JP3186971B2 - Mortar composition for repair and reinforcement of existing structures - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mortar composition for repairing and reinforcing concrete structures, and more particularly to a method for recovering civil engineering structures subjected to an earthquake disaster and for reinforcing healthy structures. The present invention relates to a technique for implementing the method well inexpensively and quickly.

[0002]

2. Description of the Related Art Many civil engineering structures were damaged by the Great Hanshin Earthquake that occurred last year. Many concrete structures are also damaged, and quick and reliable repair of the damaged concrete structures is required. In addition, the earthquake resistance of existing structures has also been reviewed from this disaster case, and the need for seismic reinforcement of existing structures to prevent possible damage to existing structures in the future is being called out. Became.

[0003] In addition to filling concrete or mortar into cracks and cavities, reinforcing columns and beams and girders by rolling steel plates are also used to reinforce damaged structures. Mortar or the like is applied to fill the gap. In the case of structural reinforcement against possible earthquakes in the future, for example, reinforcement by steel plate winding has been proposed for piers of elevated tracks and elevated roads.

[0004] Special performance is required for such mortar for repairing and reinforcing existing structures. For example, in the case of repairing mortar by filling the damaged crack or collapsed part, it is necessary that the mortar has both non-subsidence, high fluidity and low shrinkage. For this purpose, non-shrinkable mortar admixtures have been specially developed for repair. For example, a brand name “Tight 99” manufactured by NMB and a brand name “TASCON” manufactured by Denki Kagaku Kogyo are known.
These contain calcium sulfoaluminate-based expanding agents and high-performance water reducing agents, etc., and can be added to cement, water and sand by adding only one type of this admixture.
No sinking, high fluidity and low shrinkage can be achieved. Therefore, when it is necessary to knead the mortar on site, such as in a stricken area, there is an advantage that the labor of measuring and charging the material can be omitted, and the slump flow can be secured to about 80 cm by adjusting the amount of water. In addition, bleeding is so small that it cannot be measured at the laboratory level, and subsidence can be ensured.

[0005]

The known repair mortar admixtures described above are relatively expensive. Since the mortar using these admixtures has the property that the slump flow decreases over time and loses fluidity, it must be poured immediately after kneading. There is a time limit.

Accordingly, the present invention has developed an inexpensive repair / reinforcement mortar which has no sinkage, high fluidity, low shrinkage and can maintain fluidity for a predetermined time, without using the above-mentioned admixture. The task was to do so.

[0007]

According to the present invention, in order to solve the problems], a mortar composition to be subjected to repair or reinforcement of existing concrete structures, per mortar 1 m ^3, water: 260~300Kg / m ^3, the amount of cement: 500~600Kg / m ^3, the fine powder content: 300~500Kg / m ^3, fine aggregates: blending 1 m ³ and comprising remaining amount, relative to the formulation, as admixture, superplasticizer: 10-20 kg / M ³ , thickener: 0.2-0.5 kg / m ³ , if necessary, expander: 30-70 kg / m ³ aluminum fine powder: 0.1% of the total amount of cement, the fine powder and the expander. 001 to 0.01 becomes by blending wt%, compressive strength at age of 28 days 40N / m
providing repair and reinforcement mortar composition existing structures showing a m ² or more. Here, the fine powder means fine powder of limestone (stone powder), fine powder of blast furnace slag, fly ash and the like.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Repair of an existing structure according to the present invention
Reinforcing mortars exhibit various properties, such as non-sinking, low shrinkage, and high fluidity, in a comprehensive manner by the prescribed blending. Therefore, it is difficult to separately explain the relationship with these properties for each component, but the effect of each component on each property is generally as follows.

The non-settling property is ensured by adding aluminum fine powder. 50 μm as aluminum fine powder
It is desirable to use the following, and if the addition amount is 0.001 to 0.01% by weight based on the powder (the total amount of the cement, the fine powder, and the expanding material when adding the expanding material). Good. By adding an appropriate amount of this aluminum fine powder,
Since the mortar is slightly expanded in a state where it has not yet set, non-sinking is ensured.

