JPH08165154A - Cement composition, hardened cement, its production and in situ lining method - Google Patents

Abstract

PURPOSE: To enable early demolding of molded cement without using a steam- curing process and improve the development of the strength by compounding a specific Portland cement with anhydrous gypsum, aluminum sulfate, an alkali metal aluminate and a nitric acid salt. CONSTITUTION: This cement composition is obtained by compounding 100 pts.wt. of a Portland cement having a Blaine value of 3,500-7,000cm<2> /g and a 3CaO.SiO2 content of >=60wt.% with 1-5 pts.wt. of anhydrous gypsum having a Blaine value of >=2,500cm<2> /g, 0.2--3 pts.wt. (in terms of anhydride) of aluminum sulfate, 0.1-0.8 pts.wt. of an alkali metal aluminate and 0.5-5 pts.wt. of a nitric acid salt. A concrete produced by kneading the composition with water at a water/ binder ratio of 25-50wt.% is placed and cured under the application of gravitational acceleration of 1-50G and a construction joint is performed by shifting the mold.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a cement composition used in the civil engineering / construction industry, a hardened cement product using the same, a manufacturing method thereof, and a cast-in-place lining method for tunnels.

[0002]

2. Description of the Related Art Conventionally, for example, concrete pipes such as fume pipes and box culverts, centrifugal rebar concrete products such as piles and poles, and centrifugal force concretes such as steel pipe concrete composites. In the production of hardened cement products, represented by G. products, generally, ordinary Portland cement was used as the main material, and steam curing was carried out to improve the productivity so that it could be demolded in about 1 day of age. Engineering handbook, published by Asakura Shoten).

However, in order to perform steam curing,
Installation of a steam curing room, loading and unloading of products into the steam curing room,
Maintenance and management of the boiler, installation of an exhaust gas treatment device, etc. are required, which causes problems such as high cost and complicated production line.

On the other hand, as a tunnel construction method, a shield construction method, a NATM construction method in which an excavated cross section is blown while being hardened with a concrete, and a cast-in-place lining construction method in which a lining concrete is placed together with propulsion Etc. are known.

Of these, the cast-in-place lining method is a tunnel construction method developed in Europe and introduced to Japan. It is 2 kgf / cm ^{2 at the} time of concrete placing.
Since a certain amount of pressure is applied, the concrete can be brought into close contact with the ground and loosening of the ground can be eliminated, and ground subsidence can be minimized. That is, the cast-in-place lining method is a method in which a lining concrete is directly placed at the rear of a shield machine equipped with a formwork mechanism, which consists of an excavating device and a propulsion device. -At the same time as the promotion of the cold machine, the concrete is continuously poured from the introduction pipe into the roll-up concrete formwork, which is installed so that the concrete thickness is about 40 to 50 cm. It is applied with pressure, placed, and lined.

The concrete used in the cast-in-place lining method needs to have fluidity enough to be filled in the mold, such as a slump value of 20 cm or more after kneading. After kneading, it is placed using a concrete pump, so it is necessary to maintain its fluidity for a certain period of time. Furthermore, several hundred meters of shield machines /
In order to move forward at a rate of about a month, for example, the daily compressive strength must be 100 kgf / cm ² or more, and the early strength development must be excellent.

As described above, the cast-in-place lining method is required to have fluidity and good initial strength.
In the conventional concrete, when the fluidity is maintained for a certain period of time, the strength development is delayed, so that there is a problem that the efficiency of construction is significantly deteriorated.

When a concrete containing a rapid cement hardening material or a super rapid hardening cement is used for the cast-in-place lining method, the fluidity is maintained for a certain period of time even if the strength development is sufficient. It is difficult to do so, and the concrete may harden in the pump, and there is a problem that a special mixer is required and it is not practical (Japanese Patent Laid-Open No. Hei 3).
-88754 publication).

