold-weather admixture for improving cement flowability and retainability by mixing a liquid type admixture and a powder type admixture for enhancing early strength development of cement, The present invention relates to a cold-resistant admixture for a cement, which is capable of preventing slump loss and securing fluidity and retainability and improving initial compressive strength.

Concrete curing is a work that maintains the required temperature and humidity in the initial stage where the hydration process is relatively rapid, and protects from the post-installation until the required strength is developed so as not to cause harmful effects such as load or impact. Careful attention is required because it has a profound effect on the overall air and concrete durability.

Under the weather conditions where the average temperature of the day is less than 4 ℃, the curing hardening reaction is very delayed and concrete should be constructed as cold-weather concrete as it may freeze in the daytime as well as during the daytime or at dawn.

In the construction of cold concrete, appropriate measures should be taken for materials, blending, conveying, striking, chopping, curing, formwork and shore so that the quality of the concrete is not frozen.

The method of construction of cold concrete should be done with care and warming at 0-4 ℃, and it is necessary to heat water or water and aggregate at -3-0 ℃ and at the same time a certain amount of warming is required. When the temperature is below -3 ℃, the water and aggregate are heated to increase the temperature of the concrete. In addition, full-scale concrete construction is carried out such as keeping the concrete at the required temperature by proper warming and rapid heating as required.

When the concrete is frozen at the initial stage of curing, the chemical reaction of the cement does not proceed well, and even if cured at a suitable temperature thereafter, the strength, durability and watertightness will be adversely affected in the future.

Therefore, at the time of construction at low temperature, it should not be frozen at the beginning of curing hardening, have sufficient resistance to the freezing and thawing action to be taken until the temperature after curing is finished, and have sufficient strength for the expected load at each stage of construction , Curing should be done to ensure the strength, durability, and watertightness required as the finished structure.

On the other hand, a chloride-based anti-corrosive agent has been used for the low-temperature construction, but a non-chloride-based anti-corrosive agent is currently used due to corrosion of the concrete. A water reducing agent such as a formalin condensate of a sulfonated melamine or a formalin condensate of an aromatic hydrocarbon sulfonic acid is used to increase the strength as much as the water content is decreased. However, at a low temperature, there is a problem in that the water reducing effect by the water reducing agent is not large, The flowability is reduced, so that it is difficult to cast it.

Triethanolamine, thiocyanate, sulphate of alkali or alkaline earth metal, nitrate, nitrite, urea or the like are used to some extent, but it is problematic because it causes deterioration of the basic performance of concrete. Among these materials, there are many cases in which quickness and the like are caused, and it is difficult to maintain and secure the workability and the transportability.

It is known that there is a disadvantage in that the initial strength is lowered by delaying the hydration speed of the cement as the amount of the organic agitation agent is increased. Particularly, when the lignin sulfonate agitation agent is used in excess of 1% In the case of a high-performance water-reducing agent based on a carbonic acid, the initial strength development within 1 day is delayed, which is a problem to be improved.

Meanwhile, various types of crude steel cement including high-mallein cement have been used to prevent early frost damage and to secure early strength. However, when the crude steel cement and agitation agent are used together, Resulting in slump loss, which is difficult to use. Also, when a retarding admixture is used to prevent slump loss, the cementing time of the cement is delayed and the strength development may be delayed.

Therefore, it is urgently required to develop a cold-resistant admixture capable of preventing slump loss and securing initial fluidity and retention of concrete using the steel-reinforced cement and anti-corrosive agent and improving the initial compressive strength.

Domestic Registration No. 10-1630262 (Registered on February 03, 2014) Domestic Registration No. 10-0661464 (registered on December 19, 2006)

The present invention can prevent the slump loss by securing the initial fluidity and retentivity by combining the liquid type admixture for improvement of fluidity of the cement and the improvement of the retention property and the powder type admixture for enhancing the early strength development of the cement with the crude steel type cement and anti- Which is capable of improving the initial compressive strength, and a cold-resistant admixture for cement.

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

The cold-resistant admixture for cold-setting type cement according to the present invention is a first admixture for improving the flowability and maintenance of cement; And a second admixture for mixing with the first admixture and enhancing the early strength development of the cement, wherein the first admixture and the second admixture are used in combination with the crude steel cement and the activator.

