JPH0986997A - Rust preventing paste for chloride ion adsorbent and mortar and salt damage suppressing construction using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rust preventing paste capable of suppressing the continuous progress of deterioration due to salt damage by including a Portland-based cement and a chloride ion adsorbent as principal components therein. SOLUTION: This rust preventing paste consists essentially of a Portland- based cement and a chloride ion adsorbent. Since chlorides added from sea salt grains or sea sand, etc., are mainly fed as sodium chloride, not only salt damage is promoted but also alkali-aggregate reaction is readily initiated by the feed of sodium ions. Thereby, an alkali metallic ion adsorbent in addition to the chloride ion adsorbent is preferably added thereto for the purpose of suppressing the alkali-aggregate reaction. A rust preventing mortar is prepared by adding the chloride ion adsorbent and the alkali metallic ion adsorbent to a cement and further including a cement-based expansive additive therein in order to prevent cracks from occurring due to drying shrinkage. In the case of the rust preventing paste, the added chloride ion adsorbent is preferably used in an amount within the range of 10-70 pts.wt. based on 100 pts.wt. cement by considering the rust preventing effects, executability, etc.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention mainly relates to civil engineering
In the field of construction, the present invention relates to a concrete material which is deteriorated by external salt damage and internal salt damage or a concrete material which is concerned about deterioration, and a technical field used as a salt damage control method.

[0002]

2. Description of the Related Art In recent years, early deterioration of concrete due to internal salt damage caused by the use of sea sand and external salt damage caused by the action of sea salt particles has become a serious problem. Reinforcing bar corrosion due to salt damage causes cracking and floating in concrete and directly lowers the load bearing capacity of concrete structure.

[0003]

In order to prevent the continuous deterioration due to salt damage, it is necessary to reduce excessive chloride ions in concrete and prevent chloride ions and water from entering. It is possible, but no attempt has been made on the former. In the past, in order to suppress such deterioration, only surface coating intended to prevent the entry of chloride ions and water was performed exclusively. However, in actual structures, there is water that leaks from other than the surface, such as water leaks and back water, so there are many cases in which deterioration is promoted by this method alone, and this is not a drastic solution. No, there is a problem to be solved here.

[0004]

In view of the above problems, some of the present inventors adsorb excess chloride ions in concrete and release nitrite ions, thereby suppressing the progress of corrosion of reinforcing bars. Chloride ion adsorbents have already been developed as admixtures for cement. The present invention has been developed by improving this technology for use as an inorganic repair material for reinforced concrete that is deteriorated by salt damage or for reinforced concrete that is concerned about deterioration, and as a material for suppressing inorganic deterioration. The present invention provides a rust preventive paste and a rust preventive mortar. First, the present invention is a rust preventive paste or rust preventive mortar containing a Portland cement and a chloride ion adsorbent as main components. Further, there is a repairing method in which a concrete part deteriorated due to corrosion of reinforcing bars due to salt damage is scraped off, rust is removed, the surface of the reinforcing bars is coated with the rust preventive paste, and the rust preventive mortar is applied to restore and finish. Furthermore, in places where there is concern about rebar corrosion due to salt damage, the rust preventive paste is applied to the rebar of reinforced concrete as a preventive measure in advance, and the rust preventive mortar is applied to the area around the rebar or the concrete surface to prevent deterioration. is there. Furthermore, a silane-based impregnating material and / or a polymer-cement-based surface coating material and / or a surface-treating material in the repair or deterioration suppressing method.
Alternatively, it is a repair or deterioration suppressing construction method in which a silicone resin-based surface coating material is combined.

Since chloride added from sea salt particles or sea sand is mainly supplied as sodium chloride, not only salt damage is promoted but also alkali-aggregate reaction is easily caused by supply of sodium ion. Therefore, it is preferable to add an alkali metal ion adsorbent to these for the purpose of suppressing the alkali-aggregate reaction in addition to the chloride ion adsorbent. The rust preventive space is obtained by adding a chloride ion adsorbent that adsorbs chloride ions and an alkali metal ion adsorbent that adsorbs sodium ions to cement, in order to improve workability and adhesive strength with reinforcing bars. An emulsion or latex can be added to.

