JPH0940938A - Cavity filler material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a cavity filler material having good cavity filling properties by using sea water which is available inexpensively and easily. SOLUTION: This cavity filler material contains fly ash, desirably one having a mean particle diameter of 10μm or below, cement, a retarder and sea water and is obtained by mixing them with each other in such amounts that the fly ash/cement weight ratio is 8/2 to 2/8, the amount of the sea water is 50-90wt.% based on the total amount of the cement and the fly ash, and the cement hydration retarder is used in an amount of 0.1-2.0wt.% based on the cement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cavity filling material used for tunnels, abutments, retaining walls, sewer pipe work and the like.

[0002]

2. Description of the Related Art In the construction of abutments, retaining walls, sewer pipes, etc., including the shield construction method and tunnel construction, a cavity filling material is injected into the gap between the soil and the structure in order to keep the structure stable. . These cavity-filling materials are usually pumped or naturally flown down to a construction site by a gas pipe, an iron pipe, a vinyl chloride pipe or the like having a size of 5 inches or less. Therefore, the cavity filling material is required to be a material having excellent pumpability, and therefore, a cement-based slurry liquid obtained by kneading cement, which is a hardening material, with water has been often used.

Generally, in the field of civil engineering and construction, a wide range of water such as tap water, groundwater, river water, seawater is used as slurry liquid producing water, but when pumpability is required like a cavity filling material. , Seawater is rarely used. That is, in seawater, the time for which the fluidity decreases is shorter than that in the case of using tap water. Therefore, it is possible to use various retarders, but it is sufficient to use a small amount of the retarder. The effect is not obtained, and even if the retarder is added in a sufficient amount, the viscosity becomes high in the pressure-feeding pipe, the pressure-feeding property is poor, and a good cavity filling material is not obtained.

When seawater is used in this way, it is difficult to adjust the pot life with a retarder, so seawater is rarely used as a cavity filling material, and this is the case when the construction site is adjacent to the sea. However, the current situation is to procure tap water.

[0005]

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide a cavity-filling material having good cavity-filling properties using a large amount of inexpensive and easily available seawater.

[0006]

The present invention was obtained as a result of extensive studies on various experiments using a mixed hardening material of fly ash and cement as a slurry liquid mixed with artificial seawater. That is, the cavity filling material of the present invention contains fly ash, preferably fly ash having an average particle size of 10 μm or less, cement, a retarder, and seawater, and the weight ratio of fly ash to cement is 8: 2 to 2: 8,
50 seawater to the total amount of cement and fly ash
.About.90% by weight, and a cement hydration retarder in an amount of 0.1 to 2.0% by weight based on the amount of cement. Further, the present invention preferably further contains a hydrous magnesium silicate clay mineral, and it is desirable that 5 to 80 kg of this hydrous magnesium silicate clay mineral is blended per 1 m ³ . Furthermore, as the hydrous magnesium silicate clay mineral, at least one selected from attaperugite and sepiolite is preferably used. The present invention will be described in detail below.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION As the cement, various portland cements, particularly normal and early strength portland cements are preferably used, but mixed cements such as blast furnace cements can also be used. In addition, as the fly ash, when a classified product having an average particle size of 10 μm or less obtained by treating ash generated from a coal-fired power plant with an air classifier or the like is used, the breathing rate of the slurry liquid is reduced and a stable material is obtained. However, it is also possible to use the generated ash raw powder as it is, and by blending a hydrous magnesium silicate clay mineral described below, the breathing rate is significantly improved and it can be suitably used as a cavity filler.

The mixing ratio of fly ash of hardener and cement is preferably 8: 2 to 2: 8 by weight. This is because if the mixing ratio of cement is higher than 80%, the pot life is significantly shortened regardless of whether or not a retarder is added. Also, the mixing ratio of fly ash and cement is more than 8: 2. Is not preferable because the expression of strength is small.

The amount of seawater used is 50 to 90% by weight based on the total amount of fly ash and cement. If this content is less than 50% by weight, kneading becomes difficult, and
If it is more than 90% by weight, the breathing rate becomes large, which is not preferable.

