JP2851402B2 - Admixture for wet shotcrete method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention rapidly sets and hardens blown concrete without affecting the physical properties of the concrete and the reduction of dust during spraying, especially in high temperatures in summer. The present invention relates to an admixture for a wet shotcrete method, which is sometimes effective.

(Conventional technology) In the concrete spraying method, a mixture of all materials other than water, excluding water, and water are pressure-fed by separate spraying machines, and joined together before the spraying nozzle to form a lining. Dry construction method to spray as concrete,
There is a wet construction method in which a slurry in which all materials except the quick-setting agent are kneaded is pumped by a spraying machine, and if necessary, a quick-setting agent is added in front of the spraying nozzle and sprayed as lining concrete. However, the dry method has been frequently used because of its simplicity and ease of use of the quick setting agent, but recently the proportion of the wet method has been increasing.

In either case, the large amount of dust generated during spraying is a problem in the working environment, and various countermeasures have been proposed for the countermeasures, such as water-soluble cellulose ether and vinyl acetate emulsion. (Sho 61
No. -30110, JP-A-58-41158, JP-A-59-141448,
Nos. 62-1973 and 63-270334), by mixing them in the wet method, the viscosity of the sprayed concrete is increased to prevent diffusion when spraying from the nozzle,
Attempts have been made to reduce the generation of dust.

In this method, a quick-setting agent is added so that the sprayed concrete quickly sets and hardens.
In summer, especially at high temperatures of 25 ° C or higher, the quick-setting agent and cement cause a hydration reaction individually, delaying the setting and hardening of the sprayed concrete, and delaying the development of the initial strength, making it easier to peel off from the sprayed surface. There was a problem. To cope with this, a method of cooling by adding ice to the kneading water of concrete has been adopted, but there have been problems such as an increase in cost and a complicated operation. Although the water-soluble cellulose ether, which is the main component of the above-mentioned dust reducing agent, has a setting delay effect, it is not enough to suppress the deterioration of the effect of the quick setting agent.

(Problems to be Solved by the Invention) Accordingly, an object of the present invention is to provide a wet shotcrete method in which a quick-setting agent is blended and used, without affecting the physical properties of concrete and the reduction of dust during spraying work. It is an object of the present invention to provide an admixture for the above-mentioned method, which can suppress the occurrence of the above-mentioned problem at high temperatures in summer and at high temperatures.

(Means for Solving the Problems) The admixture for wet spraying concrete method according to the present invention comprises: (a) a setting retarder having a setting time difference of 20 to 100 minutes with a plain at 20 ° C by a calorimeter. 5-40
(B) 40 to 95% by weight of a water-soluble cellulose ether; and (C) 0 to 20% by weight of an antifoaming agent.

To further explain this, the admixture of the present invention is characterized in that the above-mentioned disadvantages at high temperatures are improved by including the above-mentioned specific setting retarder in a specific ratio. The ligninsulfonate used as one of the component (A) component setting retarder has been conventionally used in concrete as a water reducing agent or a dust reducing agent (JP-A-58-15056 and JP-A-58-15056). 59-141448
These are used to improve the wetting of the cement particles, and are used for applications completely different from the present invention. In fact, these publications state that those having a setting delay effect are not preferred. In these inventions, the use of the setting retarder together with the quick setting agent is to prevent clogging in the concrete transport hose, and this is also different from the object of the present invention. There is no published example of the problem at high temperature in the combination system within the range examined by the present inventors.

Further, the present invention is characterized in that not all the substances having a setting retarding effect are effective, but only the lignin sulfonate and the organic acid are used as the active ingredients for setting control of the quick-setting compounding system. Things.

In order to confirm the setting phenomenon of concrete at a high temperature in the wet spraying concrete method using a quick-setting agent and to estimate the mechanism, the present inventors used 100 parts by weight of ordinary Portland cement, 70 parts by weight of water and a quick-setting agent ( 6 parts by weight of Denkanatomic Type 5: manufactured by Denki Kagaku Kogyo Co., Ltd., and a dust reducing agent (Natom Clean: Shin-Etsu Chemical Co., Ltd.)
) Was added in three stages of 0, 0.1 or 0.3 parts by weight.
And the setting time was measured by the Vicat needle method according to JIS R-5201.

As shown in FIG. 1, it was found that, as shown in FIG. 1, when the material temperature was 28 ° C. or higher, the delay of the setting time increased as the amount of the dust reducing agent increased.

In general, it is known that setting of both cement and quick-setting agent becomes faster as the temperature becomes higher alone.
It is presumed that the development in the cement / accelerator mixture system shown in the figure occurs by the mechanism as shown in FIGS. 2 and 3. In other words, it is considered that at high temperatures, the quick-setting agents harden individually and lose their activity, so that the chance of the quick-setting agent contacting and reacting with the cement is reduced. From these, as a result of various studies from the viewpoint that the hydration of the quick-setting agent can be controlled,
Certain set retarders have been found to be effective and arrived at the present invention.

In other words, the use of a setting retarder with a setting time of the calorimeter at 20 ° C. of less than 20 minutes cannot improve the setting delay at high temperatures as in the plain,
This can be improved with a setting time of 20 minutes or more, and a setting time equivalent to that at 20 ° C. was obtained even at a material temperature of 30 ° C. This is presumably because in the mechanism described above, the setting retarder worked effectively on the quick setting agent.

On the other hand, if the setting time is slower than 100 minutes, the above effect can be achieved with respect to the setting at high temperature, but at 20 ° C., the setting of the quick-setting agent compounding system is delayed, and the use time is significantly limited. In addition, it is difficult to control and practically unsuitable for on-site use.

If the setting amount of the setting retarder is less than 5% by weight of the whole, the above effect cannot be achieved.
If the amount is more than 20% by weight, the setting of the quick-setting agent compounding system at 20 ° C. will be delayed, so that it cannot be used. It is conceivable to use less than 5% by weight of a setting time of 100 minutes or more, but it is difficult to control and is not practical. As a result, the difference in setting time with the plain at 20 ° C. in the calorimeter is 20 to 100 minutes, preferably 5 to 40 parts by weight, preferably 10 to 30 parts by weight of a setting hardening retarder of 30 to 70 minutes. Sometimes it has been found to be most effective against the setting delay at high temperatures.

Since the water-soluble cellulose ether also has a setting hardening delay property against cement, as a result of studying this, the setting time is 20 to 100 minutes, and the setting hardening delay of the present invention can be achieved even if a setting time of 100 minutes or more is used. The effect like the agent was not obtained. This is presumably because the mechanism for retarding setting is different between the water-soluble cellulose ether and the setting retarder of the present invention, and the water-soluble cellulose ether has no effect on the quick setting agent.

Examples of the setting hardening retardant used in the present invention include salts of ligninsulfonic acid such as Ca and Na, and modified products thereof; oxypolycarboxylic acids such as malic acid and citric acid, and oxymonocarboxylic acids such as glycolic acid and glycolic acid. Carboxylic acids,
Organic acids such as saturated or unsaturated carboxylic acids such as succinic acid and maleic acid, co-condensates such as acrylic acid and maleic anhydride, and salts thereof; organic derivatives such as grape and maltose; And sorbitol and the like, and inorganic substances such as a fluoride, a borate, a phosphate and the like, and these can be used alone or in combination of two or more.

Examples of the water-soluble cellulose ether as the component (b) in the admixture of the present invention include alkyl cellulose such as methyl cellulose and ethyl cellulose; hydroxyalkyl cellulose such as hydroxyethyl cellulose and hydroxypropyl cellulose; and hydroxyethyl methyl cellulose and hydroxypropyl methyl cellulose.
And hydroxyalkylalkylcellulose such as hydroxyethylethylcellulose.
It can be used as a species or a combination of two or more.

On the other hand, since these cellulose ethers have an action of entraining air into concrete, an increase in the amount of addition increases the entrainment amount of air, resulting in a decrease in concrete strength. Therefore, in order to prevent this, in the admixture of the present invention, tributyl phosphate or a nonionic or silicon-based defoaming agent is used in combination as the component (c).
It is preferable to add so as not to exceed 10%.

In preparing the admixture of the present invention, the cellulose ether may be added as it is as a powder, or may be added after being dissolved in water. Also, glyoxal can be used after adding glyoxal to prevent the occurrence of mamako.

This admixture for the wet shotcreting method is composed of cement, fine aggregate, coarse aggregate, and quick-setting agent (powder and liquid can be used) as well as ordinary concrete. Add water-reducing fluidizers such as sodium sulfonate and sodium melamine sulfonate, AE water-reducing agents such as lignin sulfonate and alkylnaphthalenesulfonic acid formalin condensate, and curing accelerators such as calcium chloride and sodium silicate. Can be used.

In addition, as a cement material used here, Portland cement (ordinary Portland cement, early-strength Portland cement, moderate heat Portland cement, white Portland cement, ultra-high-strength Portland cement), mixed cement (blast furnace cement, silica cement,
Fly ash cement) and one or more mixtures selected from special cements (alumina cement and expanded cement).

Furthermore, in addition to lightweight aggregates such as pearlite, vermiculite, and fly ash used for ordinary cement mortar, silica sand such as silica sand No. 5 to 12 made of siliceous material, similar to or less than cement Silica having a particle size, a silica material, silica fume, or the like can be used.

If necessary, the quick-setting agent may be Denkanatomic Type 3 (trade name, manufactured by Denki Kagaku Kogyo Co., Ltd.)
Inorganic salt type), same type 5 (same as above, trade name, quick-setting cement mineral), QP55 (manufactured by Pozoris Bussan Co., Ltd., trade name, same before), Cygnit U (manufactured by Nippon Sika Co., Ltd., trade name) , Aluminate), Asano Super Natom (manufactured by Nippon Cement Co., Ltd., trade name, cement mineral) and the like.

EXAMPLES Hereinafter, specific embodiments of the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

Examples 1 to 7 and Comparative Examples 1 to 7. 100 parts by weight of cement, 6 parts by weight of quick-setting agent and admixture (water-soluble cellulose ether in the amount shown in Table 1 and setting time [by calorimeter]) 0.3 part by weight of a setting retarder and 10 parts by weight of an antifoaming agent) are mixed, and the mixture is kneaded with a mortar mixer of 5 minutes for 1 minute,
After pouring 70 parts by weight of water, the mixture was kneaded for 1 minute, and the setting time was measured by the Vicat needle method while keeping the material temperature at 20 ° C and 30 ° C, and the results are shown in Table 1. did.

The materials and test methods used in each example are as follows.

1) Cement: ordinary Portland cement (manufactured by Nippon Cement Co., Ltd.) 2) Quick setting agent: dencanatomic type 5 (manufactured by Denki Kagaku Kogyo Co., Ltd.) 3) Water-soluble cellulose ether: Metroose (methyl cellulose, Shin-Etsu Chemical Co., Ltd.) 4) Antifoaming agent: tributyl phosphate (first grade reagent) 5) Setting retarder: a. Succinic acid (first grade reagent) b. Pozzolith No. 5L (lignin sulfonic acid compound, Pozoris Bussan Co., Ltd.) C. Neoace SA (oxycarboxylate, manufactured by NEOX) d. Plastkreit NC (ligninsulfonate, manufactured by Nippon Sika Co., Ltd.) e. Pozzolith No. 8 (ligninsulfonic acid compound, Pozoris Bussan Co., Ltd.) F) Sunflow R (lignin sulfonic acid derivative, manufactured by Sanyo Kokusaku Pulp Co., Ltd.) g. Pearl Rex CP (calcium lignin sulfonate, Sanyo Kokusaku pulp ( H) Palic FP-100R (polymer compound containing oxycarboxylate, manufactured by Fujisawa Palic) i. Jet setter (organic carboxylic acid, manufactured by Sumitomo Cement Co., Ltd.) j. Palic T (oxycarboxylate, Fujisawa) Above, abbreviated as "delaying agent a. (~ J.)" In the table. The setting time measured by a calorimeter is 100 parts by weight of cement, 100 parts by weight of water, 0 or 0.2 parts by weight of setting and hardening retardant. Was blended, the time difference from the plain was determined using a twin-type conduction microcalorimeter, and the delay time was determined from the calibration curve determined by the cement setting test method of JIS R-5201.

As is clear from the table, Examples 1 to 7 all show an improvement in the setting delay at high temperatures as compared with plain (no admixture added). On the other hand, in Comparative Examples 1 to 4, the setting retarder of the setting hardening retardant is too large (setting time is slower than 100 minutes), so that setting at high temperature is improved, but setting delay at 20 ° C. is large. There is a practical problem.

In Comparative Example 5, since the amount of the setting and curing retarder was small, the setting at high temperatures was not improved. In Comparative Example 6, the setting at a high temperature was improved because the amount of the setting and curing retarder was too large, but the setting at 20 ° C. was slow, which was problematic. Comparative Example 7 is an example in which a cellulose ether having a long setting time was used in place of the setting hardening retarder. However, the setting at high temperatures was not improved, the setting at 20 ° C. was slow, and the cellulose ether of the present invention was used. This indicates that it cannot be used as a cure retarder.

Examples 8 to 9 and Comparative Examples 8 to 9 In the following concrete, the setting hardening retarder d in the amounts shown in Table 2 and 60 parts by weight of a water-soluble cellulose ether (same as the previous example) and an antifoaming agent ( Same as above) 10 parts by weight of an admixture was added at a rate of 0.35 kg / m ³ and kneaded. For each sample obtained, the slump, air volume, kneading temperature, dust concentration, and compressive strength were as follows. When measured by the method, the results shown in Table 2 were obtained.

-Materials used for concrete Cement: ordinary Portland cement (manufactured by Nippon Cement Co., Ltd.) Fine aggregate: sand with a maximum particle size of 5 mm, from Shimogakugawa, Arai City, water absorption 2.29%, specific gravity 2.57, coarse grain ratio 2.81 coarse aggregate : Crushed stone with maximum particle size of 20mm, from Shimogakugawa, Arai City,
Water absorption 2.05%, specific gravity 2.61, coarse grain ratio 6.62 Quick binder: Denkanatomic Type 5 (manufactured by Denki Kagaku Kogyo Co., Ltd.) ・ Concrete blending [unit amount (kg / m ³ )] Water (tap water): 210, cement: 350, fine aggregate: 711, quick setting agent: cement x 0.06, admixture: 0.35, water / cement ratio: 60
%, S / a (fine aggregate ratio): 58%.

-Test method 1) Slump: In accordance with JIS A 1101.

2) Air volume: According to JIS A 1128.

3) Dust concentration: In a simulated tunnel of 2.5 m in height, 3.5 m in width and 5.0 m in depth, a spray gun lead gun (manufactured by Pribrico) from a place 1 m away from the wall 4 m from the entrance. cylinder, capacitive 200 spraying pressure: blown obliquely upward wall under conditions of 2.5~3.0kg / cm ^2. After the start of spraying, block the entrance and exit of the tunnel, and measure with a dust concentration meter (manufactured by Shibata Scientific Machinery Co., Ltd.) (counts / minute) 1 m from the entrance of the tunnel (3 m from the spraying location) and 1 m away from the wall. did.

4) Compressive strength: A cylindrical core was cut out from each sample every 1, 7, and 28 days and measured.

As is clear from Table 2, in all of Examples 8 to 9 compared with plain (without admixture), the early development of the initial strength (wood age 1 day) was earlier even at a concrete temperature as high as about 30 ° C. Good adhesion to the sprayed surface. Also, the dust concentration is less than half that of plain.

On the other hand, in Comparative Example 8, since the amount of the retarder was small, the initial strength was low. In Comparative Example 9, a water-soluble cellulose ether was blended as a retarder, but the initial strength was slow to develop because it did not act on the quick-linking agent blending system. The results obtained with these concretes correspond well to the results obtained with the cement paste.

(Effect of the Invention) The admixture for the wet spraying concrete method according to the present invention improves the delay in setting at high temperatures in summertime, which has conventionally been a problem, and improves the adhesion to the sprayed surface.

[Brief description of the drawings]

The drawings are all for explaining the behavior of the admixture of the present invention at high temperatures, and FIG. 1 shows the admixture in combination with the quick-setting additive (100 parts by weight of cement, 70 parts by weight of water, 6 parts by weight of the quick-setting agent). Temperature (horizontal axis) at 0, 0.1 or 0.3 parts by weight of dust reducing agent
And the setting time (vertical axis) according to the Vicat needle method. FIG. 2 shows the temperature (horizontal axis) and the setting time (vertical axis) in the case of cement alone, cement + quick setting agent and quick setting agent alone. )
FIG. 3 is a schematic diagram showing a setting state at room temperature and at a high temperature in a mixed system of cement and quick-setting agent.

Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FI // C04B 103: 22 103: 44 103: 50 (72) Inventor Yasuaki Muto 28, Nishifukushima, Oji, Kushiro-mura, Nakakushiro-gun, Niigata Shin-Etsu Chemical Co., Ltd. (56) References JP-A-58-15056 (JP, A) JP-A-59-141448 (JP, A) JP-A-2-208251 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) C04B 24/18 C04B 24/04-24/06 C04B 24/38 C04B 24/24 C04B 103: 22 C04B 103: 44 C04B 103: 50

Claims (1)

(57) [Claims] (1) 5 to 40% by weight of a setting retarder having a setting time difference of 20 to 100 minutes with a plain at 20 ° C. calorie meter; (B) 40 to 95% by weight of a water-soluble cellulose ether % And (c) a defoamer of 0 to 20% by weight.