KR20210071458A - Weak foundation treatment method - Google Patents

Abstract

The present invention relates to a weak ground rapid-treatment method and, more specifically, to a weak ground rapid-treatment method which can be used with a minimum number of curing conditions for weak ground solidification treatment construction in urgent construction or winter construction with low temperature through hardening-promotion and anti-freezing functions by byproducts containing chlorine components. In accordance with the present invention, the weak ground rapid-treatment method includes: 1) installing an injection pipe in the ground; 2) mixing a ground solidification material with water to produce a ground grouting material; 3) transferring and injecting the ground grouting material through the injection pipe; and 4) curing the ground grouting material by hardening the same. The ground solidification material, with respect to 100 parts by weight of blast furnace slag powder of which the specific surface area is 4,000-8,000 cm2/g, includes: 0.5-1,000 parts by weight of bottom ash of a circulating fluidized bed boiler having a particle size adjusted to no more than 0.1-5 mm, having a CaO content of 15-70 wt% and an SO3 content of 3-35 wt%; 0.5-500 parts by weight of ironworks sodium bicarbonate desulfurization dust having a chlorine content of 1-20 wt%; 0.5-500 parts by weight of ironworks lime desulfurization dust having a chlorine content of 0.5-10 wt%; 0.5-500 parts by weight of a solid fuel combustion material having a chlorine content of 0.1-10 wt%; and 5-300 parts by weight of cement.

Description

Soft ground rapid treatment method {WEAK FOUNDATION TREATMENT METHOD}

The present invention relates to a method for rapid treatment of soft ground, and more particularly, minimal curing during construction of soft ground in winter or urgent construction when the temperature is low by promoting hardening by byproducts containing chlorine and preventing freezing. It relates to a rapid treatment method for soft ground that can be used with conditions.

Concrete structures constructed in regions with a long winter period, such as Korea, cannot expect a certain strength and durability, so construction using the Korean-Chinese concrete construction method is unavoidable. According to the specifications of the Ministry of Land, Infrastructure and Transport, Korea-China concrete is defined as a day when the average daily temperature is below 4℃, and local governments and the Land and Housing Corporation are taking measures to suspend water works when the temperature is below 0℃. In the case of local organizations, it takes 31 to 160 days, and in the case of the Land and Housing Corporation, it takes 20 to 120 days, resulting in huge losses due to the suspension of construction. In order to prevent freezing of concrete, it must first satisfy the required performance, such as strength and durability, and must ensure that the workability in the unconsolidated state and the hydration reaction during hardening are faithfully achieved.

In particular, the most important thing for concrete is to maintain an appropriate hydration temperature condition so that the cement can have a sufficient hydration reaction in the initial stage. Hydration of cement is delayed or stopped at low temperatures, and the required performance is not achieved. In addition, when concrete is subjected to initial freezing, cracks due to volume expansion occur due to freezing of water, making it difficult to develop strength permanently. Due to this, the construction work is not performed properly in the winter season, and if the construction can be carried out regardless of the low temperature even in the winter season, it is possible to compensate for the huge losses caused by the suspension of winter construction by ready-mixed concrete companies and construction companies specializing in ground solidification. It can be said that it is very effective in terms of the effect of increasing employment.

Many of the Korean-Chinese concrete standards currently used in Korea were made based on foreign standards, but they have slightly different contents according to each domestic society or specification, so it is necessary to prepare an accurate and unified standard, and it is difficult to apply it in the field. It is necessary to establish a method that can be easily and activated. In the case of foreign countries, effective Korean-Chinese concrete is being developed actively by the use of cold-proofing agents, but in Korea, the development of this is very insignificant, and only some ready-mixed concrete companies are supplied with cold-proofing agents from developed countries. Calcium chloride, sodium chloride, potassium chloride, sodium acetate, sodium nitrite, calcium acetate, calcium nitrite, urea, bleaching powder, ethyl alcohol, ethylene alcohol, etc. have been widely used as admixtures that can lower the freezing temperature of concrete. .

