JP2021036124A - Method of repairing plastered wall - Google Patents

Abstract

To provide a method of repairing a plastered wall with a short construction period while recovering the structural strength of the damaged plastered wall.SOLUTION: The method comprises: a gap widening step S1 that widens the gap generated between the outer peripheral member and the plastered wall and shapes the end face on the plastered wall side; an injection hole drilling step S2 in which a plurality of injection holes having a depth to the inside of the plastered wall are drilled at predetermined intervals along the extending direction of a crack generated in the plastered wall; a process of shaping the cross section of the crack; an injection step S3 to inject the repair material into the widened gap; and an external repair material injection step S4 in which the repair material is injected into the crack whose cross section is shaped and the injection hole.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method of repairing a damaged earthen plaster wall in a traditional wooden building.

As a method of repairing earthen plaster walls damaged by earthquakes, etc., if the damage is minor with an interlayer deformation angle of about 1/50 rad, only the damaged part is scraped off, divided into several layers, and a glass fiber net is sandwiched. There is a method of applying wall soil (Non-Patent Document 1). It is said that this repair method can obtain the same structural strength as the original plastered wall.

The method of repairing a plastered wall that has undergone a large deformation with an interlayer deformation angle of 1/10 rad or more is the same as when building a new building after removing all the existing wall soil and re-kneading it as wall soil to repair damaged piercing and Komai foundation. In most cases, the method of painting the wall was adopted according to the procedure described in (Non-Patent Document 2).

Naoki Kokubun, 4 outsiders, "Study on Earthquake Disaster Prevention Measures for Historical Towns, Part 7 Repair Methods and Effects of Architectural Institute of Japan", Architectural Institute of Japan Conference Academic Lecture Abstract (Kanto) September 2015, Japanese Architecture Architectural Institute of Japan, 2015, P495-P496, Takashi Yamanouchi, 4 outsiders, "Study on Earthquake Disaster Prevention Measures in Historical Towns, Part 8 Experimental Verification on Repair Effect of Earth-coated Walls with Major Deformation", Architectural Institute of Japan Conference Academic Lecture Abstracts (Kanto) 2015 9 Moon, Architectural Institute of Japan, 2015, P497-P498

By the way, in the repair method disclosed in Non-Patent Document 1, since the cracks generated on the wall surface are almost closed, it is difficult to inject the repair material into the cracks. Further, even when the repair material can be injected into the crack, the interface strength with the soil-coated wall base is small, the repaired portion is peeled off without being able to resist the shearing force, and the shearing strength cannot be exhibited. Therefore, with such a repair method, the structural strength of the plastered wall cannot be sufficiently restored.

Further, in the repair method disclosed in Non-Patent Document 2, the structural strength of the earth-coated wall is greatly restored, but after removing all the existing wall soil and re-kneading it as wall soil, the damaged piercing and Komai base are repaired. Since the walls are painted in the same procedure as when building a new building, it takes a considerable amount of time to finish. Therefore, it is difficult to adopt this method when it is necessary to recover immediately.

Therefore, an object of the present invention is to provide a method for repairing a soil-coated wall having a short construction period, which can restore the structural strength of the damaged soil-coated wall.

In order to achieve the above object, the method for repairing a plastered wall of the present invention includes a plurality of injections having a depth to the inside of the plastered wall at predetermined intervals along the extending direction of cracks generated in the plastered wall. It is characterized by comprising an injection hole drilling step of drilling a hole, a step of shaping a cross section of the crack, and an external repair material injection step of injecting a repair material into the shaped crack and the injection hole.

It is preferable that the external repair material injection step further includes an injection step of injecting the repair material into the gap formed between the outer peripheral member and the earth-coated wall.

It is preferable to further include a gap widening step in which the gap is widened and the end face on the earth-coated wall side is shaped in front of the external repair material injection step.

According to the present invention, it is possible to repair a plastered wall having a short construction period while greatly recovering the structural strength of the damaged plastered wall.

