KR100726115B1 - Round pre-concreting method - Google Patents

Abstract

A method of round pre-concreting is provided to round pre-concrete around edges of a vertical structure such as a pillar to decrease cracks of concrete without a reinforcing rod. A method of round pre-concreting includes the steps of: (a) installing a rounding form(10) around a lower part of a vertical structure(1) such as a pillar and a breast wall, etc.; (b) pre-concreting and curing concrete(50) in the rounding form; and (c) concreting and curing the concrete to other floors after installing the rounding form. A plurality of support elements are fixed on a floor surface. After fixing the support elements on the floor surface, a reinforcing bar is arranged in the rounding form. The reinforcing bar is a curve reinforcing bar or a linear reinforcing bar. The curve and linear reinforcing bars are mixed and arranged around the vertical structure. After removing the rounding form, the concrete is concreted and cured in other floor surfaces.

Description

Round pre-concreting method

Figure 1 shows step by step round concrete casting method according to the invention.

Figure 2 shows a cross section and a junction of an embodiment of a rounded foam.

Figure 3a shows an example of applying the round concrete casting method according to the present invention to the basement-free concrete finish portion.

Figure 3b shows an example of applying the round concrete casting method according to the present invention on the ground-floor-free concrete finish.

<Explanation of symbols for the main parts of the drawings>

1: vertical structure (column) 2: floor surface (floor slab)

10: rounding foam 20: bracing material

30a: Curved reinforcement 30b: Straight reinforcement

40: Filler 50: Concrete (pumping, rootless)

60: concrete (futa casting, rootless)

The present invention is a concrete precasting method for reducing cracks of hardened concrete, which is placed on a floor slab, and more specifically, in contact with the floor slab by focusing on the point where the crack of the bare concrete starts from the edge of the column or retaining wall. This method is to reduce the occurrence of cracks by laying concrete round around the edges of vertical structures such as columns and retaining walls.

Plain concrete is concrete that is not reinforced with tensioning materials, such as steel bars or steel frames. Concrete has a high compressive strength and a small tensile strength, so it is used to reinforce tensile force in a structure subjected to tensile stress, but only compressive stress occurs in roads, lower floors, foundations of small buildings, gravity retaining walls, and gravity dams. In economic terms, plain concrete is used a lot.

However, since concrete is a composite material and is affected by various conditions, concrete frequently cracks due to concrete material factors, external environmental factors, and construction factors. If a crack occurs in a concrete structure, it can cause fatal losses due to structural defects, durability degradation, appearance damage, corrosion and water resistance, etc. Therefore, pay attention to the material selection, mix design, construction, and structure evaluation of concrete from the initial stage of design. Should be tilted.

When finishing floors such as basement slabs with bare concrete, cracks of bare concrete usually begin at the edges of vertical structures such as columns and retaining walls. Therefore, there is a need for measures to prevent cracks occurring from the edges of the vertical structures in advance.

The present invention for solving the above problems is to provide a concrete placing method that can block the crack of the rootless concrete generated from the edge of the vertical structure, and can absorb the crack due to the shrinkage, expansion properties of the concrete.

The present invention is a concrete pre-pouring method for reducing the crack of the rootless concrete placed on the floor surface, (a) installing a rounding foam around the bottom of the vertical structure, such as columns, retaining walls; (b) pre-casting and curing concrete inside the rounding foam; And (c) after demolding the rounding foam, placing concrete on the remaining bottom surface and curing; It provides a round concrete pour method comprising the.

Figure 1 shows step by step round concrete casting method according to the invention. Figure 2 shows a cross section and a junction for one embodiment of a rounding foam. Figure 3a shows an example of applying the round concrete casting method according to the present invention to the basement-free concrete finish portion. Figure 3b shows an example of applying the round concrete casting method according to the present invention on the ground-floor-free concrete finish.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

1.step (a)

This step shown in (a) of Figure 1 is a step of installing a rounding foam 10 around the bottom of the vertical structure (1), such as columns, retaining walls. The rounding foam 10 refers to a formwork having a concrete pouring surface of the curved surface as a kind of formwork. When finishing the floor with bare concrete, cracking occurs mainly from the edges of the vertical structure (1), so that concrete is cast in a predetermined range around the bottom of the vertical structure (1), so as to be in contact with concrete that is post-installed on the other floor. The site can act as a stretch joint for the shrinkage and expansion properties of concrete.

