JP2007161507A - Highly durable cross-section repairing material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cement based cross-section repairing material stably having high sulfuric acid resistance and mid-and-long term strength developability without deteriorating workability in the application of a Portland cement based mortar composition having high assimilation to a concrete structure or the like as the cross-section repairing material for the structure. <P>SOLUTION: The high durable cross-section repairing material contains (A) Portland cement, (B) slag having 0.75-3.0 m<SP>2</SP>/g BET specific surface area, (C) flyash or/and meta-kaolin, (D) silica fume and (E) a quick lime based expansive material and additionally contains one or more kinds of (F) a polymer dispersion or a re-emulsifying type powdery resin, (G) a water retaining agent and (H) a dispersant. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cement-based cross-sectional repair material excellent in durability used for repairing mortar and concrete structures.

Cross-section restoration materials used for restoration of mortar and concrete structures are required to have assimilation to a restoration substrate, workability during restoration, durability after restoration, and the like. When a structure that needs to be repaired is exposed to an acidic sulfuric acid solution such as a sewer structure, when a mortar composition containing Portland cement, which has good assimilation to the structure, as a main curing component is used as a repair material, Calcium hydroxide, etc., generated during hydration of Portland cement reacts with sulfuric acid, and the reaction product gypsum reacts again to form an expansive ettringite phase, which causes expansion cracks in the mortar after setting. And deteriorate. For this reason, a composition having strong resistance to sulfuric acid is required. As a cementitious composition having a strong resistance to sulfuric acid, there has heretofore been (I) a composition containing an alumina cement having a high sulfuric acid resistance as an active ingredient (see, for example, Patent Document 1) and (II) a part of Portland cement. , preferentially a latent hydraulic material is slag or pozzolanic reactive material is replaced with fly ash and silica fume etc., reacted with calcium hydroxide produced during hydration CaO-SiO ₂ -H ₂ O-based gel A composition in which the amount of calcium hydroxide produced and reacted with sulfuric acid is reduced (see, for example, Patent Document 2) is known. However, in the composition of (I), shrinkage cracks are liable to occur because of large drying shrinkage, and a slag fine powder is mixed to improve this. (For example, refer to Patent Document 3) However, since the neutralization of the alumina cement-slag composition progresses quickly, the medium- to long-term strength is likely to decrease, and the workability is not good. Further, even in the Portland cement-slag composition of the above (II), the unit cement amount is reduced by substitution with slag, etc., so that the neutralization easily proceeds, the long-term strength is reduced, and the mechanical durability is low. Become. It is also known to improve strength by reducing the unit water amount to a range that does not hinder workability by using a high-performance water reducing agent in combination with a Portland cement-slag composition without reducing the unit cement amount. . (For example, refer to Patent Document 4) In this case, the amount of slag necessary for reaction consumption of calcium hydroxide generated during Portland cement hydration to CaO-SiO ₂ —H ₂ O-based gel must also be increased. An increase in the amount of slag added becomes a neutralization progress factor and leads to a decrease in strength, so there is a limit, and even if the desired strength expression can be ensured, the sulfuric acid resistance is difficult to improve.
JP 2003-89565 A JP 2002-68793 A JP 2000-128618 A Japanese Patent Laid-Open No. 11-60316

  The present invention is a conventional problem in having both high sulfuric acid resistance and high medium- and long-term strength development in a Portland cement-slag-based composition that can easily be assimilated with a concrete structure in terms of material. It is an object of the present invention to provide a cross-sectional repair material excellent in durability and having good workability.

  As a result of intensive studies for solving the problems, the present inventors have blended Portland cement with slag, fly ash or metakaolin powder having a specific BET specific surface area, and silica fumes, and have high sulfuric acid resistance and high medium to long-term strength. The present invention was completed because a mortar having both expression properties was obtained, and a cementitious composition suitable for cross-sectional restoration was obtained by adding a quicklime-based expansion material.

That is, the present invention is a highly durable cross-sectional repair material represented by the following (1) to (3). (1) (A) Portland cement, (B) BET specific surface area of 0.75-3.0 m ² / g slag, (C) fly ash or / and metakaolin powder, (D) silica fumes and (E) quicklime expansion. A highly durable cross-section restoration material containing a material. (2) The highly durable cross-sectional repair material according to (1), wherein the slag is a slag containing 20% by mass or more of CaO and SiO ₂ as chemical components. (3) The above (1) or (2) further comprising (F) a polymer dispersion or a re-emulsifying powder resin, (G) a water retention agent, or (H) a dispersant. ) High durability cross-section repair material.

