KR20150062681A - Composition for soft ground construction pile - Google Patents

Abstract

The present invention relates to a milk grouting material for bored pile construction, and more specifically, to a milk grouting material for bored pile construction, which can implement performance higher than a type one cement by using petroleum coke desulfurization plaster, cement, and an expansion agent to blast furnace slag powder to replace the type one cement, prevents loss of a milk solution caused by underground water existed between a perforated hole and a bored pile highly improving end bearing capacity and skin friction force of the bored pile compared to an existing cement milk solution. The milk grouting material for bored pile construction comprises: 5-200 parts by weight of petroleum coke desulfurization plaster having more than or equal to 50 wt% calcium oxide and more than or equal to 15 wt% of sulfate oxide; and 50-300 parts by weight of mixing water.

Description

Technical Field [0001] The present invention relates to a milk pouring material for a pile construction,

More particularly, the present invention relates to a method for replacing one kind of ordinary cement, which is most widely used as a milk injection material for embedded piles, by using petroleum coke, desulfurization gypsum, cement and swelling agent in a blast furnace slag fine powder And it can prevent the loss of milk liquid due to the groundwater that may exist between the perforated hole and the embedded pile by using the volume expansion action, so that the end bearing force of the embedded pile and the frictional force Which can be greatly improved as compared with conventional cement milk solutions.

In recent construction sites, file construction of the purchase method is increasing in accordance with the trend of strengthening noise and vibration regulation at the file foundation.

The pile construction is a method of planting a PHC pile, which is an existing product, by drilling a hole using an auger on the ground, and filling the ground and pile spaces with a mixture of water with a pure one kind of ordinary cement or bentonite, To the pile of the pile.

Milk filling material between the perforation hole and the pile is the basic role to demonstrate the function of filling material and pile surface friction for self-standing of the pile at the initial stage of loading.

However, the bentonite is a high-priced material that does not exist as a natural resource in Korea, and it is a high-priced material that is dependent on the whole amount of imports. When it comes into contact with salt, its swelling degree is significantly lowered and water- There is a disadvantage that the required performance can not be exhibited.

In Korea, cement milk with a water cement ratio (W / C) of 83% was mainly used since 1987 when the excavation pile method was introduced from Japan. Cement milk with a water cement ratio of 83% produces 1.0m ³ , requires 880kg of cement and 730kg of water. Because the specific gravity of the cement is 3.15, it is 880 ÷ 3.15 = 280 ℓ when converted to volume, and the volume of 730 ℓ plus 1,010 ℓ, that is, about 1.0 m ³ , is added. However, cement milk having such a blending ratio does not fill up to the ground around the pile even when it is poured, and when there is a lot of ground water, the cement milk becomes diluted and becomes more vacant, and the bearing capacity becomes smaller. As a result, in the case of large permeability of the ground or a lot of groundwater, it is used as a substitute for excessive amount of cement.

However, cement can cause environmental pollution due to strong alkali and hexavalent chromium in the ground, and excessive volume contraction occurs during hydration reaction due to a large amount of water, which causes a problem that the frictional force of the embedded pile is lowered.

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a blast furnace slag fine powder which is activated by the alkali and sulfate stimulation of petro coke desulfurization gypsum, By using the expanding agent, it is possible to prevent the loss of milk liquid due to the groundwater, which may exist between the perforated hole and the embedded pile, by using the volume expansion action, so that the end bearing capacity and the frictional force of the embedded pile can be greatly improved as compared with the existing cement milk solution And to provide a milk injection material for constructing an embedded pile.

In order to solve the above-mentioned technical problem, the milk pouring injection milk material according to the present invention is characterized in that the calcium oxide content is at least 50 wt% and the sulfate oxide content is at least 15 wt%, based on 100 wt parts of the blast furnace slag fine powder, 5 to 200 parts by weight of Petro Coke desulfurization gypsum having a weight% or more, and 50 to 300 parts by weight of a compounding water.

Further, it is preferable that the cement is further comprised of cement to improve speed and strength, and the cement is any one or a mixture of two or more selected from the group consisting of one kind of cement, three kinds of cement, blast furnace slag cement and fly ash cement.

The cement is preferably mixed with 5 to 200 parts by weight based on 100 parts by weight of the blast furnace slag fine powder.

Further, it is preferable to further include an expanding material to improve the frictional force of the main surface of the buried pile through volume expansion.

Also, the expanding material may be selected from the group consisting of coal materials having a calcium oxide content of 20 wt% or more, biomass incineration residues, paper sludge incineration residues, RDF incineration residues, RPF incineration residues, steel slag fine powders, KR dust, KR slag dust, Dolomite, and dolomite, or a mixture of two or more thereof.

It is preferable that the expansion material is incorporated in an amount of 5 to 100 parts by weight based on 100 parts by weight of the blast furnace slag fine powder.

According to the present invention, the blast furnace slag fine powder is activated by the alkali and sulphate stimulation of the Petro Coke desulfurization gypsum and can exhibit strength equal to or higher than that of one kind of ordinary cement. By using the expanding agent, It is possible to prevent the leakage of the milk liquid due to the groundwater that may exist between the piles, thereby greatly improving the tip bearing capacity and frictional force of the embedded pile compared to the conventional cement milk solution.

Hereinafter, the milk injecting material for constructing a buried pile according to the present invention will be described in detail.

First, the components and the operation of the milk pouring material for embedding pile according to the present invention will be described.

The quick-hard milk-injecting material for embedded piles according to the present invention is characterized in that the blend of blast furnace slag powder and Petro-coke desulfurized gypsum powder having a calcium oxide content of not less than 50% by weight and a sulfate oxide content of not less than 15% 5 to 200 parts by weight, and a compounding number of 50 to 300 parts by weight.

Further, it is preferable to further include 5 to 200 parts by weight of cement based on 100 parts by weight of the blast furnace slag fine powder in order to improve the fastness and strength.

It is preferable that the cement is any one or a mixture of two or more selected from the group consisting of one kind of cement, three kinds of cement, blast furnace slag cement and fly ash cement.

The cement is preferably mixed with 5 to 200 parts by weight based on 100 parts by weight of the blast furnace slag fine powder.

Further, it is preferable to further include an expanding material to improve the frictional force of the main surface of the buried pile through volume expansion.

Also, the expanding material may be selected from coal materials having a calcium oxide content of 20 wt% or more, biomass incineration residues, paper sludge incineration residues, RDF incineration residues, RPF incineration residues, steel slag dusts, KR dust, KR slag dust, Dolomite, and dolomite, or a mixture of two or more thereof.

It is preferable that the expansion material is incorporated in an amount of 5 to 100 parts by weight based on 100 parts by weight of the blast furnace slag fine powder.

The blast furnace slag fine powder used as the main raw material in the present invention is discharged as a by-product of a steelmaking process. It is preferably pulverized after being subjected to water chain cooling to have a specific surface area of 3,000 cm 2 / g or more.

In addition, the Petro Coke desulfurization gypsum disintegrates the acidic film of the blast furnace slag powder in a short period of time by accelerating the release of ions in the slag and reacting with them to generate a large amount of etrinite in the early stage of hydration, It is a substance that simultaneously plays a role of a stimulant and a binding agent that generate calcium silicate hydrate and express strength. Because it is generated as a by-product of desulfurization process in a fluidized bed boiler that mixes petroleum coke and limestone, it is a material containing quicklime and anhydrous gypsum and is very economical.

It is preferable that the Petro Coke desulfurization gypsum is contained in an amount of 5 to 200 parts by weight based on 100 parts by weight of the blast furnace slag cement. If the amount is less than 5 parts by weight, the effect is insufficient as an alkali and sulfate complex irritant containing both the quicklime component and the gypsum component. If the amount exceeds 200 parts by weight, there is a surplus amount that does not react with the slag.

