JPH0248453A - Production of quick-setting concrete for covering concrete - Google Patents

Abstract

PURPOSE:To obtain the title concrete of enhance quick-setting effect without impairing the fluidity of concrete by incorporating, in advance, kneaded concrete with a specific polycarboxylic acid-based admixture and a quick-setting agent. CONSTITUTION:In a concrete-covering construction procedure to apply kneaded concrete incorporated, in advance, with a quick-setting agent on the drilled surface of the underground hollow space or tunnel, concrete to be kneaded is incorporated, in advance, with a polycarboxylic acid-based admixture consisting mainly of a copolymer containing, in part of its molecular structure, carboxyl-substituted vinyl monomer. Said admixture is e.g., a copolymer form alpha,beta-unsaturated dicarboxylic acid and olefin, a second copolymer from polyethylene glycol monoallyl ether, maleic acid-based monomer, and another monomer copolymerizable therewith. The amount of this admixture to be used is suitably 0.01-0.5wt.% (on a solid basis) based on the weight of cement.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method for producing quick-setting concrete for lining concrete using a quick-setting agent, which maintains the fluidity of concrete for a long period of time. The present invention relates to a method for producing concrete that can be quickly set in a short period of time after being set.

(Background Art) It is well known that a concrete lining method in which a quick-setting agent is added is used as a method for constructing concrete on the excavated surface of a tunnel or underground cavity. This construction method can be roughly divided into two types. Part 1
One is the spraying method, in which concrete is mixed in the air without using water, or concrete is mixed in advance with water, conveyed by an air stream, a quick-setting agent is added in the vicinity of the nozzle, and the mixture is sprayed out of the nozzle. The other method is to pour pre-mixed concrete into a form provided on the excavation surface and press it against the concrete, which is called the pressing method or crimping method. Furthermore, the above-mentioned spraying method is roughly divided into wet spraying method and dry spraying method. This dry spraying method is a method in which dry-mixed concrete is carried by air flow through a transport hose and sprayed from the mouth of a nozzle, and water is added into the transport hose at a position immediately adjacent to the mouth of the nozzle. With this method, it is difficult to control the amount of water added, and the water-cement ratio (hereinafter abbreviated as W/C), which is the most important factor governing the physical properties of concrete, is difficult to control, and a lot of dust is generated, deteriorating the working environment. This is considered to be a difficult point. In addition, the above-mentioned wet spraying method is a method in which pre-mixed concrete is conveyed by air flow through a transport hose and then blown out from the mouth of the nozzle. ). This method has the advantages of easy W/C management and less generation of dust, so it has become quite widely practiced. In both methods, the quick-setting agent is added when dry mixing the concrete or near the nozzle mouth in the dry spraying method, but it is added near the nozzle mouth in the wet spraying method. added. In addition, the above-mentioned pressing method or crimping method involves pumping pre-mixed concrete without conveying air flow, adding an quick-setting agent near the mouth of the nozzle, and applying the quick-setting agent to the excavated surface. In this method, the concrete remains highly fluid for several minutes after being poured into the formwork until just before it hardens, i.e. after adding the quick setting agent. The slump value, which is a measure of the softness of the material, is approximately 18 cm).Then, in order to increase work efficiency, the formwork is removed immediately, and in order to move on to the next process, the 1 kgf/cm" It is necessary to harden to the extent that compressive strength is obtained.

The term “accelerating agent” mentioned here is defined in JIS A 0203 r Concrete Terminology as “accelerating the water use reaction of cement.
It is defined as an admixture used to significantly shorten the setting time, and typical examples include inorganic salts (powder and liquid),
There are various types such as cement mineral type, natural mineral type, water glass type and calcium sulfo aluminum inert type. Here, the inorganic salt-based quick-setting agent is a quick-setting agent consisting of aluminate and/or carbonate, and the natural mineral-based quick-setting agent is a quick-setting agent made of aluminate and/or carbonate. Cement mineral quick setting agent is Ca0-AQ2.
01.12cao'7ALOx, CaO・2AQ201
．． 1lCaO・7AQ20.・CaF2.3Ca()3
A(220, CaF2 and other calcium aluminates) and cementitious materials that are mainly composed of these amorphous materials, and also include those containing gypsum or inorganic salt-based quick-setting agents.

The amount of these quick-setting agents added is the cement 11 in concrete.
Expressed in weight percent (referred to as usage amount) added to 1, it is approximately 2 to 8% (powder and liquid amount) for inorganic salts, approximately 5 to 10% for cement minerals, and approximately 5 to 10% for natural minerals. is about 4
~10%. This usage amount is large compared to the usage amount of ordinary admixtures, which is about 1% or less in terms of solids.

This quick-setting agent is more expensive than cement, sand, and gravel, which are the main materials used in concrete, and the amount of quick-setting agent used to achieve the desired quick-setting effect is larger than that of ordinary admixtures. , the cost ratio in lining concrete is large. Therefore, it is desirable to achieve the desired rapid setting effect with as little amount as possible.

In addition, wet spraying has a smaller rapid setting effect than dry spraying. One of the reasons for this is that before the cement particles come into contact with the quick-setting agent, they have already come into contact with water, so a thin layer of initial hydrate is formed on the surface of the cement particles. (See Japanese Unexamined Patent Publication No. 31572/1983). Another reason is that the W/C becomes large when using the wet spraying method. In other words, dry spraying is about 45%, while wet spraying is about 5%.
It is 5% or more. The rapid setting effect is sensitively affected by the size of the W/C, and the larger the W/C, the smaller the rapid setting effect, but when wet spraying is used, concrete can be transported smoothly in the transport hose. The softness of the concrete must be considerably increased in order for the concrete to proceed, and therefore the W/C must also be increased. Similarly, in the case of the pressing method and the crimping method, the softness of the concrete must be considerably increased in order to pour the concrete into the formwork with good filling properties, but increasing the W/C will cause rapid setting. The problem arises that the quality is inferior.

(Disclosure of the Invention) The present inventors have developed a concrete lining method in which a quick-setting agent is added to pre-mixed concrete on the excavated surface of a tunnel or underground cavity. We conducted extensive research with the aim of providing a means to increase the concrete's concrete fluidity without impairing its fluidity, and found that a copolymer containing a carboxyl group-substituted vinyl monomer as part of its molecular structure was added to the pre-mixed concrete. Add the polycarboxylate admixture as an ingredient,
By adding an accelerating agent to the concrete, this objective could be achieved.

That is, the present invention provides a concrete lining method in which an accelerating agent is added to pre-mixed concrete on the excavated surface of a tunnel or underground cavity, and in which polycarboxylic acid is added to the pre-mixed concrete. The present invention provides a method for producing lining concrete, which is characterized by adding a salt-based admixture.

The quick setting agent referred to here is as described above. The above-mentioned polycarboxylate-based admixture refers to a polycarboxylate-based substance itself or an admixture containing this as a water reducing agent component, and polycarboxylate-based admixtures are usually compliant with JIS A 0203. It is used as a ``water reducing agent'' as defined in ``Concrete Terminology''. The water-reducing agent components of admixtures usually used in concrete include lignin sulfonates and their derivatives, oxycarboxylate salts, naphthalene sulfonate formalin condensate salts, melamine sulfonate formalin condensate salts, and polycarboxylic acids. Although there are salt-based ones, polycarboxylate-based ones are particularly preferably used in the method of the present invention. The polycarboxylate-based admixture used in the method of the present invention refers to an admixture containing a copolymer containing a carboxyl group-substituted vinyl monomer as one component. As a specific example, the polycarboxylic M base admixture has a water-soluble σ.

Copolymers of β-unsaturated dicarboxylic acids and olefins, copolymers derived from polyethylene glycol monoallyl ether and maleic monomers, and monomers copolymerizable with these, isobutylene-styrene maleic acid monomers, Examples include copolymers of butylene-acrylic ester-maleic acid and inbutylene-styrene-acrylic ester-maleic acid.

