JP2001172063A - Setting regulator slurry, cement concrete, quick-setting cement concrete, method for working quick-setting cement concrete - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a setting regulator securing the fluidity of cement concrete over a period of time required in working site or longer and capable of setting sprayed cement concrete in a short time when incorporated with a quick-setting agent at a necessary time. SOLUTION: This setting regulator for cement concrete comprises slaked lime, an organic acid, gypsum and a water reducing agent but no quick-setting agent. Another objective method for working quick-setting cement concrete is characterized by that cement concrete formulated with no quick-setting agent is formulated with a setting regulator slurry comprising the above setting regulator and water to prepare a cement concrete and just before using the cement concrete, a quick-setting agent is mixed into the cement concrete to put the resultant cement concrete to working; wherein the organic acid is pref. an organic acid salt and the water reducing agent is pref. a naphthalenesulfonic acid-formaldehyde condensate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a setting agent for cement concrete which does not contain a quick-setting agent. The present invention relates to an excellent setting agent which can be used when required, and a method for constructing cement concrete using the same.

[0002] The cement concrete in the present invention is a general term for mortar and concrete.

[0003]

2. Description of the Related Art Conventionally, when cement concrete is used on site, a setting retarder has been used so that it can be used for a long time.

However, when a setting retarder is mixed with cement concrete to adjust the setting time of the cement concrete to 5 to 24 hours, and then a quick setting agent is mixed and hardened, the strength after hardening is set. There is a problem that the temperature is remarkably reduced as compared with the case where no retarder is mixed, and it is difficult to obtain necessary properties of cement concrete.

[0005] Furthermore, since the ready-mixed plant does not normally operate at night, when cement concrete must be used in night-time construction, the ready-mixed plant must be installed at the site of night-time construction, which is extremely economically disadvantageous. And other issues. Especially at tunnel construction sites,
It was difficult and problematic to install a ready-mix plant in the tunnel.

[0006] In order to solve the above-mentioned problems, a method of adding condensed phosphate, citric acid, slaked lime, sodium carbonate and the like to cement concrete and mixing an alkali aluminate or an organic acid immediately before use, and a method of adding polycondensate to cement concrete. A method has been proposed in which a carboxylate-based admixture is added to ensure fluidity for a long time, and a quick-setting agent is added at the time of spraying (Japanese Patent Laid-Open No. Hei 2 (1994)).
-248351, JP-A-3-153550).

[0007] However, these methods have problems such as long setting time, occurrence of breathing, and the fact that cement concrete becomes too soft to easily separate aggregate and cement.

[0008] To solve this problem, when the water-cement ratio is reduced, there is a problem that the viscosity of the cement concrete is increased, the spraying workability is reduced, and the setting delay effect is reduced.

Further, when the amount of setting retarder used is increased so that cement concrete can be used for a long time, a quick setting agent is added within a shorter time than expected, for example, within 1 to 24 hours, and spraying is performed on a tunnel or the like. Then, there were problems such as that the sprayed cement concrete was not quickly set, but was washed away by water leakage from the tunnel side wall, and peeled off from the top end portion.

[0010] The construction site is usually operated 24 hours in three shifts. However, shipment of ready-mixed concrete plants stops around 6:00 pm, and after that, ready-mixed concrete cannot be shipped until the next morning. Therefore, when performing construction at night, cement concrete that can secure fluidity until the time required by the construction site has been demanded.

[0011] In order to satisfy the above demand, a setting modifier containing slaked lime and an organic acid as active ingredients is blended with concrete containing no setting agent and mixed with the setting agent immediately before use of the concrete. A concrete construction method characterized by the following has been proposed (Japanese Patent Laid-Open No. Hei 6-263498).

[0012]

However, when preparing cement concrete to which a setting retarder is added and then preparing cement concrete containing no setting retarder in the same raw plant after preparing the cement concrete to which the setting retarder is added, the setting of the cement concrete is delayed. Therefore, there is a problem that the fresh concrete plant must be washed with water after preparing the cement concrete to which the setting retarder is added.

In order to solve this problem, it has been desired to add a setting modifier to cement concrete at a construction site such as spraying. In order to add the setting modifier at the construction site, it is necessary to improve the mixability with the cement concrete, and for that purpose, it is preferable to slurry the setting modifier.

