KR101590124B1 - Pc box culvert concrete composition unnecessary for steam aging and manufacturing method for pc box culvert using the same - Google Patents

Abstract

A concrete composition for PC culvert that does not require steam curing and a PC culvert making method using the same. The PC culvert method of the present invention comprises the steps of: (a) preparing a concrete composition; (b) casting the concrete composition into a PC culvert mold provided with reinforcing bars inserted in the concrete; (c) curing the concrete composition laid on the PC culvert mold; And (d) demolding the PC culvert mold after curing of the concrete composition is completed. In the step (a), the concrete composition is applied to crude steel cement, and in the step (c) A concrete composition for expressing a compressive strength of 10 MPa or higher within 6 hours of curing without curing is characterized in that 5 to 8 parts by weight of a curing accelerator is added to 100 parts by weight of the crude steel cement.

Description

TECHNICAL FIELD [0001] The present invention relates to a concrete composition for a PC culvert that does not require steam curing, and a method for manufacturing a PC culvert using the same. BACKGROUND OF THE INVENTION 1. Field of the Invention [0002]

The present invention relates to a concrete composition for a PC culvert and a method for manufacturing a PC culvert using the same, and more particularly, to a concrete composition for PC culvert which can exhibit early strength without steam curing in a curing process, And a manufacturing method thereof.

Generally, the Precast Concrete Box Culvert has a structure as shown in FIG. 1 and refers to a PC concrete structure used for water supply and drainage, electric power, communication facilities, ducts, tunnels, and the like. 1 is a perspective view showing an example of a series PC culvert.

This PC culvert is pre-cast as it is named, and it is pre-manufactured at the factory and assembled and transported to the construction / civil engineering site. It is possible to obtain cost reduction by repeating and mass-production.

On the other hand, the PC culvert is generally manufactured by pouring a concrete composition into a PC culvert mold or a PC culvert mold installed with reinforcing bars, curing the concrete composition for a certain period of time, and then demolding the PC culvert mold. At this time, in the curing process, steam curing or steam curing is indispensably required in order to shorten curing time and secure sufficient strength.

However, such a steam curing process causes an environmental problem due to excessive emission of carbon dioxide, and it requires a facility such as a boiler, resulting in an increase in the unit cost of production, which is problematic in terms of economy.

Accordingly, there is a need for a concrete composition for a PC culvert which can secure sufficient early strength even without steam curing in the production of a PC culvert, and a method for manufacturing a PC culvert using the same.

The related prior art document is Korean Patent Registration No. 10-0777036 entitled " PC culvert manufacturing apparatus with a liner, its assembling method, manufacturing method of a PC culvert with a liner, and PC culvert produced by the same, : Nov. 16, 2007) and Korean Patent Registration No. 10-0787379 (entitled Cement mortar composition and concrete composition, published on Dec. 24, 2007).

It is an object of the present invention to provide a concrete composition for a PC culvert which can secure sufficient early strength even when steam curing is not performed in the production of a PC culvert and shorten the curing time, and a method for manufacturing a PC culvert using the same.

The object is achieved by a method comprising: (a) preparing a concrete composition; (b) casting the concrete composition into a PC culvert mold provided with reinforcing bars inserted in the concrete; (c) curing the concrete composition laid on the PC culvert mold; And (d) demolding the PC culvert mold after curing of the concrete composition is completed. In the step (a), the concrete composition is applied to crude steel cement, and in the step (c) A concrete composition for expressing a compressive strength of 10 MPa or higher within 6 hours of curing without curing, wherein a curing accelerator is added in an amount of 5 to 8 parts by weight based on 100 parts by weight of the crude steel cement Can be achieved by a PC culvert method using a concrete composition that does not require curing.

The above object is also achieved by a cementitious concrete composition comprising a curing accelerator added to crude steel cement, wherein, in order to exhibit a compressive strength of 10 MPa or more within 6 hours of curing without steam curing, 100 parts by weight of the crude steel cement, And the curing accelerator is added in an amount of 5 to 8 parts by weight.

