JP6267296B2 - Concrete protective material, repair method of concrete structure - Google Patents

Description

  The present invention relates to a concrete protective material, a method for repairing a concrete structure, an impregnation inducer for the concrete structure, and a defect filler for the concrete structure.

  Concrete is highly resistant to various environments and is strongly alkaline, so it is used for concrete structures. Due to the strong alkalinity of the concrete, a passive film is formed on the surface of the reinforcing bar inside the concrete structure, so that the reinforcing bar is protected from corrosion caused by water or chlorine from the outside. For this reason, concrete structures are known as highly durable structures.

  However, the durability of concrete structures that have been considered to be highly durable is also reduced due to neutralization, salt damage, frost damage, alkali aggregate reaction, etc. It has become. Here, the deterioration of the concrete structure is caused by deterioration-causing substances (for example, water, carbon dioxide, chlorine, etc.) entering the inside of the concrete structure through capillaries, holes, or cracks existing in the concrete structure. It is said that it happens.

  Accordingly, concrete protective materials for repairing such deteriorated concrete structures have been proposed. For example, Patent Document 1 discloses a concrete protective material containing two or more alkali metal compounds selected from sodium silicate, potassium silicate, and lithium silicate. According to the concrete protective material described in Patent Document 1, by filling the C—S—H gel, it is possible to block capillaries and the like that become the path of deterioration causing substances, resulting in neutralization, salt damage, frost damage, Deterioration of the concrete structure such as alkali aggregate reaction can be prevented.

JP 2004-323333 A

  However, when the concrete protective material of Patent Document 1 is used, a certain repair effect can be obtained, but the size is not sufficient. For this reason, even when the concrete protective material of Patent Document 1 is used, since deterioration-causing substances from the outside enter the concrete structure, as a result, neutralization, salt damage, frost damage, alkali aggregate reaction, etc. As a result, the durability is lowered.

  Then, this invention intends to provide a concrete protective material in view of such a situation. Another object of the present invention is to provide a method for repairing a concrete structure using a concrete protective material, an impregnation inducer for the concrete structure, and a defect filler for the concrete structure.

  The concrete protective material of this invention is characterized by including the silicate containing an alkali metal and alkaline electrolyzed water.

  The concrete protective material of the present invention is characterized by containing a silicate containing an alkali metal and silicon dioxide.

  It is preferable to contain alkaline electrolyzed water. Moreover, it is preferable that the said alkali metal contains at least 1 among sodium, potassium, and lithium.

  The method for repairing a concrete structure according to the present invention is performed after a modifying agent supplying step for supplying a concrete modifying material to the concrete structure, and the modifying agent supplying step, and the concrete protective material is used as the concrete structure. A protective agent supply step for supplying to the concrete, wherein the concrete modifier contains alkaline electrolyzed water and calcium ions.

  The concrete structure impregnation inducing agent of the present invention is characterized by containing alkaline electrolyzed water.

  The defect filler of the concrete structure of the present invention is characterized by containing silicon dioxide.

  According to the present invention, a greater repair effect than that of the conventional one can be imparted to a concrete structure.

It is explanatory drawing which showed the difference in the distribution rate and the influence degree of deterioration for every defect size about the defect which exists in a concrete structure. It is explanatory drawing which shows the state with which the aggregate | assembly was filled in the defect which exists in a concrete structure. It is explanatory drawing which shows the outline | summary of the manufacturing equipment of a concrete modifier. It is explanatory drawing which shows the outline | summary of a waterproof effect test. It is explanatory drawing which shows the outline | summary of a water permeability test. It is explanatory drawing which shows the outline | summary of a promotion neutralization test.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

(Concrete protective material)
The concrete protective agent contains alkali metal silicate, silicon dioxide, and alkaline electrolyzed water. The concrete protective agent may contain a predetermined additive depending on its application.

(Alkali metal silicate)
Alkali metal silicates are primarily for producing C—S—H gels in concrete structures through reaction with calcium ions. Examples of the alkali metal silicate include sodium silicate, potassium silicate, and lithium silicate.

