KR20160014970A - Method for manufacturing ultra high performance concrete for preventing drying of concrete surface using oil-based surface finishing material - Google Patents

Abstract

Provided is a method for manufacturing ultra high performance concrete (UHPC), which prevents surface drying by applying an oil-based surface finishing material immediately after pouring the UHPC to improve surface of the poured concrete, and which improves mechanical strength of the concrete surface with respect to removal of the surface pores while enhancing durability. In addition, provided is a method for manufacturing UHPC, which can manufacture high-quality UHPC by smoothing the surface of the UHPC and secure reliable mechanical strength of UHPC by blocking vaporization of moisture through hydration reaction with respect to the hardening mechanism of UHPC, while preventing surface of the concrete from drying using an oil-based surface finishing material. The method for manufacturing UHPC comprises the steps of: a) preparing each of water (W) relevant to unit water content of UHPC and a binding material (B) which is formed by mixing cement and silica fume; b) mixing W and B to have a water-binding material ratio (W/B) less than or equal to 0.3; c) preparing mixing water by mixing a high-performance water reducing agent; d) selectively preparing aggregates while excluding coarse aggregate; e) preparing and mixing steel fiber with the binding material, fine aggregate and mixing water, and pouring UHPC into a cast; e) applying the oil-based surface finishing material immediately after pouring the UHPC; and g) curing the UHPC.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for manufacturing an ultra-high performance concrete which prevents the surface of a concrete from being dried by using a planer type surface finishing agent. [0002]

The present invention relates to the production of ultra-high performance concrete, and more particularly, to an oil-based surface finishing material to prevent the concrete surface from drying during the manufacture of ultra high performance concrete (UHPC) The present invention relates to a method for producing an ultra high performance concrete which prevents the surface of a concrete from being dried.

Typically, ultra high performance concrete (UHPC) has high strength characteristics such as compressive strength 200 MPa, tensile strength 15 MPa and flexural strength 35 MPa, penetration and diffusion rate of deterioration factor is 1/20 to 1 / 10,000 lower than that of ordinary concrete, And at the same time, a slump flow has a self-filling property of about 220 mm. Recently, studies on ultra high performance concrete mainly in Europe have been actively carried out, and application to bridges, platform roof structures, and skyscraper buildings is gradually expanding.

This ultrahigh performance concrete (UHPC) is made by microfabricating the materials and maximizing the physicochemical hydration reaction of cement-containing binders to increase the strength of the cement matrix and adding fibers with small diameters and large length / aspect ratios Fiber) is mixed with concrete to resist cracking stress. Although the maximum range of strength of this ultra high performance concrete (UHPC) can be up to 800MPa according to the curing conditions, the compressive strength range in the commercialization stage in Europe and other developed countries is about 200MPa.

This ultra high performance concrete (UHPC) has a cement matrix structure with high compressive strength, but does not have high tensile strength without fiber incorporation and brittle failure. Therefore, by adding fiber to such ultra high performance concrete (UHPC), the tensile strength can be increased along with the compressive strength, and the fracture behavior of the structure can be improved by pseudo-ductile behavior or ductile behavior can do.

This ultra high performance concrete (UHPC) minimizes the effect of interfacial expansion between aggregate and cement hydrate. In order to improve the separation resistance of the fibers used in ultra high performance concrete (UHPC), the coarse aggregate is not used, Smaller and more powdery digestion is used. Table 1 shows an example of the material composition of ultrahigh performance concrete (UHPC) with ultrahigh strength and toughness properties.

The ultrahigh performance concrete (UHPC) has a total hydration degree of about 20 to 26% due to extremely low water-binding ratio (W / B) at about 20 ° C. and 48 hours after mixing. At this time, the capillary porosity 7%. However, after curing at 90 ℃ for 24 ~ 72 hours, super high performance concrete (UHPC) has capillary porosity of about 1% and hydration degree is more than 85%.

