JP2620564B2 - Waterproofing method for underground concrete walls - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a construction method for stopping water from an underground concrete wall of a building.

[Conventional technology]

With the increase in the size of buildings, equipment is often installed to make effective use of the underground. However, in the concrete wall of a building having an underground floor, intrusion of groundwater is a serious problem. Particularly, in a telephone station where communication equipment is installed on a basement floor, water leakage has a great effect on communication equipment.

Normally, groundwater that has invaded from cracks in concrete walls and the like is drained to the ground by a pump, because there was no effective water stoppage method.

Slightly, (1) a scaffold is installed inside the concrete wall of the basement floor where water is leaking, and a plastic injection material is directly injected into the leak crack portion, or a cement coating is applied directly to the leak location. ing. (2) It has been considered that the outside of the basement floor is cut using a mountain buckle, a scaffold is built in the cut, and an asphalt waterproofing agent or the like is applied to the concrete outer wall surface.

[Problems to be solved by the invention]

However, the method (2) requires installation of a mountain retaining and excavation and excavation, resulting in large-scale civil engineering work, which is extremely economically inferior.

In this respect, the method (1) is more economical than the method (2), however, it stops at a partial water leakage location and cannot stop the whole water. Stopping water from a severely leaked area may cause leakage at other areas. Moreover, in the case of a cement coating,
Water stoppage against cracks is incomplete. Furthermore, in the construction, a space for scaffolding must be secured near the inner surface of the concrete wall on the basement floor, and dust and the like accompanying indoor work may interfere with the accommodation equipment, for example, the communication equipment. Further, when the basement floor is a double wall, it is necessary to thoroughly and restore the inner wall.

Therefore, a main object of the present invention is to provide a water stopping method which is excellent in economy of construction, has no adverse effect on accommodation equipment in a basement floor, and can reliably achieve water stopping of the entire concrete wall.

[Means for solving the problem]

The present invention for solving the above problems, towards its wall from the installation injectable rod on the outer surface side of the concrete wall of the underground building with a risk of leakage from or leakage, cement m ³ per 200kg The admixture containing the above, and containing active silica and forming a calcium silicate gel in contact with calcium hydroxide is a weight ratio of 3/100 to the cement.
Injecting the cement milk injection material containing the above, the active silica and calcium hydroxide eluted from the cement are allowed to land and fill a water-insoluble calcium silicate gel in the void portion of the concrete wall to achieve water stoppage. It is characterized by the following.

[Action]

The principle of the waterproofing method according to the present invention will be described with reference to FIG. 6. The concrete wall 1A of the underground building shown in FIG.
In the case where there is a void portion and water is leaked, the cement milk injection material G according to the present invention is applied to the concrete wall 1A.
When injected outside, the activated silica in the injected material reacts with calcium hydroxide eluted from the cement as shown in the following formula (1) to produce a water-insoluble calcium silicate gel.

SiO ₂ + Ca (OH) ₂ → CaSiO ₃ + H ₂ O (1) The calcium silicate gel produced by this reaction is accompanied by groundwater from outside the concrete wall 1A and enters the concrete void, where it is landed (( B) (See FIG. B)), unreacted activated silica and calcium hydroxide enter the concrete cavity together with the groundwater and react when entering the room through the wall to form calcium silicate gel and land on the concrete cavity. It grows while repeating the reaction, and after a few days, the voids are completely filled and the water is stopped (see FIG. (C)).

It has been found that such water stoppage occurs in all concrete voids into which groundwater flows, even if the voids are not visible. Therefore, water stoppage of the entire wall surface can be achieved instead of partial water stoppage.

On the other hand, in the present invention, since water is stopped by injecting an injection material outside the concrete wall,
Unlike the case of working in a basement room, all the effects of dust and the like on the equipment housed in the room are eliminated. Further, in terms of workability, since the method is based on the injection method from the ground, a ridge is unnecessary and the setup time is short, and in the preferred embodiment of the present invention, the stop per unit time is performed because of the high pressure injection stirring injection method. The water improvement area can be enlarged and efficient.

