JP2011136887A - Repairing material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a repairing material of a cement-based hydraulic composition which is suitable for repair of a deteriorated part by corrosion of mortar and concrete involving a reinforcing bar, a steel frame, a steel net or the like, and after repair becomes a repaired product which has solid and strong properties and does not tend to generate the corrosion of macrocells. <P>SOLUTION: The repairing material is produced by impregnating a solidified body in which a hydraulic composition containing (A) cement, (B) porous aggregate of 5-60% of open pore rate in which water is contained in the open pores and (C) metakaolin is terminated in setting with (D) an inorganic anticorrosive. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a repair material for a hydraulic composition having a strong rust prevention ability.

For repairing mortar and concrete that are cracked or deteriorated, such as peeling, cement-based repair materials are filled or covered on the part where the deteriorated part or the deteriorated part is sandwiched. . Since repairability is particularly considered in terms of workability, repair materials are usually not the same as existing mortar and concrete to be repaired, and have different electrical characteristics from the repair target. Later, re-degradation called macrocell corrosion is likely to occur in the reinforcing bars and steel frames that contact the boundary between the repaired part and the existing mortar / concrete.
On the other hand, rebars and steel frames contained in mortar and concrete may rust and corrode due to the effects of many years such as neutralization of mortar and concrete, chloride remaining in mortar and concrete, or air penetrating through fine voids. is there. As a preventive measure against this corrosion, for example, nitrite such as sodium nitrite, or an antirust agent containing an alkali metal chromate, silicate or phosphate as an active ingredient is mixed with mortar or concrete in advance. Application to the surface of a cured mortar / concrete is generally performed.

  Although such a rust preventive is effective against the above-mentioned macrocell corrosion, it is not easy to achieve sufficient rust prevention for reinforcing bars and steel frames that have been exposed to the outside once due to deterioration. A sufficient amount of, for example, nitrite ions in the rust component must be retained on the surface of the reinforcing bar or the steel frame, and an oxide film must be rapidly formed on the surface. However, since the electrical properties of the repair material and the existing mortar / concrete to be repaired are different, a sufficient amount of rust-preventive component can be used to secure a sufficient amount of nitrite ions, etc. on the repaired metal surface. Mixing is required. In cement-based repair materials, if a large amount of rust-preventive components are mixed directly, the workability is lowered, and the cohesiveness after water injection is significantly hindered and the strength development is lowered. Mass mixing means that avoid direct mixing of rust-preventing ingredients are also being studied. For example, zeolitic mineral powder that can contain a large amount of substances of various sizes from its unique structure contains rust-preventing ingredients, and the zeolite It is known that a large amount of rust-preventive components can be contained by mixing the system mineral powder itself. (For example, refer to Patent Documents 1 and 2.) It is also known to repair a deteriorated portion with a mortar containing a porous aggregate containing a large amount of an antirust component. (For example, refer to Patent Document 3.)

Japanese Patent Laid-Open No. 05-43282 JP 2008-297137 A JP 09-317195 A

  When zeolite or porous porous aggregate containing or adsorbing rust preventive components is mixed with mortar or concrete composition, it can contain a large amount of rust preventive components. In addition, it is inevitable that a large amount of the rust preventive component contained in the porous aggregate is dissolved in the aqueous slurry and affects the slurry properties and the setting properties. And in the repair material which consists of such a composition, the fall of workability and the material property as a hardening body of a construction material become low in general. Further, when the amount of the rust preventive component flowing out into the slurry increases, a sufficient prevention effect against re-deterioration due to macrocell corrosion or the like cannot be obtained. In view of such a problem, the present invention is suitable for repairing a deteriorated part due to corrosion of mortar or concrete containing reinforcing bars, steel frames, steel nets, etc., and after repair, it becomes a repair work having a robust and strong property, and macrocell corrosion is also caused. It is to provide repair materials that are unlikely to occur.

  As a result of repeated investigations to solve the above problems, the present inventor has obtained a hydraulic composition containing at least cement, metakaolin, and a porous fine aggregate having open pores in which water has been absorbed. Obtained the knowledge that a repair material made by impregnating a solidified product with a liquid rust preventive component can contain a large amount of rust preventive components that can sufficiently rust rebars and steel frames without affecting the setting and hardening properties. Completed the invention.

That is, the present invention is a repair material represented by the following [1] to [4].
[1] To a solidified solidified body of a hydraulic composition containing (A) cement, (B) porous aggregate containing 5 to 60% of open porosity contained in open pores, and (C) metakaolin. (D) Repair material impregnated with an inorganic rust inhibitor.
[2] The repair material according to claim 1, wherein the porous aggregate has an opening pore diameter at an opening end of less than 10 μm.
[3] The inorganic rust inhibitor is any one or more of nitrites, chromates, silicates and phosphates of alkali metals or alkaline earth metals. Repair material.
[4] The repair material according to any one of claims 1 to 3, wherein the hydraulic composition further contains (E) a polymer dispersion or a re-emulsifying powder resin.

  Since the repair material of the present invention can carry a large amount of rust-preventive components without causing problems in workability, setting properties, and curing properties, it can be used for repairing deteriorated parts of concrete containing reinforcing bars and steel frames. When used, it can provide a strong rust-preventing action, and the occurrence of macrocell corrosion and the like can be sufficiently suppressed without chemically approximating the concrete to be repaired. In addition, the repaired construction after the repair is robust and excellent in durability. Furthermore, since the repair material of the present invention generally uses a low-weight porous aggregate, the repair material can be reduced in weight and hardly deformed or peeled off due to its own weight regardless of the direction of the repair object.

  In the repair material of the present invention, the (A) cement used for producing the hydraulic composition may be any cement, for example, various portland cements such as normal, early strength, moderate heat, and low heat, and mixed cements such as blast furnace cement. And special cements such as alumina cement and eco-cement can be used, and two or more kinds may be used in combination. For example, normal portland cement is recommended from the economical viewpoint for mortar and concrete containing reinforcing bars, steel frames, steel nets, etc., and from the viewpoint of shortening the construction period for repairing mortar / concrete deteriorated parts Early-strength Portland cement, combined use of alumina cement and other Portland cement are also recommended, but are not limited to the examples described.

  In the repair material of the present invention, (B) the porous aggregate having an open porosity of 5 to 60% contained in the open pores used for producing the hydraulic composition has pores opened on the aggregate surface, A porous aggregate having a porosity of 5 to 60% in the open pores is used. The open porosity can be measured, for example, by a method defined in JIS A 1509 “Ceramics Test Method-Section 3: Vacuum Method of Measuring Water Absorption, Apparent Porosity and Bulk Density”. In the porous aggregate used in the present invention, the presence or absence of closed pores on the aggregate surface is not particularly limited. In addition, if the repair material is light, deformation and peeling due to its own weight after construction hardly occur and construction work is facilitated. Therefore, in the present invention, it is preferable to use a porous aggregate having a bulk volume of 0.8 kg / liter or less. The material of the porous aggregate may be any material that can be used for mortar and concrete, that is, any material that is substantially inert to water and alkali. Preferably, aggregates made of natural minerals such as igneous rocks, artificial minerals, and hard resins are used because they are easy to obtain durability. Specifically, for example, volcanic gravel, zeolites, obsidian and pearls. Examples include heated foam particles (perlite) of rocks, various slag aggregates, aluminosilicate ceramics, polypropylene, polyethylene, ethylene tetrafluoride, etc., of which those with an open porosity of 5 to 60% are used. It ’s fine. Aggregates with an open porosity of less than 5% are not preferred because the amount of delay components that can be included is too small, and aggregates with an open porosity of more than 60% are low in strength and may be damaged during construction or after repair. This is not preferable because a solid and highly durable construction cannot be obtained. Moreover, it is preferable to use a porous aggregate having an opening pore diameter of 10 μm at the opening end. More preferably, the pore diameter is 5 angstroms or more and 10 μm. If the pore diameter at the open end exceeds 10 μm, the adsorbing force for supporting the inclusions becomes insufficient due to the decrease in specific surface area, which tends to flow out. If it is less than 5 angstroms, water molecules are too large to pass. In the present invention, such a porous aggregate is hydrated, and the porous aggregate in which water is retained in the open pores is used for blending with cement or the like. For example, the porous pore aggregate is immersed in water. In the water-containing state, it is sufficient that 60% or more of the open pore volume is filled with water. If it is less than 60%, a large amount of cementitious slurry after pouring invades from the opening and condenses as it is, which is not suitable. In the repair material of the present invention, the amount of the porous aggregate used for the production of the hydraulic composition is a mass converted in an absolutely dry state not containing water, and is 1 for 100 parts by mass of cement. -100 mass parts is preferable. More preferably, it is 20-40 mass parts. If the amount is less than 1 part by mass, a necessary amount of the rust-preventive component cannot be supported, so that it is not appropriate. If the amount exceeds 100 parts by mass, the strength and durability of the repair work may be lowered.

  In the repair material of the present invention, (C) metakaolin used for preparing the hydraulic composition is an intermediate having a dehydrated structure obtained by heating kaolinite, which is a hydrous silicate mineral, usually at 550 to 1200 ° C. is there. Preferably, kaolin is calcined at 700 to 1000 ° C. because a stronger hardened body is easily obtained. Metakaolin powder is highly active and compensates for the brittleness that is likely to occur as it contains more zeolite and high porosity porous aggregates, and is often found in heavy use of other active silica and pozzolanic reactive materials This is useful for obtaining a hardened body without causing a large-scale volume reduction of the object. As for the compounding quantity of a metakaolin, 5-20 mass parts is preferable with respect to 100 mass parts of cement compounding quantities. If it is less than 5 parts by mass, a strong hydraulic composition may not be obtained, so it is not suitable. If it exceeds 20 parts by mass, for example, for placing reinforced concrete or repairing mortar / concrete degradation sites This is not appropriate because the workability of the machine is reduced.

  In the repair material of the present invention, the components used for the preparation of the hydraulic composition include the above (A) to (C), but in addition to this, (E) a polymer dispersion or a re-emulsified powder resin Can be used. Use of polymer dispersion or re-emulsified powder resin increases suitability for various construction methods as a repair material, improves work adhesion to the repair site, and the work after repair has high chemical durability. It will be a thing. Any polymer dispersion or re-emulsified powder resin may be used as long as it can be used for what is called polymer mortar or polymer concrete. Preferably, JIS A 6203 “Polymer dispersion and re-emulsification for cement admixture” is used. What is described in "powder resin" can be used. More preferably, an acrylic polymer emulsion, a vinyl acetate polymer emulsion, a styrene butadiene rubber latex, a vinyl acetate re-emulsified powder resin, or a Veova re-emulsified powder resin can be used. The blending amount of the polymer dispersion or the re-emulsified powder resin is preferably 0.5 to 5 parts by mass in terms of solid content with respect to 100 parts by mass of the cement. If it is less than 0.5 parts by mass, almost no blending effect is obtained, and if it exceeds 5 parts by mass, it is difficult to impregnate the rust preventive agent.

  In the repair material of the present invention, in addition to the components (A) to (C) and (E), the components used for preparing the hydraulic composition may be used as long as the effects of the present invention are not substantially lost. it can. Examples of such components include water reducing agents that can be used in mortar and concrete, thickeners, short fibers, aggregates having an open porosity of less than 1%, drying shrinkage reducing agents, expansion materials, setting modifiers, fast hardeners, Examples thereof include quick setting agents and antifoaming agents.

  The repair material of the present invention is blended with the above components, and water is poured in an amount of 50 to 65 parts by mass with respect to 100 parts by mass of the total amount of cement and metakaolin to condense the kneaded hydraulic composition. The solidified body impregnated with (D) an inorganic rust inhibitor. Here, the amount of water injected does not include the amount of water in the hydrated porous aggregate to be blended. The kneaded product of the hydraulic composition is applied to the repair target part. Plastering is recommended for the construction method, but it is also possible to perform spraying using a combination of quick-setting components and fast-hardening components. It is also possible to apply it to the interface between the reinforcing bar and the body with a brush. The solidified body in which the applied hydraulic composition is condensed is dried as much as possible and then impregnated with an inorganic rust inhibitor. This is because the moisture contained in the open pores of the porous aggregate in the solidified body is sufficiently lost, and when the void area in the pores is increased and impregnated with an inorganic rust preventive agent, This is because a large number of supporting places are secured and a large amount of an inorganic rust inhibitor can be contained. The impregnation method of the inorganic anticorrosive agent is not particularly limited. For example, a high concentration aqueous solution having an antirust active ingredient concentration of 50% or more is prepared and applied to the solidified body of the dried hydraulic composition. When the repair construction part is an inclined part or a ceiling part, in order to prevent dripping or peeling off, for example, a water-soluble paste such as vinyl acetate is appropriately added to the aqueous solution to provide adhesiveness.

  The (D) inorganic rust preventive agent used in the repair material of the present invention is an inorganic substance having a rust preventive ability for iron or steel, and is particularly capable of producing an aqueous solution having a concentration of at least about 20% at room temperature, for example. It is not limited. Preferably, any of alkali metal nitrites, chromates, silicates, phosphates or alkaline earth metal nitrites can be mentioned, and two or more of them may be used in combination. A more preferred inorganic rust inhibitor is alkali metal nitrite. The amount of inorganic rust inhibitor used may be determined according to the amount of reinforcing bars and steel frames contained in the repair object, the size of the repaired part, etc., but the amount that can be supported inside the repair material is porous aggregate. The total volume of the open pores is generally set to an upper limit, and if it exceeds that, it may not be impregnated.

  The zeolite to be used is not particularly limited. For example, a structure mainly composed of microcrystalline cavities of several tens of angstroms or less is difficult to carry a large amount of rust-preventive components and has a strong adsorption ability. After that, there is a possibility that it is difficult to discharge smoothly. In addition, as the porous porous aggregate, among aggregates that can be used for mortar and concrete, any porous aggregate having an open end on the surface may be used, and whether or not each pore communicates with each other. Absent. Preferably, a fine aggregate having an aperture diameter of 0.2 μm or less at the open end and an apparent porosity of 10% or more is preferable because it can carry a larger amount of rust preventive components. The aggregate is made of natural or artificial mineral, hard resin, etc.

  EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the examples shown here.

  The completely dry porous aggregate was immersed in water at about 25 ° C. and vacuum impregnated to obtain water-containing porous fine aggregates B1 to B5 shown in Table 1 below. However, B3 was used in an absolutely dry state where water was not absorbed. For comparison, B6 used a dense aggregate having substantially no open pores.

The amount of water shown in Table 2 (excluding the water content in the porous aggregate) is added to the water-containing porous aggregate and the following materials weighed and prepared so as to have the composition shown in Table 2. The mixture was kneaded with a Hobart mixer for about 2 minutes to obtain a hydraulic composition.
A: Ordinary Portland cement (commercially available)
C1: Metakaolin (A US-made kaolin calcined at 800 ° C. for 2 hours)
C2: Silica fume (Blaine specific surface area 200,000 cm ² / g, commercially available product)
E1: Styrene butadiene rubber latex polymer (solid content 45%, trade name "Pacific CXB", manufactured by Taiheiyo Materials Co., Ltd.)
E2; ethylene vinyl acetate copolymer re-emulsified powder resin (trade name “Vinapass 7055”, manufactured by Asahi Kasei Chemicals Corporation)
F: Natural No. 6 silica sand G; Polycarboxylic acid-based high-performance water reducing agent (trade name “Core Flow NP-5”, manufactured by Taiheiyo Materials Co., Ltd.)

  The kneaded product of the hydraulic composition is filled into an acrylic mold having an inner dimension of 50 mm in diameter and a height of 100 mm, left to stand for 24 hours, and then demolded to obtain a molded product in an oven at 80 ° C. After drying for 24 hours, it was immersed for 24 hours in a rust inhibitor aqueous solution (liquid temperature 20 ° C.) having a solid content concentration of 25% shown in Table 3. The amount of liquid absorbed by immersion (corresponding to increased mass by mass measurement before and after immersion) and compressive strength (measured by a method based on JIS A 1108) were examined. The results are also shown in Table 3.

  Ordinary Portland cement: Crushed stone coarse aggregate: River sand fine aggregate: Water: Sodium chloride (commercially available reagent) = 100: 347: 313: 65: 1.4 A reinforced concrete test specimen with an outer dimension of 100 × 100 × 400 mm containing one reinforcing bar with a diameter of about 10 mm was prepared on the base concrete, and about 7 days after the test specimen was prepared, The chip was removed so that 50% was exposed. The kneaded mixture of the hydraulic composition so that the exposed rebar is completely covered with a chip portion (size: approximately 100 × 20 × 400 mm) exposed to air at 20 ° C. and 60% humidity for 24 hours. Was applied with a scissors, and a construction was formed so as to have an external dimension shape (100 × 100 × 400 mm) before crushing. An aqueous rust inhibitor solution having a solid content concentration of 25% shown in Table 3 was applied to the surface of the construction that had been dried and solidified for 14 days at room temperature, and the amount applied was less than the impregnable amount shown in Table 3 above. The impregnation was confirmed visually and judged by the fact that the coating material did not substantially remain on the surface of the work. Table 4 shows the coating amount of the rust inhibitor aqueous solution. Specimens coated with a rust inhibitor were exposed for 3 years outdoors at an average temperature of 18 ° C, then carefully removed the concrete around the rebar, exposed once, and the surface of the rebar covered by the construction was exposed. The state of corrosion of the reinforcing bars on the surface of the reinforcing bars included in the concrete was examined by the presence or absence of visual rust. The case where the occurrence of rust was observed was judged as having corrosion. At the same time, the condition of the construction was also observed visually, and those that showed significant defects from the viewpoint of durability were noted. These are summarized in Table 4. In addition, repair material No. 15 is a hydraulic composition No. 15; In the base hydraulic composition composed of the same blending component as 1, the lithium nitrite aqueous solution (solid content concentration 25%) was prepared by mixing 5 parts by mass with respect to a total of 100 parts by mass of cement and metakaolin. No rust preventive agent is applied to the cured construction. In addition, repair material No. In No. 14, no rust preventive agent is applied or blended.

  From the results in Table 3, the reinforced concrete repaired using the repair material of the present invention is placed in an environment where rust is likely to occur for a long time, both of the reinforcing steel part embedded in the concrete and the reinforcing steel part covered with the repair material. However, it can be seen that the generation of rust is not observed, and a very high rust prevention ability can be imparted. Moreover, it turns out that the repair material of this invention can hold | maintain a large amount of rust preventive components rather than the conventional rust preventive agent, without affecting a coagulation property or a hardening body property from the result of Table 4.

Claims (4)

(D) solidified solidified product of a hydraulic composition comprising (A) cement, (B) porous aggregate containing 5 to 60% of open porosity contained in open pores, and (C) metakaolin (D ) A repair material that is impregnated with an inorganic rust inhibitor. The repair material according to claim 1, wherein the porous aggregate has an opening pore diameter at an opening end of less than 10 µm. The repair material according to claim 1, wherein the inorganic rust preventive is one or more of alkali metal or alkaline earth metal nitrites, chromates, silicates or phosphates. The repair material according to any one of claims 1 to 3, wherein the hydraulic composition further contains (E) a polymer dispersion or a re-emulsifying powder resin.