Wherein the first admixture is a liquid type admixture comprising polyacrylic acid, citric acid, ethylene glycol, nitrite, sodium gluconate, antifoaming agent, preservative and distilled water, and the second admixture is a powdery admixture comprising an alumina promoter and tartaric acid , ≪ / RTI >

Wherein the first admixture comprises 10 to 25 parts by weight of polyacrylic acid, 0.1 to 5 parts by weight of citric acid, 0.1 to 5 parts by weight of ethylene glycol, 0.1 to 5 parts by weight of nitrite, 0.1 to 5 parts by weight of sodium gluconate, 0.01 to 5 parts by weight of defoamer 0.01 to 5 parts by weight of an antiseptic, and 60 to 80 parts by weight of distilled water.

The second admixture may be prepared as a powdery admixture, including an alumina-based promoter and tartaric acid.

The second admixture may be prepared by blending 70 to 95 parts by weight of an alumina-based promoter and 5 to 30 parts by weight of tartaric acid.

Wherein the crude steel cement is 500 parts by weight, the agitating agent is 50 parts by weight, the sand is 1500 parts by weight, the water is 200 parts by weight, the water is 200 parts by weight, 3 to 9 parts by weight of the first admixing agent and 5 to 15 parts by weight of the second admixing agent may be compounded to prepare the mortar.

The first admixture is composed of 17 parts by weight of polyacrylic acid, 1.5 parts by weight of citric acid, 1.5 parts by weight of ethylene glycol, 3.5 parts by weight of nitrite, 1.3 parts by weight of sodium gluconate, 0.1 part by weight of defoamer, 0.1 part by weight of preservative and 75 parts by weight of distilled water , And the second admixture may be prepared by compounding 90 parts by weight of an alumina-based promoter and 10 parts by weight of tartaric acid in a weight ratio.

The details of other embodiments are included in the detailed description.

The cold-resistant admixture for cold-cement type cement according to the present invention is prepared by combining a liquid type admixture for improvement of flowability and maintenance of cement and a powder type admixture for enhancing early strength of cement with a crude steel type cement and an activator to secure initial fluidity and retention Thereby preventing the slump loss and improving the initial compressive strength.

It will be appreciated that embodiments of the technical idea of the present invention can provide various effects not specifically mentioned.

1 is a graph showing slump flow and compressive strength of Examples 1 to 6 and Comparative Examples 1 to 6 according to the present invention.

Advantages and features of the present invention, and methods of accomplishing the same, will be apparent from and elucidated with reference to the embodiments described hereinafter in detail. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments disclosed herein are provided so that the disclosure can be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be construed as ideal or overly formal in meaning unless explicitly defined in the present application Do not.

Hereinafter, the cold-resistant admixture for cold-setting steel cement according to the present invention will be described in detail.

The cold-resistant admixture for cold-setting steel cement according to the present invention is composed of a first admixture for improving the flowability and retention of cement and a second admixture for promoting the development of early strength of cement. The admixture is blended with crude steel- It is possible to prevent the slump loss and to increase the initial compressive strength by securing the initial fluidity and the retainability.

The cold-resistant admixture for cold-setting type cement according to the present invention comprises a first admixture and a second admixture used in admixture with the first admixture.

The first admixture is used as a liquid type admixture for improving fluidity of a cement and improving maintenance. The first admixture includes polyacrylic acid, citric acid, ethylene glycol, nitrite, sodium gluconate, defoamer, preservative and distilled water.

The polyacrylic acid may be used to impart fluidity to the water reducing agent. In the present invention, the polyacrylic acid may be any conventional material known in the art. For example, WRM50 (LG Chemical Company) may be used as the polyacrylic acid. In the present invention, the polyacrylic acid may be contained in an amount of 10 to 25 parts by weight based on the entire content of the first admixture.

The citric acid is used for adjusting the pH. In the present invention, the citric acid may be included in the total amount of the first admixture in an amount of 0.1 to 5 parts by weight.

The ethylene glycol is used to reduce the freezing temperature. In the present invention, the ethylene glycol may be included in an amount of 0.1 to 5 parts by weight based on the total amount of the first admixture.

The nitrite is used to reduce the freezing temperature. In the present invention, the nitrite may be included in the total amount of the first admixture in an amount of 0.1 to 5 parts by weight.

The sodium gluconate is used for a feed aid. In the present invention, the sodium gluconate may be contained in an amount of 0.1 to 5 parts by weight based on the total amount of the first admixture.

The defoaming agent is used to remove air bubbles generated when the components are mixed in the first admixture which is a liquid type admixture. In the present invention, the defoaming agent may be a conventional material known in the art. For example, As the antifoaming agent, Agitan 295 (Munzing, Germany) can be used. In the present invention, the antifoaming agent may be included in an amount of 0.01 to 5 parts by weight based on the total amount of the first admixture.

