KR100561233B1 - Ready mixed concrete contained watertight, inorganic, crack decreasing matter - Google Patents

Abstract

The present invention relates to a ready-mixed concrete composition containing a water-tight inorganic crack reducing agent, and to improve the durability, such as neutralization, chlorine ion penetration, reinforcement corrosion inhibition through the improvement of crack resistance and water tightness of concrete.

The ready-mixed concrete composition containing the water-tight inorganic crack reducing agent according to the present invention is 2.0 to 9.9 wt% of silicic salt, 20 to 40% by weight of soluble silica, and 0.5 to aromatic polymer condensate based on 100% by weight of the water-tight inorganic crack reducing agent. Water-tight inorganic crack reducing agent (a) consisting of 3% by weight, 0.2-2.0% by weight of nitrate-based inorganic compound and 45.1-77.3% by weight of water is added by 0.3 to 0.99% by weight relative to the ready-mixed binder (b). The water-tight inorganic crack reducing agent (a) hydrolyzes 10-24.9% by weight of liquid fluorosilicate to 75.9-90% by weight of water with respect to 100% by weight of the total mixture of liquid fluorosilicate and water to hydrolyze silicic ions dissociated from the fluorosilicate. Reacting to form fluorine ions and colloidal silica, mixed 1.3 to 15% by weight of a divalent metal salt group with respect to 100% by weight of the total mixture of liquid fluorosilicate and water, and dissociating from the divalent metal salt group. The divalent metal ions are reacted with the silicides to form silicides, and are then mixed with the polymer condensate and the nitrate-based inorganic compound.

Ready-mixed concrete, concrete, silicide, silica, aromatic polymer condensate, nitrate inorganic compound, crack resistance, water tightness, durability

Description

Ready Mixed Concrete contained watertight, inorganic, crack decreasing matter}

The present invention relates to a ready-mixed concrete composition containing a water-tight inorganic crack reducing agent, and more particularly, to a ready-mixed concrete composition containing a water-tight inorganic crack reducing agent so that the durability can be improved by improving the water-tightness and crack resistance.

In general, ready mixed concrete is manufactured using materials of cement, aggregate (sand, gravel), water, and mixed materials in a factory equipped with a concrete manufacturing facility, and then a truck mixer or agitator truck It refers to the concrete in the unconsolidated and flexible state that is transported to the construction site using), and is made of a mixture of cement, admixture, water, sand, gravel and admixture.

The admixtures and admixtures are admixtures added during the preparation of ready-mixed concrete, and the admixtures are admixtures having a relatively high amount of admixtures. Both types are used to improve the properties of concrete and to reduce construction costs. Especially admixtures are added like chemicals.

The admixture is one or more fly ash, blast furnace slag powder, silica fume and the like are mixed according to the amount of cement.

Classification and types according to the purpose of the admixture are as follows. ① Hardening agent, hardening agent, delaying agent (slow economy) of coagulation hardening agent used to accelerate or slow the coagulation of concrete, cement, etc. ② For surface workability and workability AE (air-entraining) agent or water-repellent agent that improves durability ③ Waterproofing agent that shows waterproofing effect ④ Foaming agent / foaming agent that improves filling property or adjusts weight by bubble action ⑤Other repair agent / adhesive agent • Anticorrosive agent (prevents rust) of steel.

In addition to the above-mentioned admixtures, in recent years, there are silica fluoride salts that have an effect of densifying the cement concrete structure while inhibiting the hydration of the cement due to the infiltration of water by coating on the surface of the cement particles, thereby delaying the setting time.

