JP2001072457A - Anticorrosive paste and mortal to which chloride ion adsorbent is added - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an anticorrosive paste or mortal which can inhibit the deterioration of concrete due to chlorides by compounding a Portland-based cement and a chloride ion adsorbent as main components. SOLUTION: This chloride ion adsorbent contained in the anticorrosive paste and the anticorrosive mortar is suitably calcium.aluminum complex hydroxide which is not consumed by a reaction with the cement, and is preferably used in an amount of 10 to 70 pts.wt. per 100 pts.wt. of the cement. The excessive use of the chloride ion adsorbent tends to deteriorate the applicability of the paste and the abnormal generation of cracks in the applied paste and mortar. The anticorrosive paste can be used for a repair construction method which comprises chipping a concrete portion deteriorated by the corrosion of reinforcing rods due to salts, removing rusts, coating the surfaces of the cleaned reinforcing rods with the anticorrosive paste, and further coating the surfaces with the anticorrosive mortar. As a preventive treatment, the anticorrosive paste may be coated on the reinforcing rods, and the anticorrosive mortar may further be coated on the periphery of the reinforcing rods and the surface of concrete.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention mainly relates to civil engineering
The present invention relates to a technical field used as a material for controlling salt damage of concrete or concrete which is likely to deteriorate due to deterioration caused by external salt damage or internal salt damage in the construction field, and a salt damage control method.

[0002]

2. Description of the Related Art In recent years, early deterioration of concrete due to internal salt damage due to the use of sea sand and external salt damage due to the action of sea salt particles has become a serious problem. Reinforcement corrosion due to salt damage causes cracks and lifts in the concrete and directly reduces the load carrying capacity of the concrete structure.

[0003]

In order to suppress the continuous progress of deterioration due to salt damage, it is necessary to reduce excess chloride ions in concrete and prevent chloride ions and moisture from entering. Probably, no attempt has been made for the former. Heretofore, in order to suppress such deterioration, only a surface coating for the purpose of preventing intrusion of chloride ions or moisture has been exclusively performed. However, in actual structures, there is water that enters from other than the surface, such as water leakage and back water.Therefore, there are many cases where such a method alone contributes to the deterioration rather than the deterioration, and is a drastic solution. No, there is a problem to be solved here.

[0004]

SUMMARY OF THE INVENTION In view of the above problems, some of the present inventors adsorb excessive chloride ions in concrete and release nitrite ions, thereby suppressing the progress of corrosion of reinforcing steel. Chloride ion adsorbents are already being developed as admixtures for cement. The present invention has been developed by improving this technology for use as an inorganic repair material and an inorganic deterioration suppressing material for reinforced concrete deteriorated due to salt damage or reinforced concrete which is likely to deteriorate. The purpose of the present invention is to provide a rust preventive paste and a rust preventive mortar for the purpose of. First, the present invention is a rust-preventing paste or a rust-preventing mortar containing Portland cement and a chloride ion adsorbent as main components. The rust-preventive paste is a repair method in which the concrete portion degraded by corrosion of the reinforcing bar due to salt damage is removed, the rust is removed, the rust-preventive paste is applied to the surface of the reinforcing bar, and the rust-proof mortar is applied and repaired. Can be used. Further, the rust-preventive mortar and the rust-preventive paste are applied to the reinforcing steel of the reinforced concrete in a preventive measure in advance at places where there is a concern that the reinforcing steel is corroded due to salt damage, and the rust-preventive mortar is applied around the reinforcing steel and the concrete surface. It can be used for the deterioration control method of attaching and finishing.

[0005] Chloride added from sea salt particles or sea sand is mainly supplied as sodium chloride, so that salt damage is accelerated and the supply of sodium ions tends to cause an alkali-aggregate reaction. 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 paste is obtained by adding a chloride ion adsorbent for adsorbing chloride ions and an alkali metal ion adsorbent for adsorbing sodium ions to cement to improve workability and adhesion to a reinforcing bar. To the emulsion or latex.

The rust preventive mortar is characterized in that a chloride ion adsorbent and an alkali metal ion adsorbent are added to cement, and further, a cement-based expanding material is contained as a component to prevent the occurrence of cracks due to drying shrinkage. Is what you do.

As the chloride ion adsorbent, a calcium / aluminum composite hydroxide which is not consumed by reacting with the cement is suitable, and "Solcut" manufactured by Nippon Chemical Industry Co., Ltd. can be used. Further, as the alkali metal ion adsorbent, synthetic zeolite “Alcat” manufactured by Nippon Chemical Industry Co., Ltd. can be used.

In the case of the rust preventive paste, the amount of the chloride ion adsorbent to be added is preferably in 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. Preferably, it is 15 to 60 parts by weight, more preferably 15 to 25 parts by weight. If the addition amount is excessive, the workability deteriorates and the paste tends to be abnormally cracked. In this case, the alkali metal ion adsorbent can be added up to 30 parts by weight based on 100 parts by weight of cement.

The emulsion and latex for improving workability have a solid content of 5 parts by weight per 100 parts by weight of cement.
To 30 parts by weight, and as a type of emulsion or latex, an acrylic resin emulsion,
Styrene / butadiene rubber latex and the like.

In the case of the rust preventive mortar, the addition amount of the chloride ion adsorbent is preferably 15 to 80 parts by weight, more preferably 25 to 50 parts by weight, based on 100 parts by weight of cement in consideration of the adsorbability, stability and workability. Part is more preferable, and 25 to 35 parts by weight is further preferable. Also in this case, the alkali metal ion adsorbent can be added up to 30 parts by weight based on 100 parts by weight of cement. Further, the addition amount of the cement-based expanding 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 expanding material, an Auyne mineral-based material or a 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. Commercially available ones can be used.

In addition, fibers such as vinylon and carbon can be added to prevent cracks due to drying shrinkage. The rust-preventing paste can be obtained by scraping concrete until corroded reinforcing bars appear at places where cracks or floats are observed, removing the rust and applying it with a brush, etc., or applying it to the reinforcing bars in advance as a preventive measure. It is valid.

The rust-proofing mortar is suitably applied by application using a trowel, and is used to remove a portion where cracks or floating is observed due to corrosion of reinforcing steel, and to apply it as a cross-section repairing material. It is effective to apply it on the surface and around the rebar. The workability of the rust-preventive mortar using a trowel 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 a brush and the rust preventive mortar using a trowel.

In order to suppress early deterioration such as salt damage and alkali-aggregate reaction, a surface treatment material is used to cut off water entering from the concrete surface such as rainwater. However, in actual structures, moisture is often supplied from other than the surface, such as underground or water leaks on the back, and if such a place is coated with completely water-absorbing resin, the water content of concrete will increase rather than degrade. Often promotes. For the above reasons, the surface treatment material is a silane-based impregnating material with high water vapor permeability, which has the function of shutting off water from the surface and discharging internal water as water vapor, a polymer cement-based surface coating material, and a silicone resin-based surface coating material. Is effective for suppressing deterioration, and a mixture of “Tight Silane Super” manufactured by Toyo Ink Mfg. Co., Ltd. and “Arma # 100” manufactured by Mitsubishi Materials Corporation mixed with “Arma # 200” admixture can be used.

Therefore, when applying the rust preventive paste and the rust preventive mortar, the combined use of the rust preventive mortar and the rust preventive mortar results in a greater anticorrosive effect, and furthermore, a silane impregnating material, a polymer cement type surface coating material, and a silicone resin. When a surface treatment material having high water vapor permeability such as a system surface coating material is applied to the concrete surface, the effect is increased.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below in detail with reference to experimental examples.

EXPERIMENTAL EXAMPLE 1 A polished steel rod coated with a rust-preventive paste or cement paste prepared by adding an appropriate amount of water to one having or not containing a chloride ion adsorbent and having a mixing ratio shown in Table 1 was used to increase the height. Embedded in the center of high salt mortar (40 × 40 × 160 mm, water cement ratio 60%) adjusted to salt concentration (Cl concentration 2% with respect to cement), about 10 mm from the surface by accelerated neutralization test equipment After neutralization, the wet area (soaked for 4 days, dried for 3 days) at 40 ° C. was repeated 7 times (49 days) to examine the corrosion area ratio. The results are shown in Table 1.

[0018]

[Table 1]

Experiment No. According to 1-1 to 1-6, the rust preventive effect increases as the amount of the chloride ion adsorbent increases, and the effect increases particularly when the amount of addition exceeds 15 parts by weight with respect to 100 parts by weight of cement. It was shown to be.

Experimental Example 2 A rust preventive paste prepared by adding an appropriate amount of water to a mixture having a mixing ratio shown in Table 2 to which a chloride ion adsorbent was added was applied to a polished steel bar, and workability was examined. Table 2 shows the results.
It is described together.

[0021]

[Table 2]

Experiment No. According to 2-1 to 2-7, it was shown that when the added amount of the chloride ion adsorbent exceeds 70 parts by weight with respect to 100 parts by weight of the cement, the workability is significantly deteriorated.

Experimental Example 3 With respect to a fresh rust-preventive varnish having a different amount of the chloride ion adsorbent, the flow value was measured using a mortar flow tester in accordance with JIS R5201, and the workability was examined. . The results are shown in Table-3.

[0024]

[Table 3]

Experiment No. According to 3-1 to 3-6, it was shown that the flow value was reduced as the added amount of the chloride ion adsorbent was increased, and that the workability was deteriorated when the amount exceeded 80 parts by weight with respect to 100 parts by weight of cement.

Experimental Example 4 A rust-proof mortar specimen (40 × 40 × 160 mm) was prepared in which the amount of the chloride ion adsorbent was changed, and JIS R
The compressive strength at 28 days of material age according to
The dry shrinkage on 28 days of age was determined based on the length immediately after demolding according to the dial gauge method of IS A 1129. The results are shown in Table-4.

