JP2812822B2 - Self-hardening mud - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cast-in-place pile, ground improvement,
The present invention relates to self-hardening mud used as a drilling mud when constructing an underground mud solidified wall or various foundations.

[0002]

2. Description of the Related Art Conventionally, self-hardening mud used as drilling mud when constructing an underground wall or the like includes 1) clay mortar mud, 2) bentonite cement slurry, and 3) addition of nonionic water-soluble cellulose ether. Mud is known.

[0003] The clay mortar mud of 1) is obtained by adding a solidifying material such as cement to a clay slurry obtained by dispersing clay in water, and further mixing and kneading sand depending on the use to impart thixotropic properties. is there. The bentonite cement slurry of 2) is obtained by adding and kneading a solidifying material such as cement to a bentonite slurry obtained by dispersing bentonite in water to give thixotropic properties. When making the self-hardening muddy water of the above 1) and 2), the clay or bentonite particles are negatively charged in water, and the particles mutually repel each other to swell and suspend, so that a stable state is maintained. I have. However, when a solidifying material such as cement is added, cations such as Ca ²⁺ resulting therefrom neutralize the charge of the clay particles and bentonite particles and weaken the repulsive force of the particles, and as a result, the particles aggregate and Due to gelation, bleeding occurred and the amount of dehydration increased. When mixing seawater, Na ⁺ , C
Since a ^2+, etc. Mg ²⁺ to the effects similar to the above, further adversely affect. For example, breathing clay mortar mud is 8-12%,
Breathing of bentonite cement slurry is 5-8
%, And both clay mortar muddy water and bentonite cement slurry have large amounts of dehydration (Q ₃₀ = 250
~ 300ml).

[0004] The nonionic water-soluble cellulose ether-added mud 3) imparts thixotropic property by the cellulose ether and clay particles. However, unlike the above 1) and 2), the substance that imparts viscosity is nonionic. Since it is a water-soluble cellulose ether and has no ionicity, it is stable even when it comes into contact with cations such as Ca ²⁺ , Na ⁺ in seawater due to a solidifying material such as cement, and JP-A-63-21248. As can be seen in the gazette, both the amount of breathing and the amount of dehydration are smaller than those in 1) and 2). However, for nonionic water-soluble cellulose ethers,
There is foaming property with its surface activity. This property has an adverse effect such as a decrease in the specific gravity of the muddy water and poor pumping of the muddy water as an increase in the foam in the muddy water. For this reason, an antifoaming agent is used in combination, but it is not perfect, and a special device is required for a stirrer, a pump, and the like. Thus, conventionally,
There is virtually no self-hardening mud that is stable to cations such as Ca ²⁺ , has no foaming properties, and is easy to handle, and it has been strongly desired to realize such self-hardening mud.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a self-hardening mud which is stable to Ca ²⁺ by adding a solidifying agent and has no foaming property, such as a nonionic water-soluble cellulose ether. Things.

[0006]

The self-hardening mud according to the present invention is obtained by mixing a solidified material such as bentonite or clay in water with a solidifying material such as cement or water glass and welan gum. It is.

[0007]

[Action] Welan gum, a type of ionic water-soluble polysaccharide, exhibits a unique thixotropic property when dissolved in water. This welan gum aqueous solution is stable against salts and does not gel or aggregate. When this is added to a slurry of bentonite, clay, or the like, welan gum has a suspending property, so that these solids are suspended and stabilized to reduce the amount of dehydration. Also, since welan gum is stable against addition of salts, muddy water does not change and the amount of dehydration does not increase.

[0008] The term "S-130" in the above water-soluble polysaccharides is known as Welan Gum, and is an alkali gene (Alca) which produces a heteropolysaccharide.
ligenes) means an extracellular gum produced by complete culture fermentation under various conditions using a medium containing a carbohydrate capable of fermenting the bacterium ATCC 31555 belonging to the genus Ligenes), a nitrogen source and other appropriate nutrients. The amount of welan gum added in the present invention varies depending on the degree of contamination of seawater, etc., and the amount of cement or the like as a solidifying material, but is 0.01 to 5 parts by weight, particularly 0.05 to 2 parts by weight per 100 parts by weight of kneading water. It is desirable.

Examples of the solidified material used in the present invention include cements such as ordinary Portland cement, blast furnace cement and fly ash cement, water glass, and the like. The amount added depends on the strength required for the solidified product. 1 to 80 parts by weight, especially 5 parts by weight, per 100 parts by weight of kneading water
It is desirable that the amount be 50 parts by weight.

The solids dispersed in the slurry include bentonite, kaolin, attapulgite, sebiolite, powdered clay and the like. The amount of the solids varies depending on the required muddy water performance. It is preferable that the amount be 5 parts by weight, especially 5 to 50 parts by weight.

[0011]

EXAMPLES Hereinafter, specific embodiments of the present invention will be described with reference to Examples and Comparative Examples. Examples 1-2, Comparative Examples 1-3 1) Kneading water: tap water 2) Clay: Kasaoka / China clay 3) Cement: Blast furnace cement type B (manufactured by Nippon Cement Co.) 4) Admixture: Welan gum (Merck Kelco) Nonionic cellulose ether: hydroxypropylmethylcellulose (hereinafter abbreviated as HPMC) Salt-resistant carboxymethylcellulose (hereinafter, salt-resistant CM)
C) (abbreviated as C) at the ratio shown in Table 1 at a rotational speed of 383 rpm.
Using a Hobart mixer, 10 minutes stirring 1 minute stirring 5 minutes stirring Kneading water + clay → (water + admixture) → cement → self-hardening muddy water The properties were measured by the following methods, and the results are shown in Table 1. 1) Specific gravity: Put 1000ml of muddy water into a 1000ml measuring cylinder and measure its weight. 2) Foaming rate: Cement added, specific gravity 5 minutes after initial addition,
Thereafter, the specific gravity after stirring for 25 minutes was defined as the specific gravity after stirring, and the foaming rate was calculated by the following equation. Foaming rate = {(initial specific gravity-specific gravity after stirring) / initial specific gravity} x 1
[0099] 3) Funnel viscosity: 500 ml of muddy water is placed in a funnel cone, and the time required to flow down is measured. 4) Dehydration amount: 500 ml of muddy water was put into a container of an API filtration tester, pressurized (3 kgf / cm ² ) with carbon dioxide gas, and the amount of filtered water (dehydration amount) after 30 minutes had elapsed was measured.

[0012]

[Table 1]

Comparative Examples 1 and 2 are examples in which HPMC which is a nonionic water-soluble cellulose ether is used. In Comparative Example 1, muddy water bubbles due to the foaming property of HPMC and cannot be used practically. Comparative Example 2 is an example in which an antifoaming agent is used in combination. However, even if an antifoaming agent is used, foaming is caused by long-time stirring, and special attention is required for a mixer, a transportation method, and the like, resulting in an increase in cost. Comparative Example 3 is an example using salt-resistant CMC,
It cannot be used for self-hardening muddy water due to agglomeration due to mixing of cement, a large amount of dehydration and poor mud wall performance. Examples 1 and 2
Is an example using welan gum, but does not agglomerate even when mixed with cement, has a small amount of dehydration, and is excellent in mud wall performance.
In addition, foaming does not occur even with long-time stirring, and it is easy to use in practical works.

[0014]

The self-hardening mud of the present invention is stable against cations (such as Ca ²⁺ and Fe ³⁺ ) in cement,
Excellent in fluidity, wall-forming properties, prevention of breathing, etc.
Therefore, not only the conventional drilling mud and the self-hardening mud are combined, but also the above properties are hardly affected by the compounding amount of the solidifying material such as cement, so that the required strength can be easily obtained by adjusting the compounding amount. be able to.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C09K 7/00-7/08 C04B 26/02-26/28

Claims (1)

(57) [Claims] 1. A self-hardening muddy water obtained by mixing a solidified material such as bentonite and clay in water with a solidifying material such as cement and water glass and welan gum.