  The highly durable cross-sectional restoration material according to the present invention does not cause deterioration under sulfuric acid acidity that is likely to occur in Portland cement-based restoration materials, and can maintain stable high strength development over the medium to long term. Since the change can be sufficiently suppressed, it has excellent applicability as a cross-section repair material for concrete structures that may be exposed to sulfuric acid for a long period of time.

The highly durable cross-sectional repair material of the present invention uses Portland cement, slag having a BET specific surface area of 0.75 to 3.0 m ² / g, fly ash or / and metakaolin powder, silica fume and quick lime-based expansion material. A mortar composition. The Portland cement used in the highly durable cross-section restoration material of the present invention is a main component forming a mortar binder phase, and for example, any Portland cement, such as normal, early strength, very early strength or moderate heat, should be used. Can do. From the viewpoint of cost and handleability, ordinary Portland cement is preferable. However, in order to carry out restoration work in a short period of time, it is more preferable to use early strength or super early strength Portland cement or to use ordinary Portland cement in combination.

The slag for use in highly durable cross restorative material of the present invention is a slag having a BET specific surface area of 0.75~3.0m ² / g, preferably a BET specific surface area of 1.0~3.0m ² / Let slag be g. The slag preferentially reacts and consumes calcium hydroxide produced during hydration of Portland cement in the presence of water and prevents it from reacting with sulfuric acid. Slag having a BET specific surface area of less than 0.75 m ² / g is not preferable because the reaction activity is low, the reaction with calcium hydroxide is sluggish, and the calcium hydroxide that reacts with sulfuric acid rapidly increases and deteriorates. In addition, slag having a BET specific surface area of more than 3.0 m ² / g has increased viscosity and the workability in dredging work is significantly deteriorated, and the strength reduction and drying shrinkage increase due to the increase in unit water amount. It is not preferable. The slag used in the present invention is not particularly limited except for the BET specific surface area. Examples of the slag include slag at the time of steelmaking and metal refining such as blast furnace slag, sewage sludge melting slag, municipal waste incineration ash melting slag Preferably, slag containing 20% by mass or more of CaO and SiO ₂ as chemical components is preferable, and more preferably slag containing 25 to 40% by mass of CaO and SiO ₂ respectively. . Such slag is recommended because it has excellent efficiency in reaction consumption of calcium hydroxide produced during cement hydration, and it is easy to obtain sulfuric acid resistance even if the amount of slag is reduced. 70-120 mass parts is preferable with respect to 100 mass parts of Portland cement, and, as for the amount of slag used for this mortar, 75-100 mass parts is more preferable. If it is less than 70 parts by mass, the amount of slag for reaction consumption of calcium hydroxide is insufficient and good sulfuric acid resistance cannot be obtained, and if it exceeds 120 parts by mass, neutralization tends to proceed. Not appropriate.

In addition, fly ash and metakaolin powder used in the highly durable cross-section restoration material of the present invention reacts with calcium hydroxide generated during hydration of Portland cement to form a robust and dense hardened body, resulting in mechanical durability And can prevent internal penetration of erodible substances. Of these, fly ash type II stipulated in JIS A6201 is recommended for use, especially fly ash having a BET specific surface area of 1.5 to 3.5 m ² / g is highly reactive and suitable for repair. It is desirable because it is easy to ensure workability without reducing durability. Metakaolin powder is desirable because metakaolin having a BET specific surface area of 8.0 to 12.0 m ² / g has high reaction activity, and it is easy to ensure workability suitable for restoration without reducing durability. On the other hand, kaolinite, mullite, etc., which have been crystallized, are not preferred because even those having a large specific surface area cannot be as active as metakaolin. Either one or both of fly ash and metakaolin can be used for the highly durable cross-sectional repair material of the present invention, and the amount used is preferably 7 to 30 parts by mass with respect to 100 parts by mass of Portland cement. 8-20 mass parts is more preferable. If the amount is less than 7 parts by mass, the above-mentioned action is hardly obtained, so that it is not suitable. The mixing ratio between fly ash and metakaolin is not limited at all. Further, since part of fly ash and metakaolin is likely to obtain almost the same action, it is amorphous or has a high vitrification rate so that both Al ₂ O ₃ and SiO ₂ are contained as chemical components in an amount of about 25% by mass or more. It can also be used by replacing with inorganic fine powder.

