JPH05345652A - Grout material for repairing cross section of concrete - Google Patents

Abstract

PURPOSE:To provide the grout material having a high strength and a salt- insulating property by adding a binder, a swelling additive, a resin emulsion, methyl cellulose, a high performance water-reducing agent and small aggregate to specific furnace slag fine powder as a main component. CONSTITUTION:The grout material comprises 100wt.% of a cement composition, 5-25wt.% of a resin emulsion (e.g. a rubber latex), 0.005-0.5wt.% of methyl cellulose, 0.2-2.0wt.% (as solid content) of a high performance water-reducing agent (e.g. melaminesulfonic acid-formaldehyde condensate salt), 80-200wt.% of a <=5mm small aggregate and, if necessary, 0.3-1.0mol.% of non-metal monofilament (e.g. polypropylene monofilament). The cement composition is produced by adding 3-15wt.% of a swelling additive (e.g. dolomite clinker) to 100wt.% of a binder comprising 40-85wt.% of Portland cement and 15-60wt.% of a furnace slag fine powder (e.g. quenched furnace slag) having a maximum particle size of 16-8mum and a JIS-defined basicity of >=1,7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grout material for repairing and reinforcing a cross section of a deteriorated concrete structure by an injection method.

[0002]

2. Description of the Related Art There are various methods for repairing a deteriorated concrete section, but depending on the degree of deterioration and the scale, concrete is struck, and if it is a small scale, it is repaired by plastering using cement mortar or polymer cement mortar. ing. However, if there are restrictions such as the repair area, site and construction conditions, it is often more effective in terms of construction efficiency and economy to repair by the injection method by pumping. Simply calling it a grout material is interpreted in a broad sense, and grout characteristics according to various purposes are required. For example, as a grout material mainly composed of an inorganic cement mortar, there are JP-A-63-57659 and JP-A-63-25.
6829, JP-A-60-221355 and the like are known, and the characteristics thereof are to maintain the required fluidity, to minimize breathing and initial volume shrinkage, and to satisfy the required strength. However, the grout material mainly composed of cement mortar, when the cross section of the deteriorated concrete structure of the present invention is repaired by the pouring method, with the removal of the temporary formwork after construction, the repaired grout surface is exposed to the outside air condition. It is exposed and always at risk of cracking due to air-drying, temperature changes and lack of durability. A resin emulsion (hereinafter referred to as a polymer) is also used for the purpose of preventing cracking and improving durability. Self-leveling materials Japanese Patent Publication No. 40624 and Japanese Patent Publication No. 1-47032 are known as materials that can have grout properties. Is. This material maintains flatness due to its own weight, and in addition to surface hardness, in many cases, drying shrinkage reduction is an essential property to prevent cracking due to indoor drying, but strength and durability superior to concrete as in this purpose. It is not a material with

[0003]

The action of the polymer in the polymer cement mortar is that the polymer particles interposed between the cement particles form a bond and a polymer film under the curing process and drying conditions of the cement. It can be said that its strength depends on the hydration of cement. That is,
Polymer cement mortar has enough initial curing,
It is important to accelerate the hydration of cement as much as possible, and thereafter subject it to dry curing to enhance the dry strength of the polymer film and the strength of the cement through continuous hydration. From this fact, as the base cement used for polymer cement mortar, Portland cement that exhibits good initial strength is used, and air drying shows higher strength than underwater curing. On the other hand, the maximum particle size is 60 μm (Blaine specific surface area 4,0
(00 cm ² / g) Polymer cement mortar using blast furnace cement mixed with fine powder of general-purpose blast furnace slag (about 00 cm ² / g), slag particles can only function as a filler material in the initial age, and breathing increases and strength development is delayed. To be done. The compressive strength is also significantly lower than when Portland cement is used, and the aerial dry curing shows lower strength than the aquatic curing. Also, unlike ordinary mortar, polymer mortar does not have sufficient salt-blocking effect. In the case of polymer cement mortar, it is clear that blast furnace cement is inferior to Portland cement, which is why blast furnace cement is shunned.

[0004]

In order to solve the above-mentioned problems, the present invention has good workability as a grout (fluidity, breathing rate 0%, ensuring pot life) and uses Portland cement. As a result of diligently examining a grout material that surpasses the strength and salt-blocking properties of polymer cement mortar, by using as a main material a composition in which blast furnace slag high-fine powder having a certain maximum particle size range is mixed with Portland cement The present invention has been completed. The present invention is a polymer cement mortar and a polymer fiber cement mortar characterized by having a high-strength, crack-preventing and salt-shielding effect, which enables construction by an injection method to repair and reinforce the cross section of a deteriorated concrete structure. To provide a grout material.

The present invention will be described in detail below. The blast furnace slag in the present invention is a quenched blast furnace slag, and
The basicity defined by S is preferably 1.7 or more. The basicity strongly affects the initial strength development even when a polymer is used. The maximum particle size of the blast furnace slag fine powder needs to be in the range of 16 to 8 μm in the laser diffraction method (ethyl alcohol dispersion medium). When the maximum particle size exceeds 16 μm, there is no problem in the performance as grout, but the initial strength is not expressed and the compressive strength is higher than that when Portland cement is used at 28 days in the air dry material age. The high strength of 500 kgf / cm ² or more, which is the goal of the invention, cannot be achieved. Further, although the salt barrier property is improved, the drying shrinkage amount is increased. If the maximum particle size of the blast furnace slag fine powder becomes smaller than 8 μm, the amount of submicron particles will increase with the current engineering technology, and the amount of water for obtaining the required fluidity as grout will not be large, and the target high strength will be obtained. Not only can it not be obtained, but the drying shrinkage also becomes very large, increasing the risk of cracking. According to the new finding of the present invention, it is general that the amount of water for obtaining the required fluidity increases as the maximum particle size becomes smaller, but in the range of the maximum particle size 16 to 10 μm, Portland cement or general-purpose blast furnace cement ( Maximum particle size 60μ
That is, the fluidity can be secured with the same amount of water as in the case of using m). The reason for this is not clear, but it is considered that a certain amount of blast furnace slag particles are filled between the cement particles, and the polymer particles are relatively densely packed between the blast furnace slag particles and further between the blast furnace slag particles and the cement particles. .. Further, gypsum of 10% by weight or less is acceptable for the blast furnace slag. Gypsum has an effect of improving initial shrinkage rather than an effect of improving initial strength, and the amount of the expansive admixture can be adjusted.

[0006] Portland cement can be used as long as it is a JIS specified cement, but early strength and normal Portland cement are preferable, and white Portland cement can also be used. As an expansive admixture, hain-based, CaO
A system, an alunite system, and a dolomite clinker can be used. The admixture amount varies depending on the maximum particle size of blast furnace slag, the amount of gypsum contained, and the amount of admixture, but is 3 to 15 relative to the total amount of Portland cement and blast furnace slag fine powder.
By blending by weight%, the initial expansion amount (after 24 to 48 hours) which is the target value of the grout material of the present invention is 0 to 0.5.
%, Rate of change in length due to drying shrinkage 350 × 10 ^-6 (age 2
Values below 8 days can be obtained.

As the high-performance water reducing agent, a water reducing agent containing melamine sulfonic acid formaldehyde condensate salt, naphthalene sulfonic acid formaldehyde condensate, or high molecular weight lignin sulfonic acid as a main component can be used. If the solid content is less than 0.2% by weight of the cement composition defined in the present invention, the water reducing effect is insufficient and high strength cannot be expected. If it exceeds 2%, the water reducing effect is recognized, but the viscosity of the grout increases and the pump Impairs pumping. Further, depending on the main component of the water reducing agent, excessive air is entrained, resulting in a decrease in strength.

The polymer in the present invention refers to a resin emulsion for admixture with cement, which is styrene butadiene. Rubber latex (SBR) and polyacrylic acid (PAE) emulsion can be used. The concentration of commercially available polymers is often around 50%, but in some cases the concentration range is shown.
Originally, there is a method of defining the scope of claims by the resin solid content, but in the present invention, it is shown by the polymer amount. If the amount of the polymer is less than 5% by weight based on 100% by weight of the cement composition, the drying shrinkage becomes large and the elongation ability is insufficient, and the salt-shielding property is lowered in the case where the amount of fine slag powder is small. On the other hand, if it exceeds 25% by weight, the fluidity as grout is decreased, and the strength development is delayed, so that the required strength cannot be obtained.

Methyl cellulose or hydroxyethyl cellulose is used in the grout of the present invention. Methyl cellulose also has a function of preventing the material separation of grout due to the thickening effect, but in the present invention, the pot life of the grout is secured, the water retention of the cured product is increased by using it together with the polymer, and the blast furnace slag fine powder is Hydration is enhanced in the long term, and high strength is developed. Since the amount of methyl cellulose used is blast furnace slag, it is 0.0
Amounts as low as 5 to 0.2% by weight serve the purpose of the invention.
As the fine aggregate, natural sand of 5 mm or less, blast furnace slag sand, or crushed sand can be used. In terms of material separation, it is preferably 2.5 mm or less. The weight% of the fine aggregate with respect to the cement composition varies depending on the size, type, polymer and amount of the water reducing agent of the fine aggregate, but 80 to 200% by weight can achieve the object of the present invention.

The polymer cement mortar grout of the present invention is also characterized in that non-metallic single fibers can be blended. As the single fiber, polypropylene, polyacrylonitrile, vinylon, alkali resistant glass fiber, and carbon fiber can be used. The fiber length of the single fiber is 4 to 20 mm, preferably 6 to 10 mm. It is common practice to reinforce mortar concrete with fibers to improve toughness. The utility of the single fiber in the present invention is that since the blast furnace slag fine powder having a small maximum particle size is used, the fibers are easily dispersed during kneading, and a uniform grout is obtained, and the amount of the blast furnace slag fine powder is increased. Although the strength is increased, the dry shrinkage value is also increased, and the required improvement in toughness can be achieved by blending the fibers against the decrease in toughness. The monofilament has a volume ratio of 0.3 to 1.0% to the grout material of the present invention, and the required characteristics can be obtained. If the amount of fibers exceeds 1.0%, the fluidity as grout decreases.
Workability is impaired, and other properties are impaired if more water is added to obtain fluidity.

[0011]

[Example 1]

[0012] Four kinds of blast furnace slag fine powders having different maximum particle diameters were trial-produced,

As shown in Table 1, ordinary Portland cement (C) was compounded in a predetermined amount, and a grout test was conducted with the following material composition. The fluidity and pot life were judged by the flow of a J ₁₄ funnel, and the compressive strength of the test piece of 4 × 4 × 16 cm was removed from the mold for 1 day, and after 2 days in water (20 ° C.), air curing (20 ° C. RH60% ) Was performed. Dry shrink test is 1
The standard length is after demolding, and after that, in air (20 ° C RH60
%). The salt-barrier test was carried out by immersing it in a 5% NaCl solution for 14 days under the same curing conditions as in the compressive strength test, and measuring the salt penetration depth by the Fayans method 4 weeks later. For the crack generation test, a 4-inch steel cylindrical tube was set at the center in a φ15 cm mortar water permeation test mold, grout was poured into the gap, and after 1 day of demolding, air conditions (20 ° C RH60
%) And the occurrence of cracks was observed. Expandable admixture Denka CSA (trade name) 10% by weight
(For C + S) Polymer SBR Tomac Super (trade name) 12.5% by weight Methyl Cellulose Metroses 90SH4000 (trade name) 0.05% High performance water reducing agent Mighty 100 (trade name) 0.7% Fine aggregate No. 4 silica sand 150% by weight The results of this example are shown in Tables 1 and 2, but the maximum particle size was 16.
The polymer cement mortar grout material of the present invention containing 15 to 60% by weight of Portland cement containing blast furnace slag fine powder B and C of 0,8.0 μm has a high strength of 500 kgf / cm ² or more in 28 days of age. The salt barrier property is also dramatically improved. The amount of drying shrinkage is also approximately 350 × 10
It was found that it was suppressed to ^-6 or less, and the occurrence of cracks could be suppressed.

[0013]

[Table 1]

[0014]

[Table 2]

Example 2 With respect to the blast furnace slag fine powders B and C shown in Example 1, the blending amount with respect to Portland cement was 50% by weight, and the single fiber was polypropylene fiber (trade name: Mercury d = 43 μm l = 6 mm).
Was used, and the compounding conditions of the other grout materials were the same as in Example 1 and the test was conducted. The toughness was measured according to the bending strength test method of GRC, and a test piece of 1 × 5 × 30 cm was prepared.
A flexural strength test was performed with a span of 20 cm for 28 days in the air curing material, and the moving distance (deflection amount) of the crosshead was measured. At the same time, the compressive strength (4 × 4 × 16 cm) was also measured.
The results of this example are shown in Table 3, where the single fiber content is 0.2.
%, The toughness-improving effect is insufficient. If the blending amount exceeds 1%, the amount of water for securing the required fluidity increases and the toughness improves, but the compressive strength of 500 kgf / cm ² or more cannot be secured. From the present example, 0.3-1.0% monofilament
It has been found that the addition of these components provides high strength and a good toughness improving effect.

[0016]

[Table 3]

[0017]

The grout material for repairing the cross section of the concrete structure of the present invention exhibits the combined effect with the polymer and further the single fiber by utilizing the blast furnace slag fine powder having the maximum particle diameter in a certain range. The properties of the grout and the good properties of the cured product are achieved. The effect of the grout material of the present invention is proved even in the test construction, and not only the construction efficiency is improved, but also the function of concrete can be maintained and the repair of a large cross section is possible, and its utility value is great.

Front page continuation (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C04B 22:14 D 2102-4G 24:26 Z 2102-4G 24:38 A 2102-4G 24:22 A 2102- 4G 14:02 Z 2102-4G 16:06) Z 2102-4G (72) Inventor Seiichi Shimobayashi 64 Nakamachi, Muroran-shi, Hokkaido Nippon Steel Cement Co., Ltd. (72) Inventor Takeshi Mochizuki 1 Kimitsu, Kimitsu-shi Kimitsu Steel Works, Nippon Steel Co., Ltd. (72) Akira Kawamura, 1 Kimitsu, Kimitsu City Kimitsu Steel Works, Nippon Steel Co., Ltd.

Claims (2)

[Claims] 1. A blast furnace slag fine powder having a maximum particle size of 16 to 8 μm in an amount of 15 to 60% by weight, and a binder made of 40 to 85% by weight of Portland cement in an amount of 3 to 15% by weight of an expansive admixture. % Of the cement composition containing 5% by weight of the resin emulsion, 5 to 25% by weight of the resin emulsion, 0.05 to 0.5% by weight of methyl cellulose, and 0.2 to 2.0% by weight of the high performance water reducing agent in terms of solid. , Fine aggregate 80
A grout material for repairing concrete cross-sections, which is characterized by high strength and salt-blocking property, which is prepared by mixing up to 200% by weight. 2. The grout material for repairing a concrete section according to claim 1, wherein the non-metallic single fiber is contained in the grout material in a volume ratio of 0.3 to 1.0%.