In addition, inorganic salts such as chloride, carbonate, and nitrite, triethanolamine, calcium nitrate, and the like are used as substances that promote the hydration reaction of cement. However, chlorides such as calcium chloride and sodium chloride are not only higher in unit price than type 1 ordinary cement (75,000 won/ton), but also have a high risk of corrosion of reinforcing bars in reinforced concrete structures. Because the price of anti-freezing admixtures is 500,000 to 2 million won/ton, it is a situation that Korean and Chinese concrete is not widely used in Korea. However, in the case of chloride-based cold protection agents, 0.3% or more of chloride relative to the weight of cement can be used for sites such as unsupported concrete products, finishing mortars, and soft ground solidification materials that are not used with rebar, so it is very effective in the initial freeze. can do

In addition, there is a method that is used by heating water and aggregate as a method commonly used to prevent the initial freezing of concrete, but in fact, most of the ready-mixed concrete factories do not have the facilities to produce ready-mixed concrete by heating water and aggregate. to be.

In addition, there is a method that can prevent the development of initial strength and prevention of frost damage by using fast-hardening cement, but the price of fast-hardening cement is 4 to 20 times higher than that of type 1 ordinary cement, so it is difficult to use except for emergency repair work. Have.

Looking at the prior patent literature, "Concrete mixing composition and concrete mixing method for enhancing strength and preventing frost damage" of Republic of Korea Patent No. 101456041 includes 15.5% by weight to 21.5% by weight of sodium chloride, 11.5% by weight to 17.5% by weight of ammonium chloride, 32.5% by weight of calcium chloride % to 51% by weight, magnesium chloride 1.5% to 7.5% by weight, soda ash 11.5% to 17.5% by weight, surfactant 4.5% to 10.5% by weight, propylene glycol 4.5% to 10.5% by weight strength enhancement and A concrete blending composition for preventing frost damage is disclosed.

Republic of Korea Patent Registration No. 101561003 "Cement composition containing self-heating slag, Korean-Chinese concrete composition including the same, and construction method using the same" contains C ₃ A (3CaO·Al ₂ O ₃ ) as a major mineral, and Al ₂ O A composition comprising self-heating slag, cement and gypsum generated during the refining process of a steelmaking process containing 20 wt% or more of _{3 is disclosed.}

In Korean Patent Registration No. 101729216, "Cold-resistant accelerator composition for heating concrete", a composition containing cold-resistant accelerator for heating concrete that can express early strength is added to impart anti-freezing properties, and contains calcium nitrate, calcium nitrite and lithium nitrite. 1 admixture; It is added to control the setting time and heat generation time of concrete, and any one or more selected from the group consisting of potassium formate (PF), potassium acetate (PA), calcium formate (CF), potassium nitrate, tartaric acid and lithium carbonate a second admixture comprising; and a compounding water used for mixing the first admixture and the second admixture is disclosed.

The “super fast hardening cement composition” of Korean Patent Registration No. 100880930 includes 40 to 60% by weight of pulverized Irwin-based clinker containing 60 to 85% calcium sulfoaluminate, and 15 to 30 gypsum powder mixed with anhydrite and hemihydrate gypsum. A super fast hardening cement composition is disclosed, comprising % by weight, usually 20-40% by weight of Portland cement, and 1-4% by weight of slaked lime.

Korean Patent Registration No. 101418238, "High-durability super-velocity mixed cement composition" contains 29.3-43.1% by weight of crude cement containing 90-95% by weight of clinker and 5.0-10.0% by weight of dihydrate gypsum, and siloxane-based silicone 0.5 to 1.0% parts by weight, calcium sulfoaluminate (3CaO.3Al ₂ O ₃ .CaSO ₄ ) 32.5 to 33.5% by weight, C ₁₂ A ₇ 2.0 to 9.5% by weight, anhydrite 19.0 to 21.0% by weight, slaked lime High-durability super-velocity mixed cement composition using silane and siloxane-based silicone composed of 2.0 to 4.0% by weight, 0.3 to 0.5% by weight of a fluidizer, 0.1 to 0.5% by weight of a curing accelerator, and 0.5 to 0.7% by weight of a setting retarder This is disclosed.

Republic of Korea Patent No. 101456041 Republic of Korea Patent No. 101561003 Republic of Korea Patent No. 101729216 Republic of Korea Patent No. 100880930 Republic of Korea Patent No. 101418238

The present invention has been devised to solve the above problems, and an object of the present invention is to promote hardening by by-products containing chlorine and to prevent freezing in winter when the temperature is low or in an urgent construction soft ground solidification treatment construction To provide a rapid treatment method for soft ground that can be used with minimum curing conditions.

Another object of the present invention is to provide a method for rapid treatment of soft ground suitable for construction in winter when the temperature is low.

In order to solve the above technical problem, the method for rapid processing of soft ground according to the present invention comprises the steps of 1) installing an injection pipe in the ground; 2) mixing the ground solidification material with water to prepare a ground grouting material; 3) transferring and injecting the ground grouting material through the injection pipe; and 4) curing the ground grouting material by hardening; it includes, wherein the ground solidifying material has a specific surface area of 4,000 to 8,000 cm ² /g based on 100 parts by weight of the fine blast furnace slag powder, in an amount of 0.1 to 5 mm or less. 0.5 to 1,000 parts by weight of bottom ash of a circulating fluidized bed boiler with adjusted particle size, CaO content of 15 to 70% by weight and SO ₃ content of 3 to 35% by weight, and chlorine content of 1 to 20% by weight of sodium bicarbonate desulfurization dust 0.5 to 500 parts by weight, 0.5 to 500 parts by weight of ironworks lime desulfurization dust having a chlorine content of 0.5 to 10% by weight, 0.5 to 500 parts by weight of solid fuel combustion ash having a chlorine content of 0.1 to 10% by weight, and 5 to 300 parts by weight of cement It is characterized by including wealth.

In addition, the cement is preferably any one or a mixture of two or more of ordinary Portland cement, semi-crude portland cement, crude portland cement, CSA (Calcium Sulfur Aluminate), C ₁₂ A _{7 , alumina cement, and super-hard cement.}

In addition, based on 100 parts by weight of the fine blast furnace slag powder, 0.5 to 50 parts by weight of a chloride-based curing accelerator is further included, and the chloride-based curing accelerator is any one or two selected from the group consisting of calcium chloride, sodium chloride, potassium chloride, and cement kiln chlorine dust. It is preferable to further include a mixture of the above.

In addition, 0.5-50 parts by weight of a sulfate-based curing accelerator is further included with respect to 100 parts by weight of the fine blast furnace slag powder, and the sulfate-based curing accelerator is CaSO ₄ , K ₂ SO ₄ , MgSO ₄ , Na ₂ SO ₄ , Al ₂ (SO ₄ ) ₃ Any one selected from the group consisting of, or a mixture of two or more is preferable.

In addition, it is preferable to further include 0.01 to 5 parts by weight of liquid and powder fluidizing agents in order to improve fluidity with respect to 100 parts by weight of the fine powder of blast furnace slag.

In addition, it is preferable to further include 0.01 to 5 parts by weight of a thickener in order to prevent material separation with respect to 100 parts by weight of the fine powder of the blast furnace slag.

In addition, it is preferable to further include 0.01 to 5 parts by weight of an organic staple fiber in order to improve tensile strength with respect to 100 parts by weight of the fine powder of the blast furnace slag.

According to the present invention, there is an effect of preventing freezing by accelerating hardening by by-products containing chlorine in blast furnace slag.

Therefore, it is possible to improve the initial strength and prevent the initial frost damage with the minimum curing conditions in the case of cold winter construction or urgent construction of soft ground solidification treatment.

Therefore, it is possible to compensate for the huge losses caused by the suspension of winter construction in the winter season and is very effective in terms of employment increase effect.

Hereinafter, the ground solidification composition for rapid treatment of soft ground according to the present invention will be described in detail.

The ground solidification composition for rapid treatment of soft ground according to the present invention has a specific surface area of 4,000 cm ² /g or more, with respect to 100 parts by weight of fine powder of blast furnace slag, the particle size is adjusted to 0.1 to 5 mm or less, and the CaO content is 15 to 70% by weight. 0.5 to 1,000 parts by weight of bottom ash of a circulating fluidized bed boiler having an SO ₃ content of 3 to 35% by weight, 0.5 to 500 parts by weight of sodium bicarbonate desulfurization dust having a chlorine content of 1 to 20% by weight, and a chlorine content of 0.5 to 10% by weight 0.5 to 500 parts by weight of lime desulfurization dust, 0.5 to 500 parts by weight of solid fuel combustion ash having a chlorine content of 0.1 to 10% by weight, and 5 to 300 parts by weight of cement.

The fine powder of blast furnace slag is a latent hydraulic material and can be used as long as it is a pulverized product with ^{a specific surface area of 4,000 cm 2 /g or more, which is generally distributed in the market.} When a product with a specific surface area of 4,000 cm ² /g or less is used, the initial strength is delayed, making it difficult to rapidly treat the soft ground, which is the purpose of the present invention.

The bottom ash of the circulating fluidized bed boiler is generated at the bottom of the boiler in a way of desulfurizing in a furnace by mixing limestone and co-firing in a circulating fluidized bed boiler using coal as a main fuel. In the desulfurization process of a circulating fluidized bed boiler, limestone is injected into the combustion chamber and combusted with fuel. Sulfur oxide in the combustion gas and limestone react in the furnace to remove sulfur in the combustion gas and produce anhydrite, and limestone that does not react with sulfur is desulfurized. It is carbonated and transferred to the quicklime component. In particular, the bottom ash of a circulating fluidized bed boiler is burned at a temperature of about 850°C and cannot cause a pozzolan reaction because there is no glassy component, but it _{contains higher CaO and CaSO 4} components than fly ash collected from the top and contains fine blast furnace slag powder. It can be said that it has a more excellent composition as an alkali and sulfate irritant of Therefore, it is a strong alkali material with a pH of 11.5 or higher and has the property of acting as an irritant when used as fine powder of blast furnace slag.

When water is added to the normal fine powder of blast furnace slag, an amorphous film is formed on the surface, so that Ca ²⁺ , Al ³⁺ and the like are not eluted. However, when water is added after mixing the bottom ash of the circulating fluidized bed boiler, the CaO component contained in the circulating fluidized bed boiler bottom ash reacts with water and is converted to _{Ca(OH) 2} ^{OH −} generated during the desulfurization process The SO ₄ ^2- component destroys the amorphous film of the blast furnace slag fine powder, ^{making it easy to elute Ca 2+} , Al ^{3+ ,} etc., and the eluted ions _{generate CaO-SiO 2} -H ₂ O-based hydrates, etc. It promotes rapidly, and excess sulfur oxides produce _{ethringite hydration products (3CaO·Al 2} O ₃ ·3CaSO ₄ ·32H ₂ O) having a needle-like structure, thereby densifying the tissue inside the hydration body and increasing the compressive strength of the cured body. can be improved

The circulating fluidized bed boiler bottom ash generally has a particle diameter of 5 mm or less, and although the particle diameter is larger than that of cement and fly ash, it has a stimulating effect of crushed blast furnace slag itself. Therefore, it can be used directly as a paste and grouting material when mixed with water without additional aggregate input. However, in order to further improve the stimulating effect of the milled blast furnace slag, it is preferable to classify and pulverize it to a size of 1 mm or less.

The circulating fluidized bed boiler bottom ash preferably has a CaO content of 15 to 70% by weight. If it is less than 15% by weight, _{CaCO 3} , CaO content present in the form of pure CaO itself is insufficient, except for about 10% by weight of the CaO content present in the form of a compound of _{CaSO 4 .} That is, since pure CaO reacts with water and is converted to _{Ca(OH) 2} ^{, the amount of OH −} ions generated is insufficient, so it is difficult to destroy the amorphous film of the fine powder of blast furnace chain slag in a short time, and the initial strength is greatly reduced. In addition, when pure CaO present in bottom ash reacts with water to absorb, exotherm, and expand to become Ca(OH) ₂ , the reaction formula is as follows, and at this time, the volume expands about 1.99 times.

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

Therefore, the pure CaO component reacts with water and converts to calcium hydroxide and acts as an alkali stimulant for the fine blast furnace slag powder, but also promotes the hydration reaction of the fine blast furnace slag powder due to the temperature rise due to heat generation, compensates for volumetric shrinkage of the hardened body, and prevents neutralization. will perform at the same time. Conversely, when the CaO content is more than 70 wt%, the CaO content in the pure CaO form is excessive, which absorbs excessive moisture and excessively generates heat and expansion, which may cause cracks. Therefore, in the bottom ash, chemical quantitative analysis must be carried out before warehousing raw materials, and CaO content of 15 to 70% by weight must be used.

The circulating fluidized bed boiler bottom ash has an SO ₃ content of 3 to 35% by weight. If it is less than 3% by weight, the SO ₃ content that can stimulate the blast furnace slag is insufficient, so it is difficult to develop strength. If it exceeds 35%, _{there is a content of SO 3 that} did not react with the surplus amount of the blast furnace slag, so the strength may be lowered. . It is preferable to use the bottom ash within the above range by analyzing the chemical composition.

The circulating fluidized bed boiler bottom ash is preferably mixed in an amount of 0.5 to 1,000 parts by weight based on 100 parts by weight of the fine powder of blast furnace slag. When it is less than 0.5 parts by weight, the effect is not exhibited, and when it exceeds 1,000 parts by weight, the blast furnace slag content is relatively low. The strength is greatly reduced due to excessive irritant components.

The sodium bicarbonate desulfurization dust is produced before the iron ore is put into the blast furnace at the ironworks to produce sintered ore. In order to collect sulfur oxides (SOx) in the gas generated at this time, sodium bicarbonate of high powder (NaHCO ₃ ) is added. . The sodium bicarbonate desulfurization dust is finally discharged in the form of dust containing _{sodium sulfate (Na 2} SO _{4 ) and chlorine ions in part through a desulfurization reaction.}

Scheme 1 (bicarbonate desulfurization reaction)

Because sodium bicarbonate desulfurization dust lacks useful components such as Fe and Ca, it is impossible to recycle the process in the steelworks, and there is no suitable treatment method other than landfill treatment. However, landfill disposal also incurs disposal charges due to the impact of the Framework Act on Resource Circulation, which has been in effect since 2018, and the cost of entrusted landfill disposal is also rising rapidly. Therefore, an alternative treatment method is needed to reduce the amount of sodium bicarbonate desulfurization dust in landfill. However, in the case of sodium bicarbonate desulfurization dust, when reacting with water, ^{it dissolves into Na +} and SO4 ^2- to maintain a high pH and induce complex stimulation of alkali and sulfate, so that the hydration reaction of fine powder of blast furnace slag can be rapidly accelerated at the beginning. In addition, it has the property of being easily soluble in water, and there is no free CaO component, so it has the effect of improving fluidity when mixed with water. Also, since it is generated in the form of dust, it has the advantage that it can be used immediately without additional processing such as wave *?* pulverization. Therefore, there is a possibility that sodium bicarbonate desulfurization dust generated as a by-product during the ironmaking process can be used as a reaction stimulant of blast furnace slag. In addition, since it is a material containing chlorine, chlorine ions (Cl ^- ) have the property of promoting the hydration reaction of fine powder of blast furnace slag and cement, replacing calcium chloride and sodium chloride, which are commonly used in sites that require initial strength in winter. can do.

It is preferable to use 0.5 to 500 parts by weight of the sodium bicarbonate desulfurization dust compared to the fine powder of blast furnace slag. When it is less than 0.5 weight, the effect of rapid setting and fluidity improvement is insignificant, and when it exceeds 500 parts by weight, the strength is relatively greatly reduced and whitening may occur.

In order to remove sulfur (S) contained in the molten iron produced in a blast furnace such as an integrated steel mill, the lime desulfurization dust is stirred after adding a desulfurization auxiliary material such as high powder lime to the upper portion of the molten iron. Sulfur contained in molten iron is being removed by promoting a reaction. In this desulfurization process, dust is generated, which is called lime desulfurization dust. Lime desulfurization dust is mainly _{composed of Ca(OH) 2 ,} CaSO ₄ and CaCl ₂ components. It is a strong alkali material with a pH of 11.5 or higher, and there is no free CaO component, so it has the effect of improving fluidity when mixed with water. When used together with the fine powder of blast furnace slag, it has the property of acting as a stimulant and accelerator.

Preferably, the lime desulfurization dust is mixed in an amount of 0.5 to 500 parts by weight based on 100 parts by weight of the fine powder of blast furnace slag. When the amount is less than 0.5 parts by weight, the effect is not exhibited, and when it exceeds 500 parts by weight, the content of cement is relatively low. It becomes difficult to develop strength.

In addition, the solid fuel combustion material is preferably discharged from a power generation facility that burns general solid fuel (SRF, Solid Refuse Fuel) and biosolid fuel (BIO-SRF, Biomass-Solid Refuse Fuel).