The flowchart of the work process of one Embodiment of the repair method of the earth-coated wall repair method of this invention. (A) is a front view showing steps (1) and steps (2) of an external repair step of a method for repairing a plastered wall, (b) is a plan sectional view, and (c) is a side sectional view. .. (A) is an enlarged plan sectional view of a gap widening portion in the step (1) of the external repair step of the earth-coated wall repair method, and (b) is an enlarged planar sectional view of a V-cut portion. (A) is a front view showing an external repair material injection process of a method of repairing a plastered wall, and (b) is a plan sectional view of the same. (A) is a front view showing a plastered wall that has been repaired by a method of repairing a plastered wall, and (b) is a cross-sectional view of the same side surface.

Hereinafter, the method for repairing the earthen plaster wall according to the present invention and the repair material used for the method will be described with reference to FIGS. 1 to 5 and Tables 1 and 2.

FIG. 1 is a flowchart of a work process according to an embodiment of a method for repairing a plastered wall according to the present invention. This earth-coated wall repair method is large, and includes a work process (external repair process: minor damage repair process) for repairing gaps that occur on the outer circumference of the earth-coated wall and for minor damage such as cracks that occur on the wall surface. , It is roughly divided into a work process (severe damage repair process) performed by combining an external repair process and a work process (internal repair process) for repairing severe damage reaching the inside of the wall. As the method for repairing the earthen plaster wall, a minor damage repair step, a severe damage repair step, and the like are appropriately selected depending on the damage condition of the earthen plaster wall.

[How to repair earthen plaster walls]
As described above, in the method of repairing the earthen plaster wall according to the present embodiment, the external repair step will be described. The external repair process includes a preparation process and an external repair material injection process. In addition, after the repair process is completed, the finishing process is performed. Hereinafter, each step will be described.

(External repair process)
The preparation process of the external repair process is divided into three processes (1), (2), and (3).
In the void widening step (FIG. 1: S1), which is the step (1) of the external repair step, the pillar 2 and the horizontal member 10 (base) as the outer peripheral member 1 are shown in each figure of FIG. 2 and FIG. 3 (a). 3. This is a step of widening the gap (gap) 30 formed between the earth-coated wall 20 and the beam 4 and the like. As shown in FIGS. 2 (b) and 2 (c), the earth-coated wall 20 includes a piercing 21, a Komai base 22 (intermediate bamboo 23, Komai bamboo 24), a rough wall 25 coated on these, and a rough wall 25. It consists of an intermediate coat 26 smeared on. In the gap widening step S1, the gap 30 is widened so that the repair material 50 can be smoothly injected into the gap 30. First, the wall soil 28 in the floating portion of the plaster wall 20 is removed. It is desirable that the wall soil 28 be reused as the repair material 50. By reusing the wall soil 28, the repair material 50 and the plastered wall 20 become familiar with each other. As shown in FIG. 3A, the gap 30 of the intermediate coating 26 portion is formed by scraping one corner portion and performing shaping work such as chamfering 32 to fill the gap 30 between the rough wall 25 and the pillar 2. It is preferable to improve the filling property of the repair material 50. The gap 30 between the rough wall 25 and the pillar 2 is widened 33 so that the width W is as uniform as possible.

The injection hole drilling step (FIG. 1: S2), which is the step (2) of the external repair step, is predetermined along the crack 31 with respect to the crack 31 on the surface of the earthen coating wall 20 as shown in each figure of FIG. This is a step of drilling injection holes 60, 60, ... Using an electric drill or the like, injection holes 60, 60, ... Are drilled in the cracks 31 on the surface of the earth-coated wall 20 at predetermined intervals to a depth in front of the penetration 21 and the Komai base 22. The intervals between the injection holes 60, 60, ... Are appropriately determined according to the length, depth, width and the like of the crack 31. The diameter of the injection hole 60 is preferably about 10 to 20 mm. Further, as shown in FIG. 3B, it is preferable that the crack 31 of the earth-coated wall 20 is shaved so as to have a V-shaped cross section and shaped (hereinafter referred to as V-cut 34).

The step (3) of the external repair step is an auxiliary step before the injection step, and prior to the injection of the repair material 50, compressed air is applied to the widened void 30 and its surroundings, the injection holes 60, 60, ... And its surroundings. It is preferable to send and clean, and to use, that is, apply a water absorption adjusting material (NS high flex or the like) for wall surface adjustment. Cleaning can prevent the repair material 50 from floating or peeling off. Specifically, as a means for applying the water absorption adjusting material, it can be applied, injected, or sprayed. As a result, it is possible to prevent the moisture of the applied repair material 50 from being suddenly absorbed by the earth-coated wall 20, prevent dry-out, and maintain the adhesive durability between the repair material 50 and the earth-coated wall 20 for a long period of time.

In the external repair material injection step (FIGS. 1: S3 and S4), as shown in each figure of FIG. 4, the outer peripheral portion of the earth-coated wall 20, that is, the widened void 30, and the crack 31 and the perforation formed in the earth-coated wall 20 This is a step of injecting the repair material 50 into the injection holes 60, 60, ... After the curing period of the water absorption adjusting material has elapsed, the repair material 50 is injected using a foot-operated pump, a manual pump, or the like. In the present embodiment, the repair material 50 contains rough wall soil and slaked lime (calcium carbonate) as main components, and a fluidizing agent such as a high-performance AE water reducing agent is added to secure the fluidity required for injection. It is preferable to reduce the shrinkage rate.

(Finishing process)
The finishing step is a step of finishing the surface of the earthen plaster wall 20 (see FIG. 5). Since the surface of the plaster wall 20 is a mixture of the repair material 50 and the old plaster wall, it is preferable to finish the entire surface of the plaster wall 20 to make the unevenness of the surface of the plaster wall 20 inconspicuous. .. It may be finished with an intermediate coat, or it may be finished with plaster or the like.

According to the present embodiment, the gap 30 formed between the outer peripheral member (horizontal member 10 such as the pillar 2, the base 3, and the beam 4) and the earth-coated wall 20 is widened, and the crack 31 of the earth-coated wall 20 is widened. Since the repair material 50 is injected into the crack 31 and the injection holes 60, 60, ..., The repair material 50 injected into the injection hole 60 and the earthen plaster wall 20 are engaged with each other. Shear deformation can be suppressed by the effect. Therefore, it is possible to repair the earthen plaster wall with a short construction period while greatly recovering the structural strength of the damaged earthen plaster wall 20.

[Repair material for plaster walls]
The repair material 50 used in the method for repairing the earth-coated wall 20 described above is a mixed material of rough wall soil, calcium hydroxide (slaked lime), and water. As the rough wall soil, clay for rough walls produced in Aichi Prefecture was used in this embodiment. Since calcium hydroxide has the same shear strength as when cement is used, the strength of the repair material 50 can be improved, and the strength of the repaired earth-coated wall 20 can be increased. If further strength increase is required, ordinary cement may be used instead of calcium hydroxide.

The rough wall soil of the repair material 50 and calcium hydroxide are in the range of 90: 10 to 50:50 in volume ratio. If the amount of rough wall soil is more than 90%, the strength of the repair material 50 is lowered, and if the amount of calcium hydroxide is more than 50%, the repair material 50 is kneaded and the properties are deteriorated. The mixed volume ratio of water is preferably 0.5 or less. If the volume ratio of water exceeds this value, the repair material 50 will sag, and the drying shrinkage will increase, and cracks will easily occur. Further, in order to sufficiently knead the repair material 50, it is advisable to add a fluidizing agent such as a high-performance AE water reducing agent.

The outline of each test to be applied to the examples is shown below.
[Experiment of repair materials for earthen plaster walls]
(Material test of repair material)
In selecting the repair material, the material test of the repair material was conducted. When selecting materials, plasterers who prepare repair materials on site must be familiar with the materials, and in addition to the main materials being traditional materials so that they can be applied to cultural properties, they must have sufficient strength. The condition was that the shrinkage was low and that there was fluidity that could be injected into the cracked part.

A length change test was conducted to confirm the characteristics of the repair material alone. In the length change test, the shrinkage rate was determined based on the inner dimensions (40 × 40 × 160 mm) of the mold.