However, when the setting modifier is converted into a slurry, calcium ions in the slaked lime react with the organic acid, which may cause the setting regulator slurry to generate heat. Even if it is added to the
Further, there is a problem that a small coagulate may be generated in the cement concrete and the cement concrete may be hardly mixed. For this reason, there was a possibility that this setting modifier could not be used as a slurry at a construction site.

The inventor of the present invention has conducted various studies to solve the above-mentioned problems. As a result, by using a specific material, the pumping property and fluidity can be ensured for a time longer than the construction site requires, and a quick connection is made when necessary. Mixing agent can quickly set and harden rapidly setting cement concrete.
Further, the present inventors have found that the coagulation adjusting material can be slurried and can be freely added at a construction site, thereby completing the present invention.

[0016]

That is, the present invention is a setting adjusting material slurry for cement concrete containing slaked limes, organic acids, gypsum, a water reducing agent, and water, and not containing a quick setting agent. The setting regulator slurry in which the water reducing agent is a naphthalenesulfonic acid formalin condensate, and the setting regulator slurry in which the organic acid is an organic acid salt. And it is a cement concrete obtained by mixing a cement concrete containing no quick-setting agent and the setting modifier slurry. Further, it is a quick-setting cement concrete obtained by mixing the cement concrete and a quick-setting agent. or,
Cement concrete not containing a quick setting agent is mixed with a setting modifier slurry containing slaked lime, organic acids, gypsum, water reducing agent, and water to form cement concrete, and immediately before use of the cement concrete, This is a method for constructing a quick-setting cement concrete, which comprises mixing a binder.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

As the cement according to the present invention, various types of portland cement which are usually commercially available, such as ordinary, fast, moderate heat and ultra fast, and various kinds of mixture obtained by mixing these portland cements with fly ash, blast furnace slag, etc. Cement and commercially available fine particle cement and the like.
Also, various Portland cements or various mixed cements may be used after being pulverized.

The setting modifier according to the present invention is a material which is mixed with cement concrete not containing a quick setting agent.

The slaked lime according to the present invention has an effect that cement concrete containing no quick setting agent does not harden for a long time.

Further, even if a large amount of organic acids and the like are used,
In addition, even if the quick-setting agent is mixed earlier than expected, it has the effect of promoting the quick-setting hardening of the quick-setting cement concrete by coexisting with the quick-setting agent.

Specific examples include slaked lime and carbide slag by-produced when acetylene is generated from calcium carbide. Among these, carbide slag is preferred because it exhibits the best strength development after being mixed with the quick-setting agent, and is inexpensive and economical because it is a by-product.

The particle size of slaked lime is not particularly limited, but is preferably 100 μm or less, more preferably 60 μm or less.

As the organic acids according to the present invention, one or more of various water-soluble carboxylic acids such as citric acid, gluconic acid, tartaric acid and malic acid and salts thereof can be used. As the salt, a sodium salt or a potassium salt is preferable. Among these, an organic acid salt is preferable because the setting time becomes longer in direct proportion to the amount used, it is easier to control, the slurry does not easily cause a chemical reaction with the calcium component, and the slurry hardly generates heat, Sodium citrate is more preferred.

The amount of the organic acid to be used is preferably 1 to 400 parts by mass, preferably 4 to 200 parts by mass, per 100 parts by mass of slaked lime.
A mass part is more preferable, and 6 to 50 mass parts is most preferable. If the amount is less than 1 part by mass, the setting retardation effect may be small, and if it exceeds 400 parts by mass, the setting and hardening may be difficult.

As the gypsum according to the present invention, any commercially available gypsum can be used, but from the viewpoint of strength development, type II anhydrous gypsum and natural anhydrous gypsum are preferred.

The particle size of the gypsum is 3000 cm ^{2 in} Blaine value.
/ G or more is preferable, and 4000 to 7000 cm ² / g is more preferable. If it is less than 3000 cm ² / g, the initial strength development may be reduced.

The amount of gypsum used is preferably from 10 to 500 parts by mass, preferably from 20 to 200 parts by mass, per 100 parts by mass of slaked lime.
Parts by mass are more preferred. If the amount is less than 10 parts by mass, there is a possibility that the pumpability and the strength development are small. If the amount exceeds 500 parts by mass, initial setting may be difficult.

