KR101602130B1 - Mortar composition for compaction grouting process using unsintered inorganic binder bottom ash - Google Patents

Abstract

The present invention relates to a grouting method in which a foundation is reinforced in order to reinforce a soft ground or to prevent the settlement of a structure on a soft ground or to secure the safety of ground and underground structures and fixtures that have been already settled and are threatened with safety, The present invention relates to a mortar composition for a compaction grouting method using a low-fluidity mortar as an injection material, and more particularly to a mortar composition for a compaction grouting method using a low-fluidity mortar as an injection material. More specifically, It improves the performance of soft soil improvement by complementing the shrinkage properties of cement mortar by utilizing the absorption, exothermic reaction and volumetric expansion action of CaO contained in large amount in high calcium fly ash by activating amorphous material. Compaction Grouting (Com pumping grouting) method.
The mortar composition for compaction grouting according to the present invention comprises 10 to 20 parts by weight of fine blast furnace slag and 5 to 15 parts by weight of petro coke desulfurization gypsum as 100 parts by weight of an ash aggregate as a bottom ash.

Description

[0001] MORTAR COMPOSITION FOR COMPACTION GROUTING PROCESS USING UNSINTERED INORGANIC BINDER BOTTOM ASH BACKGROUND OF THE INVENTION [0001] The present invention relates to a mortar composition for compaction grouting using a non-

The present invention relates to a grouting method in which a foundation is reinforced in order to reinforce a soft ground or to prevent the settlement of a structure on a soft ground or to secure the safety of ground and underground structures and fixtures that have been already settled and are threatened with safety, The present invention relates to a mortar composition for a compaction grouting method using a low-fluidity mortar as an injection material, and more particularly to a mortar composition for a compaction grouting method using a low-fluidity mortar as an injection material. More specifically, It improves the performance of soft ground improvement by complementing the shrinkage property of cement mortar by utilizing the absorption, exothermic reaction and volumetric expansion action of CaO contained in high calcium fly ash by activating amorphous material and exhibiting strength. Compaction Grouting (Com pumping grouting) method.

In general, grouting works to improve the soft ground by filling the material, such as injecting chemical solution injecting cement milk and chemical, locally pouring aggregate piling method for buying aggregate such as gravel on excavation ground, compaction filling low slump mortar And compaction grouting method. Compaction grouting method which is evaluated to be most resistant to vertical pressure and horizontal pressure and dynamic load is applied to many sites.

The construction of the compaction grouting method is a method of drawing a low-flow mortar using a high-pressure pump immediately after piercing a hole with a perforator to a predetermined depth in a ground to be improved, and cement is used as a binder in a soft ground, It is a method of filling low-flowable mortar mixed with water by using rosy grit fine particles and stones.

However, in the case of the above-mentioned cement, the product is produced by calcining limestone, clay and iron ore at high temperature of 1,450 ° C. using imported bituminous coal as a raw material, and generates a large amount of normal carbon dioxide in the manufacturing process and produces a large amount of finite natural resources It is not environmentally friendly.

In addition, the silt used in the fine aggregate of the aggregate and the fine aggregate used as the coarse aggregate are not environmentally friendly because they are artificially produced by damaging the natural resources, and it is difficult to obtain the raw materials when there is no aggregate circle near the soft ground improvement site have.

Disclosure of the Invention The present invention has been conceived in order to solve the above-mentioned problems, and it is an object of the present invention to provide a method for producing a high- calcium fly ash by activating an amorphous material such as blast furnace slag fine powders through a combination of alkali and sulfate without stimulating cement, By utilizing the absorption of CaO, exothermic reaction and volumetric expansion, loss of cement paste caused by groundwater, which may exist between perforated holes and mortar, is reduced, and the end bearing capacity and surface friction of grouting mortar are compared with those of conventional mortars And to provide a mortar composition for compaction grouting which greatly improves the strength of the mortar composition.

Also, it is possible to provide an environmentally friendly mortar composition by replacing an aggregate produced artificially by damaging natural resources with bottom ash which is an industrial byproduct.