  Sodium silicate is extremely susceptible to C—S—H gel formation. For this reason, when a concrete protective agent containing only sodium silicate as an alkali metal silicate is applied to a concrete structure, the C—S—H gel is applied before penetration into the depth direction from the applied surface. The production reaction of occurs. As a result, the protective effect of the concrete structure is limited to the vicinity of the surface layer. On the other hand, the formation reaction of C—S—H gel occurs slowly in potassium silicate. For this reason, as an alkali metal silicate, it is preferable that potassium silicate is contained with sodium silicate. As a result, the protective effect of the concrete structure extends not only to the vicinity of the surface layer but also to the inside, so that the life of the concrete structure can be extended. For example, the mixing ratio (weight ratio) of sodium silicate and potassium silicate in the alkali metal silicate is preferably 2: 1.

  By the way, among the defects (capillaries, holes, cracks, etc.) present in the concrete structure, relatively large ones are more likely to induce deterioration of the concrete structure than small ones (see FIG. 1). In particular, a defect having a size of 20 nm or more induces deterioration of the concrete structure, and as the size increases, the deterioration of the concrete structure is likely to be induced. Therefore, it is desirable that the concrete protective material is capable of reliably filling a relatively large defect and blocking the passage of the deterioration-causing substance. For this reason, it is preferable that the particle size of alkali metal silicate is 1 nm or more and 100 nm or less. When the particle size of the alkali metal silicate exceeds 100 nm, dense filling is insufficient in the defect, and therefore a void serving as a penetration path for the deterioration-causing substance is generated in the defect.

(Silicon dioxide)
Silicon dioxide is mainly used to obtain an effect of filling defects in a concrete structure and an effect of promoting the collection of alkali metal silicates. According to the pseudo-collecting action of silicon dioxide, alkali metal silicates having silicon dioxide as a nucleus are collected to form an aggregate. The size of the aggregate is more uniform than the uniform one (see FIG. 2 (A)), but the one with the variation (see FIG. 2 (B)) has a higher filling efficiency with respect to defects in the concrete structure. The path of the causative substance is narrowed. As a result, the protective effect of the concrete structure is improved. The silicon dioxide is not particularly limited as long as it exhibits the above-described action, but is preferably amorphous silica, especially dry silica. For example, Leoroseal hydrophilic CP, QS series (Tokuyama CAS No. 7631-86-9) and the like are available.

  The size of the alkali metal silicate aggregate depends on the size of the core silicon dioxide. That is, the larger the size of silicon dioxide as a nucleus, the larger the size of the alkali metal silicate aggregate. On the other hand, the smaller the size of silicon dioxide as the nucleus, the smaller the size of the alkali metal silicate aggregate.

  Therefore, in order to exhibit the effect | action which fills the defect of the concrete structure by silicon dioxide itself, it is preferable that the particle size of silicon dioxide is 1 nm or more and 50 nm or less. In addition, in order to perform more dense filling by utilizing the action of promoting alkali metal silicate pseudo-collection, the particle size of silicon dioxide varies in a wider range (for example, 1 nm to 250 nm). It is preferable. When the particle diameter of silicon dioxide is less than 1 nm, it is not preferable from the viewpoint that the solubility becomes high as in the case of water glass. Moreover, when the particle size of silicon dioxide exceeds 250 nm, it is not preferable in that dense filling cannot be performed.

(Alkaline electrolyzed water)
The alkaline electrolyzed water preferably has a pH of 11 or higher. The upper limit of the pH of the alkaline electrolyzed water is not particularly limited. However, when supplied to a concrete structure, the degree to which no alkali-aggregate reaction occurs, that is, the description of the total amount of concrete alkali (3.0 kg / m in terms of Na ₂ O) ³ or less).

  Furthermore, alkaline electrolyzed water is likely to penetrate into the concrete structure as compared with normal water. It is estimated that the high permeability of alkaline electrolyzed water is caused by the fact that the ionic radius of hydroxide ions is smaller than the size of water molecules. And the active ingredient (dispersoids, such as alkali metal silicate and silicon dioxide, and other additives) contained in alkaline electrolyzed water is likely to penetrate into the concrete structure as compared with the case where it is contained in normal water. That is, as a concrete protective material, at least a predetermined active ingredient and alkaline electrolyzed water are contained, so that the active ingredient can be supplied to the inside of the concrete structure.