The silicide fluoride can be prepared in a stable liquid phase by dissociation with a metal cation and silicide ions (SiF ₆ ^2- ) in an aqueous solution, and when the aqueous solution containing the silicide fluoride is added to a cement of strong alkali, Hydrolytic action of SiF ₆ ^2- ) or siliceous salts (MSiF ₆ , M: Mg, Zn) as a main product by reaction with calcium hydroxide produced by cement hydration (for example, CaF ₂ ) and soluble silica (SiO ₂ ). In this case, the poorly soluble metal fluoride fills the defects in the hardened cement structure before and after hardening, thereby densifying the structure, and has an effect of reducing the temperature of the concrete hydration by absorbing cement heat of hydration during the formation of the poorly soluble metal fluoride. Soluble silica affects the strength of concrete by participating in pozzolanic reactions that produce CSH gels by reacting with calcium hydroxide continuously produced by cement hydration. Therefore, by adjusting the type, composition or amount of the silicic acid salt in the silicic acid salt solution added to the cement, it is possible to control the watertightness, strength and hydration temperature of the concrete to be produced.

Because of the characteristics of the above-described silica fluoride salt has been proposed a technique for a ready-mixed concrete composition with a silica fluoride salt.

For example, Korean patent application No. 1998-65526 has been filed a composition of multifunctional high performance mortar. In the prior art, 0.1 wt% to 1.0 wt% of silicides such as magnesium silicate, potassium silicate and sodium silicate is added to control the setting speed of the high performance mortar. In addition, the soil coagulation curing agent composition and the domestic patent application No. 1997-18934 have been applied for the soil coagulation curing agent composition in the domestic patent application No. 1984-6714 as another prior art, in the prior art to control the coagulation rate and curing rate of the soil Magnesium fluoride is used as a admixture to make.

However, the conventional ready-mixed silica compound added with the fluorofluoride has the following problems.

Magnesium fluoride is very sensitive to the amount of use, which leads to excessive coagulation delay of cement, which is easy to lower the strength of concrete. Zinc fluoride is effective for improving the concrete and improving waterproofness. There is a problem in that a large amount of metal fluoride is generated to increase the overall solid content to significantly lower the initial fluidity. In addition, the combined use of magnesium fluoride and zinc fluoride, which has been previously performed, also does not produce a satisfactory overall result for physical properties including initial fluidity, strength and waterproofness of concrete.

In addition, since similar materials using other silofluoride salts are manufactured considering only the waterproof side without considering the crack resistance of concrete, some effects are realized in the waterproof side, but the fluidity and crack resistance of the concrete are deteriorated. .

The present invention is to solve the above-mentioned conventional problems, by adding a water-tight inorganic crack reducing agent mixed with a silica fluoride salt and other components in an optimum condition compared to cement to improve the initial workability, water tightness, and crack resistance of concrete to improve durability It is an object of the present invention to provide a ready-mixed concrete composition containing a watertight inorganic crack reducing agent which can be improved.

In order to achieve the above object, the ready-mixed concrete composition containing the water-tight inorganic crack reducing agent according to the present invention is 2.0 to 9.9% by weight of a silica fluoride, 20 to 40% by weight of soluble silica, based on 100% by weight of the water-tight inorganic crack reducing agent. Water-tight inorganic crack reducing agent (a) formed by mixing 0.5 to 3.0% by weight of aromatic polymer condensate, 0.2 to 2.0% by weight of nitrate-based inorganic compound and 45.1 to 75.3% by weight of water is 0.3 to 0.99 based on the ready-mixed binder (b). It is characterized in that the weight percent added.

The features and advantages of the present invention will become more apparent from the following detailed description. 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.

The ready-mixed concrete composition containing the water-tight inorganic crack reducing agent according to the present invention is formed by mixing cement, admixture, water, sand, gravel, admixture, and water-tight inorganic crack reducing agent.

Cement and admixtures are binders for combining aggregates such as sand and gravel in ready-mixed concrete compositions, and the amount of mixing is not limited because the amount of use varies depending on the strength of the building.

The admixture is one or more of fly ash, blast furnace slag powder, silica fume, and the mixing amount depends on the conditions such as cement strength.

The admixture is a workability and freeze-thawing action by the hardening agent, the fastening agent, the delaying agent (the slow economy), and the surfactant activity of the coagulation hardening agent used to accelerate or slow the coagulation of concrete and cement. AE (air-entraining) agent, water-repellent agent that improves durability against water, water-repellent agent exhibiting waterproofing effect, foaming agent, foaming agent, and other repairing agent to improve filling property or control weight by foaming action · Anti-rust agent (prevents rust) of adhesives and rebars.