As a result of various efforts to solve the above-mentioned problems, the inventor of the present invention can use a specific cement composition to remove the mold at an early stage without steam curing. According to the present invention, it is possible to obtain a cement hardened product having a good expression property, and also to maintain the fluidity of the kneaded product for a certain period of time, and also to realize early strength development and high strength. It came to completion.

[0010]

[Means for Solving the Problems] That is, the present invention is based on 3CaO.S
100 parts by weight of Portland cement with iO ₂ content of 60% by weight or more, 1-5 parts by weight of anhydrous gypsum, 0.2-3 parts by weight of aluminum sulfate in terms of anhydride, alkali metal aluminate salt
0.1-0.8 parts by weight, and a cement composition containing a nitrate, further a cement composition containing a water reducing agent, and a cement hardened product using the cement composition and This is a manufacturing method, which is a cast-in-place lining method of a tunnel in which a concrete containing the cement composition is cast, pressure is applied thereto, and after hardening, the form is moved and spliced.

The present invention will be described in more detail below.

The Portland cement used in the present invention is a Portland cement having a 3CaO.SiO ₂ content of 60% by weight or more. The content of 3CaO / SiO ₂ is preferably 66% by weight or more, and usually commercially available early-strength Portland cement can be used. If the 3CaO / SiO ₂ content is less than 60% by weight, sufficient initial strength may not be obtained. Portland cement blur of the present invention - down value is preferably ^{3,500~7,000cm 2 / g, 4,000~5,000cm 2 /} g is more preferable. 3,500 cm ² /
If it is less than g, sufficient initial strength may not be obtained.
If it exceeds 00 cm ² / g, concrete slump loss may increase.

The anhydrous gypsum used in the present invention is not particularly limited as long as it is an anhydride, and naturally-occurring natural anhydrous gypsum, anhydrous gypsum obtained by heat-treating semi-water gypsum or dihydrate gypsum can be used. Besides, it is possible to use anhydrous gypsum or the like generated as an industrial by-product. The particle size of the anhydrous gypsum, blur - preferably 2,500 cm ² / g or more in emission values, 4,000 cm ² / g or more is more preferable. If it is less than 2,500 cm ² / g, expansion failure may occur due to unhydrated residual gypsum in the long term. The amount of anhydrous gypsum used is 1 to 5 parts by weight, preferably 3 to 4 parts by weight, based on 100 parts by weight of Portland cement. If it is less than 1 part by weight, the initial strength is poorly expressed, and if it exceeds 5 parts by weight, expansion failure due to unhydrated residual gypsum may occur in a long-term age.

The aluminum sulfate used in the present invention is usually a salt containing about 0 to 20 mol of bound water, and is not particularly limited, and any salt containing bound water can be used. . The amount of aluminum sulphate used is 0.2 in terms of anhydride based on 100 parts by weight of Portland cement.
To 3 parts by weight, preferably 1 to 2 parts by weight. If it is less than 0.2 parts by weight, the initial strength is poorly expressed, and if it exceeds 3 parts by weight, workability may be deteriorated.

Although the alkali metal aluminate salt used in the present invention is used in a small amount, it is indispensable for improving the strength development in the initial, middle and long term, and the components are not particularly limited. It is possible to use sodium aluminate or potassium aluminate instead of
Among them, it is economically preferable to use sodium aluminate. The amount of alkali metal aluminate used is
It is 0.1 to 0.8 parts by weight, preferably 0.3 to 0.8 parts by weight, based on 100 parts by weight of Portland cement. If less than 0.1 part by weight, sufficient strength development may not be obtained, and
If it exceeds 8 parts by weight, workability may deteriorate.