On the other hand, it is conceivable to perform the injection material by general injection at a low pressure and a low flow rate.However, it has a long construction time, and the pressure due to the injection acts on the concrete wall surface, causing a structural mechanical hindrance. Due to uneven distribution, it is difficult to stop the entire wall. On the other hand, according to the high-pressure injection-stirring-injection method, all of these points can be solved.

In addition, when the injection is performed outside the concrete wall according to the present invention, the ground of the injection is strengthened, and the above-described reaction causes the injection area to also act as a water-stop wall, thereby exhibiting a further water-stop effect.

[Specific configuration of the invention]

 Hereinafter, the present invention will be described in more detail.

First, the construction example of the method of the present invention will be described with reference to FIGS. 1 and 2. When the target building 1 has basement floors Z-1 and Z-2 and is surrounded by a concrete outer wall 1A, the outer wall 1A An injection machine 2 is installed on the ground above, and an injection material is injected from the injection rod 3 gripped by the injection machine 2 for a predetermined length. In addition, as shown in FIG. 2, the injection is repeated at a predetermined pitch along the outer wall 1A so that the injection area overlaps in plan view.

For injection, the injection rod 3 is usually inserted and installed to a predetermined depth, and the cement 4 and the admixture 5 according to the present invention, and if necessary, other additives such as a setting retarder such as “Pozzolith” (trade name) are also used. , The mixture is stirred into a grout mixer 6 and mixed with a predetermined amount of water. Then, the mixture is fed by a grout pump 7, and the injection material is supplied to the injection rod 3 via a hose 8.
Injection is performed by an injection nozzle (not shown) provided at the tip portion while injecting in a high pressure and high speed state, and pulling up while rotating the injection rod 3 in the circumferential direction.

As the admixture according to the present invention, all that contain active silica and form a calcium silicate gel upon contact (reaction) with calcium hydroxide are used. As this example, "Beston A" (manufactured by Odakyu Construction Materials Beston Co., Ltd.) can be preferably used, and the composition example is as shown in Table 1. The table also shows the chemical composition of the cement.

The injection material according to the present invention is a cement milk type,
Cement 1m ³ per, 200kg more than ~1000kg, especially 250 to 600
It is preferable to use a weight of kg. If the amount of cement is small, the water stopping effect is low. The admixture is used in an amount of at least 3 parts by weight, preferably at least 4.5 parts by weight, based on 100 parts by weight of cement. Although there is no upper limit, even if it is added in an amount of 10 parts by weight or more, the effect of improving water stoppage is not observed. Also, in the injection material,
When the setting retardant is added, unreacted particles ride on the flow of groundwater and enter the concrete void, thereby improving the water stopping effect. For example, in the case of "Pozzolith 89" (trade name), it is preferable to add 0.5 to 1.2 parts by weight to 100 parts by weight of cement.

On the other hand, the injection method is preferably a high-pressure injection stirring method rather than a general injection method. Since this method itself is known as a known so-called jet grout method, CCP method, JSG method, column jet method, etc., it will not be described in detail. The injection pressure is 50 kgf / cm ² G or more, particularly 100 kgf / cm ² G or more, and the injection is performed at a flow rate of 50 m / sec, particularly 100 m / sec or more from the small-diameter nozzle.

〔Example〕

 Hereinafter, the effects of the present invention will be clarified by examples.

(Example 1) Five box-shaped concrete boxes (the unit of a numerical value is mm) shown in FIGS. 3 and 4 are prepared, and a waterproofing agent having the composition shown in FIG. 5 is put therein. At the same time, water was supplied from a water supply hose so that a pressure of 0.3 kgf / cm ² G constantly applied, and the state of water leakage from the concrete outer wall was visually observed for 90 days.

Judgment of the water leakage situation was as follows. That is, the following evaluation criteria are given for each face (four faces) of the concrete box, and the score in parentheses is given to a portion corresponding to the criteria.