Incidentally, the ratio of the chloride ion concentration _{X Cl} for hydroxide ion concentration _{X OH (= X Cl / X} OH) exceeds a predetermined value, it is known that corrosion of the reinforcing bars is started. As a result of the application of the above-described concrete protective material, a large amount of hydroxide ions is supplied to the concrete structure. As a result, a large amount of hydroxide ions is present in the concrete structure. In this way, when chloride ions invade a concrete structure in which a large amount of hydroxide ions exist, that is, a concrete structure with increased alkalinity, The proportion of the product ion concentration is kept low. Therefore, the concrete structure with increased alkalinity is less likely to exceed the limit value at which corrosion of the reinforcing bar starts even when chloride ions enter, and as a result, corrosion of the reinforcing bar can be suppressed. .

  The solubility of calcium ions in alkaline electrolyzed water is higher than that of normal water. For example, the solubility of calcium ions per 100 g of the alkaline electrolyzed water at 25 ° C. is, for example, 5.0 g, and the solubility of calcium ions when calcium hydroxide is dissolved in 100 g of water (25 ° C., pH 7) ( Higher than 0.17 g). When the concrete protective material containing such alkaline electrolyzed water is supplied to the concrete structure, the C—S—H gel generation reaction is promoted.

  Here, the promotion of the generation of the C—S—H gel is presumed as follows. The calcium ion contained in the concrete structure is taken into the alkaline electrolyzed water by the action of promoting the dissolution of calcium ions by the alkaline electrolyzed water. The incorporated calcium ions contribute to the generation of C—S—H gel.

  The ratio of each component in a concrete protective agent will not be specifically limited if the effect | action of the said component is acquired. In addition, about the preferable range of each component, it is as follows. The alkali metal silicate in the concrete protective agent is preferably 15% by weight or more and 50% by weight or less, and more preferably 20% by weight or more and 40% by weight or less. The lower limit of silicon dioxide in the concrete protective agent is preferably 0.5% by weight or more. On the other hand, the upper limit is preferably such that the appearance defect of the concrete structure (decrease in design) does not occur. For example, the upper limit is preferably 10% by weight or less, more preferably 5% by weight or less, and further preferably 3% by weight or less. And it is preferable that the alkaline electrolyzed water in a concrete protective agent is 50 to 85 weight%, and it is more preferable that it is 60 to 80 weight%. In addition, when the effect | action by silicon dioxide is unnecessary, silicon dioxide can be abbreviate | omitted as a component of a concrete protective material. Similarly, when the action of alkaline electrolyzed water is unnecessary, water may be used instead of alkaline electrolyzed water.

  The action of the concrete protective agent will be described.

  When the concrete protective agent is supplied to the concrete structure, C—S—H gel (hereinafter referred to as wet gel) is generated in the concrete structure by reaction with calcium ions. By this wet gel, it is possible to block defects that become the path of deterioration-causing substances. For this reason, deterioration (neutralization, salt damage, frost damage, alkali aggregate reaction, etc.) of the concrete structure due to the presence of defects can be prevented. Furthermore, the wet gel becomes a dry gel due to a decrease in water content. The dry gel becomes a wet gel having fluidity by contact with water or moisture. In such a concrete structure where a dry gel exists, even when water or moisture from the outside enters, the water etc. comes into contact with the wet gel and is taken in as a wet gel. Water and moisture can be prevented from entering. Furthermore, since the wet gel has fluidity, it can also exhibit a self-repairing function of filling defects (for example, cracks) that occur later.

  Since the concrete protective material contains silicon dioxide, particles of various sizes (aggregates of alkali metal silicate and silicon dioxide) exist in the wet gel produced by the concrete protective material (FIG. 2 ( B)). For this reason, defects such as capillaries, holes, cracks and the like can be reliably filled, and the passage of deterioration-causing substances can be blocked, and as a result, deterioration of the concrete structure can be prevented.