The compounding water is used as a general water which does not cause any abnormality in cement condensation such as ground water, tap water, industrial water and seawater, and makes the powder cement slurry to facilitate the transportation through the piping.

The blended water is preferably mixed with 50 to 300 parts by weight based on 100 parts by weight of the blast furnace slag fine powder. When the amount is less than 50 parts by weight, the fluidity is insufficient and the milk liquid is difficult to be conveyed. When the amount exceeds 300 parts by weight, the strength is greatly lowered.

The cement is a KS product generally sold in the market as one kind of cement, three kinds of cement, blast furnace slag cement and fly ash cement.

It is preferable that 5 to 200 parts by weight are included in the blast furnace slag fine powder of 100 parts by weight. If the amount is less than 5 parts by weight, curing of the milk injecting material may not be effective in improving the fastness and strength. If the amount is more than 200 parts by weight, economical efficiency may be insufficient and the volume may shrink during the hydration reaction.

Further, it is preferable that an expansion member is further included to improve frictional force on the main surface of the embedded pile.

The expanding material is selected from the group consisting of coal ash with a calcium oxide content of 20 wt% or more, biomass incineration residue, paper sludge incineration residue, RDF incineration residue, RPF incineration residue, steel slag dust, steel dust, KR dust, KR slag dust, And light dolomite, or a mixture of two or more thereof.

In addition, an expanding material having a calcium oxide content of 20 wt% or more reacts with water to be absorbed, exothermic, and expanded, resulting in calcium hydroxide. The reaction formula is as follows.

CaO + H ₂ O-> Ca (OH) ₂ + 15.6 kcal mol ^-1

Generally, coal ash discharged from a thermal power plant having a separate desulfurization unit is recycled as a concrete admixture material with a calcium oxide content of 5% by weight or less. However, as described above, when a large amount of calcium oxide (CaO) Coal materials, incineration residues, steel slag dust, steel dust, KR dust, and KR slag dust can not be used as concrete admixture because they have absorption, heat and expansion characteristics.

Therefore, the present invention is to utilize industrial by-products, which can not normally be utilized as concrete admixture, as an expansion material.

Among the above expanding materials, quicklime and light dolomite can be used as long as they are general products distributed on the market.

If the mixing amount of the expanding material is less than 5 parts by weight, the expansion effect is insufficient for improving the frictional force of the main surface of the embedded pile. If the amount exceeds 100 parts by weight, the expansion effect is increased, but the strength of the cured material is insufficient .

Hereinafter, preferred embodiments and comparative examples of the present invention will be described. The following examples are intended to illustrate the invention and should not be construed as limiting the scope of the invention.

Example

First, 30 parts by weight of Petro coke desulfurization gypsum, 50 parts by weight of first type cement and 60 parts by weight of an expanding agent were uniformly mixed with 100 parts by weight of fine powder of blast furnace slag to prepare a filler for fillet pouring.

Next, water was added to the binder material for injection so that the water binder ratio (W / B) was 83%, and the mixture was sufficiently mixed with a forced mixer to prepare a milky liquid.

Next, in consideration of the fact that the soil of the pierced hole is collapsed and mixed into the milk liquid, the flowability is measured by mixing 50%, 60%, 70%, and 100% of the clay soil with the milk liquid weight ratio. Compressive strength specimens with 70% clay soil were prepared and the compressive strength according to age was measured.

Comparative Example  (1 kind of ordinary cement)

First, water was added to the first kind of cement so as to have a water binder ratio (W / B) of 83% and sufficiently mixed with a forced mixer to prepare a milk solution.

Next, in consideration of the fact that the soil of the pierced hole is collapsed and mixed into the milk liquid, the flowability is measured by mixing 50%, 60%, 70%, and 100% of the clay soil with the milk liquid weight ratio. Compressive strength specimens containing 70% clay soil were prepared and the compressive strengths according to age were compared with the experimental results.