The preservative is used to prevent the first admixture, which is a liquid type admixture, from being decomposed during long-term storage. As the preservative in the present invention, conventional materials known in the art may be used. For example, PG100 (CDI Corporation) can be used. In the present invention, the preservative may be included in an amount of 0.01 to 5 parts by weight based on the entire content of the first admixture.

The distilled water is used for mixing the components included in the first admixture, and it is preferable to use distilled water purified without purification, though it is not limited thereto. In the present invention, the distilled water may be contained in an amount of 60 to 80 parts by weight based on the entire content of the first admixture.

The second admixture is a powdery admixture and is used for promoting the development of early strength of the cement. The second admixture includes an alumina-based promoter and tartaric acid.

The alumina-based accelerator is used to improve the compressive strength. When the cement admixture is mixed with cement, the compression strength obtained after several days can be obtained within a few hours.

In the present invention, the alumina-based promoter may be a conventional material known in the art. For example, as the alumina-based promoter, liquid CSA (Chemicon Co.) may be used. In the present invention, the alumina-based promoter may be contained in an amount of 70 to 95 parts by weight based on the total amount of the second admixture.

The tartaric acid is used to adjust the pH in the second admixture. In the present invention, the content of the tartaric acid may be 5 to 30 parts by weight based on the total amount of the second admixture.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a cold-resistant admixture for a cryogenic steel according to the present invention will be described in detail with reference to the accompanying drawings.

In the following Examples and Comparative Examples according to the present invention, the mortar was prepared by varying the mixing ratio of the compositions to measure the slump flow and compressive strength by measuring the temperature behavior at -5 ° C of the mortar. The mixing ratio is as shown in Table 1 below.

In the examples and comparative examples according to the following Table 1, the mixing ratio of the admixture was varied to measure the slump flow and the compressive strength according to the cold-resistant admixture for the cryogenic steel of the winter season.

That is, in Table 1 below, the admixture P is a blend of conventionally used water reducing components commonly used, and is prepared by blending polyacrylic acid, nitrite, sodium gluconate, antifoaming agent, preservative and distilled water. 20 parts by weight of polyacrylic acid, 3.5 parts by weight of nitrite, 1.3 parts by weight of sodium gluconate, 0.1 part by weight of anti-foaming agent, 0.1 part by weight of preservative and 75 parts by weight of distilled water.

In the following Table 1, the admixture A is prepared by using the same compositions as the first admixture constituting the cold-resistant admixture for cold-weather cement according to the present invention. The admixture A is a mixture of polyacrylic acid, citric acid, ethylene glycol, Nitrite, sodium gluconate, defoamer, preservative and distilled water. That is, the admixture A is composed of 17 parts by weight of polyacrylic acid, 1.5 parts by weight of citric acid, 1.5 parts by weight of ethylene glycol, 3.5 parts by weight of nitrite, 1.3 parts by weight of sodium gluconate, 0.1 parts by weight of defoamer, 0.1 parts by weight of preservative, . ≪ / RTI >

In Table 1 below, the admixture B is prepared using the same compositions as the second admixture constituting the cold-resistant admixture for cold-setting steel according to the present invention. The admixture B includes alumina-based promoter and tartaric acid . That is, the admixture was prepared by blending 90 parts by weight of an alumina-based promoter and 10 parts by weight of tartaric acid.

The mortar was prepared by mixing the prepared admixture P, admixture A, and admixture B with high-malt cement, sand, rheology agent, and water (curing temperature -5 ° C) The compounding ratios according to Comparative Examples 1 to 6 are as shown in Table 1 below.

Experiment to measure temperature behavior at -5 ℃ Experimental mortar formulation
(Curing temperature: -5 캜) Experimental formulation (mixing unit: parts by weight) Burial mound
cement Sand
(sand) Anti-aging agent W
(water) Admixture Admixture P Admixture A Admixture B Example Example 1 500 1500 50 200 3 Example 2 500 1500 50 200 6 Example 3 500 1500 50 200 9 Example 4 500 1500 50 200 3 5 Example 5 500 1500 50 200 6 10 Example 6 500 1500 50 200 9 15 Comparative Example Comparative Example 1 500 1500 50 200 3 Comparative Example 2 500 1500 50 200 6 Comparative Example 3 500 1500 50 200 9 Comparative Example 4 500 1500 50 200 3 5 Comparative Example 5 500 1500 50 200 6 10 Comparative Example 6 500 1500 50 200 9 15

The admixture P, the admixture A and the admixture B were prepared in the same weight as in Table 1, and the mortar was prepared at the same mixing ratios as in Examples 1 to 6 and Comparative Examples 1 to 6.

