JP2972080B2 - Lightweight soil cement for underwater construction - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lightweight soil cement for underwater construction, which is used as a construction material for artificial ground materials when constructing artificial islands, constructing quays and seawalls and repairing them.

[0002]

2. Description of the Related Art Conventionally, embankments have been buried in water for the construction of artificial islands for effective use of marine space, and the construction and repair of quays and seawalls.

[0003] In order to stabilize the ground such as artificial islands at an early stage, there is a construction method of burying earth and sand in a closed space and deeply mixing cement or the like to improve the ground. In this method, since cement is added later, there is a drawback that uniform and stable ground cannot be obtained.

[0004] On the other hand, there is a method in which water is previously mixed with cement, sand or earth and sand, viscosity, etc., and the mixture is poured into water as an underwater embankment material.
We call it soil cement.) However, this method has a problem that fine particles contained in sand, earth and sand, and cement are separated at the time of construction and pollute water quality because the material has no adhesive force.

On the other hand, adding a water-soluble cellulose ether as a thickener to soil cement [The 41st Annual Meeting of the Japan Society of Civil Engineers (November 1986) 225,
Page 226, "Study on Underwater Casting Method of Soil Cement (Part 1)", Obayashi Corporation; and Injection of underwater embankment material mixed with water-soluble polyacrylamide and kneaded (Japanese Patent Laid-Open No. 2-69341) ) Has been done.

[0006] However, simply adding a thickener increases the unit volume weight to a specific gravity of about 1.4 t / m ³ or more, and increases the earth pressure due to these soil cements. This could cause land subsidence.

[0007] On the other hand, there is a lightening device in which a thickener and a foaming agent are combined to reduce the weight (Japanese Unexamined Patent Publication No. Hei.
106224). However, when this soil cement is cast, there are many entrained air bubbles due to the thickener, and since this is entrapment air, the air cement has a relatively large particle size unlike air bubbles caused by the foaming agent. For this reason, at the time of casting, fine particles such as cement were separated due to the rise of the air bubbles, causing turbidity. In addition, the amount of entrained bubbles differs depending on the stirring conditions and the material properties such as earth and sand and clay used, and it is difficult to control the bubbles and specific gravity.

[0008]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems, to be lightweight, excellent in workability, less in breathing, pumpable, and less turbid at the time of submerged casting. It is an object of the present invention to provide a lightweight soil cement for underwater construction, which has no problem of land subsidence.

[0009]

To achieve the above object, the gist of the present invention is to add at least a thickening agent, an antifoaming agent and a foaming agent to a soil cement and knead them. Underwater construction lightweight soil cement manufactured by the company.

According to a second aspect of the present invention, in the lightweight soil cement for underwater construction according to the first aspect, the defoaming agent is represented by the following general formula (I):

Embedded image Acetylene glycol derivative having the following general formula (II):

Embedded image And at least one compound selected from the group consisting of polyoxyethylene / polyoxypropylene block polymers having

According to a third aspect of the present invention, in the lightweight soil cement for underwater construction according to the first or second aspect, a nonionic water-soluble cellulose ether is used as a thickener.

The lightweight soil cement for underwater work according to the present invention is a thickening agent, a foaming agent and a defoaming agent for a soil cement containing a hydraulic powder material such as cement, earth and sand, sand, clay and water. It can be obtained by adding a foaming agent, kneading and producing.

The hydraulic powdery substances contained in the above-mentioned soil cement include 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, One type or a mixture of two or more types selected from silica cement, fly ash cement), special cement (alumina cement, expanded cement) and the like can be mentioned.
The clay component contained in the above soil cement is clayey soil,
Examples include clay minerals such as bentonite and masa earth. The mixing ratio of the hydraulic powder material varies depending on the required strength, but is about 50 to 400 kg / m ³ .

In order to suppress turbidity during casting in water and to prevent separation of cement binder, a cement-based thickener is necessary. The present inventors have studied various thickeners and found that the material separation resistance and good material separation resistance were improved. It has been concluded that nonionic cellulose ethers are preferred to maintain fluidity (soil cements with water-soluble polyacrylamide have poor fluidity). Examples of the nonionic cellulose ether include alkyl cellulose such as methyl cellulose (MC); hydroxyalkyl cellulose such as hydroxyethyl cellulose (HEC) and hydroxypropyl cellulose (HPC); and hydroxyethyl methyl cellulose (HEMC) and hydroxypropyl methyl cellulose (HPMC). , Hydroxyethylethylcellulose (H
And hydroxyalkylalkylcellulose such as EEC). Of these, hydroxyalkylcellulose and hydroxyalkylalkylcellulose are preferable. These can be used alone or as a mixture of two or more. The viscosity is not particularly limited, but it is desirable that the 1% viscosity be 100 to 50,000 cP. If the viscosity is 100 cP or less, the adhesive strength required for preventing turbidity during casting in water cannot be obtained. Also, 50,000
Above cP, economical industrial production is difficult. further,
An appropriate amount of addition is 0.5 to 7 kg / m ³ .

For the purpose of further increasing the fluidity, lowering the water-cement ratio, and increasing the strength, water reducing agents, high-performance water reducing agents, AE water reducing agents, and the like can be used. Examples of the water reducing agent include a highly condensed triazine compound, a formalin condensate of melamine sulfonate, a polycarboxylate derivative, a modified lignin sulfonate compound, an aminosulfonic acid polymer compound, and a formalin naphthalene sulfonate. Condensates, isoprene-based compounds, and the like, among which highly condensed triazine-based compounds [NL-4000
(Manufactured by Pozoris), a formalin condensate of melamine sulfonate [SMF (manufactured by Nissan Chemical Industries)], a polycarboxylate derivative [SP-8 (manufactured by Pozoris)], a modified lignin sulfonate compound [ SP-9 (manufactured by Pozzolith) and an isoprene-based compound [Dynaflow (manufactured by Nippon Synthetic Rubber)] are preferred in combination with a nonionic cellulose ether because a relatively small amount of the compound is excellent in water reducing effect.

In order to reduce the weight and reduce the amount of land subsidence, it is necessary to add a foaming agent. As the foaming agent, those generally used in air mortar, cement milk and the like are used. Possible products include animal proteins (such as Glufoam (manufactured by Sun Orient Chemical)), alkyl allyl sulfonates (such as manufactured by Takemoto Yushi), and surfactants (such as escort (manufactured by Manol)). The addition amount varies depending on the required specific gravity, but about 10 to 300 L is used as air bubbles.

In the present invention, an antifoaming agent is used which eliminates air bubbles caused by the thickener and does not affect the air bubbles caused by the foaming agent.

The present inventors have conducted intensive studies and as a result, in particular,
The following general formula (I)

Embedded image Acetylene glycol derivative having the following general formula (II):

Embedded image At least one compound selected from the group consisting of polyoxyethylene / polyoxypropylene block polymers having the following formula:

Either one of the acetylene glycol derivative having the general formula (I) and the polyoxyethylene / polyoxypropylene block polymer having the general formula (II) may be used alone, and both may be used. It can also be used. In addition, the above general formulas (I) and (II)
Represents a plurality of compounds, and it is a matter of course that one or more compounds of the general formula (I) and the compound of the general formula (II) can be selected and used in combination.

The acetylene glycol derivative is 2,4,4
7,9-tetramethyl-5-decyne-4,7-diol with ethylene oxide, which is represented by the above general formula, and has various performances depending on the number of moles of ethylene oxide added (m + n). Can be synthesized. This is because, when the addition mole number is low, the solubility in water is low. Therefore, the addition mole number is preferably 1 to 20, and when it is less than 1, the solubility in water is small and the defoaming performance is poor. . If the number of moles exceeds 20, the solubility in water is high, but the soil-cement type is inferior in defoaming performance. More preferably, the number of moles to be added is 2 to 15.

The polyoxyethylene-polypropylene block polymer is represented by the following general formula:
Ethylene oxide occupying 8% by weight or less in total molecules,
It is preferable that the molecular weight of the polypropylene glycol as the hydrophobic group is 3,500 or more. Outside of these ranges, the use of the present invention is inferior in defoaming performance, and has the drawback that the effect is not exhibited unless it is added in a large amount.

[0022]

EXAMPLES Examples and comparative examples of the present invention are described below, but the present invention is not limited to these examples and comparative examples.

Examples 1 to 3 and Comparative Examples 1 to 6 Underwater embankment materials composed of the following components 1 to 5 were blended according to the ratio of 6 and kneaded according to the method of 7. ~
12． Various tests were conducted. The amount of the defoamer added in each example is as shown in Table 1. Table 1 shows the results.