The repair materials were 8 cases shown in Table 1 1-1 to 3-3. In each case, the main material was raw soil for rough walls, and the admixture for obtaining fluidity was a high-performance AE water reducing agent. There are three types of hardened material: no hardened material (rough wall soil alone), slaked lime, and ordinary cement. It was used as a parameter. Case 0 is a case without repair material.

(Length change test, strength test)
Table 2 shows the results of the length change test (shrinkage rate), compressive strength, and shear strength test at the age of 4 weeks. Each value is the average value of 3 specimens.

(1) Length change test The shrinkage rate was higher in the order of rough wall soil alone, slaked lime mixture, and cement mixture. The density of rough wall soil alone became higher than in other cases due to drying shrinkage.

(2) Strength test In order to confirm the strength of the repaired surface, a compression test using a standard specimen mold and a direct shear test of the repaired surface using a flat plate specimen were carried out (see Table 2). In a direct shear test, a specimen is placed in a shear box divided into upper and lower parts, and a horizontal force (shearing force) is applied to the upper box or the lower box in a vertically loaded state. At this time, the resistance force generated in the specimen is measured to obtain the relationship between the shear strength and shear stress of the soil and the shear displacement. The specimen of the direct shear test was molded by filling a wooden frame of 300 × 300 × 90 mm with a rough wall soil material, and then the center was cut into two parts and air-dried. The specimen was attached to the mold with a gap of about 4 mm in width simulating a crack, and the gap was filled with various repair materials. At that time, high flex was applied to both sides of the joint surface to adjust the water absorption. Case 0 is a single plate that is not divided into two. Since this experiment is a test to confirm the shear strength of the repaired surface, the force angle was set so that fracture would always occur at the joint.

According to previous studies, in the direct shear test method adopted in this test, the shear stress degree τ and the normal stress degree σn are constant except for the edge of the specimen, and cracks occur when the specimen is broken. Since the stress distribution is considered to be uniform, the experimental results are evaluated by the following equation.
τ = Psinθ / A
P: Load, θ: Angle formed by the normal of the repair surface and the force direction, A: Area of the repair surface (dimensions measured at the fracture surface position after the test)

The shear strength was higher as the slaked lime substitution rate was higher in the slaked lime mixed product and as the W / C was lower in the cement mixed product.

Elemental tests were conducted on the repair material for the painted mud wall, and the following conclusions were obtained.
1) As a repair material for the coated clay wall, it is desirable to use a traditional material as much as possible. Therefore, a rough wall soil mixed with slaked lime, which has a slightly larger shrinkage than that of a normal cement mixture but has the same shear strength, is used.
2) The higher the slaked lime replacement rate, the smaller the shrinkage rate and the higher the shear strength. However, if the replacement rate is high, it is difficult to adjust the fluidity. Therefore, the slaked lime replacement rate of the repair material was set to 30%.

The present invention is not limited to the above-described embodiments and experimental examples, and various modifications can be made within the scope shown in each claim. That is, an embodiment obtained by combining technical means appropriately modified within the scope of the claims is also included in the technical scope of the present invention.

1 Outer peripheral member 2 Pillar 3 Base 4 Beam 10 Horizontal material 20 Earth coating wall 25 Rough wall 26 Intermediate coating 30 Void 31 Crack 50 Repair material 60 Injection hole

Claims (3)

An injection hole drilling step of drilling a plurality of injection holes having a depth to the inside of the clay wall at predetermined intervals along the extending direction of cracks generated in the clay wall.
The process of shaping the cross section of the crack and
A method for repairing an earthen plaster wall, which comprises an external repair material injection step of injecting a repair material into the shaped crack and the injection hole. The method for repairing an earth-coated wall according to claim 1, wherein the external repair material injection step further includes an injection step of injecting the repair material into a gap formed between the outer peripheral member and the earth-coated wall. The method for repairing a clay-coated wall according to claim 2, further comprising a gap widening step in which the gap is widened and the end face on the soil-coated wall side is shaped in front of the external repair material injection step.

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