Wherein the curing accelerator is selected from the group consisting of 1 to 70% by weight of potassium nitrate, 5 to 10% by weight of alumina cement, 0.1 to 10% by weight of an α-hemihydrate gypsum, 0.1 to 3% by weight of sodium thiocyanate, 1 to 5% and limestone powder: 5 to 20%.

Instead of the alumina cement, at least one of magnesium oxide, silica fume, CSA, MgO, anhydrous gypsum and β-hemihydrate gypsum may be added.

Instead of potassium nitrate, at least one of nitrite, thiocyanate, monovalent ethanolamine, diethanolamine, tetrahydroethanolamine, alkanolamine, aluminum sulfate, potassium sulfate, triethanolamine and alpha -hydroxycarboxylate is added .

The crude steel cement further comprises silica sand, calcium carbonate, defoamer, shrinkage reducing agent, methyl cellulose and methyl ethyl cellulose, wherein the crude steel cement is 25-30 wt% : 35 to 45% by weight calcium carbonate 15 to 25% by weight antifoaming agent 0.05 to 0.10% by weight crude accelerating agent 0.5 to 4.0% shrinkage reducing agent 0.1 to 5% by weight methyl cellulose: 0.001 to 0.005% by weight, and methyl ethyl cellulose: 0.001 to 0.005% by weight.

The antifoaming agent may include a single or a mixture of two or more selected from the group consisting of a silicone type, an alcohol type, and an ethylene oxide propylene (EOPO) type.

The waterproofing agent may further comprise 0.6 to 1.0 part by weight based on 100 parts by weight of the crude steel cement. At this time, it is preferable that the water reducing agent is a polycarbonate water reducing agent.

The concrete composition in water 150kg / m ^3, the steel cement: 450 ~ 550kg / m ^3, Sand: 750 ~ 850kg / m ^3, gravel: 950 ~ 1000kg / m ^3, a water-reducing agent: ³ ~ 4kg / m 3, and Curing accelerator: 25 to 40 kg / m < ³ >. At this time, the water-cement ratio (W / C) is preferably 25 to 35.

The present invention provides a PC concrete cement composition in which a curing accelerator is added at an optimum amount ratio to crude steel cement at an optimum content ratio, so that a sufficient strength (compressive strength of 10 MPa or more within 6 hours of curing) .

Accordingly, the present invention eliminates the need for steam curing in the curing process unlike the conventional PC culvert manufacturing method in which steam curing is required for early strength development, so that the production of PC culvert reduces the emission of carbon dioxide, In addition, it is possible to improve the economical efficiency by reducing the production cost by omitting the equipment such as the boiler which is necessary for curing the steam.

Fig. 1 is a perspective view showing an example of a series PC culvert. Fig.
2 is a flowchart for explaining a PC culvert making method using a concrete composition that does not require steam curing according to the present invention.
3 is a graph showing the results of fluidity tests according to the amounts of cement and hardening accelerator for the samples according to Comparative Examples 1 to 4.
4 is a graph showing the results of fluidity tests according to the amounts of cement and curing accelerator for the samples according to Comparative Examples 5 to 7 and Example 1. FIG.
5 is a graph showing the results of the condensation test on the samples according to Comparative Examples 1 to 7 and Example 1. Fig.
6 is a graph showing the results of early strength tests on samples according to Comparative Examples 1 to 4.
7 is a graph showing the results of early strength tests on samples according to Comparative Examples 5 to 7 and Example 1. Fig.

In order to fully understand the present invention, operational advantages of the present invention, and objects achieved by the practice of the present invention, reference should be made to the accompanying drawings and the accompanying drawings which illustrate preferred embodiments of the present invention.

Hereinafter, the present invention will be described in detail with reference to the preferred embodiments of the present invention with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in order to avoid unnecessary obscuration of the present invention.

2 is a flowchart for explaining a PC culvert making method using a concrete composition that does not require steam curing according to the present invention.