As the cement hydration retarder, various retarders such as gluconic acid-based, citric acid-based, tartaric acid-based, malic acid-based oxycarboxylic acid-based, organic phosphorus-based and sulfonic acid-based delay agents can be used. , 0.1 for the amount of cement
It mix | blends in the ratio of -2.0 weight%. If the amount of the retarder is less than 0.1% by weight, there is almost no effect of addition and the pot life becomes short, which is not preferable. Further, if it is blended in an amount of more than 2.0% by weight, it will not cure, but the viscosity will be remarkably increased, the pot life will be shortened, and the strength development will be delayed.

Further, the present invention can be made into a cavity filling material having a further improved breathing rate by blending a hydrous magnesium silicate clay mineral in addition to the above-mentioned various materials. As the hydrous magnesium silicate clay mineral, attaperugite, sepiolite, and the like are preferably used, and the amount is 5 to 80 kg per 1 m ³ . If it is less than 5 kg, there is not much mixing effect, and
If the amount is more than 80 kg, the fluidity is deteriorated, which is not preferable. Further, clay minerals such as bentonite are not preferable because they do not exhibit thickening in seawater.

The cavity filling material of the present invention described above is
Appropriate selection and formulation of each of the above materials, and their synergistic effects make it possible to use seawater and to provide a suitable cavity filling material with little breathing, which will be described further below.

Generally, when seawater is used as kneading water in the field of civil engineering and construction, the result is often different from the case where tap water is used. For example, when sea water is used in the case of concrete, the setting time is accelerated and the initial strength is increased as compared with the case where tap water is used, but it is reported that the strength reverses in 91 days of age. However, even in this case, there is no great difference in the long-term strength results up to about 30 years, and judging from the long-term stability in this way, the influence of the mixing water is rarely seen. Therefore, seawater is generally used as kneading water.

However, when seawater is used as the kneading water for the cavity filling material / slurry liquid, the chloride in seawater lowers the pH of the liquid phase, as compared with the case of using tap water.
The hydrolysis of cement, which is a hardening material, is promoted, and the hydration of C ₃ S becomes active, so that the fluidity decreases quickly. Therefore, in order to delay the hardening of cement, a proper amount of a retarder such as gluconic acid is usually added. The retarder is Ca ^{2+ in} cement
By combining with an ion to form a chelate ring for a certain period of time, C
_It can be adsorbed on the surface of ₃ S and delay the hydration of C ₃ S. When seawater is used as the kneading water, the pot life is naturally shortened if the amount of the retarder is small, but the pot life is shortened even if the retarder is added in a sufficient amount. It is considered that this is because the hydration of C ₃ S is activated by seawater, so that the amount of chelate rings generated increases and this gel acts as a kind of thickener.

Therefore, when seawater is used and the hardener is plain cement, it is difficult to adjust the pot life with a retarder, and it is necessary to reduce the amount of cement as much as possible within the range where appropriate strength can be obtained. There is. However, the method of increasing the water content ratio is not preferable because the breathing rate is remarkably deteriorated. Therefore, the method of mixing fly ash having no short-term strength development property in the cured material is effective. Fly ash is a typical substance that has a pozzolanic reaction, and of course it contributes to the strength development of long-term age after 3 months, but especially when using seawater, tap water is used. Compared with the case, the generation of ettringite is accelerated, which contributes to the strength development and the breathing rate reduction.

Further, the fly ash has a finer shape than the cement particles, and most of them are spherical particles. Therefore, 1) the fine ash effect allows the particles to enter the cement particles to reduce the breathing rate. 2) Suppressing the thickening effect of the amount of retarder mixed in an appropriate amount with respect to the amount of cement. And so on. These effects are remarkable when the average particle size of the fly ash is 10 μm or less, and when this fly ash is used, it is possible to mix without using a thickener.

