JP2005239523A - Concrete modifying material and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a concrete modifying material having a desired reaction rate of gelation in a continuous pores of concrete and capable of appropriately modifying the concrete, and to provide a method of manufacturing the concrete modifying material. <P>SOLUTION: The concrete modifying material is prepareed by mixing sodium silicate with potassium silicate in the molar ratio of 1:1 and adding sodium hydroxide into the mixed solution of sodium silicate with the potassium silicate. In the manufacture, the concrete modifying material is manufactured by separately obtaining sodium silicate and potassium silicate and mixing with each other to prepare the mixed solution , adding sodium hydroxide, stirring for a prescribed time and filtering. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a concrete reforming material for concrete such as a building structure (building), a bridge, a tunnel, a concrete secondary product such as PC concrete, a manhole, and the like, and a method for producing the same.

  Concrete has a high compressive strength, can support a large load, can be shaped arbitrarily, has excellent fire resistance, heat resistance, durability, etc., and is relatively inexpensive. It is used in various fields such as civil engineering and buildings.

  However, after concrete is placed, the moisture contained in the curing process evaporates and escapes, and cracks occur due to drying shrinkage. Cracks also occur due to corrosion of reinforcing bars, alkali aggregate reaction, and the like.

  For this reason, there are many continuous pores composed of pores having a large diameter or pores having a small diameter.

  In a concrete structure, these continuous pores continue from one surface of the concrete block to another. That is, as shown in FIG. 2, since the continuous pores 3 generated in the concrete 2 are connected to each other, acid rain, chlorine, and the like gradually enter the concrete 2 through the continuous pores 3 and the concrete. 2 is deteriorated and internal reinforcing bars are damaged, resulting in deterioration in durability due to poor appearance, neutralization, freeze-thawing, salt damage, alkali aggregate reaction, and the like.

  Therefore, it is necessary to waterproof the concrete 2 or to modify the concrete itself by deeply infiltrating the concrete 2 with an effective modifier.

  Conventionally, as a prior example of this type, for example, Japanese Patent No. 2937309 exists.

  That is, this precedent example applies or injects an inorganic permeable waterproofing material mainly composed of sodium silicate to a waterproof part or a repaired part and repeats watering several times after drying to infiltrate the waterproofing material into concrete. The penetration waterproof protective layer is formed.

  In this prior example, sodium silicate is reacted with calcium in concrete so as to be gelled, and penetration of acid rain or the like is prevented by a permeation waterproofing protective layer made of this gel-like body.

  However, in this preceding example, the main component of the modifier is sodium silicate alone, and in this case, the reaction rate with calcium in the concrete is fast and gels in a short time, as shown in FIG. There was a problem that the reforming material 1 ′ penetrated only to a shallow portion (about 45 mm) of the crack 3 of the concrete 2 and the effect as the modifying material 1 ′ was low.

  In addition, in the work, after applying or injecting an inorganic permeable waterproof material to infiltrate as deeply as possible and drying it, the process is repeated 3 times while waiting for 5 to 7 hours for drying and watering. It takes a long time. In addition, as described above, the main component of the modifying material is sodium silicate, and one kind of alkali metal is easily gelled. Therefore, there is a problem that even if drying and watering are repeated for a long time, they do not penetrate deeply.

  In order to improve this, the present applicant previously proposed Japanese Patent Application No. 2003-123838.

According to this prior invention, at least two or more of sodium silicate, potassium silicate, and lithium silicate are selected and combined, and water is mixed to produce a concrete modifier, which reacts with calcium in the concrete. The speed was reduced, gelation was delayed, and the drawbacks of the previous examples were improved.
Patent No. 2937309 Japanese Patent Application No. 2003-123838

  According to this Japanese Patent Application No. 2003-123838, an excellent concrete reforming effect is obtained as a concrete reforming material as compared with the preceding example (Japanese Patent No. 2937309), which is preferable from a commercial viewpoint.

  The inventor has further studied means for adjusting the gelation reaction rate.

  The present invention has been proposed in view of the above, and an object thereof is to provide a concrete modifier capable of adjusting the reaction rate and a method for producing the same.

  The invention of claim 1 is characterized in that sodium silicate and potassium silicate are mixed at a molar ratio of 1: 1, and sodium hydroxide is added to the sodium silicate / potassium silicate mixed solution.

  The invention of claim 2 is characterized in that sodium silicate and potassium silicate are fractionated and mixed, sodium hydroxide is added to this sodium silicate / potassium silicate mixed solution, stirred for a predetermined time, and then filtered. To do.

According to the present invention, the rate of gelation can be adjusted by adjusting the amount of sodium hydroxide added to the sodium silicate / potassium silicate mixed solution, so that it was appropriately prepared and prepared according to the state of deterioration of the concrete. It is possible to appropriately infiltrate a concrete crack using a desired concrete modifier.
For this reason, it is possible to prevent the air from entering the concrete and deteriorating the concrete, and also neutralize the acid rain to prevent the deterioration.
In addition, since the concrete modifier gels in the pores and closes the pores, water can be prevented from entering the concrete and the effect of mixed alkali prevents alkali-aggregate reaction, salt damage, freezing and thawing, etc. can do.
The characteristics of the mixed alkali effect are as follows.
1. Even if salt enters from the outside, free chlorine is not released.
2. Air pollutants such as NOX and SOX are taken into the gel.
3. Highly acidic substances are incorporated into the gel and do not adversely affect the calcium in the concrete.