Referring to FIG. 2, the method for manufacturing a PC culvert according to the present invention includes a step S110 of producing a concrete composition, a step S120 of placing a concrete composition in a PC culvert mold provided with a reinforcing bar, (S130) curing the concrete composition laid down on the concrete composition, and demolding the PC culvert mold after the curing of the concrete composition is completed (S140).

In the concrete composition production step (S110), the concrete composition is added to the crude steel cement at an optimum content ratio so that sufficient early strength, i.e., compressive strength of not less than 10 MPa within 6 hours of curing can be achieved without performing steam curing in the curing step (S130) . The details of the concrete composition including the concrete mixture design will be described later. ≪ tb > < TABLE >

In the pouring step S120, a concrete composition is cast in a pre-fabricated mold for culvert pouring. Here, the mold for PC culvert or the mold for PC culvert is a frame for manufacturing a PC culvert provided in a shape corresponding to the PC culvert to be manufactured, and includes a reinforcing bar inserted into the concrete before the concrete composition is installed A ring, a long filling material, and a concrete buried material are installed. On the other hand, in order to facilitate demoulding, the mold for PC culvert can be coated with an appropriate amount of releasing agent on its inner surface and can be manufactured by assembling two or more unit molds. For reference, the mold for PC culvert is a member to be recycled, not to be used once, but to remove impurities remaining in the mold by using compressed air or cleaning tools before using the PC culvert mold after demolding. Is required.

In the curing step (S130), the concrete composition placed in the mold for PC culvert is cured for a certain period of time. Conventionally, in the PC culver making method, steam curing is indispensably required in order to shorten the curing time and ensure sufficient early strength. However, the PC culvert making method according to the present invention is not required to sufficiently cure at the curing step (S130) (Compressive strength of not less than 10 MPa within 6 hours of curing) can be ensured by the effect of the concrete composition for early strength development prepared by adding the hardening accelerator to the crude steel cement at an optimum content ratio. Will be described later.

In the demolding step (S140), the mold for the PC culvert is demolded after the curing of the concrete composition is completed. Care should be taken not to cause cracks, partial dropouts or stresses in the result of reinforcing concrete curing during demolding of the PC culvert molds. PC culvert, which is the result of reinforced concrete curing removed from the mold for PC culvert, is shipped to the product after inspection and repair work.

Hereinafter, the concrete composition for PC culvert without the need for steam curing according to the present invention will be described in detail.

The concrete composition for PC culvert according to the present invention does not require steam curing and is applied to crude steel cement and is capable of exhibiting a compressive strength of 10 MPa or more within 6 hours of curing without conducting steam curing.

To this end, it is preferable that the PC concrete composition for culvert without steam curing according to the present invention is added with 5 to 8 parts by weight of a curing accelerator based on 100 parts by weight of crude steel cement.

The crude steel cement may further contain silica sand, calcium carbonate, defoamer, shrinkage reducing agent, methyl cellulose, and methyl ethyl cellulose, wherein the crude steel cement is 25-30 wt% : Methyl cellulose: 35 to 45 wt%, calcium carbonate: 15 to 25 wt%, crude steel promoter: 0.5 to 4.0 wt%, defoaming agent: 0.05 to 0.10 wt%, shrinkage reducing agent: 0.001 to 0.005% by weight, and methyl ethyl cellulose: 0.001 to 0.005% by weight.

Here, the antifoaming agent may include a single or a mixture of two or more selected from the group consisting of a silicone type, an alcohol type, and an ethylene oxide propylene (EOPO) type, and a shrinkage reducing agent is preferably a heavy glycol type shrinkage reducing agent Do.

The crude steel cement has a high hydration rate due to its rapid hydration reaction, and therefore, it has a role of improving hardening and strength.

The crude steel cement is preferably added at a content ratio of 25 to 30% by weight of the total weight. If the content of crude steel cement is less than 25% by weight, it may be difficult to secure sufficient rigidity. Conversely, when the content of crude steel cement exceeds 30% by weight, there is a fear that the production cost will be raised without further effect of addition, which is not economical.

Silica sand is added for the purpose of improving the surface roughness of the mortar after application. It is preferable to use such a sandpaper having an average diameter of about 0.01 to 0.3 mm. When the average diameter of the silica sand is less than 0.0 mm, the effect of increasing the surface roughness against the time and cost required for obtaining the fine particles may be insignificant, which is not economical. On the contrary, when the average diameter of the silica sand is more than 0.30 mm, not only is it difficult to exhibit the surface roughness improving effect properly, but also the crack resistance sharply decreases.

The silica sand is preferably added at a content ratio of 35 to 45% by weight of the total weight of the cement. When the content of silica sand is less than 35% by weight, it may be difficult to exhibit the surface roughness improving effect properly. On the other hand, when the content of silica sand is more than 45% by weight, there is a great possibility of raising the manufacturing cost without further adding effect.

Calcium carbonate (CaCO ₃ ) is not soluble in water and precipitates in an aqueous solution, so it is used as a fine powder filler.

The calcium carbonate is preferably added at a content ratio of 15 to 25% by weight of the total weight of the cement. When the content of calcium carbonate is less than 15% by weight, it may be difficult to properly exhibit the particle size dispersion efficiency. On the other hand, if the content of calcium carbonate exceeds 25% by weight, there is a great possibility that the increase of the cost is caused only by no further effect of addition.

The antifoaming agent is added for the purpose of preventing the formation of bubbles and removing the generated bubbles. As the antifoaming agent, it is preferable to use a single or a mixture of two or more selected from the group consisting of a silicone type, an alcohol type, and an ethylene oxide propylene (EOPO) type.

The antifoaming agent is preferably added at a content ratio of 0.05 to 0.10% by weight of the total weight of the cement. If the content of the antifoaming agent is less than 0.05% by weight, the addition amount of the antifoaming agent is insignificant, so that it may be difficult to exhibit the bubble formation inhibiting and removing effect properly. On the other hand, if the content of the defoaming agent exceeds 0.10% by weight, the defoaming agent can be a factor for raising the manufacturing cost without further increase in the effect, which is not economical.

The shrinkage reducing agent is added for the purpose of reducing the shrinkage, and as the shrinkage reducing agent, a heavy-glycol shrinkage reducing agent may be used.

In the present invention, the shrinkage reducing agent is preferably added in a content ratio of 0.1 to 5% by weight based on the total weight of the cement. If the content of the shrinkage reducing agent is less than 0.1% by weight, it may be difficult to exhibit the effect of addition properly. On the other hand, if the content of the shrinkage reducing agent exceeds 5% by weight, it may be a factor for raising the manufacturing cost without further increase in the effect, which is not economical.

Methylcellulose is one of the alkylcelluloses and increases the viscosity in the alkaline condition, so that it has the adhesive and moisturizing properties. However, when methyl cellulose is used alone, there is a problem that the workability is lowered as the content of methyl cellulose is increased. Therefore, methyl ethyl cellulose, which is an auxiliary additive to be described later, is mixed together It is desirable to improve adhesion and long-term durability while preventing excessive deterioration of the workability.

Therefore, methylcellulose is preferably added at a content ratio of 0.1 to 0.3% by weight of the total weight of the cement. If the content of methylcellulose is less than 0.1% by weight, it may be difficult to exhibit the above effects properly. On the contrary, when the content of methylcellulose exceeds 0.3% by weight, the tackiness is excessively tacky and the workability is deteriorated.

Methyl ethyl cellulose is added for the purpose of preventing an excessive drop in the workability due to an increase in the amount of methyl cellulose.

It is preferable that methyl ethyl cellulose is added at a content ratio of 0.1 to 0.2% by weight based on the total weight of the cement. If the content of methyl ethyl cellulose is less than 0.1% by weight, it may be difficult to exhibit the effect of preventing the drop in workability. On the contrary, when the content of methyl ethyl cellulose is more than 0.2% by weight, there is a high possibility of raising the production cost compared to the effect of addition, which is not economical. Further, a phenomenon of tagging due to a drop in viscosity may occur.