Solid fuel combustion ash serves to increase the viscosity in order to suppress material separation. The property of absorbing moisture is also less than that of a circulating fluidized bed boiler fly ash using coal as a fuel, so the fluidity is good. In addition, the solid fuel combustion ash contains a part of chlorine, which is effective in improving initial strength. Preferably, the solid fuel combustion material is mixed in an amount of 0.5 to 500 parts by weight based on 100 parts by weight of the fine powder of blast furnace slag. When the amount is less than 0.5 parts by weight, the effect is not exhibited, and when it exceeds 500 parts by weight, the strength is significantly reduced. .

In addition, the cement is necessary to secure initial strength, and any one or a mixture of two or more of ordinary Portland cement, semi-strength portland cement, crude steel portland cement, CSA (Calcium Sulfur Aluminate), C ₁₂ A _{7 , alumina cement, super-velocity cement} It is preferable to be In addition, the cement is preferably mixed in an amount of 5 to 300 parts by weight with respect to 100 parts by weight of the fine blast furnace slag powder. If it is less than 5 parts by weight, the initial strength cannot be expressed, and if it exceeds 300 parts by weight, the initial strength increases, but economic efficiency is low. It is disadvantageous and harmful heavy metals such as hexavalent chromium may be eluted.

In addition, based on 100 parts by weight of the blast furnace slag fine powder, 0.5 to 50 parts by weight of a chloride-based curing accelerator is further included, and the chloride-based curing accelerator is any one selected from the group consisting of calcium chloride, sodium chloride, potassium chloride, cement kiln chlorine dust, or It is preferable to further include a mixture of two or more. Chloride-based hardening accelerator helps to prevent the initial freezing damage by accelerating the hydration _{of C 3} S of fine powder of blast furnace slag and cement, thereby rapidly exhibiting initial strength. In addition, the chloride-based hardening accelerator is preferably mixed in an amount of 0.5 to 50 parts by weight based on 100 parts by weight of the fine blast furnace slag powder, but when it is less than 0.5 parts by weight, the anti-freezing function and the effect of accelerating the hydration reaction of the blast furnace slag fine powder and cement are insufficient. , when it exceeds 50% by weight, it reacts with the _{cement hydration product Ca(OH) 2 to form crystals of CaO, CaCl 2} ·2H ₂ O, Mg ₂ (OH) ₃ Cl·4H ₂ O, and the volume can be expanded Salt damage may occur, and it hardens too rapidly, making it difficult to secure workability.

In addition, the specific surface area further comprises 0.5 to 50 parts by weight of a sulfate-based curing accelerator based on 100 parts by weight of the fine powder of blast furnace slag, and the sulfate-based curing accelerator is CaSO ₄ , K ₂ SO ₄ , MgSO ₄ , Na ₂ SO ₄ , Al ₂ (SO ₄ ) ₃ Any one selected from the group consisting of, or a mixture of two or more is preferable. The sulfate ion acts as an irritant to break the acid film of the fine blast furnace slag powder, and the alkali component plays a role in inducing the rapid setting of the fine blast furnace slag powder and cement. The sulfate-based curing accelerator is preferably mixed in an amount of 0.5 to 50 parts by weight based on 100 parts by weight of the fine blast furnace slag powder. When the amount is less than 0.5 parts by weight, the stimulating effect of the fine blast furnace slag powder is insufficient, and when it exceeds 50% by weight It is greatly disadvantageous to economic feasibility, and strength may be lowered on the contrary.

In addition, in order to improve fluidity with respect to 100 parts by weight of the fine powder of blast furnace slag having a specific surface area of 4,000 cm ² /g or more, 0.01 to 5 parts by weight of a liquid and powder fluidizing agent is preferably further included. The fluidizing agent is preferably any one selected from the group consisting of naphthalene-based, melamine-based, amine-based, lignin-based, and polycarboxylic acid-based, or a mixture of two or more. The fluidizing agent is preferably incorporated in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the fine blast furnace slag powder. If it is less than 0.01 parts by weight, there is no effect of improving the fluidity, and if it exceeds 5 parts by weight, the fluidity is excessively improved and material separation may occur. and lack of economics.