The anticorrosive mortar is also characterized in that a chloride ion adsorbent and an alkali metal ion adsorbent are added to the cement, and further a cement-based expansive material is contained as a component in order to prevent cracking due to drying shrinkage. To do.

As the chloride ion adsorbent, calcium-aluminum composite hydroxide which is not consumed by reacting with cement is suitable, and "Solcut" manufactured by Nippon Kagaku Kogyo Co., Ltd. can be used. Further, as the alkali metal ion adsorbent, a synthetic zeolite "Arcut" manufactured by Nippon Kagaku Kogyo Co., Ltd. can be used.

In the case of the rust preventive paste, the amount of the chloride ion adsorbent added should be within the range of 10 to 70 parts by weight with respect to 100 parts by weight of cement in consideration of the rust preventive effect and workability. It is preferably 15 to 60 parts by weight, more preferably 15 to 25 parts by weight. If the amount added is excessive, the workability will deteriorate and the paste will tend to crack abnormally. Further, in this case, the alkali metal ion adsorbent can be added up to 30 parts by weight with respect to 100 parts by weight of cement.

Emulsions and latexes for improving workability have a solid content of 5 per 100 parts by weight of cement.
It can be added so as to be up to 30 parts by weight, and the type of emulsion or latex is an acrylic resin emulsion,
Examples include styrene / butadiene rubber latex.

In the case of the rust preventive mortar, the amount of chloride ion adsorbent added is preferably 15 to 80 parts by weight, preferably 25 to 50 parts by weight, based on 100 parts by weight of cement in consideration of adsorption ability, stability and workability. Parts is more preferable, and 25 to 35 parts by weight is further preferable. Also in this case, up to 30 parts by weight of the alkali metal ion adsorbent can be added to 100 parts by weight of cement. Further, the addition amount of the cement expansive material is preferably up to 10 parts by weight with respect to 100 parts by weight of cement, and if it exceeds 10 parts by weight, abnormal expansion may occur.

As the cement-based expansive material, a hain mineral-based or calcium oxide-based material is preferable from the viewpoint of dimensional stability, such as "Denka CSA" manufactured by Denki Kagaku Kogyo Co., Ltd. and "Onoda Expan" manufactured by Onoda Cement Co., Ltd. What is marketed can be used.

Fibers such as vinylon and carbon may be added to prevent cracking due to drying shrinkage. The anticorrosive paste is peeled off concrete until a corroded reinforcing bar portion appears at a place where cracks and floats are observed, and after removing the rust, it is applied with a brush or the like, or when applied to the reinforcing bar in advance as a preventive measure. It is valid.

The rust preventive mortar is suitable to be applied by applying it with a trowel, and a part where cracks and floats are observed due to corrosion of the reinforcing bar is peeled off, and as a preventive measure, a reinforced concrete structure is prepared beforehand. It is effective to apply it on the surface or around the reinforcing bars. The workability of the rust preventive mortar with the iron is further improved by adding silica fume. Further, the addition of the alkali metal ion adsorbent further improves the workability of the rust preventive paste using the brush and the rust preventive mortar using the iron.

In order to suppress early deterioration such as salt damage and alkali-aggregate reaction, a surface treatment material is used to block water such as rainwater that enters from the concrete surface. However, in actual structures, water is often supplied from the ground in the back and from other than the surface such as water leakage, and if water-repellent resin is applied to such places, the water content of the concrete will increase and deterioration will occur. Is often promoted. For the above reasons, as a surface treatment material, a silane-based impregnating material, a polymer cement-based surface coating material, a silicone resin-based surface coating material, which has a function of cutting off water from the surface and discharging internal water as water vapor, Is effective for suppressing deterioration, and “Tight Silane Super” manufactured by Toyo Ink Mfg. Co., Ltd. or “Arma # 100” manufactured by Mitsubishi Materials Co., Ltd. can be used by kneading them with an “Arma # 200” admixture.

Therefore, when the anticorrosive paste and the anticorrosive mortar are applied, the anticorrosive effect is greater when used in combination than when used alone. Further, the silane-based impregnating material, the polymer cement surface-coating material, and the silicone resin are used. When a surface treatment material having a large water vapor permeability, such as a system surface coating material, is applied to the concrete surface, its effect increases.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to experimental examples.