However, if the concrete pour site is composed of an angular shape such as a lozenge, cracks may occur again from the corners of the concrete site after the concrete is poured and cured on the remaining bottom surface. Pre-casting concrete to form a stretch joint, but to prevent the occurrence of cracks in the post-cast concrete surface by rounding the concrete casting site. The width of the rounding foam 10 is preferably manufactured according to the height of the rootless concrete placing.

After the rounding foam 10 is installed, the rounding foam 10 further includes a step of arranging a plurality of bracing materials 20 around the rounding foam 10 and fixing the bracing material 20 to the bottom surface. 10) In the process of pouring and curing concrete in the installation position of the rounding foam 10 can be prevented from changing.

After fixing the support material 20 to the bottom surface, it may further include a step of reinforcing the reinforcing bar for suppressing the occurrence of cracks in the concrete placing portion inside the rounding foam (10). As the reinforcing bar, a reinforcing bar or a wire mesh may be used. The curved reinforcing bar 30a and the straight reinforcing bar 30b may be mixed around the vertical structure to be reinforced to effectively prevent cracking in various directions. At this time, the curved reinforcement (30a) and the straight reinforcement (30b) is not to play a role of bearing the tensile load, but to be reinforced for cracking, so the concrete 50 to be poured in this step can also be made of bare concrete.

The rounding foam 10 is easy to manufacture a metal material. In addition, after the rounding foam 10 is installed, a release agent is applied to the inner circumferential surface of the rounding foam 10 to facilitate the deforming operation of the rounding foam 10 to be described later.

FIG. 2 (a) is a cross-sectional view of the rounded foam 10 cut vertically, and FIG. 2 (b) shows the details of the joint when the rounded foam 10 is formed in two semicircles to be bonded to each other. It is also.

The rounding foam 10 is mounted along the outer circumferential surface of the formwork 11, the formwork as shown in Fig. 2 (a), spaced apart at regular intervals to form an integral with the formwork 2 A rod-shaped member inserted between the reinforcing board 12 of the sheet and the reinforcing board 12 of the sheet and arranged at a predetermined interval, comprising a plurality of reinforcing rods 13 integrally with the reinforcing board 12 to constitute concrete It is possible to sufficiently counteract the lateral pressure generated during the casting and curing process.

On the other hand, when the rounding foam 10 is installed around the lower end of the column 1, as shown in Figure 2, the two rounding foam 10 separated in a semicircular contact with each other to form a round formwork Each end of the semi-circular rounding foam 10 is coupled between the two reinforcing boards 12 and penetrates through the reinforcing plate 14 and the reinforcing plate 14 which are integral with the reinforcing board. By further comprising a fastener, it is possible to greatly improve the construction efficiency of the work of installing the rounding foam 10 around the bottom of the column as well as providing the convenience of manufacturing, transporting the rounding foam (10). The fastener may use a variety of bolts (15a), nuts (15b), rivets, and the like.

2. Step (b)

This step shown in Figure 1 (b) is the step of placing and curing the concrete 50 inside the rounding foam (10). Precast concrete 40 in this step can be used to suppress the occurrence of cracking of the concrete using the addition of the fiber reinforcement. Nylon fiber may be used as the fiber reinforcing material, and when nylon fiber is added, the bonding strength of cement paste may be strengthened by mutual electrostatic action between nylon and water, and the effect of reducing cracks may be enjoyed, as well as chemical resistance, abrasion resistance, and magnetic resistance. Is improved.

On the other hand, in this step, before the concrete 50 is placed inside the rounding foam 10, the filler 40 may be installed on the lower side of the vertical structure (1). The filler 40 separates the vertical structure 1 and the precast concrete 50 to minimize the possibility of cracking due to expansion and expansion that occurs at the joint surface of the vertical structure 1 and the precast concrete 50. Is to install. At this time, the filler 40 is installed to protrude higher than the finish surface of the precast concrete 50 inside the rounding foam 10, as shown in Figure 1 (b), the precast concrete 50 After curing, it is possible to finish by removing the filler 40 higher than the finish surface of the pre-cast concrete 50, it is preferable to use a material that can be easily removed, such as iso pink as the filler 40.

When placing concrete 50 in this step, it is necessary to thoroughly control and compact the upper level to prevent cracking due to construction errors.

3. Step (c)

This step shown in (c) of FIG. 1 is a step of pouring and curing concrete 60 without reinforcement on the remaining bottom surface 2 after demolding the rounding foam 10. When dismantling the rounding foam (10), check whether there is sufficient curing and cracking, and pay attention to the impact. When cracking occurs in the precast concrete 50, the cracking site may be repaired by micro cement. Microcement is an ultra fine injection material, and is mainly used for grouting, repairing cracked rock or soft ground.In the case of cracking in the cast-in-place concrete 50, the microcement, which is similar to the elasticity of concrete, is used to It can be repaired primarily.

3A and 3B are respectively The application of the round concrete casting method to the basement-free concrete finishing and the example of the ground-floor-free concrete finishing.

In the basement floor, as shown in FIG. 3a, the concrete 50 is cast in a circular shape around the column 1 in contact with the floor slab 2, and the drainage plate 3 is installed on the remaining bottom surface. You can finish by pouring concrete (60) without reinforcement.

In the ground layer, as shown in FIG. 3b, the concrete 50 is cast in a circular shape around the column 1 in contact with the floor slab 2, and the waterproofing layer 4 and the protective mortar 5 are disposed on the remaining bottom surface. After the construction in sequence, can be finished by pouring concrete 60 without reinforcement of the rebar.

According to the present invention as described above, i) expansion joint between the vertical structure and the pre-pouring concrete, the pre-pouring concrete and the post-pouring concrete is formed to prevent cracking due to the contraction and expansion of the concrete, ii) the pre-pouring concrete It is a rounding foam that is formed in a curved shape such as a circle to prevent the occurrence of cracks from the edges. Ⅲ) Reinforcement is added before the pour concrete, the pour concrete is reinforced with fiber reinforcement, The cracking area can be repaired with microconcrete to minimize the occurrence of cracking in the concrete.

Therefore, the maintenance cost due to cracking of the bottom surface treated with plain concrete is reduced, and the quality of the plain concrete finish surface is excellent, and the tile, epoxy coating, and resin mortar that are applied on the top of the plain concrete finish surface Damage to the back can be prevented.

Claims (11)

In concrete casting method to reduce cracks of plain concrete placed on the floor, (a) installing a rounding foam around the bottom of a vertical structure such as a column or a retaining wall; (b) pre-casting and curing concrete inside the rounding foam; And (c) after demolding the rounding foam, placing concrete on the remaining bottom surface and curing; Round concrete casting method, characterized in that it comprises a. The method of claim 1, wherein step (a) comprises: After the rounding foam installation, the round concrete casting method, characterized in that it further comprises the step of arranging a plurality of support material around the rounding foam, and fixing the support material to the bottom surface. The method of claim 2, wherein step (a) comprises: After fixing the brace material to the bottom surface, round concrete casting method, characterized in that further comprising the step of reinforcing the reinforcement inside the rounding foam. The method of claim 3, wherein step (a) comprises: Round concrete casting method, characterized in that the reinforcement by mixing the curved reinforcement and straight reinforcement around the vertical structure. In claim 2, The rounding foam is made of a metal material, Step (a), after the rounding foam installation, round concrete casting method, characterized in that further comprising the step of applying a release agent on the inner peripheral surface of the rounding foam. In claim 5, The rounding foam, the formwork of the curved surface; Two reinforcement boards mounted along the outer circumferential surface of the formwork, spaced apart from each other at a predetermined interval to form a unit with the formwork; And a rod-shaped member interposed between the two reinforcing boards and disposed at a predetermined interval, the plurality of reinforcing bars integral with the reinforcing board; Round concrete casting method, characterized in that comprising a. In claim 6, The rounding foam is to be installed around the bottom of the column, two rounding foam separated in semicircular contact with each other to form a circular formwork, At each end of the semi-circular rounding foam, the reinforcing plate is sandwiched between the two reinforcement boards and integral with the reinforcement board; And Fasteners coupled to and fixed through the reinforcing plate; Round concrete casting method, characterized in that further comprises a. The method of claim 2, wherein step (b) Round concrete pre-pouring method characterized in that it further comprises the step of installing a filler on the lower side of the vertical structure before the concrete is placed inside the rounding foam. In claim 8, The filler is installed higher than the precast concrete finishing surface inside the rounding foam, In the step (b), after the curing of the pre-cast concrete, round concrete pre-pouring method further comprising the step of removing the filler higher than the finish surface finish. The method of claim 2, wherein step (c) comprises: Before and after the rounding foam demoulding check whether or not cracking of the pre-pouring concrete, if the crack occurs round concrete pre-pouring method characterized in that it further comprises the step of repairing the cracks with a micro cement. The method according to any one of claims 1 to 10, The step (b), the concrete round casting method, characterized in that the concrete reinforcement, pour concrete added.

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