KR101636277B1 - Pile grouting materials composition using light burned dolomite - Google Patents

Abstract

The present invention relates to a pile grouting material composition includes, based on 100 wt part of light burned dolomite fine aggregates, 100-300 wt part of blast furnace slag fine aggregates and 50-200 wt part of gypsum containing at least 50 wt% of calcium oxide, and at least 15 wt% of sulfate oxide at hydrogen ion concentration (pH) of 12 or more. According to the present invention, CaO and SiO_2 ingredients obtained by vitrificating ferronickel slag fine aggregates and granulated blast furnace slag are activated by alkali and sulphate stimulus of the gypsum including at least 50 wt% of calcium oxide, and at least 15 wt% of sulfate oxide at hydrogen ion concentration (pH) of 12 or more, so that strength equal to or greater than that of type I ordinary cement used as the pile grouting material can be obtained. In addition, end bearing capacity and skin friction of a bored pile can be more improved as compared with those of existing injected cement liquid by preventing injected liquid from leaking by underground water filled in a gap between a bored ground and an original ground and existing between bores and the bored pile through a volume expansion reaction in which at least 30 wt% of MgO ingredients contained in light burned dolomite fine aggregates meet water (H_2O) to change into Mg(OH)_2 to be expanded.

Description

TECHNICAL FIELD [0001] The present invention relates to a pile grouting material composition,

The present invention relates to a pouring material composition for pile construction using lightweight dolomite. More particularly, the present invention can replace one kind of ordinary cement, which is most widely used as a piercing material for piling during construction of a pile excavation method, The present invention relates to a pouring material composition for pile construction, which is capable of exhibiting performance equivalent to or higher than that of slag cement.

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.

In recent years, there have been a lot of pile construction methods for building houses, large-scale buildings and constructions, for excavating paperboard, removing floating soil, and buying piles.

This method of constructing a pile is to use auger to pierce the hole and to plant the PHC pile or extended pile of the foundation product. In this method, bentonite is added to the soil and the pile space in the portland one kind of ordinary cement or one kind of cement And filling the injection liquid prepared by mixing water with the powder 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, for example, SIP (Soil-cement Injected Precast Pile), SAIP (Special Auger and Soil-cement Injected Precast Pile) and SDA (Separated Donut Auger) have been introduced from Japan since 1987 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 m ³ of cement paste with a water cement ratio of 83%, 880 kg of cement and 730 kg of water are required. This is because the mass of the cement is about 3.15, which is converted into a volume of 280ℓ (880 ÷ 3.15), and 730ℓ of water adds 1,010ℓ, that is, a volume of about 1.0m 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 causes environmental pollution caused by strong alkali and hexavalent chromium (Cr ⁺⁶ ) in the ground. As the water content is increased, water is absorbed into the surrounding ground in addition to the volume shrinkage characteristics of the cement itself during the hydration reaction. And excessive volume shrinkage occurs due to the loss of the pile, which causes the frictional force on the main surface of the pile to be lowered.

Recently, several techniques for improving the problem of using such existing 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.

Therefore, it is urgent to develop an injection material that exhibits excellent injection effects while solving the above problems.

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 it is an object of the present invention to provide a method for producing a slag cement which is capable of exhibiting strength equal to or higher than that of one kind of ordinary cement and slag cement, And to provide a pile-filling material composition capable of exhibiting an expansion action.

In order to solve the above-mentioned technical problem, the pile forging material composition according to an embodiment of the present invention comprises 100 to 300 parts by weight of a blast furnace slag fine powder, 100 to 300 parts by weight of a calcium oxide And 50 to 200 parts by weight of a gypsum having a calcium oxide content of 50% by weight or more and a sulfate oxide content of 15% by weight or more.

The pile-filling material composition according to the present invention may further include cement, and the cement may be any one or a mixture of two or more selected from the group consisting of a first type cement, a third type cement, a blast furnace slag cement and a fly ash cement .

The cement is preferably mixed with 50 to 200 parts by weight based on 100 parts by weight of the lightweight dolomite fine powder.

Further, the pile forging material composition according to the present invention may further include fly ash exhibiting pozzolanic activity.

The fly ash is preferably a coal-fired fly ash having a silicon dioxide content of at least 30 wt.%.

The fly ash is preferably incorporated in an amount of 50 to 200 parts by weight based on 100 parts by weight of the finely divided dolomite fine powder.

According to the present invention, the vitrified CaO and SiO ₂ components of the blast furnace slag fine powder have a hydrogen ion concentration (pH) of 12 or more, a calcium oxide content of 50 wt% or more and a sulfate oxide content of 15 wt% And activated by the alkali and sulphate stimuli of the gypsum so that it is possible to develop a strength equal to or higher than that of using one kind of ordinary cement as a pile filling material.

In addition, the pile-feeding material composition according to the present invention is characterized in that the MgO component contained in 30 wt% or more of the finely divided dolomite is mixed with water (H ₂ O) and is expanded to Mg (OH) ₂ , And it is effective to prevent the loss of the injection liquid due to the groundwater that may exist between the perforated hole and the embedded pile, thereby greatly improving the end bearing capacity and the frictional force of the embedded pile compared to the existing cement injection fluid .

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 injection material composition using light dolomite, and each component and action included in the pile injection material will be described below.

(PC, PHC) according to the present invention comprises 100 to 300 parts by weight of fine blast furnace slag powder, 100 parts by weight of calcium oxide having a hydrogen ion concentration (pH) of 12 or more, And 50 to 200 parts by weight of a gypsum having a sulfate oxide content of 15% by weight or more.

In the present invention, dolomite is a material produced by calcination of 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 lightweight dolomite powder according to the present invention is shown in Table 1 below.

ingredient(%) SiO ₂ MgO CaO Al ₂ O ₃ Fe ₂ O ₃ SO ₃ 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.

In addition, the blast furnace slag fine powder contained in the pile-feeding material composition of the present invention has a specific surface area of not less than 3,000 cm2 / g which is dried and pulverized by cooling the blast furnace slag discharged from the steelmaking process by water- The blast furnace slag fine powder is usually a commercially available product. The blast furnace slag fine powders exhibit a cement-like cement-like effect due to their potential hydraulic properties due to alkali and sulphate stimuli as main components CaO and SiO ₂ .

The blast furnace slag fine powder is preferably contained in an amount of 100 to 300 parts by weight based on 100 parts by weight of the light finely divided dolomite fine powder. When the amount of MgO is less than 100 parts by weight, the content of CaO as a latent hydraulic material is relatively low, so that the required strength can not be exhibited. When the amount of CaO exceeds 300 parts by weight, So that the required amount of expansion does not occur and the predetermined purpose can not be achieved.

The peg-feeding material composition according to the present invention may contain gypsum having a hydrogen ion concentration (pH) of 12 or more, a calcium oxide content of 50% by weight or more and a sulfate oxide content of 15% 50 to 200 parts by weight based on 100 parts by weight of the resin.

In addition, the gypsum breaks down the acid film of the blast furnace slag by the combined alkali and sulfate complex stimulation in a short period of time to accelerate the release of ions in the slag and react with them to produce a large amount of etrinite at the beginning of hydration. In addition, it is a substance that simultaneously acts as a stimulant and a binding material for generating calcium silicate hydrate and exhibiting strength as age elapses.

The gypsum having such a function is made to have an alkali of pH 12 or more, preferably 12 to 12.5, so that the acidic coating of the blast furnace slag compound is stimulated with an alkali and a sulfate to induce destruction in a short time to obtain a desired effect .

It is also preferable that the content of calcium oxide in the gypsum is 50% by weight or more, preferably 65 to 75% by weight and the content of sulfate oxide is 15% by weight or more, preferably 20 to 30% by weight desirable.

Generally, the purity of high grade gypsum means that the calcium oxide content and the sulfate oxide content are 95% or more. Silicon dioxide, ferric oxide, aluminum oxide, and the like contained in the gypsum are considered to be impurities. Therefore, if the content of calcium oxide in the gypsum is less than 65% by weight, the alkali-stimulating effect is not sufficient and the strength development may be delayed. If the calcium oxide content in the gypsum exceeds 75% by weight, The fade oxide content is lowered and the sulfate stimulating effect is reduced.

If the sulfide oxide content is less than 20 wt%, the effect of the sulfate stimulation is insufficient and the strength development may be delayed. If the sulfide oxide content exceeds 30 wt%, the relative calcium oxide content in the gypsum is lowered, The stimulation effect is reduced.

Specific examples of the gypsum of the present invention having the above characteristics may be one or a mixture of two or more selected from the group consisting of natural gypsum, flue gas desulfurization gypsum, petro coke desulfurization gypsum, and coal coke desulfurized gypsum.

The gypsum is preferably contained in an amount of 50 to 200 parts by weight based on 100 parts by weight of the lightweight dolomite fine powder. If the amount is less than 50 parts by weight, the effect of the combined stimulant of alkali and sulfate containing the quicklime component and the gypsum component at the same time is insignificant. If the amount of the stimulant exceeds 200 parts by weight, There is a possibility that the strength is lowered.

The pile-filling material composition according to the present invention may further include cement to induce hydration reaction of the pile-filling material at an early stage and to enhance 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 portland cement, three kinds of cement, blast furnace slag cement and fly ash cement.