  Moreover, any silica fume may be used for the highly durable cross-sectional repair material of the present invention. By using silica fume, a denser hardened body can be obtained, and sulfuric acid solution and other corrosive fluids hardly penetrate into the repaired layer after cross-sectional repair, and durability is improved. 5-15 mass parts is preferable with respect to 100 mass parts of Portland cement, and, as for the usage-amount of a silica fume, 8-12 mass parts is more preferable. If the amount of silica fume used is less than 5 parts by mass, the blending effect is hardly manifested, so that it is not appropriate. If it exceeds 15 parts by mass, the workability may be significantly reduced, so that it is not appropriate.

  Moreover, the quicklime expansion material used for the highly durable cross-section repair material of the present invention is one that uses quicklime as an active ingredient, hydrates and expands, and does not substantially contain a sulfate or a sulfate-forming component. By using the quicklime-based expansion material, drying shrinkage can be mainly suppressed, and the shape and dimension stability of the repaired portion can be achieved and the occurrence of shrinkage cracks can be prevented. 1-7 mass parts is preferable with respect to 100 mass parts of Portland cement, and, as for the usage-amount of a quicklime type expansion material, 2-6 mass parts is more preferable. If the amount of the quicklime-based expansion material used is less than 1 part by mass, the shrinkage cannot be sufficiently suppressed, so that it is not appropriate. If it exceeds 7 parts by mass, there is a risk of overexpansion.

  In addition, the highly durable cross-sectional repair material of the present invention is one in which one or more of a polymer dispersion or a re-emulsifying powder resin, a water retention agent, and a dispersant are blended in addition to the essential components. It is preferable.

  The polymer dispersion or re-emulsifying powder resin used in the highly durable cross-section repair material of the present invention may be any one that can be used in cement, mortar, or concrete. For example, the polymer dispersion defined in JIS A6203 John or re-emulsified powder resin can be used. More specifically, examples of the polymer dispersion include resins such as polyacrylic acid ester, styrene butadiene, and ethylene vinyl acetate, and examples of the re-emulsifying powder resin include vinyl acetate / versaic acid vinyl ester, vinyl acetate / versaic acid. Examples include vinyl / acrylic acid esters. By blending the polymer dispersion or the re-emulsified powder resin, the adhesion to the concrete structure is enhanced, and the water barrier is greatly improved. The amount of the polymer dispersion or re-emulsified powder resin used is preferably 2 to 20 parts by mass in terms of solid content with respect to 100 parts by mass of Portland cement. If the amount exceeds 20 parts by mass, the workability and the thickness are likely to deteriorate, which is not appropriate.

  In addition, the water retention agent used in the highly durable cross-sectional repair material of the present invention may be any as long as it can be used in mortar or concrete, and among these, a water-soluble cellulose compound is preferable. Specific examples include cellulose derivatives such as methylcellulose, carboxymethylcellulose, hydroxypropylmethylcellulose, hydroxyethylmethylcellulose, hydroxypropylcellulose, and cellulose sulfate. By adding a water retention agent, it is possible to suppress the rapid release of moisture in the restoration material, and it is possible to prevent the occurrence of dry cracks after the repair, as well as peeling and peeling off. The amount of the water retention agent is preferably 0.15 to 0.5 parts by mass with respect to 100 parts by mass of Portland cement, and if less than 0.15 parts by mass, almost no blending effect can be obtained. If it exceeds 5 parts by mass, the viscosity becomes too high and the mixing resistance at the time of blending increases, which may hinder the workability, and the strength developability also decreases, so that it is not suitable.

  In addition, the dispersant used in the highly durable cross-section repair material of the present invention may be any one that can be used in mortar or concrete, and includes a fluidizing agent, a water reducing agent, a high performance water reducing agent, an AE water reducing agent, a high performance. What is called an AE water reducing agent can be used. Specifically, water reducing agents such as naphthalene sulfonic acid, melamine, lignin, and polycarboxylic acid can be exemplified. By blending a dispersant, the unit water amount can be lowered and the strength can be improved without affecting the workability, and it becomes easy to obtain a homogeneous blend.

  Moreover, the highly durable cross-sectional repair material of this invention may mix | blend components other than the above in the range which does not lose the effect of this invention. Examples of such components include fibers, fine aggregates, air entraining agents, antifoaming agents, shrinkage reducing materials, pigments, and the like made of components such as polymers, metals, carbon, or alkali resistant glass.