  In addition, since the concrete protective material contains alkaline electrolyzed water, it easily penetrates into the concrete structure. For this reason, the filling with respect to the defect of a concrete structure can be performed reliably in a short time. Furthermore, since the concrete protective material contains alkaline electrolyzed water, a large amount of hydroxide ions are present in the concrete structure. As a result, corrosion of the reinforcing bars of the concrete structure can be suppressed. The ease of penetration of the concrete protective material due to the alkaline electrolyzed water is exhibited even when the alkali metal silicate contained in the concrete protective material is only sodium silicate.

  Next, the manufacturing method of a concrete protective agent is demonstrated.

  The manufacturing method of a concrete protective agent has an electrolysis process and an addition process. In the electrolysis process, water is electrolyzed to produce alkaline electrolyzed water and acidic electrolyzed water. The electrolysis process can utilize the manufacturing equipment 2 shown in FIG. 3 (described later). In the adding step, a predetermined component (alkali metal silicate or silicon dioxide) is added to the alkaline electrolyzed water.

  In the above embodiment, the concrete structure is repaired by the protective agent supplying step of supplying the concrete protective agent to the concrete. However, the present invention is not limited to this, and the concrete structure repair and the concrete modifier are used in combination. You may repair concrete structures.

(Concrete modifier)
The concrete modifier is alkaline electrolyzed water in which calcium ions are dissolved. In addition, the predetermined solute may be added to alkaline electrolyzed water as needed.

The alkaline electrolyzed water preferably has a pH of 11 or higher. The upper limit of the pH of the alkaline electrolyzed water is not particularly limited. However, when supplied to a concrete structure, the degree to which no alkali-aggregate reaction occurs, that is, the description of the total amount of concrete alkali (3.0 kg / m in terms of Na ₂ O) ³ or less). The solubility of calcium ions per 100 g of the alkaline electrolyzed water at 25 ° C. is, for example, 5.0 g. The solubility of calcium ions when calcium hydroxide is dissolved in 100 g of water (25 ° C., pH 7) (0. Higher than 17g). That is, alkaline electrolyzed water acts as a calcium ion concentration improver in the modifier. For example, the calcium ion concentration in the alkaline electrolyzed water is preferably 10 mg / L or more. The alkaline electrolyzed water is not limited to the calcium ion concentration improver in the modifier, but can also be used as a concentration improver for cations (for example, alkali metal ions such as lithium ions, sodium ions, and potassium ions) in a predetermined solution. Works.

(Repair method for concrete structures)
The method for repairing a concrete structure includes a modifying agent supplying step for supplying a concrete modifying agent to the concrete structure and a protecting agent supplying step for supplying a concrete protecting agent to the concrete. In the modifier supply step, alkaline electrolyzed water containing calcium ions is applied to the concrete structure as a concrete modifier. In the protective agent supplying step, the above-described concrete protective agent is applied to the concrete structure as a concrete modifier. In addition, in each process of a modifier supply process and a protective agent supply process, it will not specifically limit if a predetermined chemical | medical agent contacts a concrete structure, such as spraying.

  By the concrete structure repairing method, calcium hydroxide, alkali metal silicate, and water react with each other in the concrete to produce gel-like calcium silicate (C—S—H gel). The generated calcium silicate can improve the durability of the concrete structure because the surface layer portion of the concrete structure can be made dense to prevent intrusion of deterioration-causing substances from the outside.

  For example, in a concrete structure in a deteriorated state (for example, concrete having a pH of less than 11 or concrete that has passed about 10 years since it was newly installed), calcium that was originally included due to the entry of deterioration-causing substances from the outside, etc. Ions are almost lost. Even if a concrete protective agent is applied as it is to such a deteriorated concrete structure, a sufficient amount of calcium ions does not exist, so that calcium silicate is not produced, or it is long to produce calcium silicate. It will take time.

  Therefore, a modifying agent supply process is performed prior to the protective agent supply process for a deteriorated concrete structure. Thereby, calcium ion can be replenished to the said concrete structure. When a concrete protective agent is applied to a concrete structure supplemented with calcium ions, the supplemented calcium ions contribute to the generation of calcium silicate. As a result, application of the concrete modifier facilitates the formation of calcium silicate in the concrete structure.

