KR20230066704A - Eco-friendly general purpose solidifying composition - Google Patents

Abstract

The present invention relates to an eco-friendly general purpose solidifying composition which is made from industrial by-products such as steelmaking by-products and thermal power generation by-products as raw materials to ensure eco-friendliness, and the strength of each ground, which is divided into cohesive soil, sandy soil, and stony soil, is measured to meet the performance standards of the Ministry of Land, Infrastructure and Transport's Temporary Construction Standard Specification (2014). The present invention provides an eco-friendly general purpose solidifying composition comprising: 20 to 30 parts by weight of cement; 30 to 40 parts by weight of blast furnace slag fine powder; 5 to 20 parts by weight of desulfurized gypsum; and 15 to 25 parts by weight of circulating fluidized bed boiler ash containing CaO and free-CaO components.

Description

Eco-friendly general purpose solidifying composition {Eco-friendly general purpose solidifying composition}

The present invention is composed of industrial by-products such as steelmaking by-products and thermal power generation by-products as raw materials to secure eco-friendliness, and the strength of each ground classified into clay soil, sandy soil, and sandy soil meets the performance standards of the Ministry of Land, Infrastructure and Transport Standard Specification for Construction Works (2014) It relates to an eco-friendly universal solidifying material composition that can be metered to do.

According to the design section of the temporary construction standard specification (2014), soft ground such as cohesive soil, sandy soil, and sandy soil must be improved to meet the performance standards shown in [Table 1] below.

Sat Jill Performance standard (MPa, 28 days) clay soil 1~2 sandy soil 2 to 8 sand soil 6-12

Conventionally, cement paste or a paste in which other admixtures are applied as a binder has been mainly used as a solidifying material, and has been used by adjusting the amount of the solidifying material, the water-binder ratio, etc. according to the soil quality of the soft ground.

1. Registered Patent No. 10-2158524 "Eco-friendly solidifying material composition for soft ground" 2. Registered Patent No. 10-1168151 "Fixing material for ground reinforcement" 3. Registered Patent No. 10-1889783 "Solidification material using high calcium fly ash and steel industry by-products and its manufacturing method" 4. Registered Patent No. 10-2187933 "Consolidation composition using industrial by-products"

The present invention utilizes industrial by-products such as cogeneration by-products, thermal power generation by-products, and steelmaking by-products, which have conventionally been limited or insoluble, and can be universally applied to soft ground of various soils on the same mixing standard. Its purpose is to provide a universal solidifying material composition.

The present invention is "20 to 30 parts by weight of cement; 30 to 40 parts by weight of blast furnace slag fine powder; 5 to 20 parts by weight of desulfurized gypsum; and 15 to 25 parts by weight of circulating fluidized bed boiler ash containing CaO and free-CaO; It provides a general-purpose solidifying material composition comprising a.

The circulating fluidized bed boiler ash contains 15 to 40 wt% of CaO and 25 wt% or less of free-CaO, and the total amount of CaO and free-CaO is 20 to 60 wt%. It is desirable to apply the composition.

In addition, 10 parts by weight or less (excluding 0 parts by weight) of bottom ash may be included, and the bottom ash preferably contains 4,000 to 6,000 ppm of chloride.

In addition, the general-purpose solidifying material composition provided by the present invention may further include 30 parts by weight or less (excluding 0 parts by weight) of KR slag,

The KR slag preferably contains 45 to 65 wt% of CaO.

The eco-friendly universal solidifying material composition provided by the present invention,

1. Regardless of soil quality (cohesive soil, sandy soil, and sandy soil) of soft ground, even if the same amount of agitation (amount of binder) is applied with the same water-binder material ratio, the standard performance criteria of each soil quality is met, so construction and improvement ground quality management efficiency this improves

2. Based on the component analysis of industrial by-products such as circulating fluidized bed boiler ash, bottom ash, and KR slag, an appropriate mix of solidifying material composition for improving soft ground was derived, and reduction of environmental load and production of solidifying material by utilizing these industrial by-products It can contribute to cost reduction.

The present invention is "20 to 30 parts by weight of cement; 30 to 40 parts by weight of blast furnace slag fine powder; 5 to 20 parts by weight of desulfurized gypsum; and 15 to 40 parts by weight of circulating fluidized bed boiler ash containing CaO and free-CaO; It provides a general-purpose solidifying material composition comprising a.

Circulating fluidized bed boiler ash is fly ash produced in cogeneration plants. Unlike fly ash produced in general thermal power plants, circulating fluidized bed boiler ash has a high CaO component and exhibits hydration reaction characteristics. In a circulating fluidized bed boiler of a combined heat and power plant, limestone is introduced to smoothly remove NOx and SOx, and CaO components are present in the circulating fluidized bed boiler ash generated accordingly. CaO reacts with water to become Ca(OH) ₂ , and Ca(OH) ₂ contributes to the formation of cement hydration products. Accordingly, a method of applying circulating fluidized bed boiler ash as a solidification material by mixing it with cement was reviewed.

However, in order to reduce the amount of cement used and increase the amount of industrial by-products due to carbon reduction problems, etc., the components of the solidification material composition that have been applied in various fields have been reviewed, and the blast furnace slag fine powder and desulfurized gypsum are applied together with the circulating fluidized bed boiler ash. Plans to do so were reviewed.

On the other hand, there is a difference in the content of circulating fluidized bed boiler ash generated for each power plant, and there is also a difference in the free-CaO content that affects the hydration reaction rate. Free-CaO contributes to accelerating the cement hydration reaction, but if it is excessively contained in the solidification material, there is a concern such as expansion failure of the improved ground, so an appropriate level of content is required.

Accordingly, the components contained in the circulating fluidized bed boiler ash generated for each power plant, the respective contents of CaO and free-CaO, and the total amount of CaO and free-CaO (hereinafter referred to as 'Tata1 CaO') were analyzed ([Table 2] and [Table 2] and [ see Table 3).

As described in the [Background of the invention] section, conventionally, the solidifying material mixture or amount used has been changed according to the soil quality of the soft ground. For example, conventionally, when soft ground is sandy soil, 240 kg of cement (OPC) per 1 m 3 of sandy soil was mixed under conditions of a water-binder ratio of 140 (336 kg of water), which was improved by stirring the paste. In this case, the improved ground As shown in [Table 4] below as a 'comparative example', the compressive strength test result for each age showed a compressive strength of 2.55 MPa at 28 days of age, satisfying the standard performance criteria of 2-8 MPa for sandy soil.

In order to compare the results of conventional sandy soil improvement as above, the circulating fluidized bed boiler ash discharged from four cogeneration plants was dried at 105 ° C and included as a binder, and the unit material amount and water-binder ratio were the same conditions as in the comparative example above. After preparing a solidifying material composition and stirring it in sandy soil, the compressive strength by age was measured.

Briefly explaining the binder mixture of Test Example 1-A to Test Example 1-D,

To start the hydration reaction, cement was included in an amount of 30 wt% of the binder, and 40 wt% of the blast furnace slag fine powder was included in the binder so that the long-term strength was developed, and desulfurized gypsum was mixed with 5 wt% of the blast furnace slag fine powder. It was intended to activate latent hydroponics. In addition, circulating fluidized bed boiler ash, which promotes the hydration reaction by CaO and free-CaO components, was classified for each power plant and incorporated into the binder at a ratio of 25 wt%.

As a result of the compressive strength test by age for the above test examples, the compressive strength at age 7 days lacked the relationship between CaO, free-CaO content, or total CaO in circulating fluidized bed boiler ash, but at age 28 days, which is the standard for improved soil compressive strength. The compressive strength tended to be proportional to Total CaO and was expressed in the range of 2.11 to 2.59 MPa, indicating that all of Test Examples 1-A to 1-D met the sandy soil performance criteria (age 28 days, compressive strength of 2 to 8 MPa). appear.

In addition, in Test Example 1-B in which Total CaO in the circulating fluidized bed boiler ash was 40 to 60 wt%, negative phenomena such as expansion failure of the improved ground did not occur.

Therefore, it was examined that all of Test Examples 1-A to 1-D can be applied as a solidifying material composition for improving sandy soil.

[Table 5] below summarizes the test results applied to the improvement of cohesive soil and sandy soil while maintaining the mixing conditions of Test Example 1-A to Test Example 1-D.

As for the above test results, the compressive strength at 28 days of age of the improved soil tended to be proportional to Total CaO, and the cohesive soil was expressed in the range of 1.06 to 1.25 MPa after improvement, and the sandy sand soil was expressed in the range of 6.33 to 7.77 MPa after improvement. expressed,

It was found that all of Test Examples 1-A to 1-D satisfied the clay performance criteria (age 28 day compressive strength 1-2 MPa) and sand sand soil performance criteria (age 28 day compressive strength 6-12 MPa).

In addition, negative phenomena such as expansion failure of the ground improved in Test Example 1-B did not occur.

Therefore, it was reviewed that all of Test Examples 1-A to 1-D can be applied to the solidifying material composition for improving clayey soil and sand sand soil.

Accordingly, the circulating fluidized bed boiler ash contains 15 to 40 wt% of CaO, 25 wt% or less of free-CaO, and a total amount of 20 to 60 wt% of CaO and free-CaO can be stably applied. there is.

That is, Test Example 1-A to Test Example 1-D (hereinafter referred to as 'the solidifying material composition of the present invention') are general-purpose solidifying material compositions that can be applied regardless of soil quality, and other existing solidifying material compositions including cement paste It can be said that the range of utilization has been greatly expanded compared to the need to apply different mixtures or amounts of solidification materials according to the soil quality of the ground to be improved. In addition, the solidification material composition of the present invention is multipurpose by mixing blast furnace slag fine powder and circulating fluidized bed boiler ash, which are industrial byproducts, and is environmentally friendly in terms of recycling industrial byproducts, and can achieve cost reduction effects.

The present invention provides a general-purpose solidifying material composition characterized in that the binder further contains 10 parts by weight or less (excluding 0 parts by weight) of bottom ash.

The bottom ash is a by-product generated by wet (seawater) cooling of coal-fired power plants, and has a low CaO content, but contains some Cl ^- in a chloride state by seawater cooling. Since Cl ^- contributes to the early steel performance of the solidifying material composition and does not cause problems such as corrosion of reinforcing bars, which has been a problem in concrete, it was judged that it can be applied to the solidifying material composition used for ground improvement without negative effects. However, since there is a possibility of corrosion of pumping equipment, it is preferable to apply bottom ash containing 4,000 to 6,000 ppm of Cl ^- .

[Table 6] below shows the results of analyzing the composition of bottom ash (BA) discharged from a thermal power plant by randomly obtaining it.

The test results shown in [Table 7] are the compressive strength test results of 28 days of age for each soil type of the improved ground under the condition of improving by mixing 240 kg of binder per 1㎥ of soft ground with a water-binder ratio of 140 (336 kg of water).

In Test Example 2, 10 wt% of the bottom ash was mixed instead of limiting the ash content of the circulating fluidized bed boiler to 15 wt% in the binder of Test Example 1-C.

The mixed bottom ash is dried at 105 ° C and pulverized at 3,000 ~ 5,000 cm 2 / g.

As shown in the test results of [Table 7] above, Test Example 2 in which bottom ash was incorporated was considered to be applicable as a solidifying material composition for improving clayey soil, sandy soil, and sandy sand soil.

In addition, the present invention provides a general-purpose solidifying material composition characterized in that it further contains 30 parts by weight or less (excluding 0 parts by weight) of KR slag.

KR slag is highly basic slag generated in the molten iron pretreatment process using the Kanvara Reactor during the steelmaking process. The main component of the KR slag is slaked lime (calcium hydroxide [Ca(OH) ₂ ]), which is strongly alkaline but has a very stable hexagonal plate-like or columnar crystal structure compared to calcium oxide. The KR slag can be pulverized through a grinding process, and ferrous materials can be separated and removed through magnetic separation in a pulverized state.

[Table 8] below shows the results of analyzing the composition of KR slag discharged from the steelmaking process by randomly obtaining it. As a result of the five analyzes, the CaO content in KR slag was found to be 49.45 to 66.12 wt%, but the CaO content variation is expected to be larger depending on the KR slag discharge process. Therefore, the KR slag applied to the solidifying material composition of the present invention is preferably selected to contain 45 to 65 wt% of CaO and quality control so that the compressive strength of the improved ground does not appear excessively.

The test results shown in [Table 9] are the compressive strength test results of 28 days of age for each soil type of the improved ground under the condition of improving by mixing 240 kg of binder per 1㎥ of soft ground with a water-binder ratio of 140 (336 kg of water).

In Test Example 3, KR slag was mixed at 10 wt% instead of limiting the circulating fluidized bed boiler ash content to 15 wt% in the binder of Test Example 1-C.

In Test Example 4, 10 wt% of bottom ash was mixed instead of limiting the content of cement (OPC) in the binder to 20 wt% in Test Example 3 above.

In Test Example 5, the content of the blast furnace slag fine powder in the binder in Test Example 4 was limited to 20 wt%, and KR slag was mixed at 30 wt% instead of bottom ash.

The mixed KR slag was dried at 105 ° C and pulverized at 5,000 to 6,000 cm 2 / g, and then sieved to select powder with a particle size of 0.5 mm or less.

As shown in the test results of [Table 7] above, it was reviewed that all of Test Examples 3 to 5 could be applied as a solidification composition for improving clay soil, sandy soil, and sandy sand soil.

However, since the 28-day compressive strength of the improved cohesive soil in Test Example 5 containing 30 wt% of KR slag in the binder was expressed as high as 1.81 MPa, when the KR slag content exceeds 30 wt%, the CaO content in KR slag and Depending on the ingredients and mixing conditions of other raw materials, it may exceed the range of standard performance criteria for improved clay soil. Therefore, it is preferable to limit the content of KR slag in the binder of the solidifying material to 30 wt% or less.

Although the present invention has been described in relation to the test examples as mentioned above, various modifications and variations are possible within the scope without departing from the gist of the present invention, and can be used in various fields. Accordingly, the claims of the present invention include modifications and variations that fall within the true scope of the foregoing invention.

Not applicable

Claims (6)

20-30 parts by weight of cement;
30 to 40 parts by weight of blast furnace slag powder;
5 to 20 parts by weight of desulfurized gypsum; and
CaO and free-CaO components are 15 to 25 parts by weight of circulating fluidized bed boiler ash; A universal solidifying material composition comprising a.
In paragraph 1,
The circulating fluidized bed boiler ash,
15 to 40 wt% of CaO is contained,
25 wt% or less of free-CaO is contained,
A universal solidifying material composition, characterized in that the total amount of CaO and free-CaO is 20 to 60 wt%.
In paragraph 1,
A general-purpose solidifying material composition, characterized in that it further contains 10 parts by weight or less (excluding 0 parts by weight) of bottom ash.
In paragraph 3,
The bottom ash is a general-purpose solidifying material composition, characterized in that Cl ^- is contained in 4,000 ~ 6,000 ppm.
In any one of claims 1 to 4,
KR slag is 30 parts by weight or less (excluding 0 parts by weight) of the general-purpose solidifying material composition, characterized in that further included.
In paragraph 5,
The KR slag,
A general-purpose solidifying material composition characterized by containing 45 to 65 wt% of CaO.