KR20160093901A - Pile grouting materials - Google Patents

Abstract

The present invention relates to a pile grouting composition comprising, based on Type 3 blast furnace slag cement, 10-100 parts by weight of ferro-nickel slag micropowder and 10-100 parts by weight of calcined dolomite. According to the present invention, free CaO and SiO_2 ingredients of ferro-nickel slag micropowder and calcined dolomite micropowder are activated by the stimulation of alkali and sulfate produced during the hydration of Type 3 blast furnace slag cement, thereby providing strength at least equal to the strength of Type 1 general cement. In addition, MgO ingredient contained in ferro-nickel slag micropowder and calcined dolomite micropowder each in an amount of 30 wt% or more is combined with compounding water (H_2O) so that it is converted into Mg(OH)_2 to realize strength while undergoing expansion. Such a volumetric expansion action is used to grout the voids in perforated ground and natural ground and prevents loss of a grouting solution caused by ground water that may exist between a perforation hole and an embedded pile. Thus, it is possible to significantly improve the tip supporting power and circumferential surface frictional force of the embedded pile as compared to the conventional grouting solution.

Description

[0001] PILE GROUTING MATERIALS [0002]

More particularly, the present invention relates to a pile or toe extension type pile injection composition capable of minimizing the amount of cement and replacing one kind of ordinary portland cement most widely used as a pile filler.

In the grouting method for ground improvement or soft ground reinforcement, the injection material is a liquid chemical injection material containing various chemical admixtures which meet the ground conditions and construction purpose, a mortar injection material containing cement as a main material and other admixtures, And a concrete injection material containing a cement paste.

Injection method of injection material is a liquid injection method in which the injection fluid is injected only into the pores in the ground with the structure of the ground as it is, the heat injection technique which partially extends the injection area and increases the injection range and reinforcement effect, Or a substitution method and a consolidation injection method in which substitution is performed.

Among these various methods, there are many pile construction methods that excavate paperboard, remove floating soil, and purchase pile in a construction site where new houses or large-scale buildings and constructions are newly built.

A pile construction method is a method of piercing a hole using an auger on the ground and planting a PHC pile or an extended pile of a standing product. A method of manufacturing a pile of a portlet in a ground and a pile and a powder in which bentonite is added to a normal cement or a first cement And filling the pouring solution prepared by mixing water with water to strengthen the frictional force and the supporting force of the pile.

The injection material between the perforation hole and the pile plays a fundamental role in strengthening the filler material and pile surface friction during the initial stage of loading.

However, the above-mentioned one-kind cement has a problem in that it is not an environment-friendly material because it is manufactured by calcining at 1,450 ° C using imported coal as a raw material, such as limestone, iron ore, clay, and silica.

In addition, bentonite is a high-priced material that does not exist as a natural resource in Korea, and it is a high-priced material that depends on imports. When it comes into contact with salt, its swelling degree is significantly lowered and water permeability is greatly deteriorated. There is a disadvantage that the required performance can not be exhibited.

In Korea, the piling method was introduced from Japan in 1987, and the piling method was introduced in 1987. In the case of piling, Cement injection solution with water / cement ratio (W / C) of 83% was mainly used, which is also specified in the special specification of the land and housing corporation.

To make 1.0 cement paste with 83% water cement ratio, 880 kg of cement and 730 kg of water are needed. This is because the mass of the cement is about 3.15, and when it is converted into the volume, it becomes 280 L (880 ÷ 3.15), and when it is added with 730 L of water, the volume becomes 1,010 L, that is, about 1.0 m 3.

However, the cement paste having such a blend ratio does not fill up to the ground around the pile even if it is poured, and when the groundwater is large, the cement paste is diluted and becomes more vacant, so that the bearing capacity is lowered. 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.

In addition, cement can cause environmental pollution due to strong alkali and hexavalent chromium in the ground, and due to the large amount of water, it causes the volume contraction of the cement itself in addition to the water absorption and loss during the hydration reaction Excessive volume contraction occurs and the frictional force on the main surface of the pile is lowered.

Recently, several techniques for improving the problem of using such conventional cement as an injection material have been proposed.