  Furthermore, a large amount of calcium ions is required to promote the production of calcium silicate. Since the concrete modifier has a higher calcium ion concentration than a normal calcium hydroxide aqueous solution, the reaction with the concrete protective agent starts in a short time.

  In the above embodiment, the concrete modifier and the concrete protective agent are applied in this order to the concrete structure in order to repair the concrete structure. However, this combination may be repeated a plurality of times. .

(Concrete modifier manufacturing equipment)
Next, a concrete modifier manufacturing facility will be described.

  First, as shown in FIG. 3, the concrete modifier production facility 2 includes a water tank 10, an ion exchange membrane 20, an anode 30, a cathode 40, and a power source that applies a predetermined voltage to the anode 30 and the cathode 40. 50.

  The water tank 10 stores tap water in which the calcium agent is dissolved. Examples of calcium agents include water-soluble calcium-containing compounds (calcium salts such as calcium lactate, calcium gluconate, and phosphorylated oligosaccharide calcium).

  The internal space of the water tank 10 is partitioned by the ion exchange membrane 20, and the anode 30 and the cathode 40 are provided in the two spaces partitioned by the ion exchange membrane 20, respectively. Thereafter, using the power source 50, a predetermined voltage is applied to the anode 30 and the cathode 40 to perform electrolysis. By this electrolysis, hydrogen is generated on the cathode 40 side, and alkaline electrolyzed water 80 in which calcium ions are dissolved is generated. On the other hand, on the anode 30 side, acidic water containing lactic acid, chloride ions, bicarbonate ions, and the like are generated separately from the alkaline electrolyzed water.

  The alkaline electrolyzed water containing calcium ions thus obtained can be used as a concrete modifier. Since such alkaline electrolyzed water does not contain substances harmful to the human body or environmental pollutants, the work can be used safely and easily for the human body and without any special preparation.

  Experiments 1 to 5 were performed by the following method.

(Preparation for Experiments 1-2)
Hereinafter, the procedures of Experiments 1 and 2 will be described.

Two samples of concrete board were prepared, one was coated with protective agent A, and the other was coated with protective agent B). Hereinafter, the sample coated with the protective material A is referred to as sample A, and the sample coated with the protective material B is referred to as sample B. The application amount was 0.25 liter / m ^{2 in} all cases. The curing time was 14 days.

(sample)
The concrete plate sample is formed into a plate shape of 300 mm square and 50 mm thickness. The formulation is cement: sand = 1: 3 and the water cement ratio is 65%.

(Protective agent A)
The protective agent A is an inorganic colloidal sol containing the following components.
Sodium silicate 15.7% by weight
Potassium silicate 4.3% by weight
Alkaline electrolyzed water 79.7% by weight
Silicon dioxide 0.3 wt%

(Protective agent B)
The protective agent B is an inorganic colloidal sol containing the following components (product name: RC guard, introduced by ABC Corporation).
Sodium silicate 10-20% by weight
Potassium silicate 20-40% by weight
Water _(H 2 O) _40~70 wt%

(Experiment 1)
As shown in FIG. 4, the measuring tube T was set up on the sample A and fixed with a sealing material (see FIG. 7). Thereafter, water was accumulated in the measuring tube T. The water level was 5 mm. In order to prevent evaporation, paraffin was placed on the water surface in the measuring tube T, and the test was started. Changes in the water level were examined at a predetermined elapsed time from the start of the test. The change in water for each elapsed time is shown in Table 1. The environment in which the test was performed was a temperature of 23 ± 2 ° C. and a humidity of 50 ± 5%.

(Experiment 2)
The same procedure as in Experiment 1 was performed except that sample B was used instead of sample A.

  The results of Experiments 1 and 2 are shown in Table 1.

(Experiment 3)
A concrete plate sample prepared with a protective agent A applied (hereinafter referred to as sample C) and a concrete plate sample applied with nothing (hereinafter referred to as sample D) were prepared. The coating amount of the protective agent A was 0.25 liter / m ² . The curing time was 14 days.