The slump flow and compressive strength were measured using the mortar prepared in the same proportions as in Examples 1 to 6 and Comparative Examples 1 to 6. The results are shown in Table 2 and FIG.

Experimental mortar formulation
(Curing temperature: -5 캜) Experiment result Slump flow
(-5 ° C) Compressive strength
(-5 DEG C) (MPa) Initial flow 20 minute flow 3 day strength 14 day strength Example Example 1 112 109 4.46 9.04 Example 2 118 116 4.9 9.64 Example 3 117 116 4.88 9.27 Example 4 112 110 5.28 10.64 Example 5 118 115 6.1 12.56 Example 6 117 114 6.55 16.41 Comparative Example Comparative Example 1 110 104 4.36 9.23 Comparative Example 2 118 106 4.84 9.95 Comparative Example 3 121 108 4.55 9.61 Comparative Example 4 110 104 4.3 9.23 Comparative Example 5 118 106 4.84 10.5 Comparative Example 6 121 108 4.55 11.38

1 is a graph showing slump flow and compressive strength of Examples 1 to 6 and Comparative Examples 1 to 6 according to the present invention.

Referring to Table 2 and FIG. 1, the initial flow of the mortar prepared by adding the conventional general water reducing agent (admixture P) (Comparative Examples 1 to 3) and the admixture A (the first admixture) according to the present invention and Although the compressive strength is similar, it can be confirmed that the mortar prepared by adding the admixture A (the first admixture) according to the present invention has an effect of continuing the flow for 20 minutes.

It can be confirmed that the effect of reducing the fluidity both in the initial stage and in the 20-minute stage can be confirmed when the conventional general water reducing agent (admixture P) and the admixture B (second admixture) according to the present invention are used together (Comparative Examples 4 to 6) When the admixture A (the first admixture) according to the present invention and the admixture B (the admixture) are used together (Examples 4 to 6), the flow is maintained and the strength is further enhanced.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be possible. It is therefore to be understood that one embodiment described above is illustrative in all aspects and not restrictive.

Claims (7)

A first admixture for improving the flowability and maintenance of cement; And
A second admixture used for mixing with the first admixture and for promoting the development of early strength of the cement,
Wherein the first admixture and the second admixture are used in combination with the steel-making cement and the activator.
The method according to claim 1,
Wherein the first admixture is a liquid type admixture comprising polyacrylic acid, citric acid, ethylene glycol, nitrite, sodium gluconate, defoamer, preservative and distilled water.
3. The method of claim 2,
Wherein the first admixture comprises 10 to 25 parts by weight of polyacrylic acid, 0.1 to 5 parts by weight of citric acid, 0.1 to 5 parts by weight of ethylene glycol, 0.1 to 5 parts by weight of nitrite, 0.1 to 5 parts by weight of sodium gluconate, 0.01 to 5 parts by weight of defoamer 0.01 to 5 parts by weight of an antiseptic, and 60 to 80 parts by weight of distilled water.
3. The method according to claim 1 or 2,
Wherein the second admixture is a powdery admixture, and is made of an alumina-based promoter and tartaric acid.
5. The method of claim 4,
Wherein the second admixture is prepared by blending 70 to 95 parts by weight of an alumina-based promoter and 5 to 30 parts by weight of tartaric acid in a weight ratio.
The method according to claim 1,
The mortar further comprises sand and water in addition to the crude steel type cement and antifreezing agent,
500 parts by weight of the crude steel cement, 50 parts by weight of the agitating agent, 1500 parts by weight of the sand, 200 parts by weight of water, 3 to 9 parts by weight of the first admixture, 5 to 15 parts by weight of the second admixture By weight based on the total weight of the cement admixture to produce the mortar.
The method according to claim 6,
The first admixture is composed of 17 parts by weight of polyacrylic acid, 1.5 parts by weight of citric acid, 1.5 parts by weight of ethylene glycol, 3.5 parts by weight of nitrite, 1.3 parts by weight of sodium gluconate, 0.1 part by weight of defoamer, 0.1 part by weight of preservative and 75 parts by weight of distilled water ≪ / RTI >
Wherein the second admixture is prepared by blending 90 parts by weight of an alumina-based accelerator and 10 parts by weight of tartaric acid in a weight ratio.

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