For example, in Korean Patent No. 10-1377552, 100 to 300 parts by weight of a blast furnace slag fine powder, 20 to 100 parts by weight of petroleum coke desulfurization gypsum and 20 to 100 parts by weight of a sulfate stimulant 20 To 50 parts by weight based on 100 parts by weight of coal as an expansion material. The present invention also provides a milk injection material for cement-free pile construction.

Also, in Korean Patent No. 10-1402877, it is disclosed that 55 to 65 wt% of blast furnace slag fine powder, 10 to 20 wt% of F grade fly ash, 10 to 20 wt% of C grade fly ash having a calcium oxide content of 20% To 5% by weight of pulp slurry and 10 to 20% by weight of paper ash sludge incineration ash.

In addition, in Korean Patent Application No. 2013-147586 of the present applicant, 5 to 200 parts by weight of petroleum gypsum desulfurization gypsum and 50 to 300 parts by weight of compounding water are added to 100 parts by weight of the blast furnace slag fine powder, and the expansion material is blended with 100 parts by weight of blast furnace slag fine powder And 5 to 100 parts by weight based on 100 parts by weight of the composition.

These techniques are based on the theory of alkali activated slag that activates blast furnace slag fine powders as a byproduct of the desulfurization process by alkali and sulfate stimulation by gypsum and is a technical content of utilizing high calcium incineration as an expansion material. That is, the above-mentioned patents can be regarded as a technique for early stabilizing the ground by utilizing the strength development of the alkali activated slag and the expandability of the high calcium incineration ash.

However, some of the above technologies have not been commercialized due to reasons such as the complexity of the manufacturing process and the cost of expensive raw materials such as the use of more than five types of raw materials to be mixed or the use of expensive drugs as sulfite stimulants.

In addition, while the above-mentioned techniques separately include an expansion agent in the composition, the present invention utilizes the activation reaction and the expansion action of the ferronickel slag and the light dolomite, so that there is a difference in that the expansion agent is not used.

Korean Patent No. 10-1377552 Korean Patent No. 10-1402877 Korean Patent Application No. 2013-147586

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a pile material composition capable of exhibiting a strength equal to or higher than that of conventional one kind ordinary cement as a pile filling material while minimizing cement content There is.

In order to solve the above technical problems, the pile casting material according to the present invention is characterized in that 10 to 100 parts by weight of the ferronickel slag fine powder and 10 to 100 parts by weight of the fine dolomite fine powder are added to 100 parts by weight of the third type blast furnace slag cement .

The ferronickel slag fine powder may be obtained by pulverizing a water-quenched ferronickel slag obtained by quenching slag with water.

The pile material composition may further include fly ash.

The fly ash is preferably a coal-fired fly ash having a silicon dioxide (SiO ₂ ) content of 30 wt% or more.

The fly ash is preferably incorporated in an amount of 10 to 100 parts by weight based on 100 parts by weight of the third blast furnace slag cement.

According to the present invention, the vitrified CaO and SiO ₂ components of the ferronickel slag fine powder and the lightly dolomite fine powder are activated by the stimulation of the alkali and the sulfate generated in the hydration reaction of the three kinds of blast furnace slag cement, It is possible to exhibit strength equal to or higher than that at the time of use.

In addition, the MgO component contained in each of the ferronickel slag fine powder and the lightweight dolomite fine powder is contained in an amount of 30% by weight or more, and is mixed with the compounding water (H ₂ O) and transferred to Mg (OH) ₂ to exhibit the strength and to utilize the expanding volume expansion function The pile bearing and ground surface friction force of the pile can be greatly improved compared to that of the existing cement pile. It is effective.

FIG. 1 shows the results of visual observation of the volume change of the pile material according to the mixing time according to the examples and the comparative examples.

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

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a,""an," and "the" include singular forms unless the context clearly dictates otherwise. Also, " comprise "and / or" comprising "when used herein should be interpreted as specifying the presence of stated shapes, numbers, steps, operations, elements, elements, and / And does not preclude the presence or addition of one or more other features, integers, operations, elements, elements, and / or groups.

The present invention relates to a pile or a tip-extended pile injection material composition minimizing the use of cement, and each component and action included in the pile injection material composition will be described below.