As described above, in the present invention, the curing accelerator accelerates the hydration reaction of crude steel cement so that the degree of supersaturation of calcium hydroxide (Ca (OH) ₂ ) in the solution reaches its maximum and precipitation of hydration products such as cement gel The initial strength is increased, which affects the crystal shape of the cement gel, so that the long-fiber crystals tighten the structure and increase the strength.

The curing accelerator is preferably added in an amount of 5 to 8 parts by weight based on 100 parts by weight of crude steel cement. When the addition amount of the curing accelerator is less than 5 parts by weight based on 100 parts by weight of the crude steel cement, the addition amount thereof is insignificant, so that it may be difficult to exhibit early strength. On the contrary, when the addition amount of the curing accelerator is more than 8 parts by weight based on 100 parts by weight of the crude steel cement, it is not economical because it acts only as a factor for raising the production cost without increasing the effect.

At this time, the curing accelerator is preferably selected from the group consisting of 1 to 70% by weight of potassium nitrate, 5 to 10% by weight of alumina cement, 0.1 to 10% by weight of α-hemihydrate gypsum, 0.1 to 3% by weight of sodium thiocyanate, To 5% and limestone powder: 5 to 20%. At this time, in place of the alumina cement, one having at least one of magnesium oxide, silica fume, CSA, MgO, anhydrous gypsum and β-hemihydrate gypsum added may be used. In place of potassium nitrate, at least one of nitrite, thiocyanate, monovalent ethanolamine, diethanolamine, trivalent ethanolamine, alkanolamine, aluminum sulfate, potassium sulfate, triethanolamine and alpha -hydroxycarboxylate is added .

Meanwhile, the concrete composition for PC cage which does not require steam curing according to the present invention may further contain 0.6-1.0 parts by weight of a water reducing agent based on 100 parts by weight of crude steel cement.

Such a water reducing agent is preferably, but not limited to, a polycarbonate-based water reducing agent. That is, as a water reducing agent, a polycarboxylate-based water reducing agent derived from a monomer capable of polymerization or copolymerization with an unsaturated carboxylic acid monomer, more specifically, a copolymer of these unsaturated carboxylic acid monomer and styrene may be used.

At this time, when the addition amount of the water reducing agent is less than 0.6 part by weight with respect to 100 parts by weight of crude steel cement, rapid slump loss and subsequent slump loss may not be improved. On the other hand, when the addition amount of the water reducing agent is less than 1.0 part by weight with respect to 100 parts by weight of the crude steel cement, the water reducing rate reaches the limit state and the curing failure may occur

More specifically, the concrete composition for PC underdrain does not require steam curing according to the invention in water 150kg / m ^3, the steel cement: 450 ~ 550kg / m ^3, Sand: 750 ~ 850kg / m ^3, gravel: 950 M ³ , a water reducing agent: 3 to 4 kg / m ^3, and a curing accelerator: 25 to 40 kg / m ³ . At this time, the water-cement ratio (W / C) is preferably 25 to 35.

INDUSTRIAL APPLICABILITY As described above, the PC concrete composition for culvert, which does not require steam curing according to the present invention, can provide a PC concrete composition for culvert with curing accelerator added at an optimum ratio in crude steel cement, (Compressive strength of 10 MPa or more within 6 hours of curing) can be ensured even without carrying out the curing.

Accordingly, the present invention eliminates the need for steam curing in the curing process unlike the conventional PC culvert manufacturing method in which steam curing is required for early strength development, so that the production of PC culvert reduces the emission of carbon dioxide, In addition, it is possible to improve the economical efficiency by reducing the production cost by omitting the equipment such as the boiler which is necessary for curing the steam.

Hereinafter, the configuration and operation effects of the present invention will be described in more detail with reference to FIGS. 5 to 7 through a preferred embodiment of the present invention.