  The manufacturing method of the highly durable cross-sectional repair material of this invention should just add each compounding component, for example to a commercially available mortar mixer, and may add and mix water, and the mixing | blending component mixing method etc. are not specifically limited. The blending amount of water is preferably 14 to 18 parts by mass with respect to 100 parts by mass of the total powder component in the restoration material. If it is less than 14 parts by mass, the kneading resistance at the time of blending is increased, so that it is not appropriate. If it exceeds 18 parts by mass, the strength development is reduced and the thickness during construction tends to be difficult. In addition, the repair work using the highly durable cross-sectional repair material of the present invention can be performed by a method substantially the same as a conventional cement-based cross-section repair material, and no special consideration is required.

Hereinafter, the present invention will be described in detail by way of examples.
[Production of Restoring Material] Table 1 shows materials and water selected from A1-A2, B1-B7, C1-C4, D1-D2, E1-E2, F1-F2, G, H, and J. It put into the mortar mixer so that it might become the compounding quantity described, and it mixed for 3 minutes under the temperature of about 20 degreeC, and produced the restoration | repair material (this invention goods 1-10, reference goods 11-17).
A1: Normal Portland cement (manufactured by Taiheiyo Cement Co., Ltd.)
A2: Early strong Portland cement (manufactured by Taiheiyo Cement Co., Ltd.)
A3: Alumina cement (manufactured by Taiheiyo Material Co., Ltd.)
B1; blast furnace slag powder having a BET specific surface area of 0.5 m ² / g (main chemical component content CaO; 45.4 mass%, SiO ₂ ; 29.4 mass%, Al ₂ O ₃ ; 14.1 mass%, MgO 5.2 mass%, Fe ₂ O ₃ ; 0.8 mass%)
B2: Blast furnace slag powder with a BET specific surface area of 1.5 m ² / g (containing chemical components are the same as B1)
B3: Blast furnace slag powder with a BET specific surface area of 2.5 m ² / g (containing chemical components are the same as B1)
B4: Blast furnace slag powder having a BET specific surface area of 4.0 m ² / g (containing chemical components are the same as B1)
B5; Sewage sludge molten slag powder with a BET specific surface area of 0.5 m ² / g (major chemical component content CaO; 35.0 mass%, SiO ₂ ; 28.2 mass%, Al ₂ O ₃ ; 14.0 mass% MgO; 3.1% by mass; Fe ₂ O ₃ ; 7.3% by mass)
B6; BET specific surface area 1.0 m ² / g sewage sludge melted slag powder (containing chemical component is the same as B5)
B7; Sewage sludge molten slag powder with a BET specific surface area of 2.5 m ² / g (main chemical component content CaO; 38.4% by mass, SiO ₂ ; 17.2% by mass, Al ₂ O ₃ ; 15.8% by mass) MgO; 3.5% by mass, Fe ₂ O ₃ ; 8.0% by mass)
C1; fly ash C2 having a BET specific surface area of 1.5 m ² / g; fly ash C3 having a BET specific surface area of 3.5 m ² / g; metakaolin powder (BET specific surface area of 14.5 m ² / g)
C4: Kaolinite powder (BET specific surface area 4.0 m ² / g)
D1: Silica fume (BET specific surface area 20.0 m ² / g)
D2: Lithium sulfate (commercially available)
E1; Quicklime expansion agent (trade name “Pacific Expan”, manufactured by Taiheiyo Materials Co., Ltd.)
E2: Calcium sulfur aluminate-based swelling agent (trade name “Denka CSA”, manufactured by Denki Kagaku Kogyo Co., Ltd.)
F1: Styrene butadiene polymer dispersion (trade name “Pacific CXB”, manufactured by Taiheiyo Materials Co., Ltd.)
F2: Acrylic styrene re-emulsified powder resin (trade name “LL512”, manufactured by Asahi Kasei Chemicals Corporation)
G: Hydroxypropyl methylcellulose (trade name “90SH-4000”, manufactured by Shin-Etsu Chemical Co., Ltd.)
H: Polycarboxylic acid-based high-performance water reducing agent (trade name “Core Flow NF-100”, manufactured by Taiheiyo Materials Co., Ltd.)
J: Fine aggregate (mountain sand having a particle size of 0.15 to 2.5 mm and a coarse particle ratio of 3.58)

  [Evaluation of workability] About the prepared restoration material, four items of flaw cutting, wrinkle elongation, dripping resistance and spraying work compatibility were examined, and the workability as a cross-sectional restoration material was evaluated. The test methods and evaluation criteria for each item are as follows. The evaluation results are shown in Table 2.