The watertight inorganic crack reducing agent is mixed at a ratio of 0.3 to 0.99% by weight with respect to 100% by weight of the ready-mixed concrete binder (material cement and admixture combined material). Here, when the amount of the water-tight inorganic crack reducing agent is less than 0.3% by weight, the properties of the water-tight inorganic crack reducing agent are not sufficiently exhibited in the ready-mixed concrete. When the amount of the water-tight inorganic crack reducing agent is not more than 0.99% by weight, the improvement characteristics of the ready-mixed concrete composition with an excessive amount compared to the expected properties of the ready-mixed concrete composition And considering the economics, it is preferable to mix in a ratio of 0.3 to 0.99% by weight relative to the weight of the binder.

The watertight inorganic crack reducing agent is 2.0 to 9.9% by weight of a siliceous salt, 20 to 40% by weight of soluble silica, 0.5 to 3.0% by weight of an aromatic polymer condensate, and 0.2% of a nitrate inorganic compound based on 100% by weight of the watertight inorganic crack reducing agent. -2.0 weight% and 45.1-77.3 weight% of water are mixed.

Water-tight inorganic crack reducing agent can be prepared by the following process.

Silica fluoride (H ₂ SiF ₆ ) is added to water to dissolve it. About 10% by weight to 24.9% by weight of liquid silicate fluoride is prepared based on 100% by weight in total, and the silicate fluoride is added / dissolved in 75.1% by weight to 90% by weight of water.

Based on 1 kg of watertight inorganic crack reducing agent, the amount of silicic acid fluoride is about 100 g to 249 g, and the water is about 751 g to 900 g.

As a result, some of the dissociated fluoride ions (SiF ₆ ^-2 ) that are dissociated in the course of dilution of the hydrofluoric acid with water are hydrolyzed to transfer into colloidal phase soluble silica (SiO ₂ ) and fluorine ions (6F ⁻ ). .

The fluorine ions generated at this time react with alkali ions eluted from the cement when the water-tight inorganic crack reducing agent is used in cement to function as a source of poorly soluble metal fluoride (MF ₂ ).

Next, divalent metal salt groups are added / mixed to the mixture of soluble silica and fluorine ion in the colloidal state. At this time, the ratio of the divalent metal salt is about 1.3% to 15% by weight relative to the total 100% by weight of the mixture of the liquid fluorosilicate and water constituting the water-tight inorganic R crack reducing agent, 1kg of water-tight inorganic crack reducing agent When it is about 13g to 150g.

The divalent metal salt group is composed of two kinds of metal salts, a magnesium metal salt of about 0.1% by weight to 5% by weight and a zinc metal salt of about 1.2% by weight to 10% by weight. What is used for production of a magnesium type metal salt can illustrate magnesium oxide, magnesium hydroxide, magnesium carbonate, magnesium sulfate, etc. Examples of zinc-based metal salts that can be exemplified are zinc oxide, zinc hydroxide, zinc carbonate, and zinc sulfate. When the magnesium-based and zinc-based metal salts enumerated as described above are added / mixed, divalent metal ions of magnesium- and zinc-based are dissolved while they are dissolved, and they react with silicic ions dissociated from silicic acid fluoride to produce siliceous salts.

At this time, when the magnesium-based and zinc-based metal salts are dissolved, when gelation proceeds due to an increase in pH, the above-mentioned colloidal soluble silica can be transferred to 3-dimensional network silica.

Aromatic polymer condensate is added to the silofluoride prepared as described above to ensure the initial fluidity of the ready-mixed concrete when added to the ready-mixed concrete binder.

The loading ratio of the aromatic polymer condensate is about 0.5 to 3.0% by weight, and the loading amount is about 5 g to 30 g when the watertight inorganic crack reducing agent is 1 kg. The polymer condensate is aromatic, which improves the dispersion stability of the soluble silica in the colloidal state, gives a unique color to the product, and improves the fluidity of concrete when a water-tight inorganic crack reducing agent is added to the ready mixed concrete. You can give a function.