The cement is preferably mixed with 50 to 200 parts by weight based on 100 parts by weight of the lightweight dolomite fine powder. If the content of the cement is less than 50 parts by weight, the effect of inducing the hydration reaction early in the curing of the pile filler is insufficient. If the amount exceeds 200 parts by weight, the material having a relatively high price is included and the economical efficiency is lowered. There is a concern.

In addition, it is preferable that the pile material composition according to the present invention further includes fly ash exhibiting pozzolanic activity for the purpose of promoting long-term cementation strength. 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.

It is preferable that such fly ash is incorporated in an amount of 50 to 200 parts by weight based on 100 parts by weight of the light dolomite fine powder. If the amount of the fly ash is less than 50 parts by weight, the effect of improving the long-term strength of the pile injection material is insufficient due to insufficient pozzolanic active materials. If the amount of the fly ash is more than 200 parts by weight, The predetermined purpose can not be achieved.

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

200 parts by weight of fine blast furnace slag powder, 100 parts by weight of petroleum coke desulfurization gypsum (pH 12.4, calcium oxide content: 72% by weight, sulfate oxide content: 25% by weight), 100 parts by weight of one kind of cement 100 And 100 parts by weight of fly ash having a silicon dioxide content of 49% were uniformly mixed to prepare a pile filler composition.

Next, water was added to the pile material composition so as to have a water / binder ratio (W / B ratio) of 83% and sufficiently mixed with a forced mixer to prepare an injection solution.

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

Comparative Example  : 1 kind of pile injection material using ordinary cement

First, water was added so that the ratio of water / binder (W / B) was 83% and sufficiently mixed with a forced mixer to prepare an injection solution.

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 2 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

The flowability change (flow) of the pile injection material was measured and the results are shown in Table 3 below.

Unit (cm) Soil weight ratio (%) 0 50 60 70 100 Example 64 39 38 33 28 Comparative Example 68 42 40 36 31

Referring to Table 3, the fluidity decreases as the soil incorporation rate increases. Also, the fluidity of the pile material according to the present invention tends to be slightly lower than that of the pile material using one kind of ordinary cement. This is because the injected material of the present invention has a relatively low mass of 3.01 as compared with the cement weight of 3.15, so that the amount of the powder increases and the relative surface area is large and the fluidity is deteriorated.

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 4 shows the results of uniaxial compressive strength test according to the soil incorporation ratio of the pile material according to the examples and comparative examples.

Young 3 days 7 days 28th Soil weight ratio (%) 70% 70% 70% Example Compressive Strength (MPa) 10.4 15.1 20.7 Comparative Example Compressive Strength (MPa) 10.9 15.5 18.9

As can be seen from Table 4, the initial strength of the pile material according to the present invention was comparable to that of the pile material using the first type cement, which was a comparative example, but the long-term strength was remarkably high. Although the amount of cement was relatively insufficient, potash hydraulic dolomite and blast furnace slag fine powders were stimulated by petroleum coke desulfurization gypsum, and latent hydraulics were expressed and it is considered that they were caused by pozzolanic activity of fly ash. In other words, it is judged that the result of the sustained hydration of the light dolomite, the blast furnace slag fine powder and the fly ash amorphous material by the sulfuric acid and alkali stimulus of petro coke.

Therefore, when the same amount of injection amount was used, the compressive strength of the example was excellent, so that the same strength as that of the first type cement can be exhibited even when the unit bonding material amount is reduced in actual field 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 Fig. 1, the volume of the example was increased by compensating for the amount of shrinkage caused by the swelling property of MgO, which is abundant in the light dolomite, It was visually confirmed that the shrinkage occurred.

Claims (6)

About 100 parts by weight of a powdery dolomite fine powder
100 to 300 parts by weight of fine blast furnace slag powder, and
Wherein the pH value is 12 to 12.5, the content of calcium oxide is 65 to 75 wt%, the content of sulfate oxide is 20 to 30 wt%, the content of calcium oxide and sulfate oxide And 50 to 200 parts by weight of gypsum having 95% or more of gypsum. The method according to claim 1,
The pile-in-filler composition may further comprise cement, wherein the cement is any one or a mixture of two or more selected from the group consisting of a first type cement, a third type cement, a blast furnace slag cement and a fly ash cement. . 3. The method of claim 2,
Wherein the cement is incorporated in an amount of 50 to 200 parts by weight based on 100 parts by weight of the lightweight dolomite fine powder. The method according to claim 1,
Wherein the pile-casting material composition further comprises fly ash. 5. The method of claim 4,
Wherein the fly ash is coal-fired fly ash having a silicon dioxide (SiO ₂ ) content of at least 30 wt.%. 5. The method of claim 4,
Wherein the fly ash is incorporated in an amount of 50 to 200 parts by weight based on 100 parts by weight of the lightweight dolomite fine powder.

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