1. Thickener 1) Nonionic cellulose ether: hydroxypropylmethylcellulose (1% viscosity: 6,500 cP, manufactured by Shin-Etsu Chemical Co., Ltd., abbreviated as HPMC in the table). 2) Ionic cellulose ether: carboxymethyl cellulose (1% viscosity: 5,000 cP, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., abbreviated as CMC in the table). 2. Antifoaming agent: 1) Acetylene glycol derivative: Ethylene oxide having an added mole number of 3.5 moles (abbreviated as AG in the table). 2) Polyoxyethylene / polypropylene block polymer: ethylene oxide 3.0% by weight Polypropylene glycol having a polymerization degree of 15,500 (abbreviated as PEPP in the table). 3) Tributyl phosphate: C ₁₂ H ₂₇ O ₄ P (reagent primary, abbreviated as TBP in the table). 3. Cement: Blast furnace cement B type (manufactured by Nippon Cement Co., Ltd.). 4. Cohesive soil: Cohesive soil from Niigata (85% or less of silt content)
(85% of 0.02 mm or less)). 5. Foaming agent: surfactant type, Sumishield A (manufactured by Sumitomo Cement). 6. Blending water Fill material: all cement (by a foaming agent) 120 kg Clay 300kg thickener 4.0kg seawater 700kg bubbles 150L or more is the amount per soil cement 1 m ^3. 7. 5. Mixing of underwater embankment material: Of the above materials, a cement and a thickener were put into a Hobart mixer, mixed for 30 seconds, then water and a viscous soil were added, and after mixing for 3 minutes, various measurements were performed. 8. Funnel viscosity: Measured according to API RP13B (time of efflux from funnel cone). 9. Breathing: According to the standards of the Japan Society of Civil Engineers, the method for testing the breathing rate and expansion rate of inflow mortar of prepacked concrete. Ten. Underwater separation resistance of underwater embankment material: Underwater non-separable concrete manual, Appendix 1, Testing of underwater non-separable concrete, Separation resistance test in water (suspended material / pH
Measurement test). (Put 800 ml of water in a beaker, and put 300 g of underwater embankment material.
ml was taken and the suspended material, pH was measured). 11． Pumpability: 8. Using the underwater embankment material obtained in (1), the pumping state of the pumping pump when pumping 50 L / min at a pumping rate (tube pump) was determined according to the following evaluation criteria. ◎: extremely good ○: good △: slightly difficult to discharge ×: difficult to discharge (due to aggregate sedimentation, etc.)

[0025]

[Table 1]

As is clear from Table 1, Examples 1 to 3
Are all excellent in prevention of turbidity in water, fluidity, pumpability, and low specific gravity. On the other hand, Comparative Example 1 was inferior in pumping property because no thickener was added, turbidity was large, and breathing was large. Comparative Example 2 is a case where CMC, which is an ionic cellulose ether, was added as a thickening agent. In the case of a cement system, there was no thickening, so that there was much turbidity and much bleeding. Comparative Examples 3 and 4 are cases in which TBP was used as the defoaming agent. When trying to eliminate entrained bubbles, even bubbles caused by the foaming agent were erased, and the specific gravity was increased. On the other hand, if the addition amount is small, the entrained bubbles cannot be eliminated, and the turbidity increases due to the floating of the fine particles with the relatively large bubbles. As described above, when the antifoaming agent of the present invention is not used, it is difficult to remove only the entrained bubbles without affecting the foaming agent. Comparative Example 5 is a case where a foaming agent is not used, and the specific gravity becomes large. Comparative Example 6 is a case where no antifoaming agent is used, and has many entrained air bubbles, and accordingly, turbidity increases.

[0027]

As is apparent from the above description, according to the first aspect of the present invention, a soil cement in which a hydraulic powder material such as cement, earth and sand, clay, water and the like are mixed as an underwater embankment material. By adding a thickener, defoaming agent and foaming agent, kneading and using the manufactured product, there is no breathing, and water pollution and strength deterioration due to fine particle separation during casting in water are reduced. The present invention provides a lightweight soil cement for underwater construction, which has a small specific amount, eliminates entrapped air bubbles by using an antifoaming agent, does not adversely affect the foaming agent, and has a predetermined specific gravity.

According to the second aspect of the present invention, the entrained bubbles can be further effectively eliminated, and the foaming agent is not adversely affected. According to the invention of claim 3, it is possible to effectively increase the viscosity of the underwater construction lightweight soil cement, and it is possible to further reduce the turbidity during breathing and underwater casting.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C04B 24/38 C04B 24/38 D C09K 17/44 C09K 17/44 P 17/48 17/48 P 17/50 17/50 P // C04B 111: 70 C09K 103: 00 (56) Reference JP-A-6-298559 (JP, A) JP-A 64-33043 (JP, A) JP-A-5-106224 (JP, A) JP Hei 2-69341 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C04B 28/02 C04B 24/02 C04B 24/32 C04B 24/38 C04B 111: 70

Claims (3)

(57) [Claims] 1. A lightweight soil cement for underwater construction, which is produced by adding at least a thickener, a defoaming agent and a foaming agent to a soil cement and kneading the mixture. 2. An antifoaming agent having the following general formula (I): An acetylene glycol derivative having the following general formula (II): The lightweight soil cement for underwater construction according to claim 1, wherein the soil cement is at least one compound selected from the group consisting of a polyoxyethylene / polyoxypropylene block polymer having the following. 3. The method according to claim 1, wherein a nonionic water-soluble cellulose ether is used as the thickener.
Lightweight soil cement for underwater construction.