[Embodiment 1]
This invention uses sodium silicate (SiO ₂ -Na ₂ O) and potassium silicate (SiO ₂ -K ₂ O) from various materials, and these ratios are mixed at a molar ratio of about 1: 1. Produced.

  A predetermined amount of sodium hydroxide (NaOH) was added to the mixed solution of sodium silicate and potassium silicate to prepare.

  Next, a specific manufacturing example will be described.

  First, a predetermined amount of sodium silicate and potassium silicate were mixed and mixed so as to have a molar ratio of 1: 1. Next, a desired amount of sodium hydroxide is added to the sodium silicate / potassium silicate mixed solution, and the mixture is stirred for about 1 hour. And this mixed solution was filtered with a 3 micrometer main blank filter, and the concrete modifier was produced.

  This concrete modifier is a mixed aqueous solution of alkali silicate containing two kinds of sodium and potassium.

  When this concrete modifier is applied to the concrete surface, the surface of the pores is covered and protected, and when the concrete has continuous pores 3, as shown in FIG. It penetrates deeply into the pores (voids) (about 200 mm) and gels inside the pores to fill the pores.

  That is, the conventional patent No. 2937309 has sodium silicate as a main component, and since this gelates quickly, it does not penetrate deep into the continuous pores of concrete, and the effect of preventing deterioration of concrete is not sufficient.

On the other hand, in the alkaline silicate aqueous solution containing two kinds of alkalis of sodium and potassium and adding sodium hydroxide in the present invention, the alkali (Na ⁺ ion, K ⁺ ion) is conversely silicate anion chain. Therefore, the time required for gelation is lengthened, and the aqueous solution of alkali silicate as a modifier penetrates deeply as shown in FIG. 1 (b).

That is, the mixed aqueous solution of alkali silicate of the present invention dissolves Ca (OH) ₂ in concrete and becomes alkali calcium silicate. Ca ²⁺ ions combine with silicate anion chains to form calcium silicate chains, which combine with each other to cause gelation.

  At this time, on the contrary, if the gel does not gel indefinitely, the action of the gel for preventing the intrusion of water or the like is not exhibited. Therefore, in the present invention, the ratio of sodium silicate to potassium silicate is about 1: 1 in molar ratio. When mixed at this rate, the so-called mixed alkali effect slowly gels and penetrates deeply into the concrete through continuous pores.

  Therefore, when this modifier is sprayed and applied to concrete, it will solidify as a gel after penetrating deeply into the concrete to about 200 mm as well as the concrete surface. The penetration depth can be adjusted by the amount of sodium hydroxide added.

  As shown in FIG. 1 (c), the gelled modifier 1 in the continuous pores 3 is again shown in FIG. 1 (b) due to moisture in the air, rainwater, etc. even after drying and solification. Returning to a gel with a large volume, a waterproof effect is exhibited.

  Moreover, with respect to acid rain, an alkali component neutralizes an acidic component and detoxifies, absorbs a carbon dioxide gas, suppresses white flower, absorbs salt, and detoxifies. For this reason, deterioration of a concrete structure can be prevented and durability can be improved notably.

Further, the gel to absorb CO _2, it is possible to CO ₂ in the air to prevent next CaCO ₃ reacts with Ca _{(OH) 2,} a neutralization of the concrete.

  Further, the crack can be prevented from expanding by infiltrating the cracked concrete.

Moreover, alkali aggregate reaction can be prevented. That is, the alkali aggregate reaction is a reaction in which alkali reacts with the silica component (SiO ₂ ) of concrete aggregate to decompose the aggregate and reduce the strength of the concrete. In order for the alkali-aggregate reaction to occur, it is necessary that moisture enters the concrete and an aqueous alkali solution is generated. Since this modifier gels in concrete and absorbs and stabilizes calcium hydroxide, it protects calcium hydroxide and does not produce an alkaline aqueous solution, and therefore no reaction with aggregate occurs.

  In the construction, for example, the base of the concrete surface is cleaned so that the modifying material can easily penetrate. Next, the modifying material is applied or sprayed with a brush, or low pressure injection is performed with a plastic capsule or the like. Thereafter, in order to promote the reaction with calcium in the concrete, watering may be performed, and the operation can be easily performed.

(A)-(c) is a conceptual diagram which shows a mode that the modifier of this invention osmose | permeates. The explanatory view of the continuous pore state of concrete is shown. The penetration state into the concrete of the conventional modifier is shown.

Explanation of symbols

1 Modified material 2 Concrete 3 Continuous pores

Claims (2)

A concrete modifier characterized by mixing sodium silicate and potassium silicate at a molar ratio of 1: 1 and adding sodium hydroxide to the sodium silicate / potassium silicate mixed solution. Production of concrete modifier characterized by separating and mixing sodium silicate and potassium silicate, adding sodium hydroxide to this sodium silicate / potassium silicate mixed solution, stirring for a predetermined time, and then filtering to produce Method.

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