The water reducing agent according to the present invention maintains the effect of retarding the setting, and can be used in any form of liquid or powder.

Examples of the water reducing agent include polyol derivatives, lignin sulfonates and derivatives thereof, and high-performance water reducing agents, and one or more of these can be used. Among these, a high-performance water reducing agent is preferred because of its large setting delay effect, fluidity, and pumpability.

Examples of the high-performance water reducing agent include a formalin condensate of a naphthalene sulfonate, a melamine sulfonate, and an alkylaryl sulfonate, and a polycarboxylic acid polymer compound. Can also be used. Among these, a naphthalenesulfonic acid formalin condensate (hereinafter, referred to as NS) is preferred because of its large setting delay effect, fluidity, and pumpability. As NS, β-naphthalenesulfonic acid formalin condensate is usually used.

The amount of the water reducing agent to be used is preferably 1 to 10 parts by mass in terms of solid content, based on 100 parts by mass of slaked lime.
-7 parts by mass is more preferred. If the amount is less than 1 part by mass, the setting retardation effect, the fluidity, and the pumpability may be small.
If the amount exceeds the mass part, the cement concrete may be separated.

The setting modifier according to the present invention is used in the form of a slurry. By making it into a slurry, it can be added later to a concrete mixer truck, and has the effect of improving the slump retention of cement concrete.

The amount of water used to prepare the setting modifier slurry is based on 100 parts by mass of the setting modifier.
The amount is preferably from 30 to 300 parts by mass, more preferably from 40 to 200 parts by mass. If the amount is less than 30 parts by mass, the viscosity of the cement concrete is large, the setting agent and the water are difficult to mix, and the workability may be poor. If it exceeds 300 parts by mass, the strength development may be reduced. However, if the amount of water in the setting modifier slurry is large, the water-cement ratio of the cement concrete must be reduced, and the mixing property of the cement concrete may be reduced. Therefore, it is preferable that the amount of water in the setting modifier slurry is not large.

The amount of the setting modifier used is preferably 0.5 to 15 parts by mass, more preferably 1 to 10 parts by mass in terms of solid content, based on 100 parts by mass of cement. If the amount is less than 0.5 part by mass, the setting retardation effect and the slump retention may not be good, and if it exceeds 15 parts by mass, the setting and hardening may be difficult.

According to the present invention, a setting accelerator is mixed with cement concrete containing no quick-setting agent, and then the quick-setting agent is mixed during spraying to obtain a quick-setting sprayable cement concrete.

The quick-setting agent according to the present invention is not particularly limited as long as it can be mixed into sprayed cement concrete. Examples of the quick-setting agent include inorganic salts such as sodium aluminate and sodium silicate, and calcium aluminate. And minerals such as cements. Among these, cement mineral quick-setting agents are preferred, and calcium aluminates are more preferred, in terms of excellent setting properties such as quick setting and hardening of cement concrete, and good strength development.

The amount of the quick setting agent used is preferably 3 to 25 parts by mass, more preferably 5 to 15 parts by mass, based on 100 parts by mass of cement. If the amount is less than 3 parts by mass, the setting property is delayed, and the rebound loss at the time of spraying may increase. If the amount exceeds 25 parts by mass, the rebound loss at the time of spraying may increase.

The water-cement ratio (W / C) according to the present invention is 4
0 to 70% is preferable, and 50 to 65% is more preferable.
If it is less than 40%, the viscosity of the cement concrete is large and the spraying workability may be reduced, and the setting delay effect may be small. If it exceeds 70%, the strength development and the setting properties may be adversely affected. The water-cement ratio here includes water in the setting modifier slurry.

The mixing conditions such as the mixing order of slaked lime, organic acids, gypsum, and water reducing agent are not particularly limited as long as they are uniformly mixed with the cement concrete before adding the quick setting agent. Split mixing is also possible.

[0041]

The following describes an experimental example.

