KR20040069521A - Preparing method of soil solidifier and solidifying soil thereof - Google Patents

Abstract

PURPOSE: A soil solidifier is provided to maintain the alkalinity of soil low when being in contact with water and to inhibit the elution of heavy metals to a maximum. CONSTITUTION: The rapid hardenable cement-based soil solidifier is prepared by the steps of: mixing 80-90 wt% of a composition containing calcium aluminate(3CaO 5Al2O3), tricalcium silicate(3CaO SiO2), calcium sulfoaluminate(4CaO 3Al2O3 SO3), calcium, iron, magnesium silicate((Ca, Fe, Mg)SiO3), 0.5-5 wt% of desulfurized gypsum and 5-15 wt% of fumed silica or fly ashes at a constant temperature with dry-stirring at a high speed. In the solidifier, the fumed silica has a particle size of about 0.1 micrometer or less, and the fly ashes have blaine surface area of 3000 m2/g or more. The soil solidifier is added in the amount of 4-8 wt% to soil such that soil maintains a compressive strength to a range of 50-70 kg/cm2 .

Description

Soil solidification method and soil solidification method using same {PREPARING METHOD OF SOIL SOLIDIFIER AND SOLIDIFYING SOIL THEREOF}

The present invention relates to a method for manufacturing solidified materials used for solidifying soils generated at construction sites, soft ground improvement of reclaimed land, opening roads, installation of water repellent walls for waste landfills, and eco-friendly trails in parks, etc. will be.

The cement composition of the present invention will be described in more detail in terms of calcium aluminate (3CaO 5Al 2 O 3), tricalcium silicate (3CaO SiO 2), calcium sulfoaluminate (4CaO 3Al 2 O 3 SO 3) and small amounts of calcium, iron and magnesium silicates [(Ca, Fe, Mg) SiO 3] about 80 to 90% by weight, desulfurized gypsum 0.5 to 5% by weight, and fumed silica or brain specific surface area of about 0.1 μm or less to about 5 to 15% by weight of fly ash of 3000 m 2 / g or more. It relates to a method for producing a fast cement cement solidified material configured.

The fast-hardening cement-based solidified material of the present invention is a final condensation time of less than 30 minutes, as in the Korea Industrial Standard KS L 5103 "Test of the Condensation Time of Cement by Gilmore Needle". It means a solidified fire (hereinafter referred to as "soil solidified fire") that solidifies at high strength, for example, to solidify the soil generated in the construction site, about 4 to 8% by weight of the soil solidified material of the present invention is added to the soil When the mixture is mixed with the soil, the soil having a compressive strength of about 50 to 70 kg / ㎠ is obtained, and the solidified layer is obtained. To the steelmaking dust containing harmful heavy metal, about 4 to 8% of the soil solidified material of the present invention is added and mixed. The compressive strength of steelmaking dust was about 50-75 kg / cm2 after 28-day age period, and the heavy metal leaching amount was about 0.05 ~ 0.01 ppm, which satisfies the emission limit.

Soil solidifying materials which are widely used are known salts, hydroxides, cement-based solids and organic polymer materials of alkali or earth metals. For solidification, it is used for the treatment of soil generated at construction sites, soft ground improvement, soil contaminated with heavy metals, industrial waste, and drainage sludge.

The method of solidifying soil is introduced in various known materials. For example, Japanese Patent Laid-Open No. 2002-167582 discloses magnesium oxide and ferrous chloride salt when solidifying soil or high-function soil generated at a construction site. In the method of using the present invention, in 2002-020747, an alkali metal salt, a method of using a trivalent iron salt and a slag-based solid material, in the Patent Publication No. 2001-262141, a phosphate, Organic acid, and the like. In Korean Patent No. 1998-015384, cement, sand, bentonite, and the like, and Japanese Patent Laid-Open Nos. 1998-279940 and 1998-127161, Materials such as using acrylic acid have been introduced. However, solidified materials such as metal salts and alkali metal oxides shown in these publications have economic problems due to re-dissolving or expensive heavy metals, and organic polymer materials also have limitations for long-term solidification and safety maintenance due to deterioration and decomposition. On the other hand, solidified materials, such as general Portland cement, are concerned about contamination of alkaline leachate leached with high alkalinity. In particular, by using various compounds in combination, secondary environmental pollution, such as elution of harmful substances, may be raised.

The present invention attempts to achieve the desired purpose effectively by using a single additive material by achieving a solidification of the soil despite the reduction of contamination by alkali leaching and relatively small addition amount using a low alkaline fast hard cement-based soil solidifier. In particular, it is an object of the present invention to add to the soil contaminated with heavy metals to suppress heavy metal leaching as much as possible to maintain below the environmental standard value, and to maintain strength for a long time.