For piling construction milk  Performance test method and result of injection material

As shown in Table 1 below, the flow test was conducted by KS F 2594 and the compressive strength test was conducted by the KS F 2343 method.

Experiment Way Remarks Slump flow KS F 2594 Slump flow test method Compressive strength KS F 2343 Uniaxial Compressive Strength Test Method Degree of material separation Visual inspection Volume change Visual inspection

(One) Flow  Test result

As a result of observing the fluidity change of the milk injection material, the fluidity decreased as the soil incorporation rate increased. Referring to Table 2, the fluidity of the Examples tends to be slightly lower than that of the one-kind ordinary cement, which is a comparative example. It is judged that the fluidity is lowered due to absorption, exothermic and expansion action when the calcium oxide component comes into contact with water by further incorporating the expanding agent. However, in the case of milk injection material, the fluidity deterioration can be advantageous in terms of resistance to material separation and in the ground of large pores such as sandy soil in the state where there is no drop of feed pipe and clogging phenomenon.

Flow measurement result Soil weight ratio (%) 0 50 60 70 100 Example
Flow (cm) 62 40 33 32 26 Comparative Example
Flow (cm) 68 42 40 36 31

(2) Uniaxial compressive strength  change

Table 3 shows the results of uniaxial compressive strength test according to the mixing of soil in the examples and comparative examples.

As shown in Table 3 below, the initial and long-term strengths were significantly higher than those of the first-grade cement, which is comparative example, although the amount of cement was relatively insufficient. However, the blast-furnace slag fine powder was stimulated by Petro- coke desulfurization gypsum, Because. That is, it is judged that the amorphous material of the blast furnace slag and the expanding material continuously produce hydrates by the sulfuric acid and alkali stimulus of petro coke.

Compression strength measurement result Young 3 days 7 days 28th Soil weight ratio (%) 70% 70% 70% Example
Compressive strength (MPa) 11.6 17.4 21.4 Comparative Example
Compressive strength (MPa) 10.2 15.1 17.3

As can be seen from Table 3 above, when the same amount of milk injection was used, the compressive strengths of the examples were excellent, and even when the amount of unit binders was reduced in practical application, the same strength as that of one kind of cement could be exhibited It is considered that it is possible to secure economical construction.

(3) Other

As a result of observing the volume change visually, after 12 hours, the volume of the example was increased by compensating for the amount of shrinkage due to the expandability. However, In the comparative example, it was visually confirmed that volume shrinkage occurred.

Claims (6)

5 to 200 parts by weight of PetroCokes desulfurization gypsum having a calcium oxide content of not less than 50% by weight and a sulfate oxide content of not less than 15% by weight based on 100 parts by weight of the blast furnace slag fine powder, By weight based on the weight of the filler.
The method according to claim 1,
Wherein the cement comprises one or more selected from the group consisting of a first cement, a third cement, a blast furnace slag cement, and a fly ash cement. Milk filling material.
3. The method of claim 2,
Wherein the cement is incorporated in an amount of 5 to 200 parts by weight based on 100 parts by weight of the blast furnace slag fine powder.
The method according to claim 1,
Wherein an expansion material is further included to improve frictional force on the main surface of the embedded pile through volume expansion.
5. The method of claim 4,
The expanding material is selected from the group consisting of coal ash with a calcium oxide content of 20 wt% or more, biomass incineration residue, paper sludge incineration residue, RDF incineration residue, RPF incineration residue, steel slag dust, steel dust, KR dust, KR slag dust, And a mixture of two or more selected from the group consisting of light earth dolomite and light earth dolomite.
6. The method of claim 5,
Wherein the expandable material is incorporated in an amount of 5 to 100 parts by weight based on 100 parts by weight of the blast furnace slag fine powder.