On the other hand, in the case of such an ultra high performance concrete (UHPC), since the coarse aggregate is excluded from the material composition and the silica fume added to the binder has a high powder degree, the amount of entrained air In the hydration process and the heating steam curing process, the capillary pore is reduced extremely, resulting in an ultra high strength and a high durability.

In addition, the mechanical properties of such ultra high performance concrete (UHPC) are shown in Table 2 as compared with ordinary concrete and fiber reinforced concrete.

In order to realize the deformation hardening phenomenon and the multiple cracking property of the ultra high performance concrete (UHPC), the force generated by the crosslinking action by the fiber in the crack surface is the tensile force generated in the crack of the matrix The larger the ratio, the more cracks are likely to occur and the toughness capability is improved. Such a crosslinking action is mainly affected by the strength of the fiber, the strength of the matrix, the adhesion strength of the fibers and the matrix, the mixing ratio of the fibers, the air quantity of the matrix and the like, but also the dispersibility and workability of the fibers.

As described above, the ultra high performance concrete (UHPC) has a very low water-to-binder ratio and incorporates a high powder filler and admixture, and does not use coarse aggregate. Therefore, the ultra high performance concrete does not cause bleeding phenomenon, .

In the case of such an ultra-high-performance concrete, when the surface is exposed to the outside, since there is no low water-binding ratio and no bleeding phenomenon, the surface is dried in a short time.

FIGS. 1A and 1B are photographs showing a state where a surface finish agent is not applied in a super high-performance concrete according to a conventional technique.

Fig. 1 (a) shows the finishing work performed on the ultra-high-performance concrete 10 without applying the surface finishing agent, and Fig. 1 (b) shows the surface condition of the ultra-high-performance concrete 10 before applying the surface finishing agent.

1A and 1B, trapped air generated in the concrete when the ultra-high performance concrete 10 is poured onto the mold 20 should be raised and removed at a slow speed due to high viscosity, but in a short time As the surface is dried, trapped air is concentrated on the surface portion. Due to such a phenomenon, the surface portion of the ultra-high-performance concrete 10 is very rough because it can not perform the finishing work, and a large number of voids are generated as shown by a reference A in Fig. 1B.

Therefore, there is a problem in that the surface strength of the poured surface is lowered due to the pores generated by the trapped air on the placement surface of the ultra high-performance concrete 10, and the performance of the surface portion is deteriorated.

Korean Patent No. 10-1094755 filed on Jul. 27, 2011, entitled "Surface Protective Composition of Concrete Structures and Neutralization, Korean Patent No. 10-829988 filed on November 13, 2007, entitled "Epoxy resin mortar composition and concrete surface construction method using the same, Korean Patent No. 10-1209282 filed on November 23, 2010, entitled "Ultra High Performance Fiber Reinforced Concrete and Its Manufacturing Method" Korean Patent No. 10-314393 filed on March 31, 2000, entitled "Cementitious Concrete Surface Finishing Coating Material" Korean Patent Publication No. 2012-15429 (Publication date: February 21, 2012), title of the invention: "High performance or ultra high performance concrete"

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an ultra high performance concrete, It is an object of the present invention to provide a method for manufacturing an ultra high performance concrete which prevents the surface of a concrete from being dried by using an oil type surface finishing agent capable of improving the strength of the concrete surface portion and increasing the durability.

As a means for achieving the above technical object, there is provided a method for manufacturing an ultra high performance concrete which prevents the surface of a concrete from being dried by using a planer type surface finishing agent according to the present invention is characterized by a compressive strength of 120 MPa or more, a tensile strength of 8 MPa or more, A method of producing an ultrahigh performance concrete (UHPC) having a flexural strength and a water-to-binder ratio (W / B) of 0.3 or less, comprising the steps of: a) Preparing a binder (B) in which cement and silica fume are mixed, respectively; b) the ratio of water-binding material (W / B) is less than or equal to 0.3; c) preparing a compounding water by mixing a high-performance water reducing agent; d) preparing aggregates without coarse aggregate; e) preparing a steel fiber, mixing it with the binder, fine aggregate and blended water, and casting super high performance concrete on the form; f) preventing the surface of the concrete from being dried by applying the oil-based surface finishing agent immediately after the pouring of the ultra high performance concrete; And g) curing the ultra-high performance concrete with the surface finish applied to the surface of the concrete.

