How to install concrete floors and dirt floors

Abstract

To provide a construction method for floor or earth floor concrete that can reliably perform crack control at a surface layer by fiber mixing on the floor or earth floor concrete.SOLUTION: This construction method for floor or earth floor concrete includes the steps of: placing a first layer 11 of floor or earth floor concrete by means of concrete with no fiber mixed; and placing a second layer 12 directly superimposed on the first layer by means of concrete with synthetic fiber mixed in advance before the first layer being hardened. The second layer extensively constitutes the surface layer of the floor or earth floor concrete 10.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a method for constructing floor / earth floor concrete containing synthetic fibers. [Background technology]

[0002] Conventionally, there are known methods for controlling cracks in the surface layer by mixing fibrous materials such as steel fibers or synthetic fibers into a concrete floor. Such conventional floor surface layer reinforcing methods (1) to (5) are described below.

[0003] (1) Steel fiber scattering and holding method In this method, the floor and dirt floor concrete is poured, roughly leveled, and then steel fibers are spread evenly over the surface area, and pressed into the concrete from the surface layer during the first floor pressing, and the surface layer of the dirt floor and dirt floor is finished during the second and subsequent floor pressings. In this method, a vibrating tamping tamper is used on the surface layer during floor pressing to prevent the steel fibers and coarse aggregate from appearing on the surface, improving the quality and precision of the floor surface.

[0004] (2) Steel fiber mixed / evenly distributed direct pressing method In this method, the mixed concrete is put into an agitator truck, then a specified amount of steel fiber is mixed in from the top of the hopper, and the steel fiber is mixed evenly into the concrete by the high speed rotation of the drum. At the pouring site, the concrete mixed with steel fiber is poured in one layer on the floor or dirt floor to be poured, and during rough leveling, the steel fiber and coarse aggregate are sunk while checking the dryness of the surface layer, and depending on the condition, a vibrating tamping damper is effectively used to improve the quality and precision of the floor surface, just like in method (1).

[0005] (3) Synthetic fiber mixed / evenly distributed direct pressing method Methods (1) and (2) aim to achieve a mechanical effect on floor and concrete floors, and both involve mixing steel fibers into the concrete. However, this method involves mixing in polypropylene fibers (PP fibers), which are synthetic fibers that are mechanically inferior to steel fibers but have relatively superior mechanical properties, in the hope of controlling cracks on the surface of the components. In addition, this method does not cause problems such as rusting, as occurs with steel fibers.

[0006] (4) Synthetic fiber scattering method The synthetic fiber scattering method involves scattering a specified amount of PP fiber on the surface of the concrete after roughly leveling the poured concrete, and then using a trowel or tamper to press the concrete down while mixing the PP fiber into the surface layer of the concrete. The amount of fiber needed per area is measured in advance, and the fiber is scattered manually by workers or mechanically using a spreader. In either case, the amount is scattered while checking a photo of the target amount to be scattered in advance. This method allows a large number of PP fibers to be placed horizontally on the surface layer of the concrete, and the amount of fiber to bridge cracks can be placed more efficiently than in method (3).

[0007] (5) Self-leveling material Self-leveling slurry materials are commercially available as base materials for long sheets, carpets, and floor coverings. A mixer is manufactured on-site, and a specified amount is pumped with a mortar pump and poured onto the base slab, causing it to level under its own weight. The standard thickness is 10 to 15 mm, and some products contain fiber materials to prevent cracking, but in recent years, a system has been established to supply self-leveling materials using a dedicated vehicle that can handle mixing, transportation, and pumping all in one vehicle.

[0008] Patent Document 1 discloses a method of concrete construction in which concrete is poured approximately horizontally onto a dirt floor, slab, etc., chopped strands of glass fiber, polypropylene (PP) fiber, etc. are scattered on top of the concrete, the chopped strands are impregnated into the surface layer of the concrete, the concrete is buried in the surface layer, the concrete is leveled with a trowel, and then the concrete is dried and hardened.

[0009] Patent Document 2 discloses a method for suppressing the progression of cracks in concrete, in which short fiber-mixed concrete, such as synthetic fibers or steel fibers, is poured into the area in contact with the deck to construct a short fiber-mixed concrete section, and then, before the short fiber-mixed concrete hardens, regular concrete is poured continuously over the short fiber-mixed concrete section to construct the main body of the concrete wall, thereby minimizing the width of cracks that occur in the short fiber-mixed concrete section.