0.2-2.0 weight% of nitrate type inorganic compounds are thrown in here. Nitrate-based inorganic compounds improve the resistance to cracking due to the temperature stress by the effect of lowering the hydration temperature of the concrete, and at the same time, to improve the resistance to dry shrinkage.

Such watertight inorganic crack reducing agents are mixed with cement, water, sand, gravel, admixtures and admixtures to form ready-mixed concrete.

When the watertight inorganic crack reducing agent is added to the binder mixed with the cement and the mixture, the following reaction occurs.

Water-tight inorganic crack reducing agent is a mixture of silica fluoride salt, soluble silica, aromatic condensate, nitrate inorganic compound and water, and when added to cement, the silica fluoride salt is dissociated into divalent metal ions and silica ions. Fluoride ions are hydrolyzed by water to produce silica and fluorine ions.

In this case, the fluorine ions react with alkali ions of the cement to generate poorly soluble metal fluoride, and in this process generates an endothermic reaction that cancels the heat of hydration of the cement. Therefore, the heat of hydration of the cement is suppressed and a chemical reaction structure is provided to reduce the crack of concrete generated by the heat of hydration. In addition, the nitrate-based inorganic compound absorbs the heat of hydration generated in addition to the endothermic effect of the poorly soluble metal fluoride, and serves to suppress the hydration delay effect of the fluoride salt.

In addition, in the state in which the silica fluoride salt is not dissociated, it is directly reacted with calcium hydroxide generated during cement hydration. The silicide fluoride reacts with the calcium hydroxide in the form of magnesium-based and zinc-based salts to produce poorly soluble metal fluoride (MF ₂ ) and colloidal soluble silica.

Among these, the soluble silica reacts with the remaining calcium hydroxide and water to form calcium silicate hydrate (C-S-H) represented by calcium oxide, silica and water as the main reaction products. This is called a pozzolanic reaction, and in the present invention, activation of the pozzolanic reaction in which the C-S-H is gelled may be induced by the generation of the aforementioned soluble silica.

The divalent magnesium and zinc ions dissociated from the fluorinated salts react with the fluorine ions to form poorly soluble metal fluorides, and the alkali metal ions released from the cement also react with the remaining fluoride ions and additionally produce poorly soluble metal fluorides. . The endothermic reaction occurs during the formation of these metal fluorides. Occurrence of this endothermic reaction results in the heat of hydration of the cement being canceled out.

The results of testing the durability and reinforcing corrosion resistance of the ready-mixed concrete containing watertight inorganic crack reducing agent according to the present invention are as follows.

1. Durability (promoting neutralization)

end. Test Methods

(1) The accelerated neutralization test was carried out in accordance with KS F 4926 [Waterproofing material for concrete mixing], and the test body was molded to 100 × 100 × 400mm in a state where the coarse aggregate was sifted into concrete, and after about 24 hours When it elapsed, it was demolded and cured in water at 20 ± 2 ℃ for 27 days.

(2) After curing, remove the test body, dry for 24 hours at a temperature of 20 ± 2 ℃, humidity 60 ± 5%, put into a neutralization tester, fixed at a temperature of 20 ± 2 ℃, humidity 50 ± 5%, CO ₂ concentration 5% Neutralization was carried out for 7 days, 28 days and 56 days, respectively.

(3) The neutralized specimen was cut to a thickness of 100mm by using a concrete cutter, the surface was dried, and a 1% aqueous solution of phenolphthalein was applied to the specimen to determine the neutralized depth.

As shown in Table 1 below, the conventional concrete was neutralized in the neutralization depth of 7.8mm → 9.4mm → 11.2mm as neutralized for 7 days → 28 days → 56 days, whereas the concrete according to the present invention was 4.2mm → 5.3. The neutralization depth of mm → 6.7 mm is shown.

About 46.2% on day 7, about 43.6% on day 28, and about 40.2% on day 56, neutralization depth was suppressed, and neutralization was significantly suppressed regardless of age. This is believed to be the result of the watertightness of the hardened concrete body is enhanced by the addition of the watertight inorganic crack reducing agent according to the present invention, thereby significantly improving the penetration resistance of the CO ₂ gas.

Also in the neutralization progress rate with the increase in the neutralization treatment period, it can be seen that the neutralization rate is suppressed due to the addition of the watertight inorganic crack reducing agent according to the present invention.

<Table 1>

division Species The present invention 7 days processing

Neutralization Depth: 7.8mm Neutralization Depth: 4.2mm 28 days processing

Neutralization Depth: 9.4mm Neutralization Depth: 5.3mm 56 days processing

Neutralization Depth: 11.2mm Neutralization Depth: 6.7mm

2. Durability (chlorine ion penetration resistance)

end. Test Methods

(1) Concrete test specimen is molded into 100 × 100 × 100mm cubic form, and curing is allowed to stand in a humidity of 20 ± 3 ℃ and humidity of 80% or higher for 24 hours after molding, and then demolded to give a temperature of 20 ± 2 ℃. It was carried out up to 19 days of age in the water.

(2) Cured specimens shall be dried for at least 8 days after removal of both sides of the latencies until they become constant at a standard condition of 20 ± 2 ° C and 65 ± 5% relative humidity, and 2.5% of sodium chloride specified in KS M 8115. Immerse in aqueous solution for 7 days and 56 days at 20 ± 2 ℃.

(3) After immersion of chlorine ion, remove the test body, dry it at room temperature for 24 hours, divide the test body into 2 parts, spray the 0.1 N aqueous solution of silver nitrate specified in KS M ISO 6353-2 R28 on the cross section, and Three parts of the color developed by spraying were measured to determine the depth of chlorine ion penetration.

As can be seen from Table 2 below, the chlorine ion penetration depth of the test specimens immersed for 7 days after 28 days of curing was 5.1 mm, while the present invention reduced the penetration depth by about 47.1% to 2.7 mm.

When immersed for 56 days, the conventional 11.8mm, the present invention is 6.9mm to improve the penetration depth resistance to about 41.5% chlorine ions, regardless of the age of the water-tight inorganic crack reducing agent according to the present invention 100% by weight Concrete added 0.5% by weight tends to reduce the chloride penetration depth by more than 40%. It is confirmed that the penetration resistance of concrete to chlorine ions is greatly improved by the addition of the watertight inorganic crack reducing agent according to the present invention, and this effect is considered to be a direct cause of the watertightness of the concrete hardened structure.

<Table 2>

division Species The present invention Immersion 7 days

Chlorine ion penetration depth: 5.1mm Penetration depth of chlorine ion: 2.7mm 56 days of immersion

Chlorine ion penetration depth: 11.8mm Chlorine ion penetration depth: 6.9mm

3. Others (Rebar Corrosion Resistance)

end. Test Methods

In order to examine the effect on reinforcing corrosion by adding SWP-2 in concrete structures with reinforced steel at the bottom of the underground structure, water and SWP-2 were selected as the immersion medium, and the reinforcing bar was immersed at room temperature for 1 day. Corrosion conditions on the surface of the rebar were observed after exposure to the atmosphere for one and seven days.

When the steel is immersed in water, the rusted surface of the reinforcing steel is diffused to change the water to a red color. When the steel is immersed in the watertight inorganic crack reducing agent according to the present invention, no rust is observed on the surface of the steel. Dark brown color of inorganic crack reducing agent.

Table 3 below shows photographs of rebars exposed to air for 3 days and 7 days after being immersed in water and the watertight inorganic crack reducing agent according to the present invention for 1 day, as shown in Table 3, as shown in Table 3. The formation of red rust was observed on the part of the surface of the rebar exposed for 3 days afterwards, but the corrosion did not proceed in the rebar exposed after immersion in the watertight inorganic crack reducing agent according to the present invention.