It is effective to add an appropriate amount of a clay mineral, which is a thickening agent, to improve the behavior of the breathing rate, and clay minerals that can be used here include attaperugite, sepiolite, and clintile asbestos. Is. Since these materials have a fibrous structure or have a hydroxyl group that is highly reactive, they are highly capable of absorbing and fixing Na and exhibit a thickening effect in seawater. However, in the case of clay minerals such as bentonite, sodium ions in the material cause an ion exchange reaction with calcium ions in seawater, which causes the swelling property to be lost, which is not preferable.

[0018]

The present invention will be further described below based on experimental examples. Table 1 shows a list of materials used in the experimental examples, and Table 2 shows the results of laser diffraction particle size measurement of the fly ash used. The artificial seawater was prepared using Swing Hymarin (trade name), which is an artificial seawater for breeding marine products manufactured by Hipet. In addition, all the following percentages represent weight percentages.

[0019]

[Table 1]

[0020]

[Table 2]

(Example 1) As a material property evaluation item, a flow value, a final (after 2 days) breathing rate, a pot life, and a uniaxial compressive strength were measured. Flow value is KODAN 305
According to the method, the pot life was measured by placing 500 ml of the cavity filling material in a vinyl bag (10 cm × 40 cm), closing the upper part, and repeating the vertical movement 20 times until the slurry liquid could not be uniformly mixed. . The uniaxial compressive strength test is Φ
= 5 cm, h = 10 cm, mold the test piece, and remove the form 20 °
It was cured in the water of C and measured by the test method of JSF T511 of Japan Society of Geotechnical Engineering. The test results are shown in FIGS.

1 and 2, tap water and artificial seawater are used as kneading water, respectively, and the water / hardening material (early strength cement + classified fly ash) ratio is 70%, and the retarder is 0.5% of the cement amount. The table shows the pot life and the final breathing rate at each mixing ratio of the early-hardening cement hardener and the classified fly ash under the mixed conditions. In FIG. 1, when tap water is used as the kneading water, the pot life is 24 hours or more at any mixing ratio of the hardening materials, but when artificial seawater is used as the kneading water, when the hardening material is cement only. Indicates that the pot life is significantly shortened to about 4 hours, which is not preferable.

Further, in FIG. 2, when artificial seawater is used as the kneading water rather than tap water, the breathing characteristics are improved at any mixing ratio of the hardeners, but when the hardener is pure fly ash. However, the breathing characteristics are not so improved.

In FIG. 3, artificial seawater is used as kneading water,
FIG. 3 shows the relationship between the amount of retarder and the pot life with respect to the amount of early-strength cement at a mixing ratio of water / hardening agent ratio of 70%, early-strength cement of hardening material and classification fly ash. In Fig. 3, when cement alone is used as the hardening material, good pot life characteristics cannot be obtained by adding any amount of retarder, but a mixture of cement and fly ash is used as the hardening material. In this case, when the retarder amount relative to the cement amount is set to 0.5%, it is understood that the pot life is 24 hours or more, which is a good result. However, if the amount of the retarder is set to 3.0%, the pot life is rather shortened, which is not preferable.

In FIG. 4, artificial seawater is used as kneading water,
FIG. 3 shows the relationship between the water / hardening agent ratio and the final breathing rate when a 3: 7 mixture of early-strength cement as a hardening agent and classified fly ash is used. In FIG. 4, when the water / curing material ratio is 60% and 80%, good results are obtained, but when the water / curing material ratio is 100%, the breathing rate becomes extremely high, which is not preferable. When the water / hardening material ratio was 40%, the hardening material and artificial seawater could not be kneaded.

In FIG. 5, artificial seawater is used as kneading water,
When the ratio of water / hardening agent is 70%, and 3: 3 mixture of high-strength cement and JIS fly ash as hardening agent is used, the relationship between the thickening agent and the final breathing rate in 1 m ³ is shown. It is a thing. In FIG. 5, when JIS products are used as the hard ash and no thickening agent is blended, the breathing rate shows a high value of about 20%. Attaperugite is ³⁰ or 70 kg in 1 m ^3.
When blended, the breathing characteristics were significantly improved and good results were obtained. However, it is not preferable to mix 100 kg in 1 m ³ because the viscosity becomes extremely high.