[0010] Patent Document 3 discloses a method for constructing a cement-based solidified body, which includes the steps of pouring concrete up to a position that will become the surface of the cement-based solidified body, arranging synthetic short fibers so that they are scattered on the surface of the concrete before hardening, and pressing down the surface on which the synthetic short fibers are arranged, in order to efficiently arrange reinforcing fibers that suppress the occurrence of cracks in the surface layer. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] JP 2003-213932 A [Patent Document 2] JP 2009-133083 A [Patent Document 3] JP 2020-93457 A Summary of the Invention [Problem to be solved by the invention]

[0012] In the above-mentioned steel fiber scattering and holding method (1), if the timing of floor holding is not caught, the three-dimensional corrugated steel fibers may not sink completely, and the fiber ends may become exposed, or even rust and stain the floor surface. In the case of the steel fiber mixing and evenly distributed direct holding method (2), the steel fibers are evenly distributed in the vertical cross-sectional direction of the floor and earth floor, so the mechanical effect of the fiber material on the surface layer must be evaluated lower than in method (1). In addition, the cost efficiency of the fiber material for the entire method is also lower. Furthermore, there is a possibility that the steel fibers may become exposed and stain the floor and earth floor surface with rust-causing substances.

[0013] In the case of the synthetic fiber mixed and evenly distributed direct pressing method (3), like the method (2), the PP fibers are evenly distributed in the vertical cross-sectional direction of the floor and floor, and some PP fibers are arranged to bridge the cracks that occur on the concrete surface, while many PP fibers are arranged parallel to the cracks and do not contribute to the crack suppression effect, so the mechanical effect of the fiber material in the surface layer must be evaluated lower than that of the method (1) and the like. The method of Patent Document 1 also has the same problem, but the cost efficiency of the fiber material is low compared to other methods. The method using the self-leveling material (5) has a limited range of application because the load-bearing capacity of the finishing material to which it is applied is about human load + α, and wheel loads such as automobiles and forklifts are not applicable.

[0014] The method of Patent Document 2 is intended to reduce the width of cracks that occur in the short fiber-mixed concrete section located between the deck and the main wall body made of ordinary poured concrete, but cannot be said to be a measure to prevent cracks on the entire surface of the floor concrete.

[0015] In the method (4) and the method of Patent Document 3, the uniform distribution of fibers is not necessarily statistically guaranteed, and there is doubt as to whether the pressing of the fibers that accompanies the floor pressing work can be achieved without defects together with the appearance of the floor surface. In other words, there is a problem that the degree of crack control in the floor surface is highly likely to be greatly affected by the probability of construction.

[0016] In view of the problems of the conventional technology as described above, the present invention has an object to provide a method for constructing floor and floor concrete that can reliably control cracks in the surface layer by mixing fibers in the floor and floor concrete. [Means for solving the problem]

[0017] A method for constructing floor and floor concrete to achieve the above object includes the steps of: casting a first layer of floor and floor concrete using concrete without any fiber mixed therein; and casting a second layer of concrete with synthetic fiber mixed therein directly on the first layer before the first layer hardens; The first layer is poured to a height such that at least a part of the surface of the uppermost outer reinforcing bar of the floor / slab concrete is exposed so that the uppermost outer reinforcing bar is positioned along the boundary between the first layer and the second layer; The second layer constitutes the entire surface of the floor / floor concrete.

[0018] According to this method of construction of floor concrete, the first layer, which is not related to surface cracks of the floor concrete, is poured as concrete without mixing in fibers, and then the second layer, which is made of concrete with synthetic fibers mixed in beforehand so that the synthetic fibers are evenly distributed, is poured directly on top of the first layer before the first layer hardens after pouring the first layer of concrete, and the second layer with synthetic fibers mixed in constitutes the entire surface layer of the floor concrete, so that crack control by mixing synthetic fibers can be reliably performed in the surface layer of the floor concrete, and surface cracks can be effectively suppressed. Also, since the second layer of concrete is poured when the first layer of concrete has adhesion before hardening, the first and second layers can be reliably integrated. Furthermore, by not mixing synthetic fibers into the first layer of the floor / floor concrete, and only mixing them into the second layer, the crack control effect of mixing the fibers can be concentrated on the surface layer. Also, less synthetic fiber is mixed in than when synthetic fibers are mixed into the entire floor / floor concrete, making it more cost-effective.

[0019] It is preferable that the first layer and the second layer are made of concrete of the same mix, and the second layer is made of concrete of the same mix with the synthetic fibers mixed in.

[0020] It is preferable that the concrete without fiber is transferred to an agitator car after mixing for pouring the first layer, the concrete without fiber after mixing is transferred to an agitator car for pouring the second layer, and the synthetic fibers are mixed into the concrete in the agitator car and mixed. In this case, it is preferable that about half of the amount of the synthetic fibers is mixed and mixed, and then the remaining synthetic fibers are mixed and mixed.