Experimental Example 1 A polished steel rod coated with a rust preventive paste or a cement paste prepared by adding an appropriate amount of water to a mixture ratio shown in Table 1 with or without addition of a chloride ion adsorbent was prepared. It is embedded in the center of high salt mortar (40 × 40 × 160 mm, water cement ratio 60%) adjusted to a salt concentration (Cl concentration of 2% with respect to cement), and about 10 mm from the surface by an accelerated neutralization tester. After the neutralization, dry and wet conditions (immersion for 4 days, drying for 3 days) were repeated 7 times at 40 ° C. (49 days) to examine the corrosion area ratio. The results are also shown in Table-1.

[0018]

[Table 1]

Experiment No. According to 1-1 to 1-6, the anticorrosive effect becomes larger as the amount of the chloride ion adsorbent added increases, and particularly when the amount added exceeds 15 parts by weight with respect to 100 parts by weight of cement, the effect becomes large. It was shown that

Experimental Example 2 A rust preventive paste prepared by adding an appropriate amount of water to the mixture ratio shown in Table 2 to which a chloride ion adsorbent was added was applied to a brushed steel rod to examine workability. The results are shown in Table-2.
Also described in.

[0021]

[Table 2]

Experiment No. 2-1 to 2-7 showed that the workability was significantly deteriorated when the amount of the chloride ion adsorbent added exceeded 70 parts by weight with respect to 100 parts by weight of cement.

Experimental Example 3 With respect to fresh rust preventive mortar in which the amount of chloride ion adsorbent added was changed, the flow value was measured using a mortar flow tester in accordance with JIS R 5201 and the workability was examined. . The results are also shown in Table-3.

[0024]

[Table 3]

Experiment No. From 3-l to 3-6, it was shown that the flow value decreased as the amount of the chloride ion adsorbent added increased, and the workability deteriorated when it exceeded 80 parts by weight with respect to 100 parts by weight of cement.

Experimental Example 4 Anticorrosion mortar specimens (40 × 40 × 160 mm) in which the amount of chloride ion adsorbent added was varied were prepared, and JIS R
Based on 5201, compressive strength at 28 days
Based on the dial gauge method of IS A 1129, the dry shrinkage percentage on the 28th day was determined based on the length immediately after demolding. The results are also shown in Table-4.

[0027]

[Table 4]

Experiment No. It was found from 4-1 to 4-6 that the drying shrinkage rate increases as the amount of the chloride ion adsorbent added increases. Experiment No. 4-
From 7 to 4-9, it was shown that the drying shrinkage can be suppressed by adding the cement-based expansive material, but if the amount is too large, it expands.

Experimental Example 5 High salt salinity (40 × 40 × 30 mm) adjusted to a high salinity concentration (Cl concentration of 3% with respect to cement) and anticorrosion moles with varying amounts of chloride ion adsorbent added Evening (40 ×
40 × 30 mm; the basic composition is the same as in the case of Experimental Example 4) to prepare a joined specimen, which is wet cured for 3 months (4
After 0 ° C and 100% relative humidity), the chlorine concentration of the 2mm portion of the rust preventive mortar from the joint surface is energy dispersive X
It was determined by line analysis. The results are also shown in Table-5. The basic composition of the rust preventive mortar in this case is in accordance with Experimental Example 4.

[0030]

[Table 5]

Experiment No. Due to 5-1 to 5-5, as the amount of chloride ion adsorbent added to the rust preventive mole increases, the amount of chloride ion adsorbed and fixed in the high salinity mole increases. Was shown.

Experimental Example 6 High salt mortar (40 × 20 × 160 mm, water cement ratio 65%) adjusted to a high salt concentration (Cl concentration of 2% relative to cement) and rust preventive mortar (40 × 20 × 160 m)
m) was joined and the half of the rust preventive mortar side was applied to the joint with a rust preventive paste.
For 40 × 160 mm), immersion of 5% NaCl salt water at 40 ° C.-drying (4 days immersion, 3 days drying) was repeated 9 times (63 days) to determine the corrosion area ratio of the polished steel rod. The combination of rust preventive mortar type and rust preventive paste type used in the test is shown in Table-6. The side of the test piece is sealed with epoxy resin, and the high salt mortar side is accelerated neutralization test in advance. The device neutralized about 10 mm.
The basic composition of the rust preventive paste is in accordance with Experimental Example 1, and the basic composition of the rust preventive mortar is in accordance with Experimental Example 4.