As a result of the 7-day exposure, the reinforcing bar immersed in water produced a large amount of red rust due to Fe (OH) ₂ and Fe (OH) ₃ on the surface eroded by water, but the reinforcing bar immersed in the water-tight inorganic crack reducing agent according to the present invention. After 7 days of partial rust development, corrosion of rebar surface was found to be significantly suppressed. This is because the standard reduction potential of Zn and Mg in the siliceous salt is lower than that of Fe, which is transferred to the anode and corrodes to MgO and ZnO first, thus delaying the oxidation rate of Fe by the sacrificial anode effect and the water-tightness according to the present invention. Iron fluoride (FeF ₂ or Fe ^{2 +)} formed by the reaction of fluorine ions produced during hydrolysis of inorganic fluoride salts with Fe ²⁺ and Fe ³⁺ eluted from the surface of reinforcing steel The effect of forming a protective film of FeF ₃ ) -silica complex is considered to be a complex effect to suppress the erosion of rebar by water or corrosive components.

<Table 3>

division Species The present invention 3 days impression

7 days of impressions

The manufacturing method of the ready-mixed concrete composition containing the water-tight inorganic crack reducing agent according to the present invention configured as described above is as follows.

(S10) Raw material preparation. Cement, admixture (one or more of fly ash, blast furnace slag powder, silica fume), water, sand, gravel, admixture and watertight inorganic crack reducing agent are prepared as materials for producing ready-mixed concrete. The watertight inorganic crack reducing agent is prepared according to the above-mentioned method, and consists of a silicate salt, soluble silica, an aromatic polymer condensate, an nitrate inorganic compound, and water.

(S20) Raw Material Mix. Cement, admixture, water, sand, gravel, admixture, and watertight inorganic crack reducing agent are each metered into the mixer, and then mixed in a mixing time of 40 ± 5 seconds to prepare ready-mixed concrete, and the ready-mixed vehicle is supplied. Here, the mixing ratio of cement, admixture, water, sand, gravel and admixture is not limited to any one value because it varies depending on the type of ready-mixed concrete product, but the water-tightness is achieved even if the mixing ratio of cement and admixture and other components is different. The mixing ratio of the inorganic crack reducer is mixed within a certain range for the ready-mixed concrete binder. In addition, the water-tight inorganic crack reducing agent may be added to the mixer after being weighed in a metering tank and mixed with water or directly weighed separately.

As described above, according to the ready-mixed concrete composition containing the water-tight inorganic crack reducing agent according to the present invention, the water-tightness and crack resistance of the concrete prepared in the ready-mixed concrete form by the addition of the water-tight inorganic crack reducing agent neutralized, chlorine ion Durability, such as penetration and reinforcement corrosion suppression, can be improved.

In addition, the permeability of chlorine ions is reduced, and the corrosion resistance of the reinforcing bar can be improved.

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 (2)

In the ready-mixed concrete composition containing a water-tight inorganic crack reducing agent, Cement, water, sand, gravel, admixture, admixture and watertight inorganic crack reducing agent (a) The water-tight inorganic crack reducing agent (a) is 2.0 to 9.9% by weight of a fluorinated silica, 20 to 40% by weight of soluble silica in a colloidal state, and 0.5 to 3% by weight of an aromatic polymer condensate based on 100% by weight of the water-tight inorganic crack reducing agent. , 0.2 to 2.0% by weight of the nitrate-based inorganic compound and 45.1 to 77.3% by weight of water are mixed, 0.3 ~ 0.99% by weight relative to the ready-mixed concrete binder (b) mixed with the cement and water-tightness, characterized in that A ready-mixed concrete composition containing an inorganic crack reducing agent. The method of claim 1, wherein the water-tight inorganic crack reducing agent (a) is dissolved from 10 to 24.9% by weight of liquid silicate fluoride in 75.1 to 90% by weight of water based on 100% by weight of the total mixture of liquid silicate fluoride and water to dissociate from the silicate fluoride Hydrolyzing silicic ions to form fluorine ions and colloidal silica, and additionally 1.3 to 15 wt% of a divalent metal salt group is mixed with respect to 100 wt% of the total mixture of liquid silicate fluoride and water. And a polymerizable condensate and a nitrate-based inorganic compound formed by reacting a divalent metal ion dissociated from a divalent metal salt group with the silicide fluoride ion.