Here, the surface finishing agent in the step f) is sprayed in a spray form on the surface of the concrete immediately after the super high performance concrete is poured.

The surface finishing agent is applied to the surface of the concrete by 1 to 5 mm.

Here, the surface finish agent is preferably applied evenly over the entire concrete area so that the concrete surface is not dried.

According to the present invention, an oil-based surface finishing agent is applied immediately after the ultra-high performance concrete is cast so as to improve the placement surface of the ultra-high-performance concrete, thereby improving the strength of the surface portion of the concrete as the voids on the surface portion are removed, .

According to the present invention, it is possible to manufacture high-quality ultra-high-performance concrete by smoothing the surface of ultra-high-performance concrete.

According to the present invention, it is possible to secure the strength of ultra-high-performance concrete that can be relied on by preventing moisture evaporation due to hydration reaction according to the curing mechanism of ultra-high performance concrete.

FIGS. 1A and 1B are photographs showing a state in which a surface finish agent is not applied in an ultra high-performance concrete according to a conventional technique.
FIG. 2 is a flowchart illustrating a method of manufacturing an ultra-high-performance concrete that prevents the surface of a concrete from drying using a planer type surface finishing agent according to an embodiment of the present invention.
FIGS. 3A and 3B are photographs showing that an oil-based surface finish is applied to an ultra-high-performance concrete according to an embodiment of the present invention to prevent the concrete surface from drying.
4 is a view illustrating the compressive strength of an ultra-high-performance concrete which prevents the surface of a concrete from being dried using a planetary surface finish according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when an element is referred to as "comprising ", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise.

[Manufacturing method of ultrahigh performance concrete to prevent drying of concrete surface by using surface type finishing agent of oil type]

FIG. 2 is a flowchart illustrating a method of manufacturing an ultra-high-performance concrete that prevents the surface of a concrete from drying using a planer type surface finishing agent according to an embodiment of the present invention.

2, an ultrahigh performance concrete which prevents drying of the surface of a concrete using a planetary surface finish according to an embodiment of the present invention has a compressive strength of 120 MPa or more, a tensile strength of 8 MPa or more and a flexural strength of 25 MPa or more, (W) corresponding to a unit water amount of ultrahigh performance concrete (UHPC: 100), wherein the water (W) corresponding to the unit water of the ultrahigh performance concrete (UHPC: And a binder (B) in which cement and silica fume are mixed is prepared (S110).

Here, the cement of the binder may be ordinary portland cement, crude steel portland cement, mixed cement or the like, but it is preferable to use portland cement in terms of economy.

In addition, the silica fume of the binding material is formed of spherical particles, so that the silica fume can improve the rheology characteristic of the cement paste by reducing the friction, and the pores between the cement particles can be filled to suppress the bleeding, Can be improved. In addition, the silica fume enhances strength and water tightness by a pozzolanic reaction with calcium hydroxide generated during hydration of cement, so that the performance of ultra high strength concrete according to the embodiment of the present invention can be improved. For example, the silica fume is preferably used in an amount of about 6 to 20 parts by weight based on 100 parts by weight of the cement so as to satisfy KS F 2567 (Korean Industrial Standard for Silica Fume for Concrete).

More specifically, the silica fume is a very fine pozzolanic material produced as a by-product in the process of producing silicon metal or ferro silicon in an electric arc furnace. Most of the silica fume is amorphous silicon And is also referred to as condensed silica fume or micro silica. Such silica fumes are classified into a powder form (undensified type or as-produced type) produced in the form recovered in the recovery process according to a material handling method, a granular form (condensed with a constant pressure) and a slurry Type). For example, the unit mass per unit product type of silica fume is 450 kg / m 3 or less for undensified type, 700 kg / m 3 or less for granular type, 1350 to 450 kg / m 3 for slurry type, .