The pile casting material minimizing the use of cement according to the present invention comprises 10 to 100 parts by weight of the ferronickel slag fine powder and 10 to 100 parts by weight of the fine dolomite fine powder per 100 parts by weight of the third type blast furnace slag cement.

The third type of blast furnace slag cement used in the present invention is a KS (Korea Industrial Standard) certified product, which is composed of about 50% of one kind of portland cement, about 45% of blast furnace slag fine powder, about 5% of gypsum .

The principle of the third type blast furnace slag cement manifesting strength is that the portland cement first reacts with water to initiate the hydration reaction. At the beginning of hydration, the CaO component in the cement binds with the compounding water to form Ca (OH) ₂ And the transferred Ca (OH) ₂ alkaline component stimulates the blast furnace slag powder to activate the latent hydraulic property of the blast furnace slag. Also, the gypsum containing a small amount also functions as an alkali and sulfate stimulant to activate the latent hydraulic properties of the blast furnace slag.

In addition, ferronickel slag contained in the pile-filling material composition of the present invention is a by-product generated in the ferronickel manufacturing process, and as of 2014, a production process of 2 million tons per year is being operated in Korea. Ferronickel is a term for alloy iron containing 80% of iron and 20% of nickel and is mainly used as a raw material of stainless steel. The raw material of ferronickel is nickel oxide light with serpentinite as a parent rock. In general, the quality of pure nickel is as low as 2 ~ 3% of the ore, and after refining process at 1,500 ℃ or more, about 30 tons of ferronickel slag Is known to occur.

This ferronickel slag is partially recycled as a raw material for sintering, or as a part of road aggregate or aggregate for cocrit, but most of the ferronickel slag is disposed of by landfill.

The mineral composition of ferronickel slag is mainly composed of pyroxene and olivine, similar to natural Olivine. Minerals such as SiO ₂ , MgO, FeO and CaO contained in the ferronickel slag are crystallized into amorphous glass and crystalline minerals such as relaxed enstatite, forsterite and diopside. . The ratio of the mineral composition and the amount and properties of the amorphous glass vary depending on the cooling conditions of the ferronickel slag and affect the chemical properties such as reactivity by chemical stimulation.

The cooling conditions for the ferronickel slag according to the present invention are water-chain ferronickel quenched by water with slag, and the material used is powdered quench-hardened ferronickel slag. It is generally known that quenching is a prerequisite for increasing the amount of amorphous material and that the greater the amount of amorphous material, the greater the chemical activity.

The chemical composition of the ferronickel slag powder used in the present invention is shown in Table 1 below in%.

content(%) Chemical composition SiO ₂ MgO CaO Al ₂ O ₃ T-Fe T-Ni Fe-Ni slag 52.4 35.6 0.9 1.6 4.6 0.03

Referring to Table 1, the main chemical components of the ferronickel slag powder are vitrified SiO ₂ and MgO. As is well known, SiO ₂ The rate at which the strength is developed is activated later than CaO or Al ₂ O ₃ . Also MgO is a substance that reacts with water and expands when it is transferred to Mg (OH) ₂ . It is known that the limit of MgO content in cement is also due to its swelling property.

Therefore, CaO is not contained in the main component of cement, and since it shows swelling property, after the concrete is cured, the ferronickel slag is not used as raw material and admixture material because of fear of cracking due to expansion.

However, the present invention is characterized in that it is utilized as a material for increasing the confining pressure of the ground by using the expandability.

It is preferable that 10 to 100 parts by weight of the ferronickel slag fine powder is incorporated into 100 parts by weight of the three kinds of blast furnace slag cement. When the ferronickel slag powder is incorporated in an amount of less than 10 parts by weight, the content of MgO, which is an expandable material, is relatively low, so that the required expansion is not caused and the predetermined purpose can not be achieved. The effect becomes larger, but the content of CaO, which is a relatively potentially hydraulic material, is lowered, so that the required strength can not be expressed.

In addition, the pile-feeding material composition according to the present invention includes light dolomite, which is a material produced by calcining dolomite at a relatively low temperature. As the endothermic reaction (Scheme 1) according to the calcination temperature under at a temperature of 600 ~ 800 ℃ the MgCO ₃ is decarbonation first and the transition to the active magnesium in a highly reactive amorphous state, a CaCO ₃ at a temperature of 800 ~ 1000 ℃ Decarboxylated and transferred to highly reactive calcium oxide.