  <Cut-off> A restoration material was applied to a 100 × 100 cm surface of a 100 × 100 × 15 cm flat concrete plate with a commercially available hammer. Visually inspect the finish of the painted surface, confirm that the surface is substantially smooth, and that there was almost no restorative material remaining on the used hammer. Judged to be dead.

  <Stretch elongation> The restoration material collected on the flat surface of the concrete was coated with a hammer and spread with a hammer so that the entire surface of 100 × 100 cm had a thickness of about 2 cm. Those that were spread over the entire surface within 5 minutes were judged to be “good” and the others were judged to be “bad”.

  <Drip resistance> Restoration material was applied with a metal hammer so that the entire 100x100cm surface of a 100x100x15cm concrete plate placed vertically would be approximately 2cm thick, and 24 hours after the completion of painting It was visually confirmed whether sagging occurred in the applied restoration material. Those that did not sag were judged as “good” sag resistance, and the others were judged as “bad” sag resistance.

  <Compatibility with spraying construction> Using a spray gun with an inner diameter of 40 mm connected to a squeeze-type mortar pump and an outlet diameter of 12 mm attached to the end of a pressure hose, the vertical surface of the concrete retaining wall about 0.4 m away The restoration material was sprayed continuously for 5 minutes, and the restoration material pumping status and spray gun ejection status were examined. Those that could be pumped without clogging in the hose and could be sprayed onto the retaining wall without causing clogging of the spray gun outlet were judged to be “good” for spraying construction, and other parts were sprayed. The compatibility was judged as “bad”.

  [Evaluation of Durability] The prepared restoration material was examined for sulfuric acid resistance by compressive strength and two test methods, and durability was evaluated. The test method and evaluation criteria are as follows. The results are shown in Table 2.

  <Compressive Strength Test> The restoration material was filled in a mold having an inner diameter of 4 × 4 × 16 cm, cured in a constant temperature and humidity chamber at a temperature of 20 ° C. and a humidity of 80%, and then demolded. The obtained specimen was cured in water at 20 ° C. until a predetermined age. Compressive strength was measured for specimens having a material age of 3 days and 28 days according to the method of JIS R5201.

<Sulfuric acid resistance test 1> After measuring the mass of the same specimen as that prepared in the compressive strength test, it was immersed in a 5% sulfuric acid solution maintained at 20 ° C for 28 days. The specimen after immersion was washed with water, the mass was measured, and the mass change rate was calculated from the mass before and after immersion using the following formula. The sulfuric acid solution used for the immersion was replaced every 7 days.
Mass change rate (%) = 100 × (mass before dipping−mass after dipping) / mass change rate before dipping within ± 10% is judged as “good” sulfuric acid resistance, otherwise Was judged to be sulfuric acid resistant “bad”.

  <Sulfuric acid resistance test 2> A specimen similar to that prepared in the compressive strength test was immersed in a 5% sulfuric acid solution maintained at 20 ° C for 28 days. The specimen after immersion was washed with water, and a portion 8 cm from the bottom face (4 × 4 cm face) of the specimen was cut so as to be parallel to the bottom face. The phenolphthalein solution is added to the cut surface, the red colored area is regarded as the sulfuric acid penetration depth into the specimen, and the length from the specimen outer surface (4 × 16 cm face) to the deepest colored spot Was measured. Those having a length of less than 3.0 mm were judged to be sulfuric acid resistance “good”, and the others were judged to be sulfuric acid resistance “bad”. The sulfuric acid solution used for the immersion was replaced every 7 days.

  The highly durable cross-sectional repair material of the present invention can be used for repairing structures made of inorganic materials other than cement-based materials and for repairs other than cross-sections. Furthermore, since it has not only sulfuric acid resistance but generally high corrosion resistance, it may be used as a corrosion-resistant structural member such as a joint material or an animal barn, or a general building material. Moreover, it can also utilize as a grout material which can be used also by a formwork method especially by mix | blending a high performance water reducing agent and a shrinkage reducing agent together.

Claims (3)

(A) Portland cement, (B) BET specific surface area of 0.75 to 3.0 m ² / g slag, (C) fly ash or / and metakaolin powder, (D) silica fumes and (E) quick lime-based expansion material High durability cross-section repair material. High durability sectional restorative material according to claim 1, wherein the slag is a slag containing CaO and SiO ₂ more than 20 wt% respectively as chemical components. The high durability according to claim 1 or 2, further comprising any one or more of (F) a polymer dispersion or a re-emulsifying powder resin, (G) a water retention agent, and (H) a dispersant. Cross section repair material.