In order to achieve the above object, the present inventors maintain a relatively low alkalinity by increasing the content of calcium aluminate in the fast-hardening cement-based soil solidifying material of the present invention, while the fumed silica or brain specific surface area of 0.1 m or less is 3000 m 2 / By adding more than g fly ash, it maintains low alkalinity in contact with water and minimizes elution of heavy metals.

The fast-hardening cement-based soil solidified material of the present invention is used for solidifying soil generated at the construction site, soft ground improvement of reclaimed land, road opening, order wall installation of waste landfills, eco-friendly walkway in parks, etc. The present invention relates to a method for preparing the same and a method for constructing the same, and specifically, calcium aluminate (3CaO 5Al 2 O 3), tricalcium silicate (3CaO SiO 2), calcium sulfoaluminate (4CaO 3Al 2 O 3 SO 3), and a small amount of calcium, iron and magnesium silicates. Fumed silica or brain having about 80 to 90% by weight of the composition consisting of [(Ca, Fe, Mg) SiO3], 0.5 to 5% by weight of anhydrous desulfurized gypsum from the exhaust gas purification process of a thermal power plant, and a particle size of about 0.1 μm or less. It relates to a method for producing a fast-hardening cement-based solidified material comprising a specific surface area of about 5 to 15% by weight of fly ash of 3000 m 2 / g or more.

Calcium aluminate (3CaO 5Al2O3), tricalcium silicate (3CaO SiO2), calcium sulfoaluminate (4CaO 3Al2O3 SO3) and a small amount of calcium, iron, magnesium silicate [(Ca, Fe, Mg) SiO3] was limited to the range of about 80 to 90% by weight because the fume silica or fly ash, which can not exhibit the intrinsic properties of cement, such as constant physical strength, and improves the tensile properties at 80% by weight or less. It was limited to 90% by weight to add. On the other hand, the reason for limiting the range of desulfurized gypsum to 0.5 to 5% by weight is to improve the compressive strength, if necessary, and for the fly ash having a fumed silica or brain specific surface area of 3000 m 2 / g having a particle size of about 0.1 μm or less. The addition is to improve the strength of the soil to be treated by their latent hydraulicity and fineness of the particles. Its mixing range is limited to about 5 to 15% by weight because it does not exhibit desirable tensile strength, compressive strength, etc. at 5% by weight or less.

The method for producing the fast-hardening cement-based solidified material of the present invention will be described by known calcium aluminate (3CaO 5Al 2 O 3), tricalcium silicate (3CaO SiO 2), calcium sulfoaluminate (4CaO 3Al 2 O 3 SO 3) and small amounts of calcium, iron and magnesium About 80 to 90% by weight of the composition composed of silicates [(Ca, Fe, Mg) SiO3], 0.5 to 5% by weight of desulfurized gypsum, and about 5 to 15% by weight of fly ash with a fumed silica or brain specific surface area of 3000 m 2 / g or more It is prepared by dry mixing the fast cement composition composed of a high speed mixer. The mixing temperature of these mixtures is preferably 0 to 40 ° C. because they are frozen below 0 ° C. and can be mixed at temperatures above 40 ° C. like the tropics, but generally at 40 ° C. or less. On the other hand, soil means broad soil including masato, red clay, clay clay, steelmaking dust, etc. together with general soil.

Tables 1 and 2 show the results of analyzing the composition of the soil solidified material of the present invention described above.

Table 1. Qualitative analysis of soil solidified material of the present invention

Unit: weight%

Table 2. Chemical Analysis of Fast Hardening Cement Soil Solidified Materials of the Present Invention

Unit: weight%

As can be seen from the results of the chemical analysis of Table 1 and Table 2, the fast-hard cement-based soil solidifier of the present invention has a lower alkali content than ordinary Portland cement and contains no harmful heavy metals such as Pb, Cd, and Hg. Heavy metals such as Cu, Zn and Cr do not exist as soluble compounds and do not elute at all. In the particles of the soil solidifying material of the present invention, the maximum particle size is about 20 to 30 µm, but most are about 20 µm or less and about 10% of the particles are 0.1 µm or less.

When using the cement-based solidified material of the present invention of the above composition to solidify the soil contaminated in the soil, waste, etc. generated in the construction site, as in the embodiment, various fast-hardening cement-based solidified material of the present invention Can be used as a fast hardening material for soil. For example, in order to solidify the soil generated at the construction site, about 4 to 8% by weight of the soil solidified material of the present invention is mixed with soil (generally, water content: 15 to 30%), and then about 50 to 70 kg. Soil solidified layer with a compressive strength of / ㎠ can be obtained, and about 4 to 8% of the soil solidified material of the present invention is added to steelmaking dust containing harmful heavy metals and mixed. The compressive strength was about 50 to 75 kg / cm 2, and the heavy metal elution at this time was about 0.05 to 0.01 ppm, which satisfies the emission limit.

The following examples will illustrate the invention in detail but do not limit the scope thereof.

Example 1

Composition consisting of calcium aluminate (3CaO 5Al2O3), tricalcium silicate (3CaO SiO2), calcium sulfoaluminate (4CaO 3Al2O3 SO3) and a small amount of calcium, iron and magnesium silicate [(Ca, Fe, Mg) SiO3] A hard cement composition comprising 85% by weight, 3% by weight of desulfurized gypsum and 12% by weight of fumed silica was mixed at a temperature of 20 ° C. in a high-speed mixer to prepare a solid material such as Sample 1 of Table 3. .

The solidified material prepared by varying the fast-hardening cement composition of the present invention under the above conditions was prepared as shown in Table 3 below.

Table 3. Mixing example of the fast-hardening cement composition solidified material of the present invention

In order to evaluate the degree of solidification of soil, it is based on the measurement of small density, strength and permeability coefficient as in the relevant standards (KS F 2312 compaction test, KS F 2322 permeability test, KS F 2314 compressive strength test, KS F2320 CBR test). In order to characterize and evaluate the performance of the solidified material of the present invention, the compressive strength of the solidified material of the present invention was measured and its properties were compared. In general, the strength of the solidified soil is affected by the type of soil, the amount of solidified material, the curing period, and the elapsed time between mixing and compaction. The types of soil used in the embodiment of the present invention are masato, red clay and clay clay, and Table 4 shows the basic physical properties of these soils.

Table 4. Physical Characteristics of Soil Samples by Type

The soil solidification test is performed by uniformly mixing the solidified material and soil of the present invention as in the relevant standard (KS F 2312 compaction test) and compacting at the optimum function ratio, the maximum dry density, and compressing the sample in the compression mold. After the wet curing, the uniaxial compressive strength was measured for each rehabilitation period.

Table 5 shows the results of solidification according to the type of soil and the amount of solidified material of the present invention.

Table 5. Status of solidification of soil using the present fire extinguisher

As shown in Table 5, the solidified material of the present invention is slightly different depending on the type of soil and the amount of the solidified material of the present invention, but the soil having a compressive strength of about 50 to 70 kg / ㎠ by adding about 4 to 8% by weight. A solidified layer could be obtained.

Example 2

To evaluate the solidification and stabilization effects of solid waste, steelmaking dust was selected as a sample and the degree of solidification and stabilization were examined. Table 6 shows chemical analysis data of steelmaking dusts generated by steel companies.

Table 6. Chemical Analysis of General Steel Dust

In Table 6, the harmful heavy metals in steelmaking dust are Pb, Cd, Cu, Zn and the like, and other harmful elements include Cl, S, and the like. In addition, steelmaking dust can dissolve large amounts of heavy metals in water and cause environmental pollution.

Table 7 shows the results of the dissolution test of this dust sample in accordance with the Dissolution Test Act of the Environmental Pollution Control Act (Article 11 of the Waste Management Act). In this table, it can be seen that in the aqueous solution of pH 6.3, the elution amount of harmful heavy metals Cd, Pb, Cu is eluted about 10 to 20 times more than the standard value.

Table 7. Dissolution test results of general steelmaking dust

Unit: ppm

Table 8. Solidification and Heavy Metal Elution Trend of Steelmaking Dust by Addition of Solidified Material of the Invention

As shown in Table 8, when the added amount of solidified material of Sample 1 was added in an amount of about 4 to 8% by weight based on the amount of dust, the degree of solidification was about 50 to 75 kg / cm 2 at 28 days of age, and the amount of heavy metals was about 0.05 to 0.01. As ppm, the amount of elution that satisfies the standard emission limit of the Waste Management Act is shown.

By using the fast-hardening cement-based solidified material of the present invention, not only the effective solidification treatment of the soil generated on site, but also the solidification of fine solid wastes such as steelmaking dust containing harmful heavy metals and the stabilization of heavy metals, can be effectively solidified and environmentally friendly. It is expected to be used for the establishment of farm roads, the solidification of stabilization walls and hazardous solid waste in waste treatment plants.

Claims (4)

80 to 90% by weight of the composition of calcium aluminate (3CaO 5Al2O3), tricalcium silicate (3CaO SiO2), calcium sulfoaluminate (4CaO 3Al2O3 SO3) and calcium, iron, magnesium silicate [(Ca, Fe, Mg) SiO3] A method for producing a cement-based fast curing solidified material, characterized in that the composition of 0.5 to 5% by weight of desulfurized gypsum and 5 to 15% by weight of fumed silica or fly ash is mixed by high-speed stirring at a constant temperature. The method for producing a cement-based fast-curing solidified material according to claim 1, characterized by mixing at a temperature of 0 to 40 ° C. The soil solidification method according to claim 1, wherein the soil solidification material of 4 to 8% by weight is added to the soil to maintain the compressive strength in the range of 50 to 70 kg / cm 2. The method of solidifying soil according to claim 3, wherein the soil is sole or mixture among ordinary soil, masato, red clay, clay clay, and steelmaking dust.