[0021] The first layer The above Top outermost rebar Approximately half the height of the vertical cross section It is preferable to pour the concrete up to the Effect of the Invention

[0022] According to the method for constructing floor and floor concrete of the present invention, cracks in the surface layer of floor and floor concrete can be reliably controlled by mixing fibers, and surface cracks can be effectively suppressed. [Brief description of the drawings]

[0023] [Figure 1] 1A to 1C are diagrams showing a construction process for floor and earthen floor concrete according to this embodiment. [Diagram 2] FIG. 2 is a diagram showing an example of the mix ratio of concrete used in the construction of the floor and earthen floor concrete of FIG. [Diagram 3] FIG. 3 is a diagram showing an overview of PP fiber as a synthetic fiber mixed into the concrete of FIG. 2. [Figure 4] 3A and 3B are longitudinal sectional views of essential parts showing steps (a) and (b) of pouring floor / earth floor concrete according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a diagram showing a process for constructing floor and floor concrete according to this embodiment. Fig. 2 is a diagram showing an example of a mix of concrete used for constructing the floor and floor concrete of Fig. 1. Fig. 3 is a diagram showing an overview of PP fiber as a synthetic fiber mixed into the concrete of Fig. 2. Fig. 4 is a longitudinal sectional view of a main part showing steps (a) and (b) of pouring floor and floor concrete according to this embodiment.

[0025] As shown in Figure 1, in the batcher plant, the measured fine aggregate, cement, and coarse aggregate are dry mixed, then the measured tap water and chemical admixtures are added, mixed, and left to stand. The mixed concrete is then transferred to a drum in an agitator vehicle, and after high-speed mixing for 30 to 60 seconds depending on the mix, it is discharged and subjected to the required tests such as slump value and slump flow value. After confirming that the test results meet the specified values, the concrete without fiber is transported from the batcher plant to the construction site by an agitator vehicle, and poured as the first layer of floor and earthen floor concrete.

[0026] On the other hand, the mixed concrete after being left to stand is transferred to the drum of another agitator vehicle, and about half of the mixed amount of short fibers (PP fibers) made of polypropylene (PP) as synthetic fibers is added to the drum of the agitator vehicle, and after high-speed mixing, the remaining PP fibers are added, and after high-speed mixing, the concrete is discharged and predetermined tests such as slump value and slump flow value are performed. After confirming that the test results meet the specified values, the concrete is transported from the batcher plant to the construction site by the agitator vehicle, and the PP fiber-mixed concrete is poured as the second layer directly on top of the first layer of concrete. Note that the synthetic fiber-mixed concrete is manufactured, tested, shipped, and transported in sequence so that the PP fiber-mixed concrete is poured in plenty of time before the first layer of concrete hardens.

[0027] Figure 2 shows an example of the mix of fine aggregate, cement, coarse aggregate, tap water, and chemical admixture (high-performance AE water-reducing agent) in Figure 1. Mix example 1 in Figure 2 is normal concrete without fiber for the first layer, and mix example 2 is fiber-mixed concrete for the second layer with PP fiber mixed in as shown in Figure 3. Mix example 2 is mix example 1 with PP fiber mixed in, and mix examples 1 and 2 are the same mix except for the PP fiber in mix example 2.

[0028] In the blending example 2 in Fig. 2, the amount of PP fiber mixed is 0.3 vol% by external ratio, but it may be in the range of 0.2 to 0.4 vol%. PP fiber is considerably lighter (specific gravity: 0.91) than steel fiber (specific gravity: 7.85), so it is easy to add and mix.

[0029] According to the construction process in Figure 1, the concrete in which each material has been weighed and mixed is first shipped to be poured as the first layer of floor and floor concrete, and then shipped to be poured as the second layer with fiber mixed in, so that the two layers are of the same mix except for the latter fiber. In this way, the concrete for the first layer and the concrete for the second layer (excluding fiber) can be of the same mix, so there is no need for a special management process to mix them separately in the batcher plant.

[0030] The concrete pouring process of Fig. 1 will be described with reference to Fig. 4(a)(b). As shown in Fig. 4(a), a reinforcing bar assembly 13 is assembled from a lower end main bar 13a and a lower end distribution bar 13b arranged perpendicular to each other and substantially parallel to the surface of the floor concrete (floor concrete or floor concrete), and an upper end main bar 13d and an upper end distribution bar 13c arranged perpendicular to each other. The concrete without fiber (mixture example 1) manufactured as shown in Fig. 1 is poured into the reinforcing bar assembly 13 as the first layer 11 of the floor concrete. The pouring height of the first layer 11 is set to a position near the upper end main bar 13d of the reinforcing bar assembly 13, and the pouring height of the second layer 12 to be poured in the subsequent process is set to 30 to 50 mm. In addition, the position near the upper main reinforcement 13d refers to a position where at least a portion of the surface of the upper main reinforcement 13d is exposed so as to adhere to the fiber-mixed concrete of the second layer, and it is desirable that approximately half of the vertical cross section of the upper main reinforcement 13d, which is the upper outermost reinforcing bar, is exposed at this position.