Grade A: Spouted from the leak location. (54 points) B grade: It is flowing out of the leak location. (27 points) Grade C: Water leakage is seeping and dripping. (9
Point) D grade: Water leakage is seeping but not dripping.
(3 points) E grade: Concrete surface is wet. (1 point) Therefore, at a certain point in time, in one surface, if there are two places of C clade (9 × 2 = 18 points) and one place of D grade, (9 points × 2 = 18 points) (Points) + (3 points × 1 = 3 points) = 21 points, the other three planes are similarly evaluated, and the evaluation points of the total of the four planes are given. With respect to this total evaluation point, the initial evaluation point was set to 100%, and the change of the evaluation point over time (change in percentage based on the initial evaluation point) was examined. FIG. 5 shows the result.

According to the results, it is found that the cement (C) amount of 300 kg / m ³ or more and “Beston” of 6% or 10% achieve remarkable water stopping after about one month. Even when the amount of cement (C) was 300 kg / m ³ and “Beston” was 3%, excellent and satisfactory water-stopping properties were obtained.

(Example 2) At a certain local telephone office in Tokyo having a concrete outer wall from the ground surface to a depth of 26.7 m, a waterproof material was injected in the manner shown in FIGS. 1 and 2. The injection length was set from 11.7 m to 26.7 m below the ground surface, and the injection rod gap pitch was set at 600 mm. The mixture of the injection material is 450 kg of cement and 27 kg of Veston
(6% with respect to the cement amount), 792 liters of water, and the injection rate was 20 to 40 liters / min. The injection rod was rotated at about 20 rpm, and injection was performed while stepping up by 10 cm per step.

As a result, after 30 days, water leakage into the room, which would be a hindrance, was completely stopped.

〔The invention's effect〕

As described above, according to the present invention, not only economical water stoppage can be performed, but also water stoppage is extremely high,
In addition, since the construction is performed from outside the room, effects such as the effect on the accommodation equipment in the room can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of an embodiment of the process of the present invention, FIG. 2 is a plan view thereof, FIG. 3 is a vertical sectional view of a specimen in an embodiment, and FIG. IV-IV line view, FIG. 5 is a diagram showing a change in water leakage over time in the water stopping effect experiment in the embodiment, and FIG. 6 is an explanatory diagram of a water stopping principle according to the present invention. 1 ... Target building, 1A ... Outer wall, 2 ... Injector, 3 ... Injection rod, 4 ... Cement, 5 ... Admixer.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Koichi Izawa 1-1-6 Uchisaiwai-cho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Eisuke Sako Inventor 1-1-6 Uchisaiwai-cho, Chiyoda-ku, Tokyo Japan Within Telegraph and Telephone Co., Ltd. (72) Inventor Hiroyuki Shimoe Within 1-6, Uchisaiwai-cho, Chiyoda-ku, Tokyo Within Nippon Telegraph and Telephone Co., Ltd. Nippon Soil Industry Co., Ltd. Tokyo Branch (72) Inventor Morihiro Okamoto 4-32-22 Nishi Shinjuku, Shinjuku-ku, Tokyo Odakyu Construction Materials Beston Co., Ltd. (72) Inventor Eiichi Kimura 5-8 Akihabara, Taito-ku, Tokyo No. NTT Building Research Institute Co., Ltd. (72) Inventor Mutsuo Ishikawa 2-2-2 Otemachi, Chiyoda-ku, Tokyo NTT・ TIT ・ Urban Development Co., Ltd. (56) References JP-B-53-1571

Claims (1)

(57) [Claims] 1. A toward the wall from the injection rod installed on the outer surface side of the concrete wall of the underground building with a risk of leakage from or leakage, cement contains more than m ³ per 200 kg, and active silica An admixture containing calcium hydroxide, which is in contact with calcium hydroxide to form a calcium silicate gel, is injected with a cement milk injection material containing a weight ratio of 3/100 or more to the cement, and the activated silica and calcium hydroxide eluted from the cement. A water stopping method for an underground concrete wall, wherein a water-insoluble calcium silicate gel is landed and filled in a void portion of the concollite wall by a reaction to stop water.