  The sample of the concrete board is a cube having a side of 100 mm, the concrete composition is nominal strength = 21, slump = 8, the maximum size of coarse aggregate = 25, and the water cement ratio is 65%.

A water permeability test was performed on samples C and D (three each). This water permeability test is described in the surface impregnating agent test method (draft) (JSCE-K571-2005). The water head height W _pi (unit: mm) 7 days after the start of the test was read, and the water permeability was calculated from the difference from the height W _po (unit: mm) before the test (see FIG. 5). The environment where the water permeability test was performed was a temperature of 23 ± 2 ° C. and a humidity of 50 ± 5%.

From the measured value of the water permeability test, the water permeability ratio was determined based on the following equation.
Permeability ratio = water permeability of sample C / water permeability of sample D × 100

  The results of Experiment 3 are shown in Table 2.

(Experiment 4)
A concrete plate sample prepared with a protective agent A applied thereto (hereinafter referred to as sample E) and a concrete plate sample applied with nothing (hereinafter referred to as sample F) were prepared. The sample of the concrete board is a cube having a side of 100 mm, the concrete composition is nominal strength = 21, slump = 8, the maximum size of coarse aggregate = 25, and the water cement ratio is 65%. The coating amount of the protective agent A was 0.25 liter / m ² . The curing time was 14 days.

  Samples E and F (each three) were subjected to an accelerated neutralization test for 28 days in an environment of a temperature of 20 ± 2 ° C., a humidity of 60 ± 5%, and a carbon dioxide concentration of 5 ± 0.2%. This accelerated neutralization test is described in the surface impregnating agent test method (draft) (JSCE-K571-2005).

After the accelerated neutralization test, each sample E and F is split so that the impregnated surface S1 of each sample E and F is divided into two, and is opposed to the impregnated surface S1 of the split surface SX and the impregnated surface S1. The neutralization depth from the surface S2 (test surface) was measured (see FIG. 6). And the neutralization depth ratio was calculated | required from following Formula.
Neutralization depth ratio = neutralization depth of sample E / neutralization depth of sample F × 100

  The results of Experiment 4 are shown in Table 3. In addition, measurement location A1-A3 in a table | surface is a position of 25 mm on the left and right from the width center position of the sample of a concrete board, and a width center position.

(Experiment 5)
A concrete modifier was made as follows. 50 g of calcium lactate (Musashino Science Laboratory Co., Ltd.) was dissolved in 1000 ml of tap water (25 ° C.). In addition, the said tap water used the sampling point number 5-7 of Table 4. FIG. The water thus obtained was poured into the water tank 10 of the concrete modifier production facility 2 shown in FIG. 3 and electrolyzed. The alkaline electrolyzed water obtained by electrolysis was used as the concrete modifier. Based on the ICP emission spectroscopic analysis method (JIS K0101 No49), the amount of Ca ions in the concrete modifier was measured, and the amount of Ca ions in the concrete modifier was 2.5 × 10 ⁵ mg / L.

It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

Claims (5)

A concrete protective material supplied to a concrete structure after a concrete modifier containing alkaline water and calcium ions has been supplied in advance,
The concrete protective material is
A silicate containing an alkali metal;
Alkaline electrolyzed water,
The alkali metal is
With sodium,
At least one of potassium or lithium;
The concrete protective material characterized in that the silicate reacts with the calcium ions of the concrete modifier to contribute to the formation of calcium silicate .   The concrete protective material according to claim 1, comprising silicon dioxide in an insoluble state with respect to the alkaline electrolyzed water.   The concrete protective material according to claim 2, wherein the silicate is aggregated with the silicon dioxide as a nucleus. A modifier supply step for supplying a concrete modifier containing alkaline water and calcium ions to the concrete structure;
Concrete said done after modifying agent supplying step, characterized in that organic and a protective agent supplying step of supplying to the concrete protective material the concrete structure of any one of claims 1 to 3 How to repair structures.   The method for repairing a concrete structure according to claim 4, wherein the solubility of the calcium ions in the concrete modifier is a ratio exceeding 0.17g with respect to 100g of the alkaline electrolyzed water.

Images