[0027]

[Table 4]

Experiment No. According to 4-1 to 4-6, it was found that as the amount of the chloride ion adsorbent added increased, the drying shrinkage ratio increased. Experiment No. 4-
From 7 to 4-9, it was shown that drying shrinkage can be suppressed by adding a cement-based expanding agent, but it is shown that expansion occurs when the amount is too large.

Experimental Example 5 A high salinity mole (40 × 40 × 30 mm) adjusted to a high salinity (Cl concentration: 3% with respect to cement) and a rust-preventive mole in which the amount of the chloride ion adsorbent was changed. Evening (40 ×
40 × 30 mm; the basic composition was the same as that of Experimental Example 4), and a bonded specimen was prepared.
0 ° C., relative humidity 100%) After the joint surface, the energy dispersive X
It was determined by line analysis. The results are shown in Table-5. The basic composition of the rust-preventive mortar in this case is according to Experimental Example 4.

[0030]

[Table 5]

Experiment No. According to 5-1 to 5-5, the amount of chloride ions in the high-salt molar solution adsorbed and fixed increases as the amount of the chloride ion adsorbent added to the rust-proofing solution increases. Indicated.

Experimental Example 6 High salt mortar (40 × 20 × 160 mm, water cement ratio 65%) adjusted to high salt concentration (Cl concentration 2% with respect to cement) and rust preventive mortar (40 × 20 × 160 m)
m), and a test piece (40) in which a polished steel rod was buried with the half of the rust-proof mortar applied to the joint with rust-preventive paste.
× 40 × 160 mm) at 40 ° C. was repeatedly immersed and dried in 5% NaCl salt water (4 days immersion, 3 days drying) nine times (63 days) to determine the corrosion area ratio of the polished steel rod. Table 6 shows the combinations of types of rust preventive mortar and types of rust preventive paste used in the test. The sides of the test specimen were sealed with epoxy resin, and the high salt mortar side was subjected to accelerated neutralization test in advance. About 10 mm was neutralized by the apparatus.
The basic composition of the rust-preventive paste is the same as that of Experimental Example 1, and the basic composition of the rust-preventive mortar is that of Experimental Example 4.

[0033]

[Table 6]

Experiment No. According to 6-1 and 6-2, it was shown that when the added amount of the chloride ion adsorbent of the rust-preventive mortar was increased, the anticorrosion effect of the reinforcing steel was clearly increased. Experiments 6-1 to 6-4 show that the combination of a rust-preventive mortar with a rust-preventive paste to which a chloride ion adsorbent is added increases the corrosion suppression effect.

Experimental Example 7 Rust prevention mortar with chloride ion adsorbent shown in Table 7 was added to the center of a mortar specimen (40 × 40 × 160 mm) shown in Table 7 with chloride ion adsorbent added. A polished steel rod buried with is buried, and a water-based silane-based impregnating material and a polymer cement-based surface coating material are applied to the specimen surface,
5% NaC at 40 ° C for those with no surface treatment
1 The immersion-drying of salt water (4 days immersion, 3 days drying) was repeated 16 times (112 days), and the corrosion area ratio was measured. In this case, the basic composition of the rust-preventive paste was the same as that of Experimental Example 1 and the basic composition of the mortar to which the chloride ion adsorbent was added was the same as that of Experimental Example 4. The Cl concentration was adjusted to 1.5%, and before the surface treatment material was applied, each specimen was neutralized by about 10 mm by an accelerated neutralization test apparatus. The results are shown in Table-7.

[0036]

[Table 7]

Experiment No. According to 7-1 to 7-3, it was shown that when a surface treatment material having high water vapor permeability was used in combination with the rust preventive paste and the rust preventive mortar, the rust preventive effect was improved.

The materials used in the experimental examples in this specification are as follows. -Cement: Ordinary Portland cement manufactured by Mitsubishi Materials Corporation-Chloride ion adsorbent: Solcut manufactured by Nippon Chemical Industry Co., Ltd.-Alkali metal ion adsorbent: Alcut manufactured by Nippon Chemical Industry Co., Ltd.-Cement-based expander: Onoda Cement Co., Ltd. Made by Onoda Expan ・ Aggregate: dried silica sand No.4,5,7

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C04B 24:24 16:06 14:38) 103: 61 111: 24 111: 72 (72) Inventor Jun Takada 2-8-8 Hikaricho, Kokubunji-shi, Tokyo 38 Within the Railway Technical Research Institute (72) Inventor Teruhiro Kudo 38-2 Hikaricho 2-chome, Kokubunji-shi, Tokyo 38 Inside the Railway Technical Research Institute (72) Inventor Horie Hiroo 1-4-4 Tadao, Machida-shi, Tokyo Inside the Japan Road Public Corporation Testing Laboratory (72) Inventor Yoshio Iizuka 1-4-4 Tadao, Machida-shi, Tokyo Inside the Japan Road Public Testing Laboratory (72) Inventor Masayuki Watanabe 1-4-4, Tadao, Machida-shi, Tokyo Inside the Japan Highway Public Corporation Testing Laboratory

Claims (2)

[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.