[0010] Low shrinkage is ensured by adding an expanding material. Examples of the expanding material used in the present invention include those made of calcium sulfoaluminate, gypsum and calcium oxide, those made of calcium aluminate and gypsum, and those made of alumina cement and gypsum. The addition amount varies depending on the type of the expanding material, but is 30 to 70 kg /
m ³ is sufficient. By adding these expanding materials, the mortar expands moderately at the early stage of curing, which contributes to the reduction of shrinkage due to drying. When the repair / reinforcement portion is exposed to an environment that does not receive drying, the expanding material may not be added.

[0011] high flow of the present invention mortar sets the unit water amount in the range of 260~300Kg / m ^3, cement 500~600Kg / m ^3, the fine powder 300~500K
g / m ³ and secured by adding appropriate amounts of a high-performance water reducing agent and a biopolymer thickener. As a result, it is natural that no material separation occurs.
m, and this fluidity lasts more than 2 hours.

As the high performance water reducing agent, there are polycarboxylic acid type, aminosulfonic acid type, naphthalene sulfonic acid type, lignin sulfonic acid type and melamine sulfonic acid type, and any one of these high performance water reducing agents is used alone. Alternatively, an amount in which the desired fluidity can be secured is added in combination. Specifically, 1.0 to 2.0% of the powder (total amount of the expanding material when cement, fine powder, or expanding material is blended), and 10% in unit amount.
Add ２０20 Kg / m ³ .

The amount of powder is 700 kg / m ³ or more, preferably 800 kg / m ³ , depending on the combination of cement and fine powder (limestone fine powder, blast furnace slag or fly ash, etc.).
m ³ or more. However, the unit cement amount is required to be 500 kg / m ³ or more from the viewpoint of securing strength, and the amount of powder other than cement is at most about 500 kg / m ³ .

As the thickening agent, various bio-gams comprising microbial fermented polysaccharides such as welan gum are used, and the added amount thereof is 0.2 to 0.5 kg / m ³ .

In the above mortar composition, the balance substantially consists of fine aggregate. The typical range of the repair / reinforcement mortar according to the present invention is shown below. Formulation A Water 260~300Kg / m ³ Cement 500~600Kg / m ³ amount fine aggregate total volume is 1 m ³ stone powder 300~500Kg / m ³ without expanding material aluminum fine powder 40 to 60 g / m ³ superplasticizer 10-20 kg / m ³ thickeners 260~300g / m ³ formulation B water 260~300Kg / m ³ cement 500~600Kg / m ³ fine aggregate total volume is 1 m ³ volume stone powder 300~500Kg / m ³ expanded Material 30-70 kg / m ³ Aluminum fine powder 40-60 g / m ³ High performance water reducing agent 10-20 kg / m ³ Thickener 260-300 g / m ³

In the above-mentioned formulations A and B, the following physical properties are obtained when the following materials are used. Materials used Cement: Ordinary Portland cement Fine aggregate: Blend of river sand and mountain sand (specific gravity 2.56, FM
2.65, water absorption 2.20%) Stone powder: TR-200 (specific gravity 2.7) manufactured by Okutama Industry Co., Ltd.
0) Expansive material: CSA100R manufactured by Denki Kagaku Kogyo Co., Ltd. (specific gravity: 2.93) Aluminum fine powder: VA350 manufactured by Yamaishi Metal Co., Ltd. High performance water reducing agent: Mighty 2000WHZ (polycarboxylic acid type) manufactured by Kao Corporation Thickener: Mountain Viscon 200 (welan gum powder) manufactured by Souka

Characteristics of Mortar of Formula A and Formula B Non-sinking: Initial expansion: 0.5 to 2.0% High fluidity: Slump flow: 80 ± 5 cm Low shrinkage: Shrinkage by drying: About 400μ in blending B Bleeding rate: 0% Temporal change: Slump flow is maintained after 2 hours Compressive strength: 40N / mm ² or more at 28 days of age

The mixer used for mixing the mortar for repair / reinforcement of the present invention is preferably a high-speed stirring mortar mixer having a stirring blade on a vertical shaft. Also, if the kneaded mortar is stirred with an agitator wheel,
Slump flow can be held for a predetermined time.

[0019]

EXAMPLES Four kinds of mortars shown in the composition table of Table 1 were kneaded. Table 2 shows the materials used for each mortar. In Table 1, Formulations 1 and 2 are repair mortars using conventional typical non-shrinkable mortar admixtures. Formulations 3 and 4 are mortars for repair / reinforcement according to the present invention. Formulation 3 is a product to which an expanding material is added, and Formulation 4 is a product to which no expanding material is added. C in Table 1 is cement, CSA is an expanding material,
S indicates fine aggregate, and SP indicates a high-performance water reducing agent. Formulations 1-4
Various physical properties tests shown in Table 3 were performed for each mortar.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

[Table 3]

Table 4 shows the properties and time-dependent changes of each mortar immediately after kneading, and Table 5 shows the bleeding rate and the final expansion rate after 24 hours. FIG. 1 shows the change with time of the slump flow, and FIG. 2 shows the change with time of the air amount.

[0024]

[Table 4]

[0025]

[Table 5]

The following is clear from the results of Tables 4 and 5 and FIGS.

[Formulation 1]: The slump flow upon kneading is 82.0 × 80.0 cm, the amount of air is 4.7%, the final expansion rate is 1.04%, and the bleeding rate is 0.0%.
Satisfies the quality as a repair / reinforcement mortar. However, the slump loss with time was large (30 minutes later,
3.0 × 59.0cm), and the handling time is limited.

[Formulation 2]: The slump flow upon kneading is 79.5 × 79.0 cm, the amount of air is 6.3%, the final expansion rate is 0.61%, and the bleeding rate is 0.0%.
Satisfies the quality as a repair / reinforcement mortar. However, the slump loss with time was large (30 minutes later,
2.0 × 62.0cm), there is a limitation in handling time.

[Formulation 3]: The slump flow at the time of kneading is 80.0 × 79.0 cm, the amount of air is 3.9%, the final expansion rate is 1.45%, and the bleeding rate is 0.0%.
Satisfies the quality of mortar for repair and reinforcement. In addition, the slump loss with time is extremely small, and the slump flow after 90 minutes is 79.0 × 77.0 cm.
Met. After 120 minutes, the slump flow value was slightly below the target value, but it was considered that the slump flow value was sufficiently maintained if the mixture was stirred by the agitator.

[Formulation 4]: The slump flow at the time of kneading is 78.0 × 77.0 cm, the amount of air is 1.6%, the final expansion rate is 1.28%, and the bleeding rate is 0.0%.
Satisfies the quality of mortar for repair and reinforcement. In addition, there was almost no slump loss with the passage of time, and it was 78.0 × 78.0 cm even after 120 minutes, satisfying the target value.

Table 6 and FIG. 3 show the properties of the development of the compressive strength. As is evident from these results, the compressive strength of all mortars increased steadily with the passage of age, and showed a value exceeding 40 N / mm ² at 28 days of age.

[0032]

[Table 6]

FIGS. 4 and 5 show the results of the length change rate test. In addition, the length change rate test was performed in accordance with the constrained expansion and shrinkage test method B method of expansive concrete indicated in the “Guidelines for Design and Execution of Expansive Concrete” by the Japan Society of Civil Engineers. If employed, the mortar will be exposed to an environment that is relatively insensitive to drying because it is filled between the pier and the rolled steel plate. Therefore, (1) a normal B method specimen (20
Curing in water at ℃ ± 1 ℃, then 20 ℃ ± 2 ℃, humidity 60 ± 5
% Aerial curing) and (2) seal the whole specimen with polyethylene wrap paper, 20 ℃ ± 2 ℃, humidity 60% ± 5%
The test was also performed by a method of performing aerial curing of the above. FIG. 4 shows the test results of the normal B method, and FIG. 5 shows the test results of the method based on the sealed state.

From FIG. 4, it can be seen that the ratio of change in length after 4 weeks of exposure to the dry state is the smallest in the case of Formula 3, which is advantageous from the viewpoint of low shrinkage when the mortar is exposed to an environment susceptible to drying. I understand. In addition, from FIG. 5, in the test in the sealed state, the ratios of length change of the blends 3 and 4 were smaller than those of the conventional material.
It can be seen that, when exposed to an environment that is less susceptible to drying, Formulation 4 without the addition of an expander can ensure lower shrinkage than conventional materials.

Table 7 shows the standard of the material cost of each mortar. It can be seen from the table that the material cost of the repair / reinforcement mortar according to the present invention is about 1/3 of the conventional material.

[0036]

[Table 7]

Based on the results of the above examples, Table 8 shows various performances required for the repair / reinforcement mortar for each mortar by item. In Table 8, it is shown that the evaluation is good in the order of ×, Δ, ○, ◎.

[0038]

[Table 8]

[0039]

As described above, according to the present invention,
As a mortar for repair and reinforcement of civil and architectural structures damaged by an earthquake, or as a mortar for seismic reinforcement of existing structures, a mortar that is less expensive and of higher quality than conventional mortars can be obtained. While contributing, it can also be a great help as an anti-seismic material for dealing with potential disasters.

[Brief description of the drawings]

FIG. 1 is a diagram comparing the change over time of the slump flow of a mortar of the present invention with a conventional product.

FIG. 2 is a diagram comparing the change over time in the amount of air of the mortar of the present invention with a conventional product.

FIG. 3 is a diagram comparing the compressive strength of the mortar of the present invention with a conventional product.

FIG. 4 is a diagram comparing the length change rate (dry state) of the mortar of the present invention with a conventional product.

FIG. 5 is a diagram comparing the length change rate (sealing state) of the mortar of the present invention with a conventional product.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ Identification code FI C04B 14:06) 103: 32 103: 42 103: 44 111: 72 (72) Inventor Minoru Iwai 2-19, Tobita Tobita, Chofu-shi, Tokyo No. 1 Kashima Construction Co., Ltd. Technical Research Institute (56) References JP-A-3-177347 (JP, A) JP-A-3-193649 (JP, A) JP-A-63-315547 (JP, A) Kaihei 6-172004 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C04B 14/00-28/36

Claims (4)

(57) [Claims] 1. A mortar composition for repairing or reinforcing an existing concrete structure, wherein the mortar is 1 m ^3.
Per weight, 260-300 kg / m ³ , cement amount: 500-600 kg / m ³ , fine powder amount: 300-500 kg / m ³ , fine aggregate: 1 m ³ On the other hand, as an admixture material, a high performance water reducing agent: 10 to 20 kg / m ³ , a thickener: 0.2 to 0.5 kg / m ³ , aluminum fine powder: 0.001 to 0.001 of the total amount of cement and the fine powder Ri Na by blending 0.01 wt%, repair and reinforcement mortar composition existing structures compressive strength at age of 28 days indicates 40N / mm ² or more. 2. A mortar composition for repairing or reinforcing an existing concrete structure, wherein the mortar is 1 m ^3.
Per weight, 260-300 kg / m ³ , cement amount: 500-600 kg / m ³ , fine powder amount: 300-500 kg / m ³ , fine aggregate: 1 m ³ On the other hand, as an admixture, a high-performance water reducing agent: 10 to 20 kg / m ³ , a thickener: 0.2 to 0.5 kg / m ³ , an expansive material: 30 to 70 kg / m ³ , aluminum fine powder: cement, 0.001 to 0.01% by weight of the total amount of the fine powder and the expanding material should not be blended.
A mortar composition for repair / reinforcement of existing structures, which exhibits a compressive strength at the age of 28 days of 40 N / mm ² or more . 3. The mortar composition according to claim 1, wherein the thickener is a biogum comprising a polysaccharide obtained by microbial fermentation. 4. The mortar composition according to claim 1, wherein the bleeding ratio is 0% and the slump flow is 75 cm or more.