When bentonite is used as a thickener, even if ^{30 or} 70 kg is mixed in 1 m ³ , breathing characteristics are hardly improved. When a classified product is used as the fly ash of the curing material, the breathing rate shows a value of 5% or less without the addition of a thickening agent, but when 10 kg of attaperugite is mixed in 1 m ³ , the breathing characteristics are further improved. I understand that

Example 2 According to the compounding conditions shown in Table 3,
In the same manner as in Example 1, the flow value, final (after 2 days) breathing rate, pot life, and uniaxial compression strength were measured. Table 4 shows the results
Shown in

[0029]

[Table 3]

[0030]

[Table 4]

In Tables 3 and 4, the water / hardening material ratio is 60.
~ 80% of No. Good results have been obtained under the conditions of 2, 3, and 4. However, No. 1 having a water / hardening material ratio of 40%. Under the conditions of No. 1, since the hardener and the artificial seawater cannot be mixed, the water / hardener ratio of No. 1 was 100%. The condition of 5 is not preferable because the breathing rate is extremely high.

Next, No. No. 6 uses a JIS-equivalent product as fly ash and has a high breathing rate, which is not preferable. According to the results of 7-9, J
Even if fly ash equivalent to IS is used, 30 or 70 kg of attaperugite was mixed in 1 m3. Under the conditions of 7 and 8, good results are obtained. However, in No. 1 containing 100 kg in 1 m3. The condition 9 is not preferable because the viscosity becomes extremely high. In addition, No. In No. 11, an example of using bentonite as a clay mineral is shown, but it can be seen that the breathing rate is high, which is not preferable. No. In No. 10, a classified product is used for the fly ash of the curing material, and a small amount of attaperugite is added as the thickening material, but good results are obtained.

No. In Nos. 12 to 14, the mixing ratio of the hard ash fly ash and cement was 5: 5.
Under the condition of 13, good results are obtained. But,
No. using fly ash plain. In the condition of 12,
It is not preferable because the pot life is short, the breathing rate is relatively high, and the strength development is extremely slow. In addition, No. It is understood that under the condition of 14, the pot life is short and the strength development is small, which is not preferable. Then, No. In No. 15, the hardener was cement alone and the amount of the retarder was about 0.1%. In this case, however, the amount of the retarder is insufficient and the curing time is short, which is not preferable.

No. Nos. 16 and 17 show the effect of the amount of the retarder, but Nos. 16
In addition, because the pot life was short, the retarder was added to No. 3 containing 3% of the cement amount. It can be seen that in No. 17, the strength development is extremely slow, which is not preferable.

[0035]

As described above, the cavity-filling material of the present invention is excellent in strength development and injectability, and can be used for tunnel construction, even though it uses seawater that is available in large quantities, inexpensively and easily. And the like can be suitably used as the cavity filling material.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a mixing ratio of a curing material and a pot life.

FIG. 2 is a diagram showing a relationship between a mixing ratio of a curing material and a final breathing rate.

FIG. 3 is a diagram showing the relationship between the amount of retarder and the pot life with respect to the amount of cement.

FIG. 4 is a diagram showing a relationship between a water / curing material ratio and a final breathing rate.

FIG. 5 is a diagram showing the relationship between the thickening agent mixed in 1 m ³ and the final breathing rate.

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Claims (4)

[Claims] 1. Fly ash, preferably with an average particle size of 1
Fly ash, cement, retarder of 0 μm or less,
And seawater, the weight ratio of fly ash and cement is 8: 2 to 2: 8, seawater is 50 to 90% by weight with respect to the total amount of cement and fly ash, and the cement hydration retarder is the amount of cement. The cavity filling material is characterized by being compounded in an amount of 0.1 to 2.0% by weight. 2. The cavity filling material according to claim 1, further comprising a hydrous magnesium silicate clay mineral. 3. 1 m of hydrous magnesium silicate clay mineral
The cavity filling material according to claim 2, wherein 5 to 80 kg per ^{3 is} compounded. 4. The cavity filling material according to claim 2, wherein the hydrous magnesium silicate clay mineral is at least one selected from attaperugite and sepiolite.