The amount of the polycarboxylate admixture used in the method of the present invention is 0.01% to 0.0% in terms of solids based on the weight of cement.
．． A usage range of 5%, preferably 0.03% to 0.2% is suitable. When testing concrete with the same consistency and using the same amount of quick setting agent, if the amount of polycarboxylate admixture used is less than this, a satisfactory quick setting effect cannot be obtained. As the amount used increases, the rapid setting effect increases, but if the amount used exceeds the above-mentioned upper limit, a plateauing phenomenon will occur, making it uneconomical.

The concrete used in the wet spraying method has a larger proportion (s/a) of fine aggregate in the total aggregate compared to normally poured concrete, and contains lignin sulfonate or oxycarboxylate-based concrete. With admixtures such as, the water reduction effect is small in the range of normal usage of this agent, and if the usage of this agent is increased in an attempt to increase the water reduction effect, setting and hardening of concrete will be delayed, and the rapid setting agent used in combination will be delayed. Spraying is not suitable for use in construction methods as it inhibits the effectiveness. As mentioned above, wet spraying is a method in which a quick setting agent is added to pre-mixed concrete near the mouth of the nozzle and then sprayed. It is often left to stand for up to 2 hours, during which time a problem arises in that the fluidity decreases. Admixtures based on naphthalene sulfonic acid formalin condensate salts and melamine sulfonate formalin condensate salts have an excellent water-reducing effect, and even if the amount used is increased, high fluidity can be ensured without showing a large retardation of setting and hardening. However, these admixtures have the disadvantage that their water-reducing effect lasts only a short time, and the fluidity of concrete decreases significantly 20 to 30 minutes after adding the admixture, resulting in a large slump loss. Therefore, it is not appropriate to use these agents alone as water reducing agents in the method of the present invention. In the pressing method or the pressure bonding method, it is necessary to densely fill the concrete into the formwork, and it is necessary to maintain fluidity for about 2 hours, so it is also appropriate to use an admixture with a large slump loss. Not. moreover,
Naphthalene sulfonic acid formalin condensate salt admixtures include 3CaO・AQxOx, 4CaO・AQ, 03・Fe
It is known that abnormally large amounts of calcium aluminate minerals such as , O, etc. are adsorbed (Cement Technology Annual Report 35
゜See P2O2). Currently, cement mineral-based quick-setting agents are becoming mainstream as quick-setting agents for wet spraying due to their initial strength development (rapid setting and hardening development) and resistance to spring water. As mentioned above, calcium aluminate is the main component, and when mixed with a naphthalene sulfonic acid formalin condensate salt admixture, more adsorption occurs on the surface of calcium aluminate, inhibiting the rapid setting effect. Ru.

As a result of intensive study in view of this situation, the inventors of the present invention found that
As mentioned above, by using polycarboxylate-based admixtures in pre-mixed concrete, concrete can be constructed on the excavated surface of tunnels or underground cavities by adding quick-setting agents to the pre-mixed concrete. In this lining method, we succeeded in increasing the quick-setting effect of the quick-setting agent on concrete without impairing the fluidity of the concrete.

EXAMPLES Below, the present invention will be described in more detail with reference to Examples.

Example 1 According to this example, as a model test for lining concrete, concrete was mixed in a predetermined proportion, and then unit screening (using a 5 mm sieve with 7 Louis meshes was used to sieve the mortar part and the coarse aggregate part). The effect of adding the above-mentioned polycarboxylate admixture can be confirmed by separating the mortar and adding an accelerating agent to the obtained mortar.

(1) Concrete materials (a) Cement: Use a mixture of equal amounts of ordinary Portland cement manufactured by Onoda, Mitsubishi, and Juminsha.