[0033]

[Table 6]

Experiment No. It was shown by 6-1 and 6-2 that when the amount of chloride ion adsorbent added to the rust preventive mortar was increased, the anticorrosion effect of the reinforcing bar was obviously increased. Further, from Experiments 6-1 to 6-4, it is found that the combination of a rust preventive paste containing a chloride ion adsorbent and a rust preventive mortar increases the corrosion inhibiting effect.

Experimental Example 7 Anticorrosion paste containing chloride ion adsorbent shown in Table 7 at the center of the anticorrosion mortar specimen (40 × 40 × 160 mm) containing chloride ion adsorbent shown in Table 7. The polished steel rod coated with is embedded, and the water-based silane-based impregnating material and the polymer cement-based surface coating material are applied to the surface of the specimen,
5% NaC at 40 ° C for non-treated surface treatment materials
The immersion area ratio of the corroded area was measured by repeating dipping-drying (4 days immersion, 3 days drying) 16 times (112 days). In this case, the basic composition of the rust preventive paste was in accordance with Experimental Example 1, and the basic composition of the mortar with the chloride ion adsorbent was in accordance with Experimental Example 4. In contrast, the Cl concentration was adjusted to 1.5%), and all the test specimens were neutralized with an accelerated neutralization test device to about 10 mm before applying the surface treatment material. The results are also shown in Table-7.

[0036]

[Table 7]

Experiment No. 7-1 to 7-3 show that the rust preventive effect is improved by using a surface treatment material having a large water vapor permeability in addition to the rust preventive paste and the rust preventive mortar.

The materials used in the experimental examples in this specification are as follows. -Cement: Ordinary Portland cement manufactured by Mitsubishi Materials Co., Ltd.-Chloride ion adsorbent: Solcut manufactured by Nippon Kagaku Kogyo Co., Ltd.-Alkali metal ion adsorbent: Arcut manufactured by Nippon Kagaku Kogyo Co., Ltd.-Cement-based expansion material: Onoda Cement Co., Ltd. Made by Onoda Expan ・ Aggregate: Made by Tohoku silica sand Co., Ltd. Dry silica sand No. 4, 5, 7

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI technical display location C04B 24:26) 103: 61 111: 72 (72) Inventor Teruhiro Kudo Hikarimachi, Kokubunji, Tokyo 2-chome 38, Railway Technical Research Institute (72) Inventor Hiroo Horie 1-4-1, Tadao, Machida-shi, Tokyo 1 Provincial Research Institute for Japan Highway Public Corporation (72) Inventor Yoshio Iizuka 1, Tadao, Machida-shi, Tokyo 1 4-chome 1 Japan Highway Public Corporation Research Laboratory (72) Inventor Masayuki Watanabe 1-4 Tadio Tamachi, Tokyo Metropolitan Government 1 Japan Highway Public Corporation Testing Research Center

Claims (5)

[Claims] 1. A rust preventive paste containing Portland cement and a chloride ion adsorbent as main components. 2. A rust preventive mortar containing Portland cement and a chloride ion adsorbent as main components. 3. A concrete part deteriorated by rebar corrosion due to salt damage is scraped off to remove rust, and then the rust preventive paste according to claim 1 is applied to the surface of the rebar, and the rust preventive mortar according to claim 2 is applied. Repair method to repair and finish. 4. The anticorrosive paste according to claim 1 is applied to the reinforcing bar of reinforced concrete in advance as a preventive measure at a location where corrosion of the reinforcing bar due to salt damage is a concern, and the anticorrosive mortar according to claim 2 is applied around the reinforcing bar or concrete. A deterioration-preventing method that is applied by painting on the surface. 5. A repair or deterioration suppressing construction method in which the construction method according to claim 3 or 4 is combined with a silane-based impregnation material and / or a polymer cement-based surface coating material and / or a silicone resin-based surface coating material as a surface treatment material.