KR20180028048A - Ground grouting process - Google Patents

Abstract

The present invention relates to an eco-friendly ground grouting method without heavy metal elution and, more specifically, to an eco-friendly ground grouting method without heavy metal elution, which improves hydration and activity by utilizing bottom ashes discharged from a lower part of a circulating fluidized bed boiler as a stimulator of blast furnace slag powder in order to replace type 1 normal cement which is most widely used in a grouting construction for reinforcing soft ground. The eco-friendly ground grouting method according to the present invention comprises: 1) a step of installing an injection pipe on the ground; 2) a step of manufacturing a ground grouting material by mixing a solidification material including blast furnace slag fine powder and circulating fluidized bed combustion bottom ash with water; 3) a step of transferring and injecting the ground grouting material through the injection pipe; and 4) a step of hardening and curing the ground grouting material.

Description

GROUND GROUTING PROCESS -

The present invention relates to an eco-friendly ground grouting method without heavy metal leaching, and more particularly, to a bottom ash discharged from the bottom of a circulating fluidized bed boiler in order to replace one kind of ordinary cement most widely used in grouting work for reinforcing soft ground The present invention relates to an eco-friendly ground grouting method for promoting hydration reaction and activity without leaching of heavy metal by utilizing it as a stimulant for fine powdered blast furnace slag powder.

During the use of civil engineering and architectural structures, it is often necessary to reinforce the foundation and reinforcements due to tunnel construction, expansion or remodeling, change of purpose, increase of load.

The grouting method is used as a method for improving the ground which is expected of these problems and as a means for eliminating the safety problems such as order and reinforcement in constructing any objects.

The chemical solution injection method at the time of grouting construction injects the filling material such as cement liquid into the soft ground by the pressure of the pump to fill the pores or cracks in the ground to prevent the water from flowing out or to harden the ground layer by hardening And a chemical solution such as a cement liquid, a mortar liquid or a water glass liquid is used as an injection material.

Therefore, the chemical solution injection method has a complex effect such as prevention of scarring by increasing the strength of the ground by injecting a solution liquid and a solution-type chemical solution, which originally has fluidity but can be solidified after a predetermined time, Is one of the improvement methods of the ground that expects.

Generally, cement is used as a main binder in grouting chemical injecting method. Cement can cause environmental pollution due to strong alkali and hexavalent chromium in the ground, and excessive volume shrinkage occurs during hydration reaction. In particular, cement must contain hexavalent chromium because the cement kiln is made of refractory clay bricks for the low pressure part of the furnace at low temperature, and the temperature is high and the wear due to the friction of the clinker and the chemical reaction Is made of magnesium-chromium-containing bricks containing magnesium and chromium. In this process, chromium contained in the refractory bricks is known to be contained in the process of clinker formation.

On the other hand, fly ash, which accounts for about 80% of the coal combustion by-products discharged from the pulverized combustion boiler of a thermal power plant, generates vitreous (amorphous) components when burned at a high temperature of about 1,350 ° C. The bottom ash, which is about 20% of the byproducts, is also used as cement and concrete raw materials. It also means coal ash that has fallen on the bottom of the boiler due to its own weight attached to the wall and the like during pulverized coal combustion. And is a porous material containing a large amount of vitreous. The pulverized coal boiler bottom ash has a particle size similar to that of fine aggregate and coarse aggregate for concrete, and is included in the structural lightweight aggregate of KS F 2534; it is estimated that it has enough lightweight and toughness to be used as structural lightweight aggregate And studies are being actively carried out to utilize these as aggregates. In recent years, studies have been actively carried out to induce geopolymer polymerization reaction by destroying the bottom ash glass film with a chemical such as sodium hydroxide after finely pulverizing the bottom ash of the pulverized coal boiler of the thermal power plant into ultrafine particles to physically activate it Is in progress. In this connection, Korean Patent No. 1339332 entitled " Binder containing Bottom Ash, "and 1410056" Cemented Concrete by Binding Material Containing Bottom Ash, " and 1366293 entitled "Cemented Slag and Bottom Ash And a method of producing the same, a technique of inducing a geopolymer polymerization reaction by pulverizing a bottom ash of a pulverized coal-fired boiler of a thermal power plant has been proposed. In the "binder composition for concrete containing bottom ash" of Korean Patent No. 1312562, bottom ash is finely pulverized with a vibration mill at a rate of 6,000 to 8,000 cm ² / g, and the surface of the particles is subjected to activation treatment to show possibility of use as a cement admixture . All of these patents are intended to utilize a bottom ash of a pulverized coal-fired boiler of a thermal power plant.

Meanwhile, the coal combustion by-products discharged from the circulating fluidized bed boiler of the small and medium-sized cogeneration plant have low pozzolanic reactivity because the combustion temperature is as low as about 850 ° C and no vitreous is formed. In the case of circulating fluidized-bed boiler fly ash, the content of CaO and SO ₃ was higher than that of fly ash discharged from pulverized coal boiler, and the recycled content was insufficient due to insufficient SiO ₂ content. However, as the KS L 5405 2015 fly ash standard was revised, And a recycling plan was prepared so that it can be mixed with some. However, the bottom ash of the circulating fluidized bed boiler has a smaller particle size than that of the bottom ash of the pulverized coal boiler and is not porous. Therefore, it is difficult to utilize the bottom ash as a lightweight aggregate such as a pulverized coal boiler bottom ash. In addition, some recent research data on the bottom ash of pulverized coal bed boiler fly ash and thermal power plant pulverized coal boiler have been reported, but the data on the bottom ash of the circulating fluidized bed boiler has not been reported so far.

Korea Patent No. 1339332 Korea Patent No. 1410056 Korea Patent No. 1366293 Korea Patent No. 1312562

SUMMARY OF THE INVENTION It is an object of the present invention to provide a bottom ash discharged from a lower portion of a circulating fluidized bed boiler in order to replace one kind of ordinary cement most widely used in grouting work for reinforcing soft grounds. It is an object of the present invention to provide an eco-friendly ground grouting method which is free of heavy metal leaching which improves hydration reaction and activity by utilizing as a stimulant of fine powdered blast furnace slag powder.

According to an aspect of the present invention, there is provided a ground grouting method comprising: 1) installing an injection pipe on a ground; 2) blending a high fire containing blast furnace slag fine powder and a circulating fluidized bed bottom ash with water to produce a ground grouting material; 3) feeding the ground grouting material through the injection tube and injecting the grouting material; And 4) curing and curing the ground grouting material.

In addition, the step 2) may include the step of preparing 5 to 1,000 parts by weight of the circulating fluidized bed boiler bottom ash with respect to 100 parts by weight of the blast furnace slag fine powder, wherein the circulating fluidized bed boiler bottom ash has a CaO content of 15 to 75 By weight and an SO ₃ content of 3 to 30% by weight.

Also, in the step 2), it is preferable that the solidified flame includes 0.5 to 400 parts by weight of a circulating fluidized bed boiler fly ash having a CaO content of 10 to 55% by weight, based on 100 parts by weight of the blast furnace slag fine powder.

In addition, in the step 2), the solidified coal boiler fly ash may further contain 0.5 to 400 parts by weight of pulverized coal boiler fly ash, based on 100 parts by weight of the blast furnace slag fine powder, and the pulverized coal boiler fly ash has a SiO ₂ content of 35 to 60% It is preferable that the CaO content is 0.5 to 10 wt% and the SO ₃ content is 0.1 to 3 wt%, and is discharged from the pulverized combustion dust collector of the thermal power plant.

Also, in the step 2), the harsh fire may further contain 0.5 to 400 parts by weight of a sulfate stimulant based on 100 parts by weight of the blast furnace slag fine powder, and the sulfate stimulant may be selected from the group consisting of natural anhydrous gypsum, petrocoke desulfurized gypsum, It is preferable to further include any one or a mixture of two or more of them.

Also, in the step 2), the cement may further comprise 0.5 to 200 parts by weight of cement based on 100 parts by weight of the blast furnace slag fine powder, and the cement may be selected from the group consisting of a first cement, a third cement, a CSA (Calcium Sulfur Aluminate) Blast furnace slag cement, blast furnace slag cement, fly ash cement, or a mixture of two or more thereof.

Also, in the step 2), the ground grouting material preferably further comprises 0.01 to 20 parts by weight of a liquid and powder type fluidizing agent relative to 100 parts by weight of the blast furnace slag fine powder in order to improve fluidity.

Also, in the step 2), the ground grouting material preferably further comprises 0.01 to 20 parts by weight of an underwater non-separating agent based on 100 parts by weight of the blast furnace slag fine powder in order to prevent underwater separation.

The ground grouting material may further include 0.01 to 20 parts by weight of a foaming agent based on 100 parts by weight of the blast furnace slag fine powder in order to form a lightweight bubble in the step 2).

According to the present invention, one kind of ordinary cement most widely used in grouting work for reinforcing soft ground can be replaced by industrial by-products such as bottom ash and blast furnace slag fine powder.

Particularly, by using the bottom ash discharged from the lower portion of the circulating fluidized bed boiler as a stimulant for blast furnace slag fine powder, the hydration reaction and activity can be improved to provide an eco-friendly ground grouting method free from heavy metal leaching.

Hereinafter, an eco-friendly ground grouting method without heavy metal leaching according to the present invention will be described in detail.

The eco-friendly ground grouting method according to the present invention comprises the steps of: 1) installing an injection pipe on a ground; 2) blending a high fire containing blast furnace slag fine powder and a circulating fluidized bed bottom ash with water to produce a ground grouting material; 3) feeding the ground grouting material through the injection tube and injecting the grouting material; And 4) curing and curing the ground grouting material.

First, the constituent components and actions of the environmentally friendly fireproofing for the above-mentioned ground grouting method will be described in detail.

The boiler includes 5 to 1,000 parts by weight of a bottom fluid ash of a circulating fluidized bed boiler having a CaO content of 15 to 75% by weight and an SO ₃ content of 3 to 30% by weight based on 100 parts by weight of the blast furnace slag fine powder.

The blast furnace slag is a by-product obtained by quenching slag in a high-temperature molten state generated as a by-product in a steelmaking blast furnace process with water. The blast furnace slag fine powder is called a latent hydraulic material because the amorphous coating is formed when it comes into contact with water and the hydration reaction does not occur by itself. The amorphous film must be destroyed in order for the latent hydraulic properties to be exhibited. The blast furnace slag fine powder can be used if it is a commercially available product having a specific surface area of 3,000 cm ² / g or more.

The circulating fluidized bed boiler bottom ash is generated in a circulating fluidized bed boiler using coal as the main fuel and in the lower part of the boiler in a manner of desulfurizing in the furnace together with limestone. In the desulfurization process of the circulating fluidized bed boiler, limestone is injected into the combustion chamber and burned together with the fuel, so that sulfur oxide and limestone in the combustion gas react in the furnace to remove sulfur in the combustion gas and produce anhydrous gypsum. It is carbonated and transferred to the quicklime component and discharged. Particularly, circulating fluidized-bed boiler bottom ash is burned at a temperature of about 850 ° C, and thus can not cause a pozzolanic reaction because there is no vitreous component. However, the CaO and CaSO ₄ components are higher than fly ash collected at the top, It can be said that it has a more excellent composition as a stimulant for fine powders. Therefore, it is a strong alkali substance having a pH of 11.5 or more and has a property of acting as a stimulant when used in the same manner as the blast furnace slag fine powder.

When water is added to a normal blast furnace slag fine powder, an amorphous film is formed on the surface, and the internal Ca ^{2 +} , Al ^3+, etc. are not eluted. However, when water is introduced after mixing the circulating fluidized bed boiler bottom ash, the CaO component contained in the bottom ash reacts with water to convert it into Ca (OH) ₂ , resulting in OH ^- and SO ₄ ^{2 - The} component destroys the amorphous film of blast furnace slag fine powder, facilitating the elution of Ca ^{2 +} , Al ^{3 +,} etc., and the elution ions generate CaO-SiO ₂ -H ₂ O-based hydrate, (3CaO.Al ₂ O ₃ .3CaSO ₄ .32H ₂ O) having an acicular structure, the surplus sulfur oxide densifies the structure in the hydrated body to improve the compressive strength of the hardened body . Since the bottom ash generally has a particle diameter of 5 mm or less and its particle size is larger than that of cement and fly ash, it has a stimulating effect on the blast furnace slag itself, and thus can act as a stimulant and a fine aggregate. It can be used directly as paste and mortar when mixed with water without adding aggregate. However, in order to further enhance the stimulating effect of the blast furnace slag, it is preferable to classify and grind it to 1 mm or less.

The bottom ash preferably has a CaO content of 15 to 70% by weight. If it is less than 15% by weight, the content of CaO existing in the form of pure CaO itself is insufficient, except for about 10% by weight of CaO present in the form of CaCO ₃ and CaSO ₄ . That is, since the pure CaO reacts with water and is converted into Ca (OH) ₂ and the amount of OH ^- ion generated is insufficient, the amorphous film of the blast furnace slag fine powder is difficult to break down in a short period of time. The pure CaO present in the bottom ash reacts with water and absorbs, exotherms and expands to form Ca (OH) _2. The reaction equation is as follows. The volume expands about 1.99 times.

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

Therefore, the pure CaO component reacts with water to convert it into calcium hydroxide, and it also acts as an alkali stimulant of fine powdered slag powder. However, due to the increase in temperature due to heat generation, the hydration reaction of the blasted slag powder is promoted and the effect of compensating the volumetric shrinkage Role and so on. On the other hand, if the CaO content is more than 70% by weight, the CaO content existing in the pure CaO form is excessively absorbed, excessively absorbing the water, and excessive heat generation and expansion may occur and cause cracks. Therefore, it is necessary to perform the chemical quantitative analysis before the raw material in the bottom ash, and the CaO content should be 15 to 70% by weight.

The bottom ash preferably has an SO ₃ content of 3 to 30% by weight. If it is less than 3% by weight, the content of SO ₃ capable of stimulating slag is insufficient, so that the strength is difficult to manifest. If it exceeds 30%, the content of SO _{3 which} does not react with the excess amount of slag is present. It is preferred to analyze the chemical composition to use the bottom ash within the above range.

The amount of the bottom ash is preferably 5 to 1,000 parts by weight based on 100 parts by weight of the blast furnace slag fine powder. If the amount is less than 5 parts by weight, the effect is not exhibited. If the amount is more than 1,000 parts by weight, The strength is greatly lowered.

In addition, the boiler further includes 0.5 to 400 parts by weight of circulating fluidized-bed boiler fly ash relative to 100 parts by weight of fine blast furnace slag fine powder. Preferably, the circulating fluidized bed boiler fly ash is discharged from a circulating fluidized bed boiler dust collector having a CaO content of 10 to 55 wt%. The circulating fluidized bed boiler fly ash may be any one or a mixture of coal, paper sludge, solid fuel, and biomass.

The circulating fluidized bed fly ash acts both as a stimulant of blast furnace slag and as a water-absorbing agent in the soil to rapidly solidify the soil particles to physically improve and to prevent shrinkage.

The circulating fluidized bed boiler fly ash is preferably mixed in an amount of 0.5 to 400 parts by weight with respect to 100 parts by weight of the blast furnace slag fine powder. When the blending amount is less than 0.5 parts by weight, the effect is not exhibited. When the blending amount is more than 400 parts by weight, The relative amount of water is relatively reduced, and the potential hydraulic property is lowered, and the fluidity may be lowered due to a relatively large amount of water absorption.

The pulverized coal boiler fly ash may further comprise 0.5 to 400 parts by weight of a pulverized coal-fired power plant pulverized coal boiler fly ash, based on 100 parts by weight of the blast furnace slag fine powder. The pulverized coal fly ash has a SiO ₂ content of 35 to 60% 10% by weight and an SO ₃ content of 0.1 to 3% by weight, and is discharged from the pulverized coal boiler dust collector. The pulverized coal-fired boiler fly ash is collected when a combustion gas of a pulverized coal combustion boiler passes through a dust collecting apparatus in a thermal power plant having a separate desulfurization facility. Since the CaO content is less than 10% by weight, Of neutral and low alkali materials.

Fly-ash coal-fired power plant pulverized coal boiler fly ash is partially replaced with Portland cement. Since fly ash has a spherical shape, its fluidity is increased and its pozzolan-reactive property is increased to increase strength in long-term age. . That is, when mixed with Portland cement, fly ash is stimulated and hardened after the hydration product of cement, i.e., calcium hydroxide, is produced. As a result, the reaction of fly ash starts secondarily. For this reason, when fly ash is mixed with Portland cement, problems such as delayed coagulation, initial strength reduction, and neutralization are caused. Due to such a phenomenon, there may arise problems such as delays in form deformation, deterioration in initial strength, and deterioration in long-term durability due to neutralization at the construction site, and the content of fly ash relative to 100 wt% of Portland cement is used as 5 to 20 wt% . In the present invention, the pozzolanic reaction of the pulverized coal boiler fly ash is initially activated by the stimulating effect of Ca (OH) ₂ produced by the reaction of the CaO component of the bottom ash of the circulating fluidized bed boiler with water.

The pulverized coal boiler fly ash is preferably blended in an amount of 0.5 to 400 parts by weight based on 100 parts by weight of the blast furnace slag fine powder. When the blending amount is less than 0.5 parts by weight, the effect is not exhibited. When the blending amount is more than 400 parts by weight, Of the fly ash is present in a large amount.

Also, in order to increase the strength, 0.5 to 400 parts by weight of a sulfate stimulant is added to 100 parts by weight of the blast furnace slag fine powder, and any one or a mixture of two or more of natural anhydrite, petroleum coke, . It is preferable that the sulfite stimulant is mixed with 0.5 to 400 parts by weight of 100 parts by weight of the blast furnace slag fine powder. If the amount is less than 0.5 part by weight, the effect is not exhibited. If the amount is more than 400 parts by weight, It is present, and it severely lowers the strength.

The cement may further comprise 0.5 to 200 parts by weight of cement based on 100 parts by weight of the blast furnace slag fine powder to improve the initial strength. The cement may be selected from the group consisting of a first type cement, a third type cement, an agate type cement, a CSA (Calcium Sulfur Aluminate) , Blast furnace slag cement, fly ash cement, or a mixture of two or more thereof. It is preferable that the cement is mixed with 0.5 to 200 parts by weight with respect to 100 parts by weight of the blast furnace slag fine powder. When the blending amount is less than 0.5 parts by weight, the effect is not exhibited. When the blending amount exceeds 200 parts by weight, Hazardous substances can be eluted and economic efficiency is also insufficient.

Further, in the step 2), it is preferable to further include a liquid and powder type fluidizing agent for improving fluidity. The fluidizing agent is preferably one selected from the group consisting of naphthalene type, melamine type, amine type, lignin type and polycarboxylic type, or a mixture of two or more thereof. When the amount of the fluidizing agent is less than 0.01 parts by weight, the fluidity is not improved. When the amount of the fluidizing agent is more than 20 parts by weight, the fluidity is excessively improved to separate the material, Lack.

In addition, in the step 2), it is preferable to further include an underwater non-separating agent to prevent underwater separation. The water-in-oil separating agent is selected from the group consisting of HYDROXY PROPYL METHYL CELLULOSE (HPMC), HYDROXY ETHYL CELLULOSE, HEC, CARBOXY METHYL CELLULOSE, CMC, ETHYL HYDROXY ETHYL CELLULOSE, EHEC), POLYACRYL SALT, POLY SACCARIDE, HYDROXY ETHYL METHYL CELLULOSE, HEMC, POLY ETHYLENE OXIDE, PEO, ETHYLENE VINYL ACETATE, EVA), or a mixture of two or more thereof. If the amount of the water-insoluble separating agent is less than 0.01 part by weight, the effect of improving the water-insolubilization is not exhibited. If the amount of the water-insolublizing agent is more than 20 parts by weight, viscosity is excessively increased.

Further, it is preferable to further include a foaming agent in order to form lightweight bubbles. By adding a foaming agent, it is possible to minimize the load on the underground structure by replacing the volume of the fine aggregate and the coarse aggregate while reducing the weight. The foaming agent is a foaming agent used in concrete. An animal or vegetable foaming agent commonly used in Korea can be used. It is preferable to use diluted foaming agent. The diluted bubbles are preferably foamed through a bubble generator at a pressure of about 4 to 12 bar Do. The foaming agent is preferably incorporated in an amount of 0.01 to 20 parts by weight based on 100 parts by weight of the blast furnace slag. When the blending amount is less than 0.01 parts by weight, bubbling is not effected. When the blending amount exceeds 20 parts by weight, bubbles are excessively generated, Lack.

Hereinafter, the ground grouting method according to the present invention will be described.

In the step 3), the ground grouting material is injected through the injection pipe, and the grout material is required to form a bulb at the tip, or the site requiring the infiltration to the micro-pores is consolidated at a high pressure and injected, It is preferable to inject the gas at a low pressure.

In the step 4), the ground grouting material is cured. As long as the curing is sufficiently performed, it is preferable not to exert an external impact and sufficiently perform the curing at room temperature or the heat curing.

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.

Comparative Example

100 parts by weight of the first kind of cement was charged with 300 parts by weight of fine powder of 5 mm or less, followed by dry mixing, and then 100 parts by weight of water was further added thereto, followed by wet mixing to prepare a homogeneous mixture. Nine specimens of Ø10 cm × 20 cm were prepared and cured at 20 ° C., and the strengths were measured at 3 days, 7 days and 28 days.

Example  One

300 parts by weight of a coal combustion circulating fluidized bed boiler bottom ash having a CaO content of 46.7% by weight and an SO ₃ content of 16.8% by weight of not more than 5 mm was introduced into 100 parts by weight of the blast furnace slag fine powder having a specific surface area of 4,360 cm ² / g, After mixing, 100 parts by weight of water was further added thereto, followed by wet mixing to prepare a homogeneous mixture. Nine specimens of Ø10 cm × 20 cm were prepared and cured at 20 ° C., and the strengths were measured at 3 days, 7 days and 28 days.

Example  2

450 parts by weight of coal combustion circulating fluidized bed boiler bottom ash having a CaO content of 46.7% by weight and an SO ₃ content of 16.8% by weight of 5 mm or less with respect to 100 parts by weight of the blast furnace slag fine powder having a specific surface area of 4,360 cm ² / g, And 50 parts by weight of a circulating fluidized bed boiler fly ash having a CaO content of 36.5% by weight and an SO ₃ content of 9.2% by weight were discharged from a coal combustion circulating fluidized bed boiler dust collector at a rate of 3,820 cm ² / g. Thereafter, 150 parts by weight of water was further added thereto, followed by wet mixing to prepare a homogeneous mixture. Nine specimens of Ø10 cm × 20 cm were prepared and cured at 20 ° C., and the strengths were measured at 3 days, 7 days and 28 days.

Example  3

600 parts by weight of coal combustion circulating fluidized bed boiler bottom ash having a CaO content of 46.7% by weight and an SO ₃ content of 16.8% by weight with respect to 100 parts by weight of the blast furnace slag fine powder having a specific surface area of 4,360 cm ² / g, 3,450cm ² / g, and coal-fired pulverized coal boiler dust collecting a SiO ₂ content of 51.2% by weight is discharged from the plant and the pulverized coal boiler fly ash, 30 parts by weight of a CaO content of 1.9 wt% and the SO ₃ content of 0.8%, petro coke desulfurization gypsum 50 parts by weight, and 20 parts by weight of the first kind cement were homogeneously dry mixed. Thereafter, 200 parts by weight of water was further added thereto, followed by wet mixing to prepare a homogeneous mixture. Nine specimens of Ø10 cm × 20 cm were prepared and cured at 20 ° C., and the strengths were measured at 3 days, 7 days and 28 days.

Specimen  Test methods and results

As shown in Table 1 below, the compressive strength test was carried out by the uniaxial compressive strength test method of KS F 2343. The heavy metal elution test was carried out by taking a part of the sample after measuring the compressive strength at 28 days.

Experiment Way Remarks Compressive strength KS F 2343 Uniaxial Compressive Strength Test Method Heavy metal leaching Waste process test standard Heavy metal dissolution test method

division Compressive strength 3 days
(MPa) Compressive strength 7 days
(MPa) Compressive strength 28 days
(MPa) Comparative Example 8.72 13.46 21.17 Example 1 8.86 13.64 20.98 Example 2 9.12 14.18 22.37 Example 3 10.12 15.17 23.92

(One) Uniaxial compressive strength  change

Table 1 shows the uniaxial compressive strengths of Comparative Examples and Examples 1, 2 and 3. As can be seen from the results, Example 1 using the blast furnace slag fine powder and the circulating fluidized bed boiler bottom ash exhibited almost the same strength as Comparative Example 1 using the first grade cement and the stone powder, and further included the circulating fluidized bed boiler fly ash It can be confirmed that Example 3, which further comprises Example 2, pulverized coal boiler fly ash, Petro coke desulfurization gypsum and first grade cement, exhibits higher strength than Comparative Example using only first grade cement at all ages. Therefore, it can be seen that the environmentally friendly fireproofing of the present invention can replace the first type cement used in the ground grouting method.

(2) Extraction of heavy metals

KSLT Hexavalent chromium Copper Mercury cadmium lead arsenic Acceptance criteria 1.5 3.0 0.005 0.3 3.0 1.5 Comparative Example 1 0.783 0.456 Non-detection 0.259 0.145 0.089 Example 1 Non-detection Non-detection Non-detection 0.008 Non-detection Non-detection Example 2 Non-detection Non-detection Non-detection Non-detection Non-detection Non-detection Example 3 Non-detection Non-detection Non-detection Non-detection Non-detection Non-detection

The results of the heavy metal leaching experiment shown in Table 3 show that the comparative example satisfies the allowable reference value, but in the case of hexavalent chrome, the amount exceeding 50% of the reference value is eluted. All of the examples of the present invention, however, did not detect any heavy metals as well as hexavalent chromium.

 Therefore, the ground grouting method of the present invention can improve the strength by utilizing the industrial byproducts generated in the circulating fluidized bed boiler as a stimulant of the blast furnace slag fine powder, thereby replacing or minimizing the amount of the one kind of ordinary cement used in construction . In addition, it is an eco-friendly method that can solve the problem of natural resource and energy exhaustion, carbon dioxide emission, and environmental pollution caused by the release of harmful heavy metals, as well as production cost reduction by cement usage reduction.

Claims (1)

1) installing an injection pipe on the ground;
2) blending a high fire containing blast furnace slag fine powder and a circulating fluidized bed bottom ash with water to produce a ground grouting material;
3) feeding the ground grouting material through the injection tube and injecting the grouting material; And
4) curing and curing the ground grouting material,
In the step 2), 5 to 1,000 parts by weight of the bottom fluid ash of the circulating fluidized bed boiler is added to 100 parts by weight of the blast furnace slag fine powder,
The circulating fluidized bed boiler bottom ash has a CaO content of 15 to 75 wt% and an SO ₃ content of 3 to 30 wt%
In the step 2), the boiler further comprises 0.5 to 400 parts by weight of a circulating fluidized bed boiler fly ash having a CaO content of 10 to 55% by weight based on 100 parts by weight of the blast furnace slag fine powder,
In the step 2), the fireproofing further comprises 0.5 to 200 parts by weight of cement to 100 parts by weight of the blast furnace slag fine powder,
Wherein the cement further comprises at least one of a first type cement, a third type cement, a CSA (Calcium Sulfur Aluminate), a blast furnace slag cement, and a fly ash cement or a mixture of two or more thereof.