(b) Coarse aggregate: crushed hard sandstone from Ome (specific gravity = 2.64,
Water absorption rate -0.67%, F, M = 6.35, MS-15
mm) (c) Fine aggregate: Use a mixture of land sand from the Oi water system and mountain sand from Chiba (specific gravity = 2.65, water absorption -1.34%, FM = 2.69) (d) Admixture : a) Polycarboxylic acid admixture Copolymer of polyalkylene glycol monomethacrylic acid ester and methacrylic acid (abbreviation A: manufactured by Nisso Master Builders Co., Ltd.) b) Lignosulfonate admixture Product name: Hozolith No. 8 (abbreviation B: manufactured by Nisso Master Builders Co., Ltd.) C) Oxycarboxylate-based admixture Sodium gluconate (abbreviation C: reagent) d) Naphthalenesulfonic acid formalin condensate salt-based admixture Product name: Mighty 150 (abbreviation D: manufactured by Kao Corporation) e) Melamine sulfonic acid formalin condensate salt admixture Product name: NL-4000 (abbreviation E: manufactured by Nisso Master Builders Co., Ltd.) The amount of admixture used is The amount of water used to obtain the same consistency as that of plain concrete without additives and the amount of water shown in the formulation is expressed in weight % based on the weight of cement.

(ne) Quick setting agent: r) Inorganic salt powder quick setting agent brand name: QP-500 (abbreviation F: manufactured by Nisso Master Builders Co., Ltd.) g) Cement mineral quick setting agent brand name: QP-55 (Abbreviation G: Manufactured by Nisso Master Builders Co., Ltd.) The usage amount of the quick-setting agent was the standard usage amount recommended by each manufacturer, and was expressed in weight % with respect to the cement weight.

(2) Concrete mix The mix of concrete is as shown in Table 1.

(3) After mixing the test concrete, separate the mortar and coarse aggregate using a 5 mm sieve, knead the resulting mortar for 30 minutes, add an quick-setting agent, and knead by hand for 20 seconds. Regarding this product, the initial setting time (penetration resistance of 35 kgf
/crrr2) was measured. Note that the setting time is the time (minutes-seconds) after adding the quick-setting agent.

(4) Test results The test results when using quick setting agent F are as shown in Table 2, and the test results when using quick setting agent G are as shown in Table 3. In the case of using quick setting agent F and no admixture, the initial stage was not reached even after 20 minutes, but by using polycarboxylate admixture (abbreviation A), it was achieved in 13 minutes and 40 seconds. It can be seen that the starting point has been reached. All of the other admixtures did not reach the initial stage even after 20 minutes had passed, except for the admixture E, which reached the initial stage in 17 minutes and 20 seconds. Furthermore, even when using quick setting agent B,
By using the polycarboxylate admixture (abbreviation A), the initial stage was reached within 1 minute, and it can be seen that the setting time was significantly shortened with the same amount of quick setting agent.

Table 3 Measurement results of setting time (accelerating agent G) Example 2 This example shows how long the fluidity of concrete can be maintained until the accelerating agent is added.

The materials used in the test and the concrete mix were the same as in Example 11 and Comparative Examples 1 and 4.5. The admixture used in this test was a polycarboxylate admixture (abbreviation A).
, naphthalene sulfonic acid formalin condensate salt admixture (
Abbreviation D) and melamine sulfonic acid formalin condensate salt admixture (abbreviation E).

(1) Test After mixing concrete with a tilting mixer, the entire amount of concrete was discharged and slump was measured. Next, the entire amount of concrete was returned to the mixer, and the mixer was continued to rotate at a low speed (2 rpm) for a predetermined period of time, and slump was measured after 30 minutes and 60 minutes.

(2) Test results The test results are shown in Table 4. From this, it can be seen that the slump of concrete using the polycarboxylate admixture (abbreviation C) does not decrease compared to other types even after a long period of time. When Admixture G was used, the setting time was relatively quick, but the slump changed rapidly over time, and after 60 minutes it was 5.
It turns out that it is less than cm.

Table 4 Results of concrete slump loss test As work efficiency can be improved, the industrial value is extremely high.

Claims (1)

[Claims] In the concrete lining method, in which a quick setting agent is added to pre-mixed concrete on the excavated surface of a tunnel or underground cavity, a carboxyl group-substituted vinyl monomer is added to part of the molecular structure of the pre-mixed concrete. A method for producing concrete, which comprises adding a polycarboxylate admixture whose main component is a copolymer containing: