KR100427490B1 - Environment-friendly inorganic soil-stabilizer with outstanding durability - Google Patents

Abstract

The present invention relates to an environmentally friendly and durable inorganic soil stabilizer, and is useful as a stabilizer for stabilizing inorganic soil stabilizers such as silicon dioxide (SiO ₂ ) as well as materials generally added for curing and curing cements such as retarders, (Al ₂ O ₃ ) 15.0 to 35.0 wt%, iron oxide (Fe ₂ O ₃ ) 0.2 to 1.2 wt%, calcium oxide (CaO) 32.0 to 52.1 wt%, SO ₃ 20.0 to 38.1 wt% (NDS ES) powder having a particle size in the range of 4000 to 8000 cm < 2 > / g and an NDS ES powder having a powder composition of 4000 to 8000 cm < 2 > / g dissolved therein. In addition, a slag fine powder A special cement powder having a particle size of 6500 ~ 9000 ㎠ / g and a special cement powder aqueous solution in which a melanin powder admixture for admixing the special cement powder is dissolved, As there is no fear of environmental pollution caused by elution cargo can not short-term compressive strength at the same time and can adjust the condensation and hardening rate of the cement, as well as long-term compressive strength also increases an effect that can be so excellent long-term durability Fig.

Description

[0001] ENVIRONMENT-FRIENDLY INORGANIC SOIL-STABILIZER WITH OUTSTANDING DURABILITY [0002]

The present invention relates to an environmentally friendly and durable cement additive. More specifically, the present invention is free from environmental pollution due to solidified eluted water, and can freely control the setting and curing speed of cement, The present invention relates to an environmentally friendly and durable, pure inorganic inorganic soil stabilizer capable of providing long-term durability with high long-term compressive strength.

Generally, cement means a binding curing agent for minerals (inorganics) for civil engineering and construction. Among them, Portland cement is often called cement today. The portland cement is made by mixing limestone (CaCO ₃ ), silica (SiO ₂ ), alumina (Al ₂ O ₃ ), iron oxide (Fe ₂ O ₃ ) and other clay materials (shale, pumice, clay) (4 ~ 5%) is added to the clinker, and the mixture is crushed to a temperature at which a part of the raw material is melted (about 1450 ° C) in a kiln to produce a semi-finished clinker, (CaSO ₄ · 2H ₂ O) and then crushed. The main components of Portland cement are lime (CaO) and silica (SiO ₂ ). Alumina (Al ₂ O ₃ ), iron oxide (Fe ₂ O ₃ ), etc., and the constituent compounds of Portland cement clinker are 3SaO · SiO ₂ , 3CaO · SiO ₂ , 2CaO · SiO ₂ , Al ₂ O ₃ ) and an iron compound (4CaO · Al ₂ O ₃ · Fe ₂ O ₃ ). In addition to the Portland cement described above, there are blended cements and specialty cements made by mixing blended materials such as blast furnace slag, fly ash, natural or artificial pozzolan with Portland cement or clinker.

The cement is mixed with water and kneaded to form a hydrate by reacting with water. In addition, the cement is subjected to a setting process in which the fluidity is lost and hardened, and a curing process in which the cement has a strength after the coagulation.

The hydration of the cement and the phenomena occurring therefrom have been extensively studied as the most important properties of cement. However, the types of hydration products are complex and the results obtained by the researchers are different depending on the components of cement, hydration condition, However, the theory of hydration mechanism of cement can be broadly divided into the following two categories.

One of them is that the cement compound once dissolves in water and the silicate hydrate precipitates in the supersaturated aqueous solution. The other is that when the cement is mixed with water, the solubility of the SiO ₂ component and the Al ₂ O ₃ component in the liquid phase The cement compound reacts directly with water in a topochemical reaction to form a hydrate layer on the surface of cement particles. At present, both theories are accepted, and the former is known to dominate the initial hydration process and the latter dominates the longer hydration process.

Generally, when cement is mixed with cement and gypsum mixed with pozzolan components such as fly ash and blast furnace slag, a large amount of ettringite (3CaO · Al ₂ O ₃ · 3CaSO ₄ · 32H ₂ O) is produced. Component of the present invention takes a large amount of water as binding water to lower water content and at the same time inhibits the migration of the bead, thereby facilitating cementation and facilitating cementation of calcium ions or calcium ions (SiO ₂ ) and aluminum oxide (Al ₂ O ₃ ), which are contained in the soil as a long-term age, are formed by calcium silicate (Ca ²⁺ ) ) To generate calcium hydroxide and an insoluble hydrate to activate the pozzolan to accelerate curing.

That is, when only a typical artificial pozzolan, fly ash or blast furnace slag, is used as a partial substitute material of cement or itself, first fly ash reacts with water to form a cement- (Reaction with calcium hydroxide (CaOH ₂ ) liberated from cement, so-called pozzolanic reaction) to exhibit curability, but since the reaction rate thereof is slower than that of cement, rapidity can not be expected and a large amount of fly ash When blast furnace slag is used, non-hydraulic blast furnace slag is mixed with cement and water, and when it is mixed with water, it is subjected to the same alkali stimulus as the above-mentioned fly ash, However, it is also slower than the rate of reaction with cement-water and has a low compressive strength. Therefore, the strength is weak and the hardening rate is low, which is problematic for use on soft ground.

However, as described later, the slag fine powder, which is a substitute for cement contained in the Natural and Durable Stabilizer (hereinafter referred to as "NDS ES") powder of the present invention, is superficially dispersed at about 6500-7500 ㎠ / g together with cement This method solves the problem of the initial strength drop which can be caused by using the slag fine powder in general, and it is possible to perform the perfect injection even in the soil of various conditions which usually can not be injected by only the cement and slag fine powder.

On the other hand, a water glass prepared by dissolving silicon dioxide and alkali as an alkali metal salt in a concentrated aqueous solution was used as a water-soluble material used for curing with conventional cement. The water glass has a composition of Na ₂ O.nSiO ₂ (n = 2-4), a small amount of Fe ₂ O ₃ , a water content of 10-30% by weight, and a mixture of silica and soda ash produced by melting at 1300-1500 ° C. do.

The reaction of the waterglass system is instantaneously carried out by an ion salting reaction so that the concentration of cement and water glass should be changed when the gel time is adjusted. When the amount of cement and water glass is added in small amounts to increase the strength, the strength after curing becomes extremely low. On the contrary, when the amount of cement and water glass is all increased, the gel time is extremely short There is a problem that workability is deteriorated.

In addition, the use of water glass containing sodium silicate having a strong alkali as pH 11 to 12 as a conventional water-dispersible material causes an increase in the alkaline concentration of the solid eluate, thereby contaminating the environment. Particularly, when it is used as a ground filler, there is a problem of polluting the ground water and the like.

Furthermore, the lifetime of cured cement using water glass as waterproofing and ground reinforcement is generally about three years, and when it exceeds the above-mentioned period, the performance as a waterproofing and ground reinforcement can not be exhibited properly . That is, there has been a problem that long-term durability is deteriorated.

It is an object of the present invention to provide an environmentally friendly and durable inorganic soil stabilizer which is environmentally friendly and durable in accordance with the present invention. It is an object of the present invention to provide a cement mortar composition, The present invention also provides an environmentally friendly and durable inorganic soil stabilizer which can be controlled in a short period of time and has high long-term compressive strength as well as long-term durability.

In order to accomplish the above-mentioned object, the present invention can be applied not only to materials generally added for curing and hardening cement such as a setter, water and the like, but also from 1.5 to 3.0% by weight of silicon dioxide (SiO ₂ ) (Al ₂ O ₃ ) of 15.0 to 35.0 wt%, iron oxide (Fe ₂ O ₃ ) of 0.2 to 1.2 wt%, calcium oxide (CaO) of 32.0 to 52.1 wt% and SO _{3 of} 20.0 to 38.1 wt% (NDS ES) powders of 4000 ~ 8000 ㎠ / g dissolved in a special cement powder (Naturaland) with addition of slag fine powder to the general cement and a powder viscosity of 6500 ~ 9000 ㎠ / g A durable Stabilizer Ultra Fine (hereinafter referred to as 'NDS UF') and a special cement powder aqueous solution in which a melanin or naphthalene type admixture for mixing the special cement powder is dissolved.

1 schematically shows a reaction mechanism in the present invention, Fig.

2 is a view showing the behavior of each material with respect to time and intensity as axes,

3 is a graph showing the time until gelation in Examples 1 to 4 with the temperature as a horizontal axis,

FIG. 4 is a graph showing the compressive strengths by the standard mix propotions for the high-pressure jet injection method and the compressive strengths by the rod injection method (Standard Mix propotions for the rod injection method) ,

5 is a view showing the rate of change in length in the standard blend compared with the case of using a conventional water glass,

6 is a graph showing time to gelation in Examples 5 to 9 with the temperature as a horizontal axis.

Hereinafter, the structure and operation of the present invention will be described in more detail with reference to the accompanying drawings.

As described above, the inorganic soil stabilizer (cement additive)

1) In addition to materials normally added to set and cure cements such as setters and water,

2) silicon dioxide (SiO _2), 1.5~3.0% by weight, aluminum (Al ₂ O ₃ oxide) 15.0 to 35.0% by weight of iron oxide (Fe ₂ O _3), 0.2~1.2% by weight, calcium (CaO) 32.0~52.1 wt oxide %, SO ₃ 20.0 _~ 38.1 wt.%, And NDS ES powder having a powder content of 4000 ~ 8000 ㎠ / g dissolved therein.

3) Special cement powder (NDS UF) with addition of slag powder to general cement and powder viscosity of 6500 ~ 9000 ㎠ / g and melamine or naphthalene powder admixture for mixing special cement powder with special cement A powder aqueous solution may further be included.

Hereinafter, the reaction mechanism and behavior of the additive will be roughly described.

FIG. 1 schematically shows a reaction mechanism in the present invention. As shown in FIG. 1, a special cement powder containing cement or an admixture reacts with water to gel, thereby liberating calcium hydroxide (Ca (OH) ₂ ). In addition, the glass of calcium hydroxide has a large amount of Et reacted with NDS ES Lin gayiteu _{(3CaO · Al 2 O 3 ·} 3CaSO 4 · 32H 2 O) substances or similar molecular bonding structure (such _{as: 3CaO · Al 2 O 3 ·} CaSO 4 12H ₂ O). Therefore, when the amount of NDS ES used is increased, the amount of free calcium hydroxide is increased to the amount of ettringite (3CaO · Al ₂ O ₃ · 3CaSO ₄ · 32H ₂ O), so that the amount of calcium hydroxide actually present is reduced As a result, the gelation process of the cement is increased.

Fig. 2 is a graph showing the behavior of each material with respect to time and intensity. As shown in Fig. 2, the I region is a region in which the time and intensity are controlled mainly by the amount of the retarder described later, The area Ⅱ is mainly controlled by the amount of NDS ES and the area Ⅲ is mainly controlled by the amount of special cement powder containing cement or admixture (NDS UF).

Hereinafter, each material and its behavior will be described in detail.

As the cement used in the present invention, ordinary cement may be used, but Portland cement is preferably used.

The NDS ES is composed of 1.5 to 3.0% by weight of silicon dioxide (SiO ₂ ), 15.0 to 35.0% by weight of aluminum oxide (Al ₂ O ₃ ), 0.2 to 1.2% by weight of iron oxide (Fe ₂ O ₃ ) CaO) of 32.0 to 52.1% by weight and SO _{3 of} 20.0 to 38.1% by weight, and powder having a particle size of 4000 to 8000 cm 2 / g, which is a main component of a common Portland cement, .

When the amount of the component is less than the lower limit value or exceeds the upper limit value, the cement is not well fed, and when the content is lower than the lower limit of the degree of cementing, the performance as the ground stabilizer can not be exhibited.

In addition, the NDS ES is characterized in that calcium hydroxide (Ca (OH) ₂ ) separated from gelation of cement when hydrated with cement reacts rapidly with alkali (aqueous solution of calcium hydroxide) dissolved in water and neutral To produce insoluble needle crystals (Ettringite). As a result, as described above, the NDS ES increases the gelation process of the cement as the amount of the cement increases, and when the cement is reacted with the cement, the alkali component of the cement becomes neutral and produces an edtringite. The amount of generated alkali is decreased, and the effect of drastically reducing the contamination due to the solidified effluent water is obtained.

However, at the beginning of the process of cement hardening and curing, the hydration reaction rate between NDS ES and water is faster than the hydration reaction rate between cement and water, and the mixture of NDS ES and water becomes viscous over time, As a result, the NDS ES can not be used in an excessive amount, and a retarding agent described later is used.

The retarder is a kind of acid such as a general cement retarder such as potassium silicate, tartar acid and the like, and it is possible to prevent the curing reaction and the abnormal curing by the hydration reaction of the NDS ES itself So that the injecting operation can be smoothly performed, and in the long run, stable strength enhancement can be achieved.

Specifically, as described above, at the beginning of the process of cementing and curing, the hydration reaction rate between NDS ES and water is faster than the hydration reaction rate between cement and water, and the mixture of NDS ES and water becomes viscous The NDS ES solution is cured with only one NDS ES solution. In this case, the retarder forms a film on the surface of the NDS ES to inhibit hydration reaction with water (so-called ion blockade) to prevent curing. However, To accelerate the hydration reaction and the curing reaction.

On the other hand, the gel time to gelation is influenced by various variables such as the temperature (the gel time becomes longer and the initial strength becomes weaker after the gelation), the manufacturer of the Portland cement, Of the total amount. That is, it can be controlled by adding a large amount of retarding agent to increase the gel time until gelation or to reduce gel time by adding a small amount of retarder. As a result, since it is not necessary to change the amount of the main material like the conventional water glass system, stable strength can be obtained regardless of the gel time. The gel determination is based on the point at which the material has lost fluidity.

However, it is preferable that the amount of retarding agent added is limited to 4% by weight or less of the amount of NDS ES, which is the time until gelation by the adverse reaction (when the amount of retarding agent exceeds 4% as well as shortening the time to come.

It is effective to increase the amount of cement and NDS ES to increase stably after the gelation. For effective operation at low temperatures or when the water is heavily soaking in the soil that is being grouted (liquid mortar injection, the same applies below), it is essential to reduce the amount of retardant and shorten the time to gelation. In this case, it is possible to effectively control the time until gelation by increasing the amount of cement and NDS ES used as well as controlling with retarding agent.

The special cement powder aqueous solution (NDS UF) is prepared by mixing a special cement powder having a powder viscosity of 6500 ~ 9000 ㎠ / g and a melanin or naphthalene powder admixture for mixing the special cement powder with a slag powder added to a general cement It is dissolved, the injection property is improved, the time to gelation is easy to control, and the slag fine powder is added so that the initial strength of the added dyes is weak but the long-term strength can be strengthened. Therefore, special cement powder can be regarded as a kind of special cement.

When the additive of the present invention is used as a ground filler, it is easily injected into the pores of clay, silt, sand, gravel and rock to effectively reinforce and exponent the whole ground. However, in the case of sand soil injection, jamming May occur. In this case, if a small amount of bentonite is added and injected, the jamming phenomenon can be prevented.

Hereinafter, the characteristics of the cement product based on the material of the present invention will be described in more detail with reference to the tables and the accompanying drawings. It should be understood, however, that the scope of the present invention should not be construed as being limited by the following examples, and that ordinary changes may be made by those skilled in the art within the scope of the present invention.

Examples 1-4

(Hereinafter referred to as "A" solution), 120 kg of Portland cement was added to water to make a total volume of 200 L (hereinafter, referred to as "A" solution) Referred to as 'B' solution) The above solution A and solution B were mixed and the following characteristics were tested. Thereafter, the amount of the retarder of the liquid A was increased to 0.4 kg, 0.6 kg (standard formula, equal to), and to 0.8 kg, and the same procedure as described above was carried out.

1) Time measurement until gelation

Fig. 3 shows the time until gelation in Examples 1 to 4, with the temperature as a horizontal axis. As can be seen, as the amount of the retarder increases and the temperature decreases, the time to gelation increases.

2) PH measurement

The pH of the solution B (cement solution) was 12, and the pH of the solution A (when 0.2 kg of the retarder was added) was 9 and the pH of the mixed solution was 11. However, the pH of the solidification leachate was 8.4. This is because the alkali can be prevented from diffusing as it is gelled as described above, so that it is environmentally friendly.

3) Viscosity measurement

The viscosity of the liquid A (retardant 0.2 kg) was 28 cps, the viscosity of the liquid B (cement liquid) was 4 cps, and the viscosity of the mixture was 7 cps. The viscosity was changed to be rapidly increased only after gelation. Therefore, it can be seen that it is possible to work efficiently for soil weighing.

4) Compressive strength and long-term safety measurement

FIG. 4 is a graph showing the compressive strengths by the standard mix propotions for the high-pressure jet injection method and the compressive strengths by the standard injection methods (rod injection method) FIG. Fig. 5 is a view showing the rate of change in length in the standard formulation compared with the case of using a conventional water glass.

As shown in the figure, by using the additive of the present invention, not only high strength but also excellent durability can be obtained. That is, as described above, the NDS ES produces a large amount of ettringite after reacting with cement, so that the volume does not shrink after curing and exhibits a stable strength enhancement effect over a long period of time.

Examples 5 to 9

(Hereinafter referred to as "A" solution), 160 kg of Portland cement was added to water to make the total volume to 200 L (hereinafter, referred to as "A" solution) Referred to as "B" solution) The liquid A and the liquid B were mixed to measure the time until gelation. Thereafter, the amount of the retarder of the liquid A was increased to 0.3 kg, 0.6 kg, 0.8 kg, and 1.2 kg, and measured by the same method as described above.

1) Time measurement until gelation

6 shows the time until gelation in Examples 5 to 9 with the temperature as a horizontal axis. As shown in the figure, it can be seen that as the amount of the retarder is increased and the temperature is lowered, the time until gelation is increased as in Examples 1 to 4.

Examples 10 to 12

The measurement was carried out in substantially the same manner as in Examples 1 to 9 above. However, the special cement powder with the powder viscosity of 6500 ~ 7500 ㎠ / g and the melanin powder admixture for mixing the special cement powder were dissolved in the general cement. The measurement results are shown in Table 1 below.

Characteristic table by using special cement Solution B (200 liters) A solution (200 L) Come time (minutes) Compressive strength (kgf / ㎠) Special cement (kg) NDS ES (kg) 3 hours 1 day 3 days 7 days 28th 160 30 4 0.3 4 8 15 30 40 5 One 5 15 22 36 60 6 One 14 20 27 42

As can be seen from the above Table 1, the injectability is improved, the time until gelation is easy to control, and the slag powder is added to weaken the initial expression strength, but the long-term strength enhancement is strong.

As described above, the environmentally friendly and durable cement additive of the present invention is free from the environmental pollution due to the solidified effluent water and can control the setting and curing speed of the cement. In addition to the short-term compressive strength, So that it has an effect of excelling in long-term durability.

In particular, when used as a ground filler, it is easily injected into the pores of clay, silt, sand, gravel, and rock to effectively reinforce and index the entire ground (eg, repair of deteriorated tunnels, Prevention of segregation of aggregate by load, prevention of activity of ground, etc.).

Specifically,

1) It is possible to prevent leakage of water and water from the subway, the main body of the sewage system and the reservoir structure, to prevent the backfill and groundwater flow of the sheet file (to prevent leakage)

2) Prevent collapse during tunnel excavation and vertical axis excavation, contribute to stabilization of tunnel surface and foundation stabilization in shield construction and contribute to enhancement of subway, water and sewage main body, dam, bank, reservoir structure Ground stabilization effect),

3) It is applicable to all types of soil through injection grouting and has stable dimensions and strength.

Claims (3)

In mineral base stabilizers added to cure and harden cement, such as a setter and water, 1.5~3.0 wt% of silicon dioxide (SiO _2), aluminum (Al ₂ O ₃₎ 15.0~35.0% by weight oxide, iron oxide (Fe ₂ O ₃₎ 0.2~1.2% by weight, calcium (CaO) 32.0~52.1 wt% of oxide, SO ₃ 20.0 to 38.1 wt.% And having an NDS ES powder in which NDS ES powder having a powder content of 4000 to 8000 cm 2 / g is dissolved is further contained in an amount of 20 to 50 wt.% Based on the weight of the cement Which is an environmentally friendly and durable inorganic stabilizer. The method according to claim 1, In addition to the NDS ES powder aqueous solution, a special cement powder (NDS UF) having a powder viscosity of 6500 to 9000 ㎠ / g and a melanin or naphthalene powder admixture for mixing the special cement powder is added to general cement Characterized in that it further comprises a dissolved special cement powder aqueous solution. 3. The method according to claim 1 or 2, Wherein the amount of the added retarding agent is 4 wt% or less of the amount of NDS ES added.