For example, the composition of the cement and the silica fume can be shown in Table 3.

Next, the ratio (W / B) of the water-binder is adjusted to be 0.3 or less (S120).

Next, a high performance water reducing agent is compounded to prepare a compounding water (S130). That is, the compounding water is formed by mixing water and a high-performance water reducing agent, and is compounded with the binder to form a cement paste. Here, the high performance water reducing agent is, for example, polycarboxylic acid based, and the amount of the high performance water reducing agent can be adjusted depending on the fluidity. That is, the high-performance water reducing agent is based on the use of a polycarboxylic acid system, and the amount to be used can be appropriately determined depending on the water-binding ratio, the kind of the binder and the amount used.

Next, the aggregate containing no coarse aggregate is selected and prepared (S140). For example, the aggregate may be a fine aggregate, and the fine aggregate may be, for example, sand which passes through a 5 mm sieve and remains in a 0.08 mm sieve.

Next, the steel fiber is prepared, mixed with the binder, the fine aggregate and the compounding water, and the ultra-high-performance concrete 100 is placed on the mold (S150). Here, the steel fiber is introduced into the cement paste containing the binder and the blend water so as to improve the bending strength, toughness and crack resistance, and has a volume ratio (or fiber content ratio) of 0.5 to 5% with respect to the entire volume of the cement paste. Here, the steel fiber may be a steel fiber having a tensile strength of 1,500 MPa or more. For example, the steel fiber may be a steel fiber having a ratio of a fiber diameter (d) to a fiber length (L) It is preferable that the aspect ratio given is 60-100.

Next, the surface finish agent 200 of the oil type is immediately applied immediately after the ultra-high performance concrete 100 is poured to prevent the surface of the concrete from being dried (S160). In detail, the surface finish agent 200 is sprayed in a spray form on the surface of the concrete immediately after the super high performance concrete is poured, and the surface finish agent 200 is sprayed on the surface of the concrete, 5 mm. At this time, the surface finish agent 200 is uniformly applied to the whole concrete area so that the concrete surface is not dried. Here, in the case of the surface finishing agent 200, a known oil-based surface finishing agent may be used, and a detailed description of the kind of the product will be omitted.

Next, the ultra-high-performance concrete 100 is cured in a state where the surface finish agent 200 is applied to the surface of the concrete (S170).

Accordingly, according to the method for manufacturing ultra-high performance concrete which prevents drying of the surface of concrete by using the oil-based type surface finishing agent according to the embodiment of the present invention, the ultra high performance concrete is cast so as to improve the placement surface of ultra high performance concrete The oil-based surface finish can be applied to prevent surface drying.

[Experimental Example]

The formulation of the ultra high performance concrete which prevents the drying of the surface of the concrete using the oil-based type surface finishing agent according to the embodiment of the present invention can be shown in Table 4 below.

Specifically, the ultra high performance concrete which prevents the surface of the concrete from drying by using the oil-based type surface finishing agent according to the embodiment of the present invention is formed by mixing cement and silica fume, A binder (B) in which 30 parts by weight of silica fume is mixed; 80 to 130 parts by weight of fine aggregate based on 100 parts by weight of cement; 5 to 50 parts by weight of a steel fiber based on 100 parts by weight of cement; 15 to 30 parts by weight of water (W) based on 100 parts by weight of cement; And 3 to 6 parts by weight of a high-performance water reducing agent based on 100 parts by weight of cement, wherein a ratio (W / B) of the water-binding material is 0.3 or less and a fine aggregate ratio (S / a) do.

Meanwhile, FIGS. 3A and 3B are photographs showing that an oil-based type surface finishing agent is applied to an ultra-high performance concrete according to an embodiment of the present invention to prevent the surface of the concrete from being dried.

