JP4526625B2 - Method for producing precast concrete member - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a precast concrete member suitable for producing a precast concrete column in a short period of time, for example, at a construction site.
[0002]
[Prior art]
Conventionally, for example, when precast concrete pillars are manufactured in a factory, when it is necessary to complete them in a short time of about a day, the concrete is heated by steam curing or curing using a heating element as described below. By doing so, it was forced to dry.
[0003]
That is, in steam curing, for example, concrete is placed in a mold made of steel, and then the mold is covered with a sheet, and the concrete is forcedly dried by carrying it in a steam atmosphere and heating it.
[0004]
In curing using a heating element, a heating element such as a plate heater is attached to the outer peripheral surface of a steel plate mold, and the concrete is forcibly dried by heating the concrete with the heating element.
[0005]
On the other hand, when precast concrete pillars are manufactured in a short period of time, for example, at a construction site, it is normal that there is no equipment for steam curing, for example, curing using a heating element such as a plate heater. It was general.
[0006]
[Problems to be solved by the invention]
However, in the conventional steam curing or curing with a heating element, there is a problem in that the equipment is enlarged or complicated in any case and the cost is increased.
[0007]
That is, in steam curing, a boiler for generating steam is necessary, and a sealed room is required to create a steam atmosphere, and this sealed room is also a considerably large room that can accommodate a precast pillar. Will be necessary, resulting in large equipment.
[0008]
If a heating element is used, the concrete is heated by attaching it to the outer peripheral surface of the formwork. However, if the current is applied as it is, the temperature of the heating element becomes very high, so it is used for curing concrete. Is impossible. Therefore, it is necessary to control the temperature of the heating element so as to be suitable for curing the concrete, and to change the temperature with time. In order to execute this, generally, computer control or the like is required, so that the facilities become complicated. In particular, the concrete top edge away from the heating element often suffers from surface cracks due to initial effects.
[0009]
Such a problem may occur when manufacturing various types of precast concrete members as well as precast concrete columns.
Therefore, the present invention prevents the occurrence of cracks without using complex equipment such as a heating element when there is no steam curing equipment as in a construction site, etc., and precasts in a short time with a simple configuration. It aims at providing the manufacturing method of the precast concrete member which can manufacture a concrete member.
[0010]
[Means for Solving the Problems]
In order to solve the above problems, the present invention has the following configuration. That is, according to the present invention, after forming a form of a precast concrete member in which the outer periphery of the form is covered with a heat insulating material, concrete is placed in the form, and the concrete placed in the form is The top is covered with a heat insulating material, and the concrete is cured in a state where the outer periphery of the mold and the top end are covered with the heat insulating material.
[0011]
Next, the configuration of each unit will be described.
(Formwork)
Although a formwork is not specifically limited, For example, it can comprise with a steel plate etc. By making a part of this mold form openable and closable, the internal precast concrete member can be easily taken out.
(Insulation material)
It prevents the heat of hydration from escaping from the outer peripheral surface of the formwork and the top edge of the concrete to the outside. The material is not particularly limited, but it is lightweight and rigid, such as foam, which is easy to handle. It is desirable. Glass wool can also be used.
[0012]
When a foam material is used, the foam material is placed when the water on the top end is almost gone. This is because if the foam is placed when there is moisture on the top edge, the cement component contained in the moisture will penetrate into the foam bubbles and the foam will be It is because it will adhere to.
(Cover member)
The cover member prevents the heat insulating material from adhering to the top edge of the concrete or the unevenness of the surface of the heat insulating material from affecting the top edge, and it is possible to use a sheet or plate member, etc. it can.
[0013]
According to the present invention, the heat of hydration generated when the cement component in the concrete reacts with water is not released to the outside by the heat insulating material covering the outer peripheral surface of the mold and the top end of the concrete. Accumulated within. As a result, the concrete is heated with heat of hydration and forced to dry, and curing is completed in a short period of time.
[0014]
In addition, by covering the top end with a heat insulating material, the concrete including the top end is dried at a uniform speed as a whole, so surface cracks that occur when the drying speed on the surface side and inside of the concrete are different. Can be prevented.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a method for producing a precast concrete member according to the present invention will be described in detail with reference to the drawings.
[0016]
FIG. 1 is a cross-sectional view illustrating a case where the present invention is applied to a precast concrete column, and shows a state during curing of concrete.
This method for producing a precast member is suitable for producing a precast concrete column or the like in a short period of time, for example, about one day, in a place where there is no steam curing equipment or curing equipment such as a heating element such as a construction site.
[0017]
In this method of manufacturing a precast member, for example, the outer periphery of a steel plate mold 11 is covered with a heat insulating material 13 and concrete 12 is placed in the assembled mold 11. The heat insulating material 13 is prevented from falling off by the pressing plate 14. A plurality of reinforcing bars 15 are embedded in the concrete 12. This reinforcing bar 15 protrudes above the top end 12a of the concrete 12, and this protruding part is used as a main reinforcing member such as a beam member (not shown) to be placed on the precast concrete pillar when it is installed on site. Combined.