(Scheme 1)

600 to 800 ° C: CaMg (CO ₃ ) ₂ = CaCO ₃ + MgO + CO ₂ ↑

800 to 1000 ° C: CaCO ₃ + MgO = CaO + MgO + CO ₂ ↑

The chemical composition of the light mineral dolomite powder according to the present invention is shown in Table 2 below.

ingredient(%) SiO ₂ MgO CaO Al ₂ O ₃ Fe ₂ O ₃ SO ₃ Light dolomite
(Light Burned Dolomite) 4.3 30.6 52.3 3.7 1.8 0.7

Since the active magnesia of this limestone dolomite exists in an amorphous state with a very high initial reactivity as shown in the following reaction formula 2, it reacts with water and hydration to form crystalline brucite.

(Scheme 2)

As shown in the above hydration equation, a large amount of brucite (Mg (OH) ₂ ) gel is formed at the beginning of hydration, and a large amount of excess water is confined as a crystal water. This is because the ratio of pore hydrates such as ettringite As a result of forming a dense structure and consequently contributing to an increase in compressive strength.

In addition, the active magnesia exerts an expansion action similar to an expanding material such as quicklime or semi-gypsum during hydration, and the reaction formula thereof is as follows.

(Scheme 3)

In the hydration reaction, the volume of Mg (OH) ₂ crystals formed from MgO is expanded more than twice the sum of MgO and H ₂ O volume. Therefore, in the present invention, this expansion action of light dolomite and the alkali stimulating effect in which CaO is continuously transferred to Ca (OH) ₂ are utilized in combination.

On the other hand, dolomite is burned at a very high temperature (Dead-Burn), and decarbonated MgO is called periclase, which does not have an initial expansion action like active magnesia, but at a very late age Causing excessive expansion and cracking of the concrete structure. Since the calcination temperature of cement is over 1,450 ℃, MgO produced in the process of cement clinker is periclase, and therefore the content of MgO is strictly restricted in the production of cement.

It is preferable that the lightweight dolomite is incorporated in an amount of 10 to 100 parts by weight based on 100 parts by weight of the third type blast furnace slag cement. When the content of the light dolomite is less than 10 parts by weight, the effect is insufficient as an alkali irritant for stimulating and activating the vitrified silicic acid component of the ferronickel slag. When the content is more than 100 parts by weight, the ferronickel slag and the blast furnace slag Surplus amount may exist, and there is a possibility that the MgO component excessively expands and the strength is lowered.

In addition, the pile material composition according to the present invention may further include fly ash exhibiting pozzolanic activity in order to improve fluidity and enhance long-term strength selectively.

The fly ash is preferably a coal-fired fly ash having a silicon dioxide content of 30 wt% or more, preferably 45 to 65 wt%, which exhibits pozzolan activity, for pozzolan activity expression.

The fly ash is preferably incorporated in an amount of 10 to 100 parts by weight based on 100 parts by weight of the third type blast furnace slag cement. If the fly ash content is less than 10 parts by weight, the effect of pozzolanic activity is insignificant and it is difficult to expect long term strength enhancement. If the fly ash content exceeds 100 parts by weight, long term strength may increase but initial strength may decrease.

The pile material composition according to the present invention can be produced by compounding the respective components at a predetermined mixing ratio.

Further, the water may be mixed with the pile grouting material and the water / binder ratio (W / B ratio) may be adjusted to suit the application to be used, water may be added, and the mixture may be sufficiently mixed to prepare an injection solution.

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, 50 parts by weight of a water-chain-quenched ferronickel slag fine powder was mixed with 100 parts by weight of three kinds of blast furnace slag cement (50% of one kind of portland cement, 45% of blast furnace slag fine powder and 5% of gypsum) 50 parts by weight of dolomite fine powder and 50 parts by weight of fly ash having a silicon dioxide content of 49% were uniformly mixed to prepare a pile filler.

Next, water was added to the pile filler so that the water / binder ratio (W / B ratio) became 83%, and the mixed solution was sufficiently mixed with a forced mixer.

Next, in consideration of the fact that the soil of the pile is collapsed in the Auger hole at the time of actual construction, the fluidity is measured by mixing 50%, 60%, 70%, and 100% Compressive strength specimens were prepared by mixing 70% clay soil with weight ratio.

Comparative Example  : 1 species Usually Portland  Examples of using cement

First, water was added to the pile as a filler of type 1 portland cement and the water / binder ratio (W / B ratio) was 83%, and the mixture was thoroughly mixed with a forced mixer.

Next, in consideration of the fact that the soil of the pierced hole was collapsed into the infusion liquid during the actual construction, the fluidity was measured by mixing 50%, 60%, 70%, and 100% of the clay soil with the weight ratio of the infusion liquid. Compressive strength specimens were prepared by mixing 70% clay soil with a weight ratio. Compressive strengths according to age were compared with the experimental results.

Experimental Example  : Performance Test Method and Result of Pile Filler

As shown in Table 3 below, the flow test was performed with KS F 2594, the compressive strength test with KS F 2343 method, and the material separation degree and volume change were visually inspected.

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

Table 4 shows the results of measuring the fluidity change (flow) of the pile injection material.

Unit (cm) Soil weight ratio (%) 0 50 60 70 100 Example 61 40 38 34 28 Comparative Example 68 42 40 36 31

As a result of observing the fluidity change of the pile injection material, the fluidity decreases as the soil incorporation rate increases. The embodiment according to the present invention using the three-kind blast-furnace slag cement showed a tendency that the fluidity was slightly lower than that of the one-kind ordinary cement used as the comparative example. This is because the injected material of the present invention has a relatively low mass of 3.06 as compared with the cement weight of 3.15, so that the amount of the powder is increased and the relative surface area is large.

However, in the case of pile grouting material, the lowering of fluidity in the absence of the drop of the feed pipe and the clogging phenomenon causes the material separation resistance to be larger, and it can be advantageous in the ground where the pores such as sandy soil are large.

(2) Uniaxial compressive strength  change

Table 5 shows the results of uniaxial compressive strength test according to the mixing ratio of soil in the examples and comparative examples.

Young 3 days 7 days 28th Soil weight ratio (%) 70% 70% 70% Example Compressive Strength (MPa) 10.1 16.3 21.5 Comparative Example Compressive Strength (MPa) 10.9 15.5 18.9

Referring to Table 5, in the case of the example, the initial strength was comparable to that of the first-grade cement, which was a comparative example, but the long-term strength was remarkably high. This is because the amount of cement is relatively insufficient, but the latent hydroponics are expressed by the alkali irritation of the light dolomite and ferronickel slag powder, and it is considered that this is due to the pozzolanic activity of fly ash. In other words, it is judged that the result of the alkali irritation of cement hydrate and the alkali complex irritation of light dolomite, the dolomite, ferronickel slag fine powder and fly ash amorphous material continuously produce hydrates.

In addition, when the same amount of injection was used, the compressive strength of the example was excellent, so that the same strength as that of the one-kind cement can be exhibited even when the unit bonding amount is reduced at the actual site application, .

(3) Degree of material separation  And volume change confirmation

In both of the examples and the comparative examples, material separation did not occur, thus ensuring the workability in the field.

As a result of visual observation of the volume change for 72 hours after the blending, as shown in the following Fig. 1, the volume increased as the amount of shrinkage was compensated for by the swelling property of MgO, which was included in large amounts, I was able to visually confirm the vessel.

Claims (5)

Wherein 10 to 100 parts by weight of the ferronickel slag fine powder and 10 to 100 parts by weight of the fine dolomite fine powder are added to 100 parts by weight of the third type blast furnace slag cement. The method according to claim 1,
Wherein said ferronickel slag fine powder is obtained by pulverizing water-quenched ferronickel slag obtained by quenching slag with water. The method according to claim 1,
Wherein the pile-casting material composition further comprises fly ash. The method of claim 3,
Wherein the fly ash is coal-fired fly ash having a silicon dioxide (SiO ₂ ) content of at least 30 wt.%. The method of claim 3,
Wherein the fly ash is incorporated in an amount of 10 to 100 parts by weight based on 100 parts by weight of the third type blast furnace slag cement.

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