KR100876222B1 - The solidifying agent composition for softground improvement - Google Patents

Abstract

A functional solidifying agent for the modification of the weak ground is provided to improve dispersion with soil and strength, thereby solidifying the weak ground effectively. A functional solidifying agent for the modification of the weak ground comprises 60~65 wt% of portland cement; 10~15 wt% of a pozzolan material selected from blast-furnace slag powder, fly ash micropowder, volcano ash, chaff meal, diatomite, fumed silica and zeolites; 10~15 wt% of a high-early-strength agent selected from CSA (calcium sulfo-aluminate) and gypsum or CSA and alumina cements; and 10~15 wt% of a melamine-based, naphthalene-based or carboxylic-based dispersant, and has a degree of fineness of 4,000 cm^2/g.

Description

The solidifying agent composition for softground improvement

The present invention relates to a functional solidified material for improving the soft ground, and more particularly, soft ground composed of soil containing a large amount of viscous soil and organic matter having a high water content by exhibiting excellent dispersibility and strength when mixed with soil. The present invention relates to a functional ground fire for improving the soft ground having the characteristics that can effectively solidify.

In Korea, where the land is narrow, many construction and civil works are being done to reclaim coastal areas. However, in the coastal areas of the south and west coasts, the clay deposits are thickly distributed, making construction difficult.

Therefore, for the soft ground in the coastal area, cement (usually Portland cement) is used to solidify the ground, but in special cases, cement, such as slag cement or crude cement, is used instead of Portland cement to solidify the ground. The method is also used.

At this time, the cement does not immediately harden when it comes in contact with water, but hardens by maintaining a sintered state for a certain time. This step is called setting. The calcined cement undergoes a hardening step of increasing strength as the cement particles are densely packed and hardened after the condensation is finished.

This is because the compounds constituting the cement are transformed into other compounds by a unique chemical reaction with water. This action is called hydration. However, the soft ground containing clay or organic matter with high water content makes the clay and organic matter impede the hydration reaction of cement, making solidification impossible.

In order to solve this problem, by using solidified material mixed with additives according to the ground characteristics and construction purpose of cement, it generates a large amount of ettringite, absorbs a large amount of water and reduces water content, It constrains the movement of and converts it into an easy solidification state.

In addition, agglomeration of the granules is further strengthened by calcium ions (Ca +) eluted from calcium hydroxide (Ca (OH) ₂ ), calcium silicate (CaSi ₂ ), and the like, and the strength is increased by the production of calcium silicate hydrate.

In addition, soluble hydrates such as silica (SiO ₂ ) and alumina (Al ₂ O ₃ ) contained in the soil are combined with calcium hydroxide to form insoluble hydrate, which becomes harder as the age of aging increases.

However, in the case of soft ground containing a large amount of organic matter due to long-term deposition or organic waste in the soft ground, the organic matter is adsorbed on the surface of the granules and interferes with the mixed contact between the solid and the soft ground, thereby hydrates and granules of the solid fire Direct reaction between the liver was not smooth, there was a problem that the progress of solidification is difficult.

In addition, even when the water content is very high, such as the coastal region of the soft ground, there was also a problem that the solidification does not proceed smoothly even if using the conventional solidified fire to obtain a satisfactory high-strength strength.

In order to solve the problems described above, solidified materials composed of various components have been invented and distributed, but since the cement is used as a main raw material, a large amount is added, so that curing is slow and heat of hydration occurs during solidification, causing a change in volume. This problem still occurred.

In addition, there is still a problem that the solidification is not certain in the sedimented soil or the soil with high moisture content due to the efficient decomposition of organic substances or the formation of ettringite in the ratio and the solidification component added to the general cement. .

The present invention, as described above, to solve the problems of the conventional solidified material to contain a large amount of viscous soils and organic matter with a high water content to effectively solidify the soft ground composed of soil that cannot be solidified only with conventional cement I have a problem to solve.

The present invention has been invented to solve the above problems, 10 to 15% by weight of one of 60 to 65% by weight of Portland cement, blast furnace slag powder, coal ash powder, volcanic ash, rice hull ash, diatomaceous earth, silica fume and zeolite 10-15% by weight of a pozzolanic substance, CSA (Calcium Sulfo-Aluminate) and gypsum or CSA and alumina cement, 10-15% by weight of a coarse agent, and melamine-based, naphthalene-based or carboxyl dispersant. The purpose of the present invention is to provide a functional solidified material for improving the soft ground, which is composed of a dispersing agent and has a powder degree of 4,000 cm ² / g.

The present invention contains a large amount of viscous soils and organic matter with a high water content through excellent strength and excellent performance of the dispersion and agitation performance, so that it is possible to effectively solidify the soft ground composed of soil that cannot be solidified only with conventional cement, thereby improving the soft ground. Work and waste treatment can be efficiently performed, as well as it is possible to minimize the amount of slime, hexavalent chromium and harmful substances, thereby reducing the environmental pollution.

The functional solidifying material for improving the soft ground of the present invention is composed of 60 to 65% by weight of cement, 10 to 15% by weight of pozzolanic material, 10 to 15% by weight of the coagulant, and 10 to 15% by weight of dispersant. It is characterized by having a powder degree of 4,000 cm ² / g.

Its chemical composition is 20-30% of silica (SiO2), 5-10% of alumina and iron oxide (AlO ₃ + Fe ₂ O ₃ ), 45-55% of lime and magnesium oxide (CaO + MgO), sodium oxide and calcium oxide ( Na ₂ O + K ₂ O) 1-5% and sulfuric anhydride (SO ₃ ) 5-10%.

The cement is composed of Portland cement, one to five Portland cement can be used differently depending on the application.

The pozzolanic material may be selected from blast furnace slag powder, coal ash powder, volcanic ash, rice hull ash, diatomaceous earth, silica fume and zeolite.

The crude steel is to promote the curing rate and to increase the compressive strength, and may be configured by selecting one of CSA (Calcium Sulfo-Aluminate) and gypsum or CSA and alumina cement.

At this time, when the coarsening agent is less than 10% by weight, the condensation time is delayed, so that the injected solidified material has a high risk of dilution in the pore water, and when it exceeds 15% by weight, the solidified material hardens rapidly. Therefore, the mixing ratio of the crude steel should be maintained at 10 to 15% by weight.

The dispersant is for improving the stirring and injectability of the solidified material, and may be configured by selecting one of melamine-based, naphthalene-based and carboxyl-based dispersants.

At this time, when the dispersant is less than 10% by weight, the effect of improving the stirring and injectability is weak, and the compressive strength is lowered. When the dispersing agent is more than 15% by weight, it causes separation of the solidified material and thus there is no effect of improving the stirring and injectability. Therefore, the mixing ratio of the dispersant should be maintained at 10 to 15% by weight.

The functional solidifying material for improving the soft ground of the present invention configured as described above is to form a reinforcement, a water barrier, a retaining wall, a earth wall in the soft ground for foundation work, or to solidify the ground to solidify the contaminated soil.

In particular, the functional solidified material for improving the soft ground of the present invention contains a large amount of viscous soils and organic matter with a high water content, effectively solidifying the soft ground composed of soil that was not easily solidified by the existing cement only to more efficiently improve the soft ground It is characteristic that it can be done by.

As described above, the soft solid improvement functional solid material of the present invention is 60 to 65% by weight of cement, 10 to 15% by weight of pozzolanic material, 10 to 15% by weight of the steel, 10 to 15 It is due to the weight percent of the dispersant, and before explaining its characteristics, the general principle of operation of the fire is as follows.

First, when solidified material is placed on soft ground to form reinforcement, order wall, retaining wall, earth wall through powder injection stirring method, or ground to solidify contaminated soil, The condensation stage is maintained to maintain the firing state for a period of time.

At this time, through the chemical reaction between the solidified material and the pore water, a gel (Gel) absorbing the pore water is generated on the surface of the solidified material, so that the soil water content decreases and the soil properties are improved.

From the short-term aging period through the condensation step to the mid-long term aging period as described above, the particles of the solidified material are densely packed and cured by the hydration reaction between the compound constituting the solidified material and the pore water, and the strength is increased to undergo the curing step of forming the solid. do.

At this time, as shown in Formula 1 below, the aggregation and granulation of the soil particles by calcium ions (Ca +) eluted from the calcium hydroxide (Ca (OH) ₂ ) which is a hydrate by the hydration reaction is made.

<Formula 1>

_{2C 3 S + 6H 2 0 -} > 3CaO · 2SiO 2 · 3H 2 0 + 3Ca (OH) 2

2C ₂ S + 4H ₂ 0-> 3CaO · 2SiO ₂ · 3H ₂ 0 + Ca (OH) ₂

And, as shown in the following formula (2), the dehydration effect is increased from the production of the ettringite (ettringite) hydrate having a needle crystal, the granules have a network structure that is tightly bound to each other.

<Formula 2>

C ₃ A + 3CaSO ₄ 2H ₂ O + 26H ₂ O-> C ₃ A3CaSO ₄ 32H ₂ O

Therefore, the solidified material formed on the ground by the solidified material is primarily to increase the strength by the above action.

As described above, from the medium to long-term aging period of which strength is increased, the calcium hydroxide (Ca (OH) ₂ ), silica (SiO ₂ ), and alumina (Al ₂ O) produced by the hydration reaction, as shown in Formula 3 below. ₃ ) is a pozzolanic reaction that slowly reacts at room temperature to form an insoluble compound, CSH gel, thereby compacting the pores as the CSH gel is filled into the pores of the solid, thereby densifying the tissue of the solid.

<Formula 3>

Ca (OH) ₂ + SiO _2- > CaO SiO ₂ H ₂ O [CSH]

Ca (OH) ₂ + AlO _3- > CaO Al ₂ O ₃ H ₂ O [CSH]

Therefore, the solidified body which is formed on the ground by the solidifying material and whose strength is primarily increased is secondarily increased in strength by the above-described action.

As described above, the solidified material of the present invention including the working principle of the solidified material exhibits a characteristic that is different from the portland cement and the slag cement used as the general solidified material.

First, the solidified body by the solidified material of the present invention exhibits excellent strength expression compared to the solidified body by the portland cement and slag cement. This is because the cement, pozzolanic material, coarse agent, and dispersant constituting the solidified material of the present invention have an ideal mixing ratio, so that they interact with each other organically from the time of injection to the long term. Compressive strength for this is shown in Table 1 below.

TABLE 1

 division Compressive Strength of Solids (kgf / cm ² ) 3 days 7 days 28 days Functional solid fire 15.8 32.6 45.6 Portland cement 11.0 15.1 19.8 Slag cement 9.2 15.6 24.9

And solidified according to the present invention can reduce the amount of construction waste polluting the soil. This is because, as described above, the strength is excellent, and thus the same strength is expressed even when only 60% of the Portland cement and the slag cement are used.

Therefore, the amount of use can be reduced by up to 40% compared to portland cement and slag cement, which not only can significantly reduce construction waste such as slime generated during the construction of solid bodies, but also reduce construction costs.

And the solidified material of the present invention has excellent injection characteristics. This is because the dispersion and stirring performance is improved due to the proper amount of dispersant.

Therefore, when it is injected into the ground at the site and mixed with the pore water to form a slurry, the mixing ratio with the pore water is lower than that when using the portland cement, so it is advantageous for strength expression. Dispersion and stirring performance for this is shown in Table 2 below.

TABLE 2

division Water / fire mix ratio (%) Flowability (flow time, seconds) Functional solid fire 100 9.28 Portland cement 110 9.31

And solidified by the solidified material of the present invention is that the elution concentration of the water-soluble hexavalent chromium causing environmental pollution is close to zero. This is because the solidified material itself has a low content of hexavalent chromium.

Therefore, it is possible to minimize the environmental pollution on the ground, it is possible to reduce the environmental pollution due to construction and civil works. The hexavalent chromium elution concentrations are shown in Table 3 below.

TABLE 3

division Hexavalent chromium elution concentration (mg / l) Hexavalent chromium elution concentration (mg / l) Functional solid fire Not detected Not detected Portland cement 4.1 21.5

In addition to the above, the solidified body according to the present invention has a compact structure as compared with the solidified body by portland cement, and exhibits excellent water repellency even at the same strength.

In addition, the solidified body according to the present invention is cured in artificial seawater concentrated five times the concentration of natural seawater, and as a result of the mortar bar expansion rate test of the unrestrained state, the expansion rate is lower than the portland cement, showing excellent stability for seawater.

In addition, the solidified material of the present invention reduces the elution amount of harmful substances such as cadmium, hexavalent chromium, lead, arsenic, copper, and mercury when solidifying wastes and the like than using portland cement. Therefore, environmental pollution can be reduced. The elution amount of harmful substances for this is shown in Table 4 below.

TABLE 4

Test Items Cd (mg / l) Cr (mg / l) Pb (mg / l) As (mg / l) Cu (mg / l) Hg (mg / l) Waste sample 12 45 98 31 120 0.1 Functional solid fire (200kg / m ³ ) Not detected Not detected Not detected Not detected Not detected Not detected Portland Cement (200kg / m ³ ) 1.4 4.1 2.7 2.1 3.1 0.03

As described above, the functional solidified material for improving the soft ground of the present invention exhibits excellent strength expression, excellent stirring and dispersing performance, minimizing environmental pollution, excellent water quality and excellent stability against seawater, while maintaining the general function of the conventional solidified material. It is possible to more efficiently improve the soft ground.

Claims (1)

60 to 65% by weight of Portland cement, blast furnace slag powder, coal ash powder, volcanic ash, rice hull, diatomaceous earth, 10 to 15% by weight of pozzolanic material, silica fume and zeolite, Calcium Sulfo-Aluminate (CSA) and gypsum or CSA and alumina, one of 10 to 15% by weight of the crude force of the cement and, melamine-based, naphthalene-based, carboxylic acid-based and consist of one of the 10 to 15% by weight of a dispersant in the dispersant, the 4,000cm fineness of ² / g Functional solid fire retardant for improving soft ground.