[0018]
Further, in order to prevent the position of the reinforcing bar 15 from being displaced, a reinforcing plate restraining template 16 is fitted into the protruding portion of the reinforcing bar 15. Further, a heat insulating material 17 is placed on the top end 12 a of the concrete 12 while avoiding the reinforcing bars 15. Reference numeral 18 in the figure is the base of the mold 11.
[0019]
Next, the configuration of each unit will be described in detail. The formwork 11 is assembled so that the precast concrete pillar is manufactured in a standing state in the same manner as the actual installation form. The mold 11 has a very high height of about 2.3 m, for example, and is thus divided into a plurality of blocks 11a to 11e. Each of the blocks 11a to 11e is formed of a plate member such as a steel plate, and a reinforcing rib 19 is provided on the upper end thereof. These blocks 11a to 11e are stacked and fixed.
[0020]
Each of the blocks 11a to 11e is formed in a frame shape having a quadrangular cross section as shown in FIG. And the side-plate part 21 is provided in the both ends of plate member 20a-20d which comprises four surfaces of these blocks 11a-11e.
[0021]
In addition, among the plate members 20a to 20d constituting the four surfaces of each block 11a to 11e, two adjacent surfaces, in this embodiment, the plate members 20a and 20d that form the left and lower surfaces in FIG. As will be described below, they are attached to other adjacent plate members 20b and 20c so as to be freely opened and closed.
[0022]
That is, one side plate portion 21 of the plate members 20a and 20d includes a bracket 22 provided on the side plate portion 21, a bracket 23 provided on the side plate portion 21 of the adjacent plate members 20b and 20c, and these brackets 22, It is attached to the adjacent plate members 20b and 20c via pins 24 that connect 23, so that it can be opened and closed freely.
[0023]
The heat insulating material 13 affixed to the outer peripheral surface of the mold 11 prevents the heat of hydration generated when the components in the cement combine with water while curing the concrete 12 in the mold 11 to the outside. This is for forcibly drying the concrete 12 with this heat of hydration, and the thickness of the heat insulating material 13 required for this depends on the material, but in any case, the above-mentioned purpose can be achieved. Thickness.
[0024]
In the present embodiment, a foam material is used as the heat insulating material 13. This foam is convenient because it is lightweight and rigid, and is easy to handle, and also has a large heat insulating effect, so that the thickness can be reduced.
[0025]
The heat insulating material 17 (FIG. 1) placed on the top end portion 12a of the concrete 12 also uses a foam material in the same manner as the above heat insulating material 13, but here the top end portion 12a with the foam material exposed. Place on top. Thereby, the top end 12a is entirely covered with the heat insulating material (foaming material) 17.
[0026]
When the heat insulating material 17 is placed on the top end 12a, the top end 12a is flattened with a “trowel”. After that, after confirming that the water floating on the top end portion 12a has permeated into the concrete 12 or evaporated and almost disappeared, the heat insulating material 17 is placed.
[0027]
This is because when the heat insulating material 17 is placed when there is moisture on the top end portion 12a, the mortar contained in the water enters into the bubbles or gaps of the heat insulating material 17 together with the water, and when this heats, the heat insulating material This is because 17 adheres to the concrete 12 and is difficult to remove. It should be noted that the time for almost no moisture on the top end 12a is about 5 minutes to 10 minutes, and the surface hardening starts when too much time elapses.
[0028]
As shown in FIG. 3, the heat insulating material 17 includes a rectangular block 17 a that covers a portion surrounded by the reinforcing bar 15 of the top end portion 12 a and rectangular blocks 17 b and 17 c of two sizes that cover a portion outside the reinforcing bar 15. It is divided into and. Thus, by dividing the heat insulating material 17 into blocks, even if there is a reinforcing bar 15, it can be easily attached and detached.
[0029]
As shown in FIG. 4, the template 16 for restraining the reinforcing bars 15 is formed into a quadrangular shape made of wood, for example, and through holes 27 are provided inside the reinforcing holes 15 in accordance with the positions of all the reinforcing bars 15. The rebar 15 is passed through. The template 16 is fixed to the reinforcing bar 15 or an appropriate member nearby.
[0030]
Next, the construction procedure of this precast concrete member manufacturing method will be described.
Here, first, as shown in FIG. 5, the base 18 is arranged at an appropriate place on the construction site, and the mold 11 is assembled thereon. Although the heat insulating material 13 and the pressing plate 14 are attached to the mold 11 in advance, the heat insulating material 13 and the pressing plate 14 can be attached after the mold 11 is assembled.
[0031]
After assembling the mold 11, the reinforcing bar 15 is arranged in the mold 11, and an appropriate part of the reinforcing bar 15 is fixed to the mold 11 with a support member (not shown).
Next, as shown in FIG. 6, concrete 12 is placed in the mold 11 by the concrete supply hose 27. Then, after the concrete 12 is driven to a predetermined height in the mold 11, the top end 12 a of the concrete 12 is leveled with a “trowel” and finished flat.
[0032]
In this state, the apparatus waits for a short time until there is almost no moisture floating on the top end 12a. And as soon as the water | moisture content on the top end part 12a is almost lost, each block 17a-17c of the heat insulating material 17 is mounted on the top end part 12, as shown in FIG. Since the heat insulating material 17 is not likely to be blown away by the wind in the room, it may be simply placed, but when there is wind, the heat insulating material 17 is fixed by placing a weight on the heat insulating material 17. Next, the template 16 is fitted and fixed to the upper side of the reinforcing bar 15.
[0033]
When the concrete 12 is cured in this state, the cement component in the concrete 12 reacts with water to generate heat of hydration. The heat of hydration is accumulated in the concrete 12 without being released to the outside by the heat insulating material 13 covering the outer periphery of the mold 11 and the heat insulating material 17 covering the top end portion 12a.
[0034]
With the accumulated heat of hydration, the concrete 12 is heated and forcibly dried, and the curing of the concrete 12 is completed in a short period of about one day, and the concrete 12 is cured to a predetermined hardness. Here, the formwork 11 can be removed and, for example, the reinforcing bar 15 can be lifted and conveyed to the installation location.
[0035]
In addition, although the outer periphery of the mold 11 was initially covered with the heat insulating material 13, the concrete 12 was cured only by placing the sheet without covering the top end portion 12a with the heat insulating material 17. As shown in FIG. From 15 to the side end face of the concrete 12, surface cracks 28 due to initial curing occurred. The surface crack 28 continued from the top end 12a to a substantially constant depth as shown in FIG.
[0036]
As described above, the reason why the surface crack 28 is generated around the reinforcing bar 15 is that the top end 12a is exposed to the air at the top end 12a during curing of the concrete 12 when the top end 12a is not covered with the heat insulating material 17. It is thought that the portion that is dry-cured first starts to shrink and shrinks, but because the interior is before curing, a tensile stress is generated on the surface, and the concrete 12 around the reinforcing bar 15 is pulled outward by this tensile stress. The surface crack 28 is more likely to occur as the concrete has less moisture and has higher strength.
[0037]
In contrast, in the present invention, both the outer periphery of the mold 11 and the top end 12a are covered with the heat insulating materials 13 and 17, respectively, as described above. Since it became almost uniform, the occurrence of surface cracks 28 was not observed. Thus, it can be seen that the top end 12a must be covered with the heat insulating material 17.
[0038]
Thus, according to the method for producing a precast concrete column of the present invention, the outer periphery of the mold 11 and the top end portion 12a of the concrete 12 are cured in a state of being covered with the heat insulating materials 13 and 17 such as a foam material. The heat of hydration of the concrete 12 is accumulated inside, and the concrete 12 is heated and forcedly dried by the heat of hydration.
[0039]
Thereby, a precast concrete pillar can be manufactured in a short period of about one day. In addition, large-scale facilities and complicated facilities such as steam curing and heat plate curing are not required, and a significant cost reduction is possible.
[0040]
Furthermore, in the present embodiment, since the precast concrete pillar is manufactured in an upright state, when it is completed, it only moves to the installation position as it is, and it is not necessary to stand a heavy precast concrete pillar. The number of times of using large machines such as is reduced.
[0041]
In the above-described embodiment, the heat insulating material 17 is directly placed when the moisture on the top end 12a is almost exhausted. However, the heat insulation is performed with moisture remaining on the top end 12a. When the material 17 needs to be placed, as shown in FIG. 10, a cover member 26 having a smooth surface such as a sheet or a steel plate (both not shown) is placed on the top end 12a. The heat insulating material 17 can be placed on the member 26. Thereby, it can prevent that the heat insulating material 17 adheres to the concrete 12. FIG.
[0042]
In addition, when using a member whose contact surface with the top end 12a is not flat, such as glass wool, as the heat insulating material 17, a cover member 26 is laid on the top end 12a, and the heat insulating material is provided thereon. By placing 17, the top end 12a can be finished flat.
[0043]
Furthermore, in the above-described embodiment, the heat insulating material 17 or the cover member 26 is directly placed on the top end portion 12a. However, the object of forcibly drying the concrete 12 by heat of hydration generated in the concrete 12 is achieved. If possible, there may be a certain gap between the heat insulating material 17 or the cover member 26 and the top end portion 12a.
[0044]
Moreover, in the above-mentioned embodiment, although the case where it manufactures in the state which stood the precast concrete pillar like the actