KR100727654B1 - A solidifying agent composition for softground - Google Patents

Abstract

A solidifying agent composition for the soft ground is provided to improve strength of the soft ground without causing cracks and solidify soils contaminated with heavy metals in a low cost to inhibit the dissolution of heavy metals. The solidifying agent composition for the soft ground consists of mixing 52.2-59.8wt% of fly ashes, 33-39wt% of cement, 4.5-5.5wt% of white mica, and 2.7-3.3wt% of anhydrite based on 100wt% of the total composition, or mixing 45-53.5wt% of fly ashes, 33-39wt% of cement, 4.5-5.5wt% of white mica, 2.7-3.3wt% of anhydrite, and 6.3-7.7wt% of quicklime based on 100wt% of the total composition.

Description

A solidifying agent composition for softground

1 is a SEM photograph of a soft ground solidified material according to Example 1 of the present invention.

2 is a SEM photograph of the soft ground solidified material according to Example 2 of the present invention.

The present invention relates to a solid fire, and more particularly, to a soft ground solidified material to be able to strengthen the ground, such as soft ground, coastal wetlands, 뻘 difficult to solidify due to high water content.

In Korea, where the land is narrow, many construction and civil works are carried out by reclaiming coastal areas in accordance with the increase of population and industrial development. However, in the coastal areas of the south and west coasts, thick sediments composed mainly of clay are very difficult for the actual construction, and there are many problems due to ground subsidence in the soft soil of clay. In general, the clay sediment and soft ground are mainly solidified by using cement (usually Portland cement). In special cases, blast furnace cement or crude steel cement is often used instead of portland cement. Cement does not immediately harden when it comes in contact with water and maintains its firing state for a certain period of time. This step is called setting, and the setting time of Korean industrial standard is based on 1 ~ 10 hours. The cement in the sintered state undergoes a hardening process in which the hydration is continued as time passes after the condensation is completed, thereby densely filling and solidifying the cement particles. This is because the constituents of cement come into contact with water, causing their own chemical reactions, and thus becoming different compounds. This is called hydration. On the other hand, it is known that cement alone cannot be effectively treated in soils containing large amounts of organic clays that can inhibit the hydration reaction of soft clay and cement having a high water content. This is caused by the disturbance of the hydration reaction by organic matter, the difficulty of solidification treatment with only cement in the case of soft clay or mud, and the occurrence of loosening site during long-term soaking due to the occurrence of dry shrinkage when using a large amount of cement. In order to solve this problem, cement is often used as a cement-based solidified material in which Portland cement is mixed with additives according to the ground characteristics and construction purposes.

Of the existing suspension-type and solution-type solids, chemical solids such as chromium-based and acrylamide-based solids, which can cause pollution due to the problem of chemical solids, have been banned in most countries. It is becoming. Cement-based solidifying materials used in combination with cement first generate a large amount of ettringite in the process of improving the effect in the case of soft ground. Ettrinite absorbs a large amount of bound water, lowers the water content, and constrains the movement of the granules, making it easy to solidify. Then, aggregate coagulation of the granules is increased by Ca ++ ions eluted from calcium hydroxide, calcium citrate, and the like, and the strength is increased by the production of calcium silicate hydrate. In addition, soluble components such as silica (SiO 2) and alumina (Al 2 O 3) contained in the soil are known to be harder with time by combining with Ca (OH) 2 to form insoluble hydrates.

In recent years, at home and abroad, the reclaimed works that fill up the ocean's seashores are used as basic grounds by safely treating marine or contaminated sedimentary cohesive soils for the construction of general landfill sites, the construction of artificial islands, the construction of new airports, ports, and the construction of water barrier walls for them. There is a growing number of cases that require ordering methods. However, these soft ground soils contain many organic substances due to long-term deposition or organic waste. As described above, organic matter is adsorbed on the surface of the granules, which not only prevents the mixed contact between cement and the solidified soil, As a result, it is difficult to solidify by inhibiting the direct reaction between cement hydrate and granules. As a result, the water content of the high water content such as coastal water is too high for cement, so that it is not possible to use forklift cement or steel cement or In the case of using blast furnace cement, solidification did not proceed smoothly and satisfactory high strength was not obtained. Although there are solidified materials that compensate for the problems of general cement, this is also hardened because of the large amount of general cement as the main raw material. In addition, there was a problem that the solidification was not good in the sedimentary soil or the soil with high moisture content due to the efficient decomposition of organic matters or the entrained water in the solidification component and the ratio added to the general cement. .

The present invention is to solve the above-mentioned problems, the organic clay, such as soft ground, coastal wetland, 함유 is improved, the strength of the clay without the occurrence of cracks in the marine clay having a high content of moisture, and also contains pollutants such as heavy metals The purpose of the present invention is to provide a soft ground solidified material which can solidify the contaminated soil at low cost to suppress the leaching of heavy metals and promote the order effect.

The soft ground solidifying material according to the present invention for achieving the above object is characterized in that the cement, muscovite, anhydrous gypsum is mixed with a fly ash as a main component.

In addition, the present invention is characterized in that the fly ash, cement, dolomite, anhydrous gypsum and quicklime are mixed.

The features and advantages of the present invention will become more apparent from the following detailed description based on the accompanying drawings. Prior to this, the terms or words used in the present specification and claims are defined in the technical spirit of the present invention on the basis of the principle that the inventor can appropriately define the concept of the term in order to explain his invention in the best way. It must be interpreted to mean meanings and concepts.

Soft ground reinforcing solidified material according to the present invention is made of a mixture of fly ash, cement, dolomite, anhydrous gypsum.

In addition, the present invention is made by mixing quicklime with the fly ash, cement, mica, anhydrous gypsum.

According to the present invention, the mixing ratio of the components is determined so as to reliably reinforce soft ground such as shore and soil and remove heavy metals in the ground, and the composition of the solidified material is, for example, fly ash 52.2 based on 100 wt% of the total. ~ 59.8% by weight, 33-39% by weight cement, 4.5-5.5% by weight mucosa, 2.7-3.3% by weight anhydrous gypsum, fly ash 45 ~ with respect to 100% by weight total solids if more quick lime is mixed 53.5% by weight, 33-39% by weight cement, 4.5-5.5% by weight mica, 2.7-3.3% by weight anhydrous gypsum, 6.3-7.7% by weight quicklime may be mixed, but is not limited thereto.

Hereinafter, each component will be described in detail.

1. Fly Ash

end. Spherical particles with smooth surfaces, improved workability and reduced unit quantities

I. Initial strength is low, but long-term strength is increased

All. Reduction effect of concrete temperature due to hydration heat (effective for high strength and large section)

la. Filling voids in concrete to reduce permeability and improve water tightness

hemp. Improvement of resistance to volume change and freezing and thawing by wet and dry

bar. Recycling waste to solve environmental problems and reduce production costs

four. Economic Comparison (00 Years): Cement; 54 yuan / kg, fly ash; 30 won / kg

Pozzolan is a fine powder with highly active amorphous silica (SiO2), which itself is not hydrophobic, but reacts with Ca (OH) in the presence of water to form calcium silicate hydrate bonds. Say a substance that can.

C + S + H → C-S-H (Calcium silicate hydrate)

(C: CaO h: H 2 O S: SiO 2)

Pozzolan reacts with Ca (OH) produced during the hydration reaction when it is defective with Portland cement, increasing the proportion of C-S-H in the cement pool while consuming Ca (OH).

Mixing pozzolanic with cement improves the workability of cement, reduces the generation of heat of hydration, and decreases the initial strength, but in the case of long-term age, the strength is increased and the resistance to water-tightness and sulfate attack is improved. It has the advantage of being.

As the material having pozzolanic activity, there are natural products such as volcanic ash and tuff and artificial things such as fly ash. Pozzolanic material mainly used for powdery and spherical fly ash is used. Natural pozzolanic materials include diatomite. Diatomaceous earth is a shell of diatoms, which is deposited on the bottom of the sea or lake, and is a soft rock or soil mass composed of about 95% of silica and very small hollow holes. Absorbs about twice as much liquid.

The reason for mixing cement and fly ash with solidification function is to activate the pozzolanic reaction by adding fly ash, which is composed mainly of silica (SiO2).

Referring to Table 2 below, the content of silica (SiO 2) in general cement is about 21.0%, but as the fly ash addition rate increases, the content of silica (SiO 2) increases to 39.26% and 35.29%, respectively.

2. Cement (usually Portland Cement)

In the case of Portland cement, lime (CaO), silica (SiO 2), alumina (Al 2 O 3), iron oxide (Fe 2 O 3), etc., which have cementing functions, are the main components, and the lime component shows the highest content of about 63.0%.

3. Dolomite

Dolomite is composed of 44.3% of silica (SiO2) and 31.2% of alumina (Al2O3). In the case of dolomite, the content of alumina is much higher than that of other components, which increases the content of C3A when added to cement. In cement, C3A reacts with gypsum to produce ettringite (3CaO · Al2O3 · 3CaSO4 · 32H2O). If there is enough sulfate ion, the formation of ethringite continues, and once the sulfate ion is removed, it is converted into monosulfate (3CaO · Al2O3 · CaSO4 · 12H2O), which proceeds inside the structure when the structure is formed by mixing motto and solidified material. Reduces pore generation due to evaporation of internal water.

4. Anhydrous Gypsum

When the chemical component is added to the solidified material as CaSO4, it forms a needle shape in the condensation reaction and improves the watertightness by reducing the strength and permeability.

5. Quicklime

 The chemical is CaO, which reacts with water to form Ca + H2O → Ca (OH) 2. Calcium hydroxide is more bulky than quicklime and is also used as a method of reinforcing soft ground.

As described in detail in Examples below, in Example 2 (samples mixed with quicklime), quicklime was added as compared to solidified material 1 (samples not mixed with quicklime) to have a slight strength enhancing effect, but a greater effect. It can be seen that the permeability coefficient is greatly reduced due to the volume expansion caused by the hydration reaction of quicklime.

Hereinafter, specific examples of the soft ground solidified material according to the present invention will be described.

<Example>

1. Sample

Table 1. Content of each component of the sample (unit: weight%)

division Fly ash cement muscovite Anhydrous gypsum quicklime Example 1 57 35 5 3 - Example 2 50 35 5 3 7

2. Basic Properties

2.1 Physical / Chemical Composition of Examples

2.1.1 XRF (X-ray Fluorescence)

In Examples 1 and 2, it can be confirmed that silicon dioxide (SiO 2), calcium oxide (CaO), and alumina (Al 2 O 3) form main components. In Example 2, calcium oxide (CaO) is relatively high due to the addition of quicklime.

Table 2. XRF Results (Unit:%)

division SiO2 TiO2 Al2O3 Fe2O3 MnO MgO CaO Na2O K2O P2O5 L.O.I system Example 1 39.26 0.93 17.03 5.78 0.01 1.51 29.02 0.33 1.38 0.41 4.34 100 Example 2 35.29 0.79 15.52 5.16 0.01 1.52 34.97 0.32 1.26 0.31 4.85 100

2.1.2 Scanning electron microscope

As shown in FIGS. 1 and 2, SEM images of Examples 1 and 2, respectively, as shown in FIGS. 1 and 2, in which Examples 1 and 2 both have fly ash, a round cement mass, and the like. Able to know.

2.2 Specific gravity test

As can be seen in Table 3 below, the specific gravity of Examples 1 and 2 showed 2.67 tons / m 3.

Table 3. Specific gravity test results (unit: ton / ㎥)

division importance Haesung Clay 2.64 Example 1 2.67 Example 2 2.67

2.3 Liquid / Firing Limit Test

Since the plasticity index value has a great effect on the work efficiency, a large value is highly preferred in the field. In the results below, the mixed samples are classified as silty clay or clay-based soil, which shows very good field workability.

Table 4. Liquid and Firing Limit Experiments (Unit:%)

division Liquid limit Firing limit Plasticity index Example 1 34.29 21.11 13.18 Example 2 33.66 20.39 13.27 Haesung Clay 25.00 16.30 8.70 Mixed Soil 1 (95: 5) 28.86 15.39 13.47 Mixed Soil 2 (95: 5) 29.50 15.60 13.90

Soft ground solidified material according to the present invention is used independently of Examples 1 and 2 or mixed with Example 1 and 1 and clay (mixed soil 1 (or 2): marine clay = 4 to 6% by weight: 94 to 96 % By weight, preferably 5: 95% by weight), which will be used below.

Mixed soil 1: marine clay: Example 1 = 95: 5 mixed.

Mixed soil 2: Marine clay: Example 2 = 95: 5 mixed.

2.4 Compaction Experiment

As a result of the compaction test, as shown in Table 5 below, the optimum functional ratios of the mixed clays 1 and 2 mixed with the marine clays of Examples 1 and 2 were 15.5% and 15.3%, respectively, and the maximum compaction density was 1.74t / ㎥, respectively. And 1.76t / ㎥ showed almost similar results.

Table 5. Compaction Test Results

division Optimal Function Ratio (OMC) (%) Max.Dry Density (t / ㎥) Mixed earth 1 15.5 1.74 Mixed earth 2 15.3 1.76

2. pH

As can be seen from Table 6, in the case of marine clay showed a weak alkalinity of 8.27, Examples 1 and 2 showed strong alkalinity of 12.02 and 12.10, respectively, mixed soil 1,2 also showed a strong alkalinity of 11 or more heavy metals High sedimentation efficiency.

Table 6. pH Measurement Results

division pH Haesung Clay 8.27 Example 1 12.02 Example 2 12.10 Mixed earth 1 11.84 Mixed earth 2 11.88

3. Compressive strength

Table 7 shows the results according to the uniaxial compressive strength test, and the measured values of the mixed soil 1,2 and 28 after 28 days of curing were 18.97㎏ / ㎠ and 24.43㎏ / ㎠, respectively.

Table 7. Compressive Strength Test Results (Unit: ㎏ / ㎠)

division 7 days 14 days 28 days Mixed earth 1 16.63 16.63 18.97 Mixed earth 2 20.79 19.49 24.43

4. Permeability coefficient

As shown in Table 8, it was confirmed that the permeability coefficient decreases as the wet curing progresses. Compared to the mixed soil 1, the mixed soil 2 showed a greater decrease in permeability coefficient as well as an increase in strength due to the effect of quicklime. Permeability coefficient also appeared to satisfy below 1 × 10 ^-7 cm / sec.

Table 8. Permeability Measurement Results (Unit: ㎝ / sec)

division 7 days 14 days 28 days Mixed earth 1 8.77E-08 1.79E-08 1.14E-08 Mixed earth 2 4.31E09 3.42E-09 3.57E-09

5. Dry Shrink

Table 9 and Figure 10 shows the shrinkage rate of the specimen according to the moisture supply or not and the moisture supply after 28 days wet curing if not wet curing. The non-wet curing was found to have a larger shrinkage than the curing, and the supply of water decreased the shrinkage of the specimens as the specimen was dried.

Table 9. Moisture supply VS not supplied when not cured (Unit:%)

Compounding cost Hydration No moisture supply Early 7 days later 14 days later 28 days later Early 7 days later 14 days later 28 days later Mixed earth 1 0 -0.472 -0.496 -0.501 0 -1.308 -1.324 -1.331 Mixed earth 2 0 -0.441 -0.463 -0.470 0 -1.192 -1.210 -1.218

Table 10. Moisture supply VS not supplied when cured for 28 days (Unit:%)

Compounding cost Hydration No moisture supply Early 7 days later 14 days later 28 days later Early 7 days later 14 days later 28 days later Mixed earth 1 0 -0.158 -0.166 -0.169 0 -0.446 -0.468 -0.481 Mixed earth 2 0 -0.163 -0.171 -0.173 0 -0.429 -0.477 -0.459

6. Freeze-thawing

Table 11 shows the change in compressive strength after freezing and thawing, and it can be seen that the strength of the mixed soil 1,2 increases slightly as the freezing and thawing progresses. This is believed to be due to the formation of ettringite and monosulfate hydrates using the water in the specimen.

Table 11. Compressive Strength Results (Unit: ㎏ / ㎠)

division 7 days 14 days Mixed earth 1 22.09 24.56 Mixed earth 2 21.44 26.50

6.2 Permeability Factor

                                   (Unit: cm / sec)

division 7 days 14 days Mixed earth 1 1.38E-08 1.11E-08 Mixed earth 2 1.74E-09 1.56E-09

Biggest advantage of adding fire

In the case of mixed soils 1 and 2 (95: 5), the plasticity index was 13.47% and 13.90%, respectively. According to the US EPA environmental standards, the plasticity index should be more than 10 so that the performance of work performance is considered to be easy.

As described above, according to the soft ground solidified material according to the present invention, compared with the conventional portant cement or solidified material prepared by mixing a certain solidified component based on the same, it is a weak clay, organic clay containing organic matter It is excellent in the application of soil containing waste and high water content, so it can be used without restriction of the target soil. In particular, there is a remarkable effect that the manufacturing cost can be reduced compared to the case of using the existing cement as a main component.

In addition, it can be used not only in soft ground but also in heavy metal contaminated ground, so that the outflow of heavy metal can be prevented, thereby preventing environmental damage and pollution.

While the invention has been described and illustrated in connection with a preferred embodiment for illustrating the principles of the invention, the invention is not limited to the configuration and operation as such is shown and described. Rather, it will be apparent to those skilled in the art that many changes and modifications to the present invention are possible without departing from the spirit and scope of the appended claims. Accordingly, all such suitable changes and modifications and equivalents should be considered to be within the scope of the present invention.

Claims (3)

5 ~ 59.8% by weight of fly ash, 33 ~ 39% by weight of cement, 4.5 ~ 5.5% by weight of mica, and 2.7 ~ 3.3% by weight of anhydrous gypsum. 45 to 53.5% by weight of fly ash, 33 to 39% by weight of cement, 4.5 to 5.5% by weight of mica, 4.5 to 5.5% by weight of anhydrous gypsum, and 6.3 to 7.7% by weight of quicklime Soft ground fires. The soft ground solidified material according to claim 1 or 2, wherein the solidified material is used by mixing with marine clay at a ratio of 4 to 6% by weight: 94 to 96% by weight.

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