The nitrates of the present invention exert a synergistic effect when used in combination with anhydrous gypsum, aluminum sulfate, and alkali metal aluminate, and have the action of accelerating the hydration of Portland cement, The composition is not particularly limited, but it is composed of one or more of nitrates and nitrites, and specifically, examples thereof include alkali metal salts and alkaline earth metal salts of nitrates and nitrites. Of these, the use of sodium salt, potassium salt, and calcium salt is economically preferable. The amount of nitrates used is 100 parts by weight of Portland cement,
0.5 to 5 parts by weight is preferable, and 1 to 3 parts by weight is more preferable. If it is less than 0.5 parts by weight, the initial strength promoting effect may not be sufficiently obtained, and if it exceeds 5 parts by weight, it may be difficult to maintain fluidity.

The water reducing agent used in the present invention is not particularly limited, and generally commercially available water reducing agents, AE water reducing agents, high-performance water reducing agents, high-performance AE water reducing agents, and superplasticizers can be used. However, among these, it is preferable to use a high-performance water reducing agent, a high-performance AE water reducing agent, and a superplasticizer, more preferable to use a high-performance water reducing agent, and most preferable to use a polycarboxylic acid-based high-performance water reducing agent. preferable. High performance water reducing agents, high performance AE water reducing agents, and superplasticizers are roughly classified into naphthalene-based,
It is roughly classified into melamine type, polycarboxylic acid type, aminosulfonic acid type and the like. Typical examples include naphthalene-based products such as "Mighty 2000WH" manufactured by Kao, and "denka FT-500" and "denka FT-80" manufactured by Denki Kagaku Kogyo, and melamine-based Showa Denkosha The product name "Melment F-10" and the product name "Sikament 1000H" manufactured by Japan Sika Co. are listed, and the product name "Darex Super 100PHX" and "Darex Super 100PHX" manufactured by Denka Grace Co., Ltd. are used as the polycarboxylic acid type. Darex Super 200 ", NMB product name" Reobuild SP-8HS ",
In addition, trade names such as "Chupor HP-11" manufactured by Takemoto Yushi Co., Ltd. and the like, and trade names such as "Palic FP-100U" manufactured by Fujisawa Yakuhin Kogyo Co., Ltd., and the like can be mentioned as the aminosulfonic acid type. In addition, equivalent water reducing agents are commercially available from companies such as Nippon Zeon Co., Kobe Materials Co., Ltd., Nippon Paper Industries Co., Ltd., Fukui Chemical Industry Co., Ltd., and Daiichi Kogyo Seiyaku Co., Ltd. The amount of water reducing agent used is sufficient within the range specified by the manufacturer, but in the case of naphthalene-based or melamine-based water reducing agents, Portland cement, anhydrous gypsum, aluminum sulfate, alkali metal aluminate salts, and nitrates. 1 to 4 parts by weight is preferable with respect to 100 parts by weight of the binder consisting of preferable.

In the present invention, in addition to the cement composition,
Aggregates such as sand and gravel, setting regulators, AE agents, thickeners, cement expanders, rust inhibitors, antifreeze agents, soluble alkali salts such as sodium hydroxide, calcium compounds such as calcium oxide and calcium hydroxide, Sulfates such as alkali metal sulfates, alkali metal sulfites, and alkali metal bisulfites, inorganic phosphates, boric acid, clay minerals such as bentonite and montmorillonite, ions such as zeolite, hydrotalcite, and hydrocalumite One or two or more of the exchanger and the polymer emulsion can be used in combination within a range not substantially impairing the object of the present invention.

As a mixing device used for kneading the cement composition of the present invention, any existing stirring device can be used, for example, a tilting barrel mixer, an omni mixer, a V-type mixer, a Henschel mixer, and Nauta Mixer
Etc. can be used. Further, the mixing may be carried out by mixing the respective materials at the time of construction, or by mixing a part or all of them in advance.

The amount of water used in the present invention is not uniquely determined by the kind and composition of the materials used, but the water / binder ratio is preferably 25 to 50% by weight, and 30 to 40% by weight. More preferable. If it is less than 25% by weight, sufficient workability may not be obtained, and if it exceeds 50% by weight, sufficient strength development may not be obtained.

In the present invention, the molding method for producing a hardened cement product is not particularly limited as long as the cement composition and the water-mixed cement kneaded product are normally filled in the mold. However, it cannot be uniquely determined because it depends on the shape and size.
Centrifugal force molding is generally performed on the pipes, poles, piles, etc., and in the case of box carburt or U-shaped concrete groove, the cement kneaded material is placed in the frame to form a vibrator. Can be used for compaction, or the cement kneaded product itself can be molded by high fluidization and pouring, without compaction or compaction by slight vibration. Here, the centrifugal force molding conditions vary depending on the type of cement hardened product, and centrifugal force may be applied in three stages.
Usually, it is preferable to perform the acceleration by gravity of 1 to 50 G. The cement hardened product of the present invention can be demolded early, and exhibits practical strength from a material age of about 12 hours, but before demolding, it is necessary to manage the curing both after demolding from the viewpoint of quality improvement and control. preferable.

On the other hand, the physical properties required for the cement composition used for the cast-in-place lining method are that the concrete kneaded into a slump of 20 cm immediately after kneading can hold about 18 cm or more of the slump for about 1 hour. The compressive strength after 10 hours is 10 kgf / cm ² or more, and 24
It is that the compressive strength after time satisfies all that is 100 kgf / cm ² or more, and the cement composition used for the cast-in-place lining method of the present invention is particularly excellent in strength development in a short time. de and, after 6 hours 50 kgf / cm ² or more, after 12 hours it is possible to express the intensity of 200 kgf / cm ^2. The demolding strength cannot be generally limited because it depends on the size and shape of the tunnel and the composition of the materials used, but the strength at which the mortar or concrete does not drop off even if the mold is moved, for example, 30 kgf. / cm ² or more is preferable.
The mortar or concrete using the cement composition of the present invention poured into the mold can be demolded in a short time of about 4 to 6 hours, and the mold can be moved to the next span. .

The curing for producing a hardened cement product using the cement composition of the present invention is not particularly required to be steam curing, and it is preferable to perform curing while preventing water depletion such as water or water sprinkling. It is more preferable to perform heat retention curing. The curing temperature is preferably 10 to 30 ° C, 15
-25 ° C is more preferable. If the temperature is less than 10 ° C, the strength development of the hardened cement may not be fully exhibited, and if it exceeds 30 ° C, the depletion of water before the cement kneaded product is hardened may lead to poor dimensional stability. . The humidity during curing is preferably high from the viewpoint of preventing water depletion. It is also possible to cover the part exposed from the mold with a sheet or the like. Although the curing time varies depending on the curing temperature, it is possible to demold within about 6 to 12 hours after kneading. After demolding, it is preferable to carry out curing for 1 day or more under a curing condition that can prevent water depletion. It is more preferable to cure for 3 days or more. If the curing after demolding is less than 1 day, dimensional stability may deteriorate due to drying shrinkage.

Further, the curing in the cast-in-place lining method using the cement composition of the present invention may be the same as that of ordinary mortar or concrete, and it is more preferable to perform heat retention curing or the like.

[0025]

The present invention will be described in detail below with reference to examples.

Example 1 100 parts by weight of cement, 4 parts by weight of anhydrous gypsum, 1 part by weight of anhydrous aluminum sulfate, sodium aluminate
Using a binder composed of 0.5 parts by weight and 2 parts by weight of nitrate a, the unit amount in the concrete is 526 kg / m ^{3 of} binder,
Water 168 kg / m ^3, fine aggregates 551kg / m ^3, and coarse aggregate 1,117kg / m ³ and the concrete - DOO was prepared and its concrete - preparative 22kg increments, the inner diameter 200 × OD 300 × length 500mm It is put into the steel centrifugal force forming frame of No.7, GNo.4.7 (230rpm) for 2 minutes, GNo.7 (275rp)
m) for 2 minutes at low speed, GNo.12 (375 rpm) for medium speed for 4 minutes, GNo.
Centrifugal force molding was performed at a high speed of 25 (525 rpm) for 5 minutes to prepare a centrifugal force molded body, and its compression strength and external pressure strength were measured. The results are shown in Table 1.

<Materials used> Cement α: Early strength Portland cement manufactured by Denki Kagaku Kogyo Co., 3CaO / SiO ₂ content 66 wt%, Blaine value 4,460 cm ² / g Cement β: Normal Portland cement manufactured by Denki Kagaku Kogyo , 3CaO / SiO ₂ content 53% by weight, Blaine value 3,340 cm ² / g Anhydrous gypsum: Natural anhydrous gypsum, Blaine value 4,120 cm ²
/ g Aluminum sulfate: Powdered sulfuric acid band made by Mizusawa Chemical Industry Co., Ltd.,
Al ₂ O ₃ 17% by weight, water content 43% Sodium aluminate: first grade reagent, Blaine value 3,690 cm ²
/ g Nitrate a: Reagent grade 1 calcium nitrate Fine aggregate: Niigata Prefecture Himekawa river sand, specific gravity 2.62 Coarse aggregate: Niigata Himekawa river gravel, specific gravity 2.67, Gmax = 20
mm Water: Tap water

<Measurement method> Compressive strength: Measured according to JIS R 5201 Bending tensile strength σbt: Centrifugal force From the crack load P _cr , σ bt = M / 20t ² , M = 0.318 P _cr · r + 0.238 W · r, where M: bending mode generated at the bottom of the pipe when an external pressure test load is applied
Ment (kgf ・ cm), t: pipe thickness (cm), P _cr : crack load (k
gf / m), W: Tube weight (kgf / m), and r: Radius to center of tube thickness (cm)

[0029]

[Table 1]

Example 2 Example 1 was repeated except that cement α was used and the amount of anhydrous gypsum was changed as shown in Table 2.
The results are also shown in Table 2.

[0031]

[Table 2]

Example 3 Example 1 was repeated except that cement α was used and the amount of anhydrous aluminum sulfate used was changed as shown in Table 3.
I went the same way. The results are also shown in Table 3.

[0033]

[Table 3]

Example 4 Example 1 was repeated except that cement α was used and the amount of sodium aluminate used was changed as shown in Table 4. The results are also shown in Table 4.

[0035]

[Table 4]

Example 5 The same procedure as in Example 1 was carried out except that cement α was used and the kinds and amounts of nitrates were changed as shown in Table 5. The results are also shown in Table 5.

<Materials used> Nitrate b: Reagent first grade calcium nitrite Nitrate c: Reagent first grade sodium nitrate Nitrate d: Reagent first grade sodium nitrite Nitrate e: Equal amounts of nitrate a and nitrate b Mixed

[0038]

[Table 5]

Example 6 100 parts by weight of cement, 4 parts by weight of anhydrous gypsum, 1 part by weight of anhydrous aluminum sulfate, sodium aluminate
Using 0.5 parts by weight of binder and 2 parts by weight of nitrate a, the unit amount in concrete is 350 kg / m ^{3 of} binder,
Water 125 kg / m ^3, the fine aggregate 832kg / m ^3, and coarse aggregate 1,022kg / m ^3, relative to the binder 100 parts by weight, water reducing agent 2 parts by weight added with concrete - Adjust the bets, the Slump and compressive strength were measured. The results are shown in Table 6.

<Materials used> Cement γ: a mixture of 54 parts by weight of early-strength Portland cement manufactured by Denki Kagaku Kogyo Co., Ltd. and 46 parts by weight of ordinary Portland cement, 3CaO / SiO ₂ content of 60% by weight, and brain value of 3,870 cm. ² /
g Water reducing agent: Denka Grace's trade name "Darex Super 200", main component polycarboxylic acid compound

<Measurement method> Slump: Measured according to JIS A 1101 Compressive strength: Measured according to JIS A 1108

[0042]

[Table 6]

Example 7 Example 6 was repeated except that cement α was used and the amount of anhydrous gypsum used was changed as shown in Table 7.
The results are also shown in Table 7.

[0044]

[Table 7]

Example 8 Example 6 was repeated except that cement α was used and the amount of anhydrous aluminum sulfate used was changed as shown in Table 8.
I went the same way. The results are also shown in Table 8.

[0046]

[Table 8]

Example 9 Example 6 was repeated except that cement α was used and the amount of sodium aluminate used was changed as shown in Table 9. The results are also shown in Table 9.

[0048]

[Table 9]

Example 10 Cement α was used, and the types and amounts of nitrates used are shown in Table 10.
The same procedure as in Example 6 was performed except that the change was made as shown in FIG. The results are shown in Table 10.

[0050]

[Table 10]

Example 11 100 parts by weight of cement, 4 parts by weight of anhydrous gypsum, 1 part by weight of anhydrous aluminum sulfate, sodium aluminate
Using a binder composed of 0.5 parts by weight and 2 parts by weight of nitrate a, the unit amount in the concrete is 440 kg / m ^{3 of} binder,
Water 167 kg / m ^3, fine aggregates 773kg / m ^3, and coarse aggregate 879kg / m ^3, and water reducing agent was prepared 13.2 kg / m ³ and concrete. Prepared concrete with 10 cm specified by JIS G 3112
It was poured into a mold having 13 cm of deformed rebar and cured in a thermostatic chamber at 20 ° C. and a humidity of 70% and demolded after 8 hours. After removing from the mold, underwater curing was performed to manufacture a box culvert with a size of 1,200 x 1,500 mm and a thickness of 100 mm, and the crack load at each age was measured. The results are shown in Table 11.

<Measurement method> Crack load: Measured by pin-supporting two points below the neutral axis of the side wall of the bottom plate of the box culvert and loading one point at the center of the top plate.

[0053]

[Table 11]

Example 12 In a circular tunnel having a diameter of 5.3 m, concrete was cast in a concrete thickness of 40 cm and a concrete wrapping length of 10 m was mixed with cement α and used in Example 6. It was carried out. A mortar pump manufactured by Kyokuto Kaihatsu Kogyo Co., Ltd. was used for casting. As a result, the moldability was good, and when the mold was demolded after 4 hours, the mold releasability from the mold was also good. Further, a part of this tunnel was cored and a concrete specimen of 10φ × 20 cm was sampled to measure the compressive strength. The results are shown in Table 12.

[0055]

[Table 12]

[0056]

EFFECTS OF THE INVENTION By using the cement composition of the present invention, a hardened cement product exhibiting good initial strength can be obtained without steam curing, and good initial strength expression and good fluidity retention can be obtained. A concrete can be obtained, and an effect such as an efficient cast-in-place lining method is possible.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location E21D 11/10 Z // (C04B 28/04 22:14 A B 22:08 B) Z 103: 14 103: 32 111: 20

Claims (5)

[Claims] 1. 100 parts by weight of Portland cement having a 3CaO / SiO ₂ content of 60% by weight or more, 1 to 5 parts by weight of anhydrous gypsum, 0.2 to 3 parts by weight of aluminum sulfate in terms of anhydride,
A cement composition containing 0.1 to 0.8 parts by weight of an alkali metal aluminate and nitrates. 2. 100 parts by weight of Portland cement having a 3CaO.SiO ₂ content of 60% by weight or more, 1 to 5 parts by weight of anhydrous gypsum, 0.2 to 3 parts by weight of aluminum sulfate in terms of anhydride,
0.1-0.8 parts by weight of alkali metal aluminate, nitrates,
And a cement composition containing a water reducing agent. 3. A hardened cement product obtained by using the cement composition according to claim 1. 4. A method for producing a hardened cement product, which comprises kneading and molding the cement composition according to claim 1 or 2. 5. A cast-in-place for a tunnel, comprising placing a concrete containing the cement composition according to claim 2, pressurizing the concrete, and curing the concrete to move the formwork for jointing. Lining method.