Experimental Example 1 W / C = 60%, Cement / Aggregate Ratio (C / S) = 1/3
Was prepared. Note that fine aggregate was used as the aggregate. In this mortar, 100 parts by mass of slaked lime, 25 parts by mass of organic acids, gypsum in parts by mass shown in Table 1, and 100 parts by mass of a setting agent consisting of 5 parts by mass of a water reducing agent and a setting agent slurry consisting of 100 parts by mass of water Was added in an amount of 6 parts by mass in terms of solid content with respect to 100 parts by mass of cement. Thereafter, 7 parts by mass of a quick setting agent was added to 100 parts by mass of cement, and the compressive strength was measured. Table 1 shows the results.

(Materials used) Cement: Commercial product, ordinary Portland cement Fine aggregate: Natural sand from Himekawa, Niigata Prefecture, specific gravity 2.62 Slaked lime: Carbide slag, particle diameter 60 μm or less Organic acids: Commercial product, sodium citrate Gypsum: commercial product, natural gypsum, Blaine value 4000 cm ² /
g Water reducing agent: β-NS, powdery, commercial product Quick setting agent: Calcium aluminate type quick setting agent

(Measurement method) Compressive strength: Measured at a prescribed age at 20 ° C. in accordance with JIS R 5201. Setting time: Measured in accordance with the Japan Society of Civil Engineers standard “Quick-setting agent quality standard for shotcrete (JSCED-102)”.

[0045]

[Table 1]

Experimental Example 2 Cement 360 kg / m^Three708 kg / m of coarse aggregate^Three, Thin
Aggregate 1013kg / m ^ThreeAnd 194 kg / m of water^Threeage,
Concrete was prepared. This concrete has slaked lime
100 parts by mass, organic acids 25 parts by mass, mass shown in Table 2
Of gypsum and 5 parts by weight of water reducing agent 10
Coagulation adjusting material slurry consisting of 0 parts by mass and 100 parts by mass of water
Is 6 parts by mass in terms of solid content with respect to 100 parts by mass of cement.
And the slump holding time and pumpability were measured. result
Are shown in Table 2.

(Materials used) Coarse aggregate: gravel from Himekawa, specific gravity 2.65

(Measurement Method) Slump Holding Time: The time from immediately after the addition and kneading of the setting modifier slurry to the time when the slump reaches 10 cm. The slump was measured according to JIS A1101. Pumpability: The concrete was mixed with a setting adjusting material slurry, and the mixture was pumped by a concrete pump with a hose. When the hose has no pulsation and the concrete can be continuously pumped, ○: when the hose has a pulsation, but when the concrete can be almost continuously pumped, △: When the hose has a pulsation, the concrete has to be continuously pumped. The case where it was not able to be done was evaluated as x.

[0049]

[Table 2]

Experimental Example 3 100 parts by mass of slaked lime, organic acids in parts by mass shown in Table 3,
100 parts by mass of gypsum, 100 parts by mass of setting agent consisting of 5 parts by mass of water reducing agent and 100 parts by mass of setting agent slurry are used for setting 100 parts by mass of cement to 6 parts by mass in terms of solid content. Except that the time was measured, it carried out similarly to Experimental example 1. Table 3 shows the results.

[0051]

[Table 3]

EXPERIMENTAL EXAMPLE 4 100 parts by mass of slaked lime, and organic acids in parts by mass shown in Table 4
Except that 100 parts by mass of gypsum, and 100 parts by mass of a setting agent consisting of 5 parts by mass of a water reducing agent and 100 parts by mass of water, a slurry of setting agent consisting of 100 parts by mass of cement were used in an amount of 6 parts by mass in terms of solid content based on 100 parts by mass of cement Was performed in the same manner as in Experimental Example 2. Table 4 shows the results.

[0053]

[Table 4]

Experimental Example 5 100 parts by mass of slaked lime, 25 parts by mass of organic acids, gypsum 10
Coagulation adjusting material 10 consisting of 0 parts by mass and 5 parts by mass of water reducing agent
The procedure was carried out in the same manner as in Experimental Example 3, except that the setting modifier slurry composed of 0 parts by mass and 100 parts by mass of water was used in terms of solids content as shown in Table 5 with respect to 100 parts by mass of cement. Table 5 shows the results.

[0055]

[Table 5]

Experimental Example 6 100 parts by mass of slaked lime, 25 parts by mass of organic acids, gypsum 10
Coagulation adjusting material 10 consisting of 0 parts by mass and 5 parts by mass of water reducing agent
The procedure was carried out in the same manner as in Experimental Example 2, except that the setting modifier slurry composed of 0 parts by mass and 100 parts by mass of water was used in terms of solids as shown in Table 6 based on 100 parts by mass of cement. Table 6 shows the results.

[0057]

[Table 6]

Experimental Example 7 100 parts by mass of slaked lime, 25 parts by mass of organic acids, gypsum 10
Coagulation adjusting material 10 consisting of 0 parts by mass and 5 parts by mass of water reducing agent
6 parts by mass of a setting modifier slurry composed of 0 parts by mass and 100 parts by mass of water was used in terms of solid content with respect to 100 parts by mass of cement, and a quick setting agent was used for 100 parts by mass of cement.
The procedure was performed in the same manner as in Experimental Example 3 except that the parts by mass shown in Table 3 were added. Table 7 shows the results.

[0059]

[Table 7]

Experimental Example 8 360 kg / m of cement^Three708 kg / m of coarse aggregate^Three, Thin
Aggregate 1013kg / m ^ThreeAnd 194 kg / m of water^Threeage,
Concrete with a plain slump of 10 cm was prepared.
100 parts by mass of slaked lime, organic acids
25 parts by mass, gypsum 100 parts by mass, and water reducing agent 5 parts by mass
100 parts by mass of the coagulation adjusting material and 100 parts by mass of water.
Of the coagulation modifier slurry to 100 parts by mass of cement
6 parts by mass in terms of solid content. After that, remove the quick setting
100 parts by mass of the mentor, the parts by mass shown in Table 8 were added.
Spray and bounce losses (rebound rates) were measured. Conclusion
The results are shown in Table 8.

(Measurement method) Bounce loss: A quick-setting spray concrete is sprayed on a horseshoe-diameter tunnel having a width of 5.5 m and a height of 5.5 m, and the amount of the quick-setting spray concrete that bounces off / (spray) Amount of quick-setting spray concrete used for all) x 100 (%)
Indicated by

[0062]

[Table 8]

Experimental Example 9 100 parts by mass of slaked lime, 25 parts by mass of organic acids, gypsum 10
0 parts by mass, and 6 parts by mass of a setting modifier slurry composed of 100 parts by mass of a setting modifier composed of a water reducing agent and 100 parts by mass of water in terms of solid content with respect to 100 parts by mass of cement as shown in Table 10 Except for doing so, the procedure was performed in the same manner as in Experimental Example 2 to measure slump, separability, and pumpability. Table 9 shows the results.

(Measurement Method) Slump: A slump for a predetermined time was measured according to JIS A 1101 immediately after adding and kneading the setting modifier slurry. Separability: Separability of shotcrete was measured. 200
2000m sprayed concrete on 0ml graduated cylinder
1 was charged and left to stand for 10 minutes. Thereafter, concrete above the 1000 ml graduated cylinder line was sampled, sieved with a sieve having a mesh size of 5 mm, and the mass remaining on the sieve was measured.

[0065]

[Table 9]

[0066]

EFFECTS OF THE INVENTION The setting modifier slurry according to the present invention can be added to sprayed cement concrete at a spraying construction site, can be added later to a concrete mixer truck, and has good slump retention and pumpability of the sprayed cement concrete. or,
The setting properties and strength development of the quick setting sprayed cement concrete to which the quick setting agent is added are also good.

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Claims (6)

[Claims] 1. A setting modifier slurry for cement concrete containing slaked limes, organic acids, gypsum, a water reducing agent and water and containing no quick setting agent. 2. The setting modifier slurry according to claim 1, wherein the water reducing agent is a formalin condensate of naphthalenesulfonic acid. 3. The setting modifier slurry according to claim 1, wherein the organic acid is an organic acid salt. 4. A cement concrete obtained by mixing a cement concrete containing no quick-setting agent and the setting modifier slurry according to claim 1. 5. A quick-setting cement concrete comprising the cement concrete according to claim 4 and a quick-setting agent. 6. A cement concrete containing no sintering agent and a setting modifier slurry containing slaked lime, organic acids, gypsum, a water reducing agent, and water to form cement concrete. A method for constructing a quick-setting cement concrete, which comprises mixing a quick-setting agent immediately before use.