In order to solve the above technical problems, the present invention provides a fast-curing mortar composition for compaction grouting comprising 10 to 20 parts by weight of a blast furnace slag fine powder, 100 parts by weight of petro cokes ) 5-15 parts by weight of desulfurized gypsum.

It is also preferred that an expander is further included.

Further, the expanding material is composed of an in-furnace desulfurization type coal combustion incineration residue, a biomass incineration residue, a paper sludge incineration residue, an RDF incineration residue, an RPF incineration residue, a converter slag dust and a quicklime, and a light incineration dolomite having a calcium oxide (CaO) content of 20% , Or a mixture of two or more thereof.

It is preferable that the expanding agent is incorporated in an amount of 2 to 6 parts by weight based on 100 parts by weight of the bottom ash.

It is also preferable to further include water as a blending water. This water is not particularly limited as long as it does not contain salt.

The water is preferably mixed in an amount such that the mortar slump according to KS F 2402 (concrete slump test method) is 50 to 70 mm.

According to the present invention, an amorphous material such as a blast furnace slag powder and a high calcium fly ash, which is a binder of mortar, is activated by inducing and activating an alkali complex stimulus by sulfates and CaO contained in petrocokus desulfurization gypsum to exhibit strength, The amount of cement paste lost due to groundwater, which may exist between the perforated hole and the mortar, is reduced by utilizing the absorption of CaO, the exothermic reaction and the volumetric expansion action of the CaO contained in the mortar, and the leading end bearing force and the main surface friction force of the grouting mortar, The present invention provides a fast-curing mortar composition for compaction grouting.

In addition, the use of natural aggregates is completely eliminated, and the ash produced from coal-fired power plants as an industrial by-product is recycled to preserve the environment.

Hereinafter, a mortar composition for a compaction grouting method according to the present invention will be described in detail.

First, the components and the action of the mortar composition for compaction grouting according to the present invention will be described.

The mortar composition for a compaction grouting method according to the present invention comprises 10 to 20 parts by weight of a blast furnace slag fine powder and 5 to 15 parts by weight of Petro coke desulfurization gypsum as 100 parts by weight of an ash aggregate.

The bottom ash is a kind of by-product generated in the process of burning bituminous coal to produce steam for turning a turbine in a coal-fired power plant. Ash, which remains as a residue even after the coal has been completely burned, is currently in use in Korea and contains 5 to 15% ash of coal.

Meanwhile, the coal ash is divided into fly ash and bottom ash. The coal ash of the domestic thermal power plant is about 11 million tons as of 2012, and 10 ~ 15% of coal ash is generated as bottom ash. Since fly ash is mainly silicon dioxide and is activated at high temperature and is in the form of fine powder, almost all of the generated amount is recycled as a silicate raw material during concrete admixture material or cement manufacturing process using pozzolanic reactivity. However, the bottom ash has a considerably larger particle size than the fly ash due to the characteristics of the ash that is melt-agglomerated at a high temperature, and it is difficult to recycle the bottom ash. In each power plant, to be. However, the bottom ash is also a silicon dioxide as the main component, and it is a stable material having a particle size of about the same as that of the sand.

In the present invention, the bottom ash which can not be recycled is used as a substitute for natural aggregate.

In the present invention, the particle size distribution of the bottom ash is in accordance with KS L 2526 and 2527. When the coarse aggregate of 10 mm or more is included, the workability of the mortar is lowered. When the aggregate of less than 0.02 mm is included, Therefore, it is preferable to have a particle size distribution of 0.02 to 10 mm.

Further, it is preferable that an expansion material is further included to improve the friction force of the main surface of the mortar composition through volume expansion.

Also, the expanding material may be a desulfurization-type coal combustion incineration residue, a biomass incineration residue, a paper sludge incineration residue, an RDF incineration residue, an RPF incineration residue, a converter slag dust, a quick lime, and a light dolomite with a calcium oxide (CaO) content of 20% And more preferably at least one selected from the group consisting of

It is preferable that the expansion material is incorporated in an amount of 2 to 6 parts by weight, preferably 2 to 4 parts by weight based on 100 parts by weight of the bottom ash.

In addition, an expanding material having a calcium oxide (CaO) content of 20% or more reacts with water to be absorbed, exothermic, and expanded to become calcium hydroxide. The reaction formula is as follows.

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

Although the coal ash discharged from a thermal power plant having a separate desulfurization apparatus is recycled as a concrete admixture material with a calcium oxide (CaO) content of 5% or less, coal ash and incineration residues containing a large amount of calcium oxide as described above, It can not be used as a concrete admixture because of its heat and expansion characteristics.

Therefore, the present invention utilizes incineration residues, which can not normally be utilized as a concrete admixture, as an expansion material.

In the present invention, the blast furnace slag fine powder used as the main material of the non-fired inorganic binder is a product manufactured according to Korean Industrial Standard (KS), which is a commercial product that is commercially available. The blast furnace slag fine powder is preferably contained as an aggregate in an amount of 10 to 20 parts by weight, preferably 10 to 15 parts by weight, based on 100 parts by weight of the bottom ash. If the amount is less than 10 parts by weight, the amount of the binder is too small to exhibit the predetermined strength, and even when the amount exceeds 20 parts by weight, the relative amount of the petroleum coke, which is a stimulant for alkaline and sulfate complex stimulation, Is not expressed.

In addition, the PetroCoux desulfurization gypsum reacts with the fine powder of blast furnace slag at the beginning of the reaction to produce a large amount of etyne wite, and activates slag and coal as amorphous material as aged, and acts as a stimulant for expressing strength. It is more economical than natural gypsum and gypsum which are required to undergo dehydration process by gypsum and sintering because they are generated as waste and have equivalent performance.

It is preferable that the Petro Cokes desulfurization gypsum is contained in an amount of 5 to 15 parts by weight, preferably 5 to 12 parts by weight, based on 100 parts by weight of the bottom ash. If the amount is less than 5 parts by weight, the effect as an alkali and sulfate complex irritant containing the CaO component and the gypsum component at the same time is insufficient. If the amount is more than 15 parts by weight, there is a surplus amount that does not react with the slag and the coal material, have.

Further, it is preferable that an expansion material is further included to improve the frictional force of the main surface of the injection mortar.

The expansion material is composed of an in-furnace desulfurization type coal combustion incineration residue having a calcium oxide (CaO) content of 20% or more, biomass incineration residues, paper sludge incineration residues, RDF incineration residues, RPF incineration residues, converter slag dust and quicklime, Or a mixture of two or more thereof. It is preferable that 2 to 6 parts by weight, preferably 2 to 4 parts by weight, based on 100 parts by weight of the bottom ash are incorporated.

If the mixing amount of the expanding agent is less than 2 parts by weight, the expansion effect is insufficient for improving the frictional force of the main surface of the embedded pile. If the mixing amount exceeds 6 parts by weight, the expansion effect is increased, but the strength of the cured material is insufficient .

In addition, water is included as a blending water for smoothly mixing the above materials, inducing a hydration reaction of the binder, and maintaining a predetermined mortar kneader. This water is not particularly limited as long as it is water containing no salt. For example, it is preferable that at least one member selected from the group consisting of groundwater containing no salt, surface water, tap water, and industrial water is desirable.

It is also preferred that the water is incorporated in such an amount that the mortar slump according to KS F 2402 (slump test method of concrete) is 50 to 70 mm. For example, it is preferable that the water is added in an amount of 2 to 3 parts by weight based on 100 parts by weight of the bottom ash. If the amount of water is less than 50 mm, the kneading of the mortar becomes too much so that it is not sufficiently mixed in the mortar manufacturing process and the possibility of sticking during the process is increased. If the slump is over 70 mm, The kneading agent becomes too thick and the water cement ratio becomes high and the predetermined strength can not be developed.

It is also preferred that the composition does not include Portland cement, fly ash or both.

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

Example

First, 12 parts by weight of a blast furnace slag fine powder, 7 parts by weight of Petro coke desulfurization gypsum, 3 parts by weight of an expanding material and 2.5 parts by weight of a blending amount were added to 100 parts by weight of a bottom ash having a particle size distribution of 0.02 mm to 10 mm as an aggregate, To prepare a mortar mixture.

The slump test was carried out using the samples prepared in the following, and the specimens for measuring the compressive strength were prepared and the compressive strengths were measured at each ages.

Comparative Example (OPC)

First, 22 parts by weight of one kind of portland cement and 2.5 parts by weight of the compounding water were homogeneously mixed with 100 parts by weight of a bottom ash having a particle size distribution of 0.02 mm to 10 mm as an aggregate to prepare a mortar mixture.

The slump test was carried out using the samples prepared in the following, and the specimens for measuring the compressive strength were prepared and the compressive strengths were measured at each ages.

Performance test method and result of injection mortar for compaction grouting method

As shown in Table 1 below, the slump test was conducted by KS F 2402 (slump test method of concrete) and the compressive strength test was conducted by KS F 2405 (compressive strength test method of concrete).

Experiment Way designation Slump flow KS F 2402 Test method of concrete slump Compressive strength KS F 2405 Test method of compressive strength of concrete Degree of material separation Visual inspection Volume change Visual inspection

(1) Results of the slump test

The results of the measurement of the slump of the examples and comparative examples are shown in Table 2. The slump of the mortar composition of the examples was slightly lower even though the weight of the unit binder and the weight of the compounded water of the examples and the comparative examples and the weight of the aggregate were the same. This can be interpreted as a result of the increase of the unit powder amount of the binder containing the ash, which is lower in mass than the cement, and the petroleum coke desulfurization gypsum. Further, it is judged that the fluidity is lowered due to absorption, exothermic and expansion action when the calcium oxide component in the expanding material is contacted with water because the expanding material is further mixed.

Results of slump and compressive strength measurements division Slump (mm) Compressive strength (MPa) 3 days 7 days a year 28 days old Example 55 10.3 20.9 25.2 Comparative Example 65 13.7 21.3 23.9

(2) Unconfined compressive strength test performance

Table 2 shows the results of uniaxial compressive strength tests of Examples and Comparative Examples.

As shown in Table 2, the initial strength was relatively low as compared with the one-kind cement, which is the comparative example, and it is considered that the potential hydraulic response of the blast-furnace slag fine powder is slightly delayed rather than the hydration reaction of the first type cement.

On the other hand, at the age of 7 days, the strength of the cement was almost equal to that of the cement of the first grade. It is considered that slag in blast furnace slag cement and amorphous material of expanding material continuously produce hydrate by the sulfate and alkali stimulation of petro coke.

(3) Other

In all of the examples and comparative examples, no material separation occurred after mixing the mortar, and the workability of the site was ensured. By visually observing the volume change before capping, the compressive strength specimen was prepared, Although the volume of the example was increased by compensating for the amount of shrinkage caused by the expandability, it was visually confirmed that the volume shrinkage occurred in the comparative example.

Claims (7)

10 to 20 parts by weight of a blast furnace slag fine powder and 5 to 15 parts by weight of Petro coke desulfurization gypsum based on 100 parts by weight of the aggregate,
Wherein the aggregate is a bottom ash having a particle size distribution of 0.02 to 10 mm.
The method according to claim 1,
Further comprising 2 to 6 parts by weight of an expanding agent based on 100 parts by weight of the bottom ash,
The expansion material is composed of an in-furnace desulfurization type coal combustion incineration ash with a calcium oxide (CaO) content of 20% or more, biomass incineration residues, paper sludge incineration residues, RDF incineration residues, RPF incineration residues, converter slag residues, quicklime and light dolomite Wherein the mortar composition is at least one selected from the group consisting of a cement mortar composition and a mortar composition.

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