1. Sample preparation

Table 1 shows the compounding ratios for the samples according to Comparative Examples 1 to 7 and Example 1. < tb > < TABLE > At this time, as the curing accelerator, 68 wt% of potassium nitrate, 7 wt% of alumina cement, 5 wt% of α-hemihydrate gypsum, 2 wt% of sodium thiocyanate, 3 wt% of calcium formate and 15 wt% of limestone powder were used , And a polycarbonate water reducing agent was used as a water reducing agent. Table 2 shows the results of the fluidity test (the results of the slump flow and the air content of the uncured concrete) according to the amounts of cement and hardening accelerator for the samples according to Comparative Examples 1 to 7 and Example 1. [

FIG. 3 is a graph showing the results of flowability tests according to the amounts of cement and hardening accelerator for the samples according to Comparative Examples 1 to 4, FIG. 4 is a graph showing the results of the flowability test according to the amounts of cement and hardening accelerator for the samples according to Comparative Examples 5 to 7 and Example 1, A graph showing the results of fluidity experiment according to the amount of accelerator.

[Table 1]

Here, W: water, C: cement, S: sand, G: gravel, AD: water reducing agent, CS: curing accelerator.

[Table 2]

Referring to Tables 1 and 2 and FIGS. 3 and 4, specific values of the slump flow and the amount of air corresponding to the results of the fluidity test according to the amount of cement and curing accelerator added at a curing temperature of 0 ° C are shown. At this time, the optimum ratios of the slump flow and the air amount to the samples according to the comparative examples 1 to 7 and the example 1 are shown, and it was confirmed that when added in the above range, it is not hardened due to proper fluidity.

2. Property evaluation

Table 3 shows the early strength (compressive strength) of the samples according to Comparative Examples 1 to 7 and Example 1 according to the amounts of cement and curing accelerator. FIG. 5 is a graph showing the results of the condensation test according to the amounts of cement and curing accelerator for the samples according to Comparative Examples 1 to 7 and Example 1. FIG. 6 is a graph showing the results of the cement and hardening FIG. 7 is a graph showing the results of early strength test according to the amounts of cement and hardening accelerator for the samples according to Comparative Examples 5 to 7 and Example 1. FIG.

[Table 3]

As shown in Table 3 and FIG. 5 to FIG. 6, as the addition amount of the curing accelerator was increased regardless of the amount of cement, there was a large difference in the compressive strength value according to the curing time, and the addition amount of the curing accelerator As a result, it is found that the result of the second termination is shown by the difference of about 60 ~ 120 hours. In addition, the result of the end of the second result was obtained by the difference of the amount of cement within 60 minutes, and it is considered that the effect of the curing accelerator is larger than that of the reactive component contained in the cement.

As shown in the above tests, the amount of air and the fluidity tended to increase in the unconfined concrete experiment due to the incorporation of the curing accelerator. It is considered that the reaction of the curing accelerator affects the air quantity and fluidity.

In particular, as shown in Table 3, FIG. 6 and FIG. 7, it was confirmed that there was a clear difference in the initial and final time according to the incorporation of the curing accelerator. As a result of the measurement of the early strength, the samples according to Comparative Examples 1 to 7 did not satisfy the compressive strength of 30 MPa or more within 6 hours of curing time, but only the samples according to Example 1 had compressive strength within 6 hours of curing time 11.4 MPa, and it was confirmed that the target value was satisfied.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. Accordingly, such modifications or variations are intended to fall within the scope of the appended claims.

Claims (17)