In an ultra high performance concrete which prevents the surface of a concrete from being dried by using a planer type surface finishing agent according to an embodiment of the present invention, FIG. 3A shows a case where the surface finishing agent 200 is applied and then the ultra high performance concrete 100 is finishing And FIG. 3B is a view showing the surface state of the ultra-high-performance concrete 100 after the surface finishing agent 200 is applied.

According to the embodiment of the present invention, an oil-based type surface finishing agent is applied immediately after the ultra-high performance concrete is cast so as to improve the placement surface of the ultra high performance concrete (UHPC) High-performance concrete can be manufactured by smoothing the surface of ultra-high-performance concrete. In addition, it is possible to manufacture a high-performance concrete with high performance by preventing water evaporation due to hydration reaction according to the hardening mechanism of ultra- The strength of the ultra-high-performance concrete can be secured.

4 is a view illustrating the compressive strength of an ultra-high-performance concrete that prevents drying of the surface of a concrete using a planetary surface finish according to an embodiment of the present invention.

As shown in FIG. 4, the concrete having a compressive strength of about 183 MPa is applied before the oil-based surface finish is applied. However, in case of the ultra-high performance concrete according to the embodiment of the present invention, Thereby obtaining a compressive strength of about 195 MPa. That is, in the case of the ultra high-performance concrete according to the embodiment of the present invention, the compression strength of about 10% is increased by applying the oil-based surface finish.

Also, an ultrahigh performance concrete structure manufactured by a method of manufacturing an ultra high performance concrete that prevents the surface of the concrete from being dried by using the above-mentioned oil type surface finishing agent can be provided.

As a result, according to the embodiment of the present invention, an oil-based type surface finishing agent is applied immediately after the ultra-high performance concrete is cast so as to improve the placement surface of ultra high performance concrete (UHPC) High performance concrete can be manufactured by smoothly polishing the surface of the ultra high performance concrete and by preventing the water evaporation due to the hydration reaction according to the hardening mechanism of the ultra high performance concrete, It is possible to secure the strength of reliable ultra high performance concrete.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

100: Ultra High Performance Concrete (UHPC)
200: Oily type surface finish

Claims (5)

(UHPC) having a compressive strength of at least 200 MPa, a tensile strength of at least 15 MPa, and a flexural strength of at least 35 MPa, and having a ratio (W / B) of water-
a) preparing water (W) corresponding to the unit water amount of ultrahigh performance concrete (UHPC: 100), and binder (B) in which cement and silica fume are mixed;
b) the ratio of water-binding material (W / B) is less than or equal to 0.3;
c) preparing a compounding water by mixing a high-performance water reducing agent;
d) preparing aggregates without coarse aggregate;
e) preparing a steel fiber, mixing it with the binder, fine aggregate and blended water, and casting ultra-high-performance concrete (100) on the formwork;
f) preventing the concrete surface from being dried by applying the oil-based surface finish agent (200) immediately after the super high performance concrete (100) is poured; And
g) curing the ultra-high performance concrete (100) in a state where the surface finish agent (200) is applied to the surface of the concrete
Wherein the surface of the concrete is prevented from drying by using an oil-based type surface finish. The method according to claim 1,
The surface finishing agent 200 of step f) is sprayed in a spray form on the surface of the concrete immediately after the super high performance concrete is poured. A method of manufacturing an ultra high performance concrete. 3. The method of claim 2,
Wherein the surface finishing agent (200) is applied to the surface of the concrete by 1 to 5 mm to prevent drying of the surface of the concrete using the oil-based surface finishing agent. 3. The method of claim 2,
Wherein the surface finish agent (200) is applied uniformly over the entire concrete area so that the concrete surface is not dried, thereby preventing the surface of the concrete from being dried. An ultra-high-performance concrete structure manufactured by a method of manufacturing an ultra-high-performance concrete which prevents drying of the surface of a concrete using the oil-based type surface finishing agent according to any one of claims 1 to 4.

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