In addition, it is preferable to further include a thickener in order to prevent separation in water with respect to 100 parts by weight of the fine powder of blast furnace slag having a specific surface area of 4,000 cm ^{2 /g or more.} The thickener is hydroxypropyl methyl cellulose (HYDROXY PROPYL METHYL CELLULOSE, HPMC), hydroxyethyl cellulose (HYDROXY ETHYL CELLULOSE, HEC), carboxymethyl cellulose (CARBOXY METHYL CELLULOSE, CMC), ethyl hydroxytyl cellulose (ETHYL CELLULOSE) , EHEC), polyacrylic, polysaccharide (POLY SACCARIDE), hydroxyethyl methylcellulose (HYDROXY ETHYL METHYL CELLULOSE, HEMC), polyethylene oxide (POLY ETHYLENE OXIDE, PEO), ethylene vinyl acetate (ETHYLENE VINYL ACETATE, EVA) Any one selected from the group consisting of the system, or a mixture of two or more is preferable.

The thickener is preferably incorporated in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the fine blast furnace slag powder. When the amount is less than 0.01 parts by weight, there is no effect of improving separation in water, and when it exceeds 5 parts by weight, the viscosity becomes excessive and construction is difficult.

In addition, 0.01 to 5 parts by weight of organic staple fibers are added in order to secure the function of high toughness corresponding to shear stress for sites with severe seismic design and liquefaction behavior with respect to 100 parts by weight of the fine powder of blast furnace slag with a specific surface area of 4,000 cm ^{2 /g or more} It is preferable to include

The organic short fibers have very high resistance to solvents, oils, salts, and alkalis containing carbon. In addition, as a hydrophilic structure having a hydroxyl group on the fiber surface, it is well dispersed in the liquid phase, has a high elastic modulus and has excellent adhesion to powder components, and has a relatively small diameter to suppress and stabilize microcracks, thereby enabling mechanical action through crosslinking of fibers. It is very effective in increasing static properties and is effective in suppressing cracks caused by fatigue and impact loads. As for the organic staple fibers used in the present invention, all fibers used in general concrete series are commonly used, but are preferably polyvinyl alcohol-based staple fibers with a specific gravity of 1.1 to 1.3 g/cm 3 , a diameter of 9 to 12 μm, and a tensile strength of 7,000 to 9,000. kgf/cm 2 , 3 to 8 mm in length, and preferably used in an amount of about 0.1 to 5 parts by weight based on 100 parts by weight of the solidifying material composition. If it is less than 0.1 parts by weight, the effect is insignificant in suppressing plastic cracks, and if it exceeds 5 parts by weight, the economical efficiency is lowered compared to the effect, and there is a risk of lowering the compressive strength by lowering the binding force with the soil.

Hereinafter, a method for rapid treatment of soft ground will be described.

First, an injection pipe is installed in the soft ground that requires rapid processing.

Next, the ground solidifying material according to the present invention essentially comprising the above-described ground solidifying material according to the present invention, that is, blast furnace slag fine powder, circulating fluidized bed boiler bottom ash, sodium bicarbonate desulfurization dust, lime desulfurization dust, solid fuel combustion material, and cement. to prepare a ground grouting material by mixing with water.

Next, the ground grouting material is transferred and injected through the injection pipe.

Finally, the ground grouting material is cured and cured to complete.

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

[Composition of Examples 1-3 and Comparative Example 1]

Table 1 below shows the compounding ratios for the solidification composition samples of Comparative Examples and Examples 1 to 3, respectively.

combination
Raw materials used Blending ratio (wt%) comparative example Example 1 Example 2 Example 3 Class 1 Portland Cement 100 Blast Furnace Slag Fine Powder
(Specific surface area 4,650 cm ² /g) - 50 50 50 Circulating Fluidized Bed Boiler Bottom Ash
(Specific surface area 2,1504,650 cm ² /g) 20 20 20 Iron Works Desulfurization Dust
(chloride ion content 5.86 wt%) - 10 5 5 Steel Mill Lime Desulfurization Dust
(Chloride ion content 3.12% by weight) - 5 5 5 solid fuel combustion
(Chloride ion content 2.28% by weight) - 5 5 5 Semi-Forged Steel Portland Cement 10 10 10 Chloride-based curing accelerator
(CaCl ₂ ) 5 Sulfate-based curing accelerator
(Al ₂ (SO ₄ ) ₃ ) 5

[Evaluation of compressive strength characteristics of solidified soil under low temperature environment]

As a basic test to find out whether the ground solidifying composition of the present invention can express excellent strength under a low-temperature environment, it is sufficient to use a forced mixer with a type 1 cement or 400 kg ^{of the ground solidifying material of the present invention and 320 kg of water based on 1 m 3 of seacast clay.} By mixing, the milk injection material was prepared ^{and homogeneously mixed with 1m 3 of} sea-casting clay, and 9 specimens of Ø5cm×10cm were produced and cured at -2℃ using a thermo-hygrostat to increase the strength for 3 days, 7 days, and 28 days. measured. Thereafter, the results are shown in Table 2, respectively.

<Compressive strength evaluation test of solidified soil cured at -2℃ condition>

Kinds Compressive strength (MPa) 3 days 7 days 28 days comparative example 0.21 0.48 0.81 Example 1 0.42 0.98 1.78 Example 2 0.63 0.99 1.69 Example 3 0.79 1.82 2.14

The uniaxial compressive strengths of Examples 1, 2 and 3 were all shown to express high strength compared to the comparative example, which was a type 1 Portland cement.

Compared with Comparative Example 1 using only type 1 cement, Example 1 expressed twice the initial strength at the age of 3 days, and expressed about 2 times higher strength even at the age of 28 days.

Example 2, which further included a chloride-based curing accelerator in Example 1, had a strength enhancement effect of about 1.5 times at the age of 3 days compared to Example 1, and showed a similar trend on days 7 and 28.

Example 3, in which the sulfate-based curing accelerator was further included in Example 1, not only expressed a strength close to 1.9 times at the age of 3 days as compared to Comparative Example 1, but also it was confirmed that the strength was approximately 1.2 times higher at the age of 28 days.

As described above, when the soft ground is treated using the ground solidifying material of the present invention, it prevents the initial freezing of sodium bicarbonate desulfurization dust containing chlorine and promotes hydration reaction even under the low temperature condition of -2 ℃, as well as lime desulfurization dust and solid fuel combustion. It was found that due to the effect of accelerating initial curing by materials, it is possible to secure initial strength in winter construction and to exhibit very effective performance in preventing early freezing.

In addition, it is possible to expect cost reduction and environmental protection effects by reducing the amount of cement produced by consuming large amounts of natural resources and energy by using a large amount of recyclable resources that are insufficiently recycled.

Claims (6)

1) installing an injection pipe in the ground;
2) mixing the ground solidification material with water to prepare a ground grouting material;
3) transferring and injecting the ground grouting material through the injection pipe; and
4) curing the ground grouting material by curing;
The ground solidification material,
With respect to 100 parts by weight of the blast furnace slag fine powder having a specific surface area of 4,000 to 8,000 cm ^{2 /g,}
0.5 to 1,000 parts by weight of bottom ash of a circulating fluidized bed boiler having a particle size of 0.1 to 5 mm or less and a CaO content of 15 to 70 wt% and an SO _{3 content of 3 to 35 wt%;}
0.5 to 500 parts by weight of sodium bicarbonate desulfurization dust having a chlorine content of 1 to 20% by weight;
0.5 to 500 parts by weight of lime desulfurization dust having a chlorine content of 0.5 to 10% by weight;
0.5 to 500 parts by weight of a solid fuel combustion material having a chlorine content of 0.1 to 10% by weight;
A method for rapid treatment of soft ground, comprising 5 to 300 parts by weight of cement.
According to claim 1,
The soft ground rapid treatment method, characterized in that it further comprises 0.5 to 50 parts by weight of a chloride-based hardening accelerator based on 100 parts by weight of the fine powder of the blast furnace slag.
According to claim 1,
The soft ground rapid treatment method, characterized in that it further comprises 0.5 to 50 parts by weight of a sulfate-based curing accelerator based on 100 parts by weight of the fine powder of the blast furnace slag. According to claim 1,
The rapid treatment method for soft ground, characterized in that it further comprises 0.01 to 5 parts by weight of liquid and powder type fluidizing agents in order to improve fluidity with respect to 100 parts by weight of the fine powder of the blast furnace slag.
According to claim 1,
The soft ground rapid treatment method, characterized in that it further comprises 0.01 to 5 parts by weight of a thickener to prevent material separation with respect to 100 parts by weight of the fine powder of the blast furnace slag.
According to claim 1,
The soft ground rapid treatment method, characterized in that it further comprises 0.01 to 5 parts by weight of organic short fibers to enhance tensile strength based on 100 parts by weight of the fine powder of the blast furnace slag.