[0031] Next, as shown in Fig. 4(b), from the time when the concrete of the first layer 11 starts to set (initial setting) until it hardens, the fiber-mixed concrete (mixture example 2) manufactured as shown in Fig. 1 is poured directly on top of the first layer 11 to form the second layer 12. The second layer 12 is poured at a pouring height of 30 to 50 mm, which is sufficient as a cover thickness for the rebar. In other words, the pouring height of the second layer 12, 30 to 50 mm, exceeds the maximum diameter of the coarse aggregate, 20 mm, from the top end of the upper end main reinforcement 13d to the top surface 10a of the floor / earthen floor concrete, and is therefore considered sufficient as a cover thickness.

[0032] Since the fiber-mixed concrete of the second layer 12 is poured in succession from the setting (initial stage) of the first layer 11 before it hardens, the adhesive strength (before hardening) of the upper surface of the first layer 11 including the upper end main reinforcement 13d can be fully exerted to integrate the components without any special treatment at the interface between the first and second layers. The timing to start pouring the second layer 12 is related to the time required from pouring the concrete of the first layer 11 to setting (initial stage), and it is desirable to confirm and determine the optimal conditions under the same pouring conditions (air temperature, humidity, solar radiation, etc.) in advance by setting tests in accordance with JIS A 1147 (method of testing the setting time of concrete) depending on the mix of concrete to be poured, but if there is no time, the guideline for the time based on the outside air temperature specified in the Standard Specifications or JASS5 may be used.

[0033] In the above manner, floor / slab concrete 10 consisting of first layer 11 and second layer 12 can be constructed, with second layer 12 becoming fiber-mixed concrete with PP fibers evenly dispersed by mixing PP fibers in advance and thoroughly stirring, and this PP fiber-mixed second layer 12 forms the entire surface layer of floor / slab concrete 10. This ensures reliable crack control in the surface layer of floor / slab concrete 10 by mixing in PP fibers, and effectively suppresses surface cracks.

[0034] Also, by not mixing PP fiber into the first layer 11 of the floor / floor concrete 10, but mixing it into the second layer 12 only, it is possible to concentrate the crack control effect of mixing the fibers into the surface layer. Also, compared to mixing PP fiber into the entire floor / floor concrete, less PP fiber is mixed in, which is cost-effective.

[0035] Although the embodiments for carrying out the present invention have been described above, the present invention is not limited to these, and various modifications are possible within the scope of the technical concept of the present invention. For example, concrete mix examples 1 and 2 in Fig. 2 are only examples, and other mix examples may be used. In addition, polypropylene fiber (PP fiber) is used as the synthetic fiber in mix example 2, but the present invention is not limited to this, and for example, polyethylene fiber, nylon fiber, polyvinyl alcohol (PVA) fiber, polyester fiber, aramid fiber, polyethylene terephthalate (PET) fiber, and polyvinyl chloride fiber may be used. [Industrial Applicability]

[0036] According to the floor and floor concrete construction method of the present invention, crack control in the surface layer of the floor and floor concrete can be reliably carried out by mixing fibers, surface cracks can be effectively suppressed, and it is also cost-effective, so that floor and floor concrete with improved surface quality can be constructed without incurring significant costs. [Explanation of symbols]

[0037] 10 Floor / Concrete Floor 10a top surface 11 1st layer 12 2nd layer 13 Reinforcement assemblies 13d Top main bar

Claims

1. pouring a first layer of floor concrete using concrete without fiber; and before the first layer has hardened, pouring a second layer of concrete having synthetic fibers premixed therein directly over the first layer; The first layer is poured to a height such that at least a portion of the surface of the uppermost outer reinforcing bar of the floor / floor concrete is exposed so that the uppermost outer reinforcing bar is positioned along the boundary between the first layer and the second layer; A method for constructing a floor / floor concrete, in which the second layer entirely constitutes the surface layer of the floor / floor concrete.

2. the first layer and the second layer are made of concrete of the same mix; 2. The method for constructing floor / earth floor concrete according to claim 1, wherein the second layer is made of the same mix of concrete mixed with the synthetic fibers.

3. After mixing, the fiber-free concrete is transferred to an agitator car for pouring the first layer; 3. A method for constructing floor and earthen floor concrete as claimed in claim 1 or 2, in which the mixed concrete without any mixed fiber is transferred to an agitator car for pouring the second layer, and the synthetic fiber is mixed into the concrete in the agitator car and stirred.

4. 4. The method for constructing floor and earthen floor concrete according to claim 3, further comprising mixing and stirring approximately half of the amount of said synthetic fibers, and then mixing and stirring the remaining amount of said synthetic fibers.

5. 5. A method for constructing floor / earth floor concrete according to claim 1, wherein the first layer is poured to a height of approximately half the vertical cross section of the uppermost outermost reinforcing bar.

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