(a) preparing a concrete composition;
(b) casting the concrete composition into a PC culvert mold provided with reinforcing bars inserted in the concrete;
(c) curing the concrete composition laid on the PC culvert mold; And
(d) demolding the PC culvert mold after curing for the concrete composition is completed,
The concrete composition as set forth in claim 1, wherein the concrete composition is applied to crude steel cement and exhibits a compressive strength of at least 10 MPa within 6 hours of curing without steam curing in step (c)
5 to 8 parts by weight of a curing accelerator is added to 100 parts by weight of the crude steel cement,
The curing accelerator,
1 to 70% by weight of potassium nitrate, 5 to 10% by weight of alumina cement, 0.1 to 10% by weight of a-type hemihydrate gypsum, 0.1 to 3% by weight of sodium thiocyanate, 1 to 5% by weight of calcium formate, And 5 to 20% by weight of the powder.
delete The method according to claim 1,
Instead of the alumina cement,
Wherein at least one of magnesium oxide, silica fume, CSA, MgO, anhydrous gypsum and β-hemihydrate gypsum is added to the cement mortar.
The method according to claim 1,
Instead of the potassium nitrate,
Characterized in that at least one of nitrite, thiocyanate, monovalent ethanolamine, diethanolamine, triethanolamine, alkanolamine, aluminum sulfate, potassium sulfate, triethanolamine and alpha-hydroxycarboxylate is added PC culvert making method using concrete composition that does not require curing.
The method according to claim 1,
The crude steel cement may further include silica sand, calcium carbonate, defoamer, shrinkage reducing agent, methyl cellulose, and methyl ethyl cellulose,
The crude steel cement is 25 to 30% by weight, the silica is 35 to 45% by weight, the calcium carbonate is 15 to 25% by weight, the defoaming agent is 0.05 to 0.10% by weight, the crude steel promoter is 0.5 to 4.0%, the shrinkage reducing agent is 0.1 to 5% 0.001 to 0.005% by weight of methyl cellulose, and 0.001 to 0.005% by weight of methyl ethyl cellulose, based on the total weight of the concrete composition. How to make a culvert.
6. The method of claim 5,
The anti-
And a mixture of two or more selected from the group consisting of silicones, alcohols, and ethylene oxide propylene (EOPO).
The method according to claim 1,
Wherein the waterproofing agent further comprises 0.6 to 1.0 part by weight of the waterproofing agent based on 100 parts by weight of the crude steel cement.
8. The method of claim 7,
The water reducing agent
A method for producing a culvert of a PC using a concrete composition which does not require steam curing, characterized by being a polycarbonate water reducing agent.
The method according to claim 1,
The concrete composition
In water 150kg / m ^3, the steel cement: 450 ~ 550kg / m ^3, Sand: 750 ~ 850kg / m ^3, gravel: 950 ~ 1000kg / m ^3, a water-reducing agent: ³ ~ 4kg / m 3 and a curing accelerator: 25 To 40 kg / m < ³ >, respectively.
delete A concrete composition for a PC culvert comprising a curing accelerator added to crude steel cement,
The curing accelerator is added in an amount of 5 to 8 parts by weight based on 100 parts by weight of the crude steel cement in order to exhibit a compressive strength of 10 MPa or more within 6 hours of curing without performing steam curing,
The curing accelerator,
1 to 70% by weight of potassium nitrate, 5 to 10% by weight of alumina cement, 0.1 to 10% by weight of a-type hemihydrate gypsum, 0.1 to 3% by weight of sodium thiocyanate, 1 to 5% by weight of calcium formate, And 5-20% by weight of the powder.
delete 12. The method of claim 11,
The crude steel cement may further include silica sand, calcium carbonate, defoamer, shrinkage reducing agent, methyl cellulose, and methyl ethyl cellulose,
The crude steel cement is 25 to 30% by weight, the silica is 35 to 45% by weight, the calcium carbonate is 15 to 25% by weight, the defoaming agent is 0.05 to 0.10% by weight, the crude steel promoter is 0.5 to 4.0%, the shrinkage reducing agent is 0.1 to 5% Wherein the composition is comprised of 0.001 to 0.005% by weight of methyl cellulose, and 0.001 to 0.005% by weight of methyl ethyl cellulose. .
14. The method of claim 13,
The anti-
And a mixture of two or more selected from the group consisting of silicones, alcohols, and ethylene oxide propylene (EOPO).
12. The method of claim 11,
The concrete composition for a PC culvert according to claim 1, further comprising 0.6 to 1.0 part by weight of a water reducing agent based on 100 parts by weight of the crude steel cement.
12. The method of claim 11,
The concrete composition
In water 150kg / m ^3, the steel cement: 450 ~ 550kg / m ^3, Sand: 750 ~ 850kg / m ^3, gravel: 950 ~ 1000kg / m ^3, a water-reducing agent: ³ ~ 4kg / m 3 and a curing accelerator: 25 To 40 kg / m < ³ >, wherein the steam curing is not required.
delete

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