KR102272190B1 - Skin supporting agent f0r pretensioned spun high strength concrete piles - Google Patents

Abstract

The present invention relates to a main surface fixing material for PHC pile construction, and more particularly, through the desulfurization dust discharged as a by-product during the desulfurization process in a steel mill of fine powder of blast furnace slag, which is a latent hydraulic material, and bottom ash discharged as a by-product from a circulating fluidized bed boiler. It relates to a main surface fixing material for PHC pile construction that can be activated to express strength and can replace type 1 cement used as a main surface fixing material for PHC pile construction.
The main fixing material for PHC piles according to the present invention contains 100 to 2,000 parts by weight of fine blast furnace slag powder, _{10 to 50% by weight of Na 2} O, and 10 to 50% by weight of SO ₃ based on 100 parts by weight of type 1 cement. 1~500 parts by weight of sodium bicarbonate desulfurization dust discharged as a by-product from the desulfurization process of a steelworks, and 1~500 parts by weight of lime desulfurization dust discharged as a by-product from the desulfurization process of a steelworks having a _{CaO content of 40 to 70% by weight and an SO 3 content of 2 to 20% by weight} 500 parts by weight, and 1 to 500 parts by weight of circulating fluidized bed boiler bottom ash, and 1 to 500 parts by weight of solid fuel fly ash.

Description

Main surface fixing material for PHC pile construction {SKIN SUPPORTING AGENT F0R PRETENSIONED SPUN HIGH STRENGTH CONCRETE PILES}

The present invention relates to a main surface fixing material for PHC pile construction, and more particularly, through the desulfurization dust discharged as a by-product during the desulfurization process in a steel mill of fine powder of blast furnace slag, which is a latent hydraulic material, and bottom ash discharged as a by-product from a circulating fluidized bed boiler. It relates to a main surface fixing material for PHC pile construction that can be activated to express strength and can replace type 1 cement used as a main surface fixing material for PHC pile construction.

In recent construction sites, pile construction using the buried pile method is increasing according to the trend of strengthening noise and vibration regulations during pile foundation construction.

Buried pile construction is a method of digging a hole in the ground using an auger and planting a ready-made PHC pile or a tip-extended pile. It is manufactured by mixing water with type 1 cement or powder with bentonite added to type 1 cement in the space between the ground and piles. It is performed by filling the fixed solution to strengthen the friction and bearing capacity of the pile.

The basic role of the fixing material between the drilling hole and the pile is to exert the function of the fixing material and the frictional force of the pile surface for the independence of the pile in the initial stage of loading.

However, since type 1 cement is manufactured by mining limestone, the main raw material, and calcining it at a high temperature of 1,450 ° C., a large amount of CO ₂ gas, the main source of greenhouse gas, is generated during the decarboxylation process of limestone, which causes global warming.

In addition, since cement is a strong alkali with a pH of 13 or higher, it is undesirable when used in soil.

In addition, bentonite is an expensive material dependent on imports as a mineral that does not exist as a natural resource in Korea, and when it comes into contact with salt, its swelling degree is remarkably reduced, and there is a problem in that water resistance is greatly reduced.

Recently, several technologies have been proposed to improve the performance of such conventional cements. This technology uses type 1 cement as the main raw material, replaces some with blast furnace slag and pulverized coal boiler fly ash, and adds various expensive admixtures and admixture raw materials.

Therefore, the manufacturing process is very complicated, the production cost is high, and it is difficult to select a formulation according to the physical and chemical quality characteristics of the raw materials because it is necessary to use several raw materials at the same time.

On the other hand, in the LH-specialized specification, "The space around the pile that is created after the embedded pile is driven is filled with a fixing solution for the main face with a water-binding material ratio (W/B) of 0.49 MPa or more standard uniaxial compressive strength to secure the horizontal resistance and friction force of the pile. shall. If this solution permeates into the ground, and the upper surface of the fixing solution settles, it must be continuously replenished.” In other words, since the main surface fixing solution requires very low uniaxial compressive strength, even if the water-binding material ratio (W/B) is 83% or higher at the construction site, the standard uniaxial strength of 0.49 MPa or more can be sufficiently secured, but high water-bonding Even if the main surface of the empty mixing ratio having a material ratio is injected, the fixing liquid escapes to the ground around the pile and is not filled, resulting in a problem of continuously supplying the fixed liquid. Accordingly, in the ground with high permeability or at sites with a lot of groundwater, the water-binding material ratio (W/B) is changed to a sub-mix of 83% or less, and excessive cement is injected into the ground compared to the uniaxial compressive strength required for the main surface fixing solution. causes the phenomenon to be In addition, cement may cause environmental pollution due to strong alkali and hexavalent chromium in the ground, and has a problem in that volume shrinkage occurs and frictional force on the main surface of the embedded pile is lowered.

Recently, several techniques have been proposed to improve the problem of using the conventional cement as an injection material.

For example, in Korean Patent Registration No. 10-1377552, based on 100 parts by weight of coal ash having a calcium oxide content of 30 to 60%, 100 to 300 parts by weight of fine powder of blast furnace slag, 20 to 100 parts by weight of petroleum coke desulfurized gypsum, and 20 parts by weight of a sulfate stimulant A milk injection material technology for embedded pile construction without cement was presented, characterized in that it further comprises 40 to 100 parts by weight based on 100 parts by weight of coal ash in the injection material having a composition ratio of -50 parts by weight.

In addition, in Korean Patent Registration No. 10-1402877, 55 to 65% by weight of fine powder of blast furnace slag, 10 to 20% by weight of F-class fly ash, 10-20% by weight of C-class fly ash having a calcium oxide content of 20% or more, and desulfurized gypsum 2 An eco-friendly eco-filling material manufacturing technology using blast furnace slag mixed with ∼5 wt% and paper sludge incineration ash with 10 to 20 wt% was presented.

In addition, in Korean Patent Application No. 2013-147586, 5 to 200 parts by weight of petrocoke desulfurized gypsum and 50 to 300 parts by weight of mixing water are included with respect to 100 parts by weight of fine blast furnace slag powder, but the expansion material is based on 100 parts by weight of fine blast furnace slag powder. 5 to 100 parts by weight is presented, characterized in that it is further included.

These technologies are based on the theory of alkali-activated slag, which activates fine blast furnace slag powder by stimulation of alkali and sulfate by gypsum, which is generated as a by-product of the desulfurization process in the furnace, and uses circulating fluidized bed high-calcium fly ash as an expanding material. That is, the above patents can be said to be a technique for hardening the main surface of piles by utilizing the strength expression of alkali-activated slag and the expandability of high-calcium fly ash in a circulating fluidized bed boiler.

However, the above techniques are in a situation where desulfurization gypsum and high-calcium fly ash rapidly absorb a lot of moisture, and the fluidity is greatly reduced, so that the transport pipe is often clogged, and the initial strength expression is delayed, which is not currently commercialized. In the present invention, there is a difference in using iron desulfurization process dust, circulating fluidized bed boiler bottom ash, and solid fuel fly ash, which can secure fluidity and exhibit initial strength, as major stimulants for fine powder of blast furnace slag.

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

The present invention has been devised to solve the above problems, and an object of the present invention is to desulfurize fine powder of blast furnace slag, which is a latent hydraulic material, as a by-product during a desulfurization process in a steel mill, and bottom ash discharged as a by-product from a circulating fluidized bed boiler. It is to provide a main surface fixing material for PHC pile construction that can be activated to express strength through the PHC pile construction and can replace Type 1 cement used as a main surface fixing material for PHC pile construction.

Another object of the present invention is to provide a main surface fixing material for PHC pile construction that can prevent the loss of the main surface fixing solution by groundwater that may exist between the drilling hole and the buried pile by using the increase in viscosity and volume expansion action of solid fuel fly ash. is in

Another object of the present invention is to provide a main surface fixing material for PHC pile construction that can reduce the cost significantly compared to type 1 cement used as a main surface fixing material for PHC pile construction and minimize the loss of fixing liquid into the ground around the pile. is in

In order to solve the above technical problems, the main fixing material for PHC piles according to the present invention contains 100 to 2,000 parts by weight of fine blast furnace slag powder, 10 to 50% _{by weight of Na 2 O, and SO 3 based on 100 parts by weight of type 1 cement.} 1 to 500 parts by weight of sodium bicarbonate desulfurization dust discharged as a by-product from the desulfurization process of a steelworks having a content of 10 to 50% by weight, and by-products from the desulfurization process of a steelworks having a CaO content of 40 to 70% by weight and an SO ₃ content of 2 to 20% by weight 1 to 500 parts by weight of lime desulfurization dust discharged from the furnace, 1 to 500 parts by weight of circulating fluidized bed boiler bottom ash, and 1 to 500 parts by weight of solid fuel fly ash.

In addition, it is preferable that the bottom ash of the circulating fluidized bed boiler is discharged during desulfurization in a furnace by mixing and burning fuel and limestone.

In addition, the solid fuel fly ash is preferably discharged from a power plant that burns general solid fuel (SRF, Solid Refuse Fuel) and biosolid fuel (BIO-SRF, Biomass-Solid Refuse Fuel).

In addition, it is preferable to further include any one or a mixture of two or more of natural anhydrite, petrocoke desulfurization gypsum, phosphate gypsum, and hydrofluoric acid gypsum.

In addition, in order to improve fluidity, it is preferable to further include 0.01 to 5 parts by weight of liquid and powder fluidizing agents based on 100 parts by weight of the first-class cement.

In addition, in order to prevent separation in water, it is preferable to further include 0.01 to 5 parts by weight of an in-water non-separating agent based on 100 parts by weight of the first-class cement.

According to the present invention, strength is expressed by activating fine powder of blast furnace slag, which is a latent hydraulic material, through desulfurization dust discharged as a by-product during the desulfurization process in a steel mill and bottom ash discharged as a by-product from a circulating fluidized bed boiler to express strength. It has the effect of replacing type 1 cement used as a fixing material.

In addition, there is an effect of preventing the loss of the main surface fixing solution by groundwater that may exist between the drilling hole and the buried pile by using the increase in viscosity and the volume expansion action of the solid fuel fly ash.

Therefore, it is possible to reduce the cost significantly compared to the type 1 cement used as a main fixing material for PHC pile construction, and it is possible to minimize the loss of the fixing solution into the ground around the pile.

Hereinafter, components and actions of the main fixing material for PHC pile construction according to the present invention will be described.

The main fixing material for PHC pile construction according to the present invention is 100 to 2,000 parts by weight of fine blast furnace slag powder, _{10 to 50% by weight of Na 2} O, and 10 to 50% by weight of SO ₃ based on 100 parts by weight of type 1 cement. 1~500 parts by weight of sodium bicarbonate desulfurization dust discharged as a by-product from the desulfurization process of a steelworks, and 1~500 parts by weight of lime desulfurization dust discharged as a by-product from the desulfurization process of a steelworks having a _{CaO content of 40 to 70% by weight and an SO 3 content of 2 to 20% by weight} 500 parts by weight, 5 to 500 parts by weight of circulating fluidized bed boiler bottom ash, and 1 to 500 parts by weight of solid fuel fly ash to increase the viscosity to suppress material separation.

The fine powder of type 1 cement and blast furnace slag can be used as long as it is a KS product that is generally distributed in the market.

The fine powder of blast furnace slag is a latent hydraulic material, and it is preferable to use 100 to 2,000 parts by weight based on 100 parts by weight of type 1 cement. When it is less than 100 parts by weight, there is no effect of reducing the amount of cement used for the purpose of the present invention, and when it is more than 2,000 parts by weight, it is difficult to develop initial strength.

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. . Sodium sodium bicarbonate 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)

The sodium bicarbonate desulfurization dust cannot be recycled in the process due to a lack of useful components such as Fe and Ca, 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 induces complex stimulation of alkali and sulfate. can promote In addition, it has the property of being easily soluble in water and has the effect of improving the fluidity of the fixative because it does not contain free CaO components like petrocoke desulfurization gypsum.

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 crushing (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 contains some chlorine, chlorine ions (Cl ^- ) have the property of promoting the hydration reaction of fine blast furnace slag powder and cement. can be replaced

The sodium bicarbonate desulfurization dust is preferably used in an amount of 1 to 500 parts by weight compared to type 1 cement. When it is less than 1 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 the lime desulfurization dust, in order to remove sulfur (S) contained in the molten iron produced in a blast furnace such as an integrated steel mill, a desulfurization auxiliary material such as lime is added to the upper part of the molten iron and stirred, thereby reacting sulfur with the desulfurization auxiliary material In this way, sulfur contained in molten iron is removed. In this desulfurization process, dust is generated, which is called lime desulfurization dust.

The lime desulfurization dust is mainly composed of CaO, Ca(OH) ₂ and CaSO ₄ components, and has a pH of 11.5 or higher and is a strong alkali material. When used with blast furnace slag, it acts as an alkali and sulfate stimulant, resulting in potential hydraulic properties of blast furnace slag. has the ability to express Preferably, the lime desulfurization dust is mixed in an amount of 1 to 500 parts by weight based on 100 parts by weight of the first-class cement. When the amount is less than 1 part by weight, the effect is not exhibited. When it exceeds 500 parts by weight, the content of the first-class cement is relatively small This makes it difficult to develop initial strength.

The circulating fluidized bed boiler bottom ash is generated at the bottom of the boiler in a way of desulfurizing in a furnace by mixing with limestone in a circulating fluidized bed boiler. 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, it contains a higher amount of CaSO 4} than fly ash collected from the top, has a superior composition as an alkali and sulfate stimulant of fine blast furnace slag powder, and has fewer free CaO and porous components compared to fly ash, which greatly improves fluidity. can In order to further improve the stimulating effect of the fine powder of 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 is preferably mixed in an amount of 1 to 500 parts by weight based on 100 parts by weight of type 1 cement, but when it is less than 1 part by weight, the effect is not exhibited, and when it exceeds 500 parts by weight, the strength is relatively significantly lowered. do.

In addition, the solid fuel fly ash is preferably discharged from a power plant that burns general solid fuel (SRF, Solid Refuse Fuel) and biosolid fuel (BIO-SRF, Biomass-Solid Refuse Fuel). The solid fuel fly ash serves to increase the viscosity 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. It is preferable that the solid fuel fly ash be mixed in an amount of 1 to 500 parts by weight based on 100 parts by weight of type 1 cement, but when it is less than 5 parts by weight, the effect is not exhibited, and when it exceeds 500 parts by weight, the strength is relatively significantly reduced. .

In addition, it is preferable to further include liquid and powder fluidizing agents in order to enhance fluidity. 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 20 parts by weight based on 100 parts by weight of type 1 cement, but when it is less than 0.01 parts by weight, there is no effect of improving the fluidity, and when it exceeds 20 parts by weight, the fluidity is excessively improved and material separation may occur. lack of economics.

In addition, it is preferable to further include an in-water non-separating agent in order to prevent separation in water. Non-separating agents in water include hydroxypropyl methyl cellulose (HYDROXY PROPYL METHYL CELLULOSE, HPMC), hydroxyethyl cellulose (HYDROXY ETHYL CELLULOSE, HEC), carboxymethyl cellulose (CARBOXY METHYL CELLULOSE, CMC), ethyl hydroxytyl cellulose (ETHYL HYDROXY) ETHYL CELLULOSE, EHEC), poly acrylic, polysaccharide (POLY SACCARIDE), hydroxyethyl methyl cellulose (HYDROXY ETHYL METHYL CELLULOSE, HEMC), polyethylene oxide (POLY ETHYLENE OXIDE, PEO), ethylene vinyl acetate (ETHYLENE, VINYL ACETHYLENE) EVA) is preferably any one selected from the group consisting of or a mixture of two or more. It is preferable that the water non-separation agent be incorporated in an amount of 0.1 to 20 parts by weight based on 100 parts by weight of the first-class cement. If it is less than 0.01 parts by weight, there is no effect of improving the separation in water, and if it exceeds 20 parts by weight, the viscosity becomes excessive and construction is difficult. do.

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.

Example 1

First, with respect to 100 parts by weight of type 1 cement, 200 parts by weight of fine powder of blast furnace slag, 30 parts by weight of sodium bicarbonate desulfurization dust and 30 parts by weight of lime desulfurization dust, 200 parts by weight of circulating fluidized bed boiler bottom ash, and 30 parts by weight of solid fuel fly ash uniformly A pile fixing material was prepared by mixing.

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

Example 2

First, with respect to 100 parts by weight of type 1 cement, 200 parts by weight of fine blast furnace slag powder, 30 parts by weight of sodium bicarbonate desulfurization dust and 30 parts by weight of lime desulfurization dust, 200 parts by weight of circulating fluidized bed boiler bottom ash, 30 parts by weight of solid fuel fly ash, natural A pile fixing material was prepared by uniformly mixing 10 parts by weight of anhydrite, 5 parts by weight of a fluidizing agent, and 5 parts by weight of a non-separating agent in water.

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

comparative example

First, water was added so that the water binder ratio (W/B) was 83% with respect to type 1 cement, and the mixture was sufficiently mixed with a forced mixer to prepare a fixed solution.

Performance test method and result of milk injection material for buried pile construction

As shown in Table 1 below, the slump flow test was performed according to KS F 2594 and the compressive strength test was performed according to the KS F 2343 method.

Experiment Way remark slump flow KS F 2594 Slump flow test method compressive strength KS F 2343 Uniaxial compressive strength test method Material separation resistance and volume shrinkage Visual inspection

(1) Slump flow test result

As a result of observing the change in the flowability of the pile fixing solution, Example 1 was 62 cm and showed similar flow characteristics to Comparative Example 64 cm using type 1 cement, but Example 2 further containing natural anhydrite, a fluidizing agent and a water non-separating agent in Example 1 is 68 cm, showing a tendency to significantly improve fluidity.

(2) uniaxial compressive strength test result

Unit (MPa) age 3 days 7 days 28 days Example 1 7.6 10.7 14.3 Example 2 8.2 11.3 14.8 Example 3 10.9 14.3 18.4

In the case of the example of the present invention, compared to the comparative example, type 1 cement, the overall strength was about 70 to 80% lower, but the strength was much higher than 0.49 MPa, which is the standard of the LH specialized specification. Therefore, it is judged that it is appropriate to use it for the upper middle and upper layers where the frictional force of the main surface is important.

(3) Material separation resistance and volume shrinkage

In Examples 1 and 2, material separation and volumetric shrinkage were not observed with the naked eye, but in Comparative Examples, it was confirmed that the upper surface was settled and a large amount of bleeding water was generated. In addition, as a result of observing the volumetric shrinkage after curing for 7 days, it was confirmed that the volume shrinkage occurred by about 3% or more in the comparative example.

Claims (6)

Based on 100 parts by weight of type 1 cement,
100 to 2,000 parts by weight of fine powder of blast furnace slag;
1 to 500 parts by weight of sodium bicarbonate desulfurization dust discharged as a by-product from the desulfurization process of a steelworks having a Na ₂ O content of 10 to 50% by weight and an SO _{3 content of 10 to 50% by weight, and}
1 to 500 parts by weight of lime desulfurization dust discharged as a by-product in the desulfurization process of a steel mill having a CaO content of 40 to 70% by weight and an SO _{3 content of 2 to 20% by weight;}
1 to 500 weight of circulating fluidized bed boiler bottom ash;
Contains 1 to 500 parts by weight of solid fuel fly ash that increases viscosity to suppress material separation,
The solid fuel fly ash is a main surface fixing material for PHC piles, characterized in that discharged from a power plant that burns general solid fuel (SRF, Solid Refuse Fuel) or biosolid fuel (BIO-SRF, Biomass-Solid Refuse Fuel).
According to claim 1,
The main surface fixing material for PHC piles, characterized in that the circulating fluidized bed boiler bottom ash is discharged in the process of desulfurization in the furnace by mixing fuel and limestone.
delete According to claim 1,
Main surface fixing material for PHC piles, characterized in that it further comprises any one or a mixture of two or more of natural anhydrite, petrocoke desulfurization gypsum, phosphate gypsum, and hydrofluoric acid gypsum.
According to claim 1,
Main surface fixing material for PHC piles, characterized in that it further comprises 0.01 to 5 parts by weight of liquid and powder fluidizing agents based on 100 parts by weight of the first-class cement in order to improve fluidity.
According to claim 1,
Main fixing material for PHC piles, characterized in that it further comprises 0.01 to 5 parts by weight of an underwater non-separating agent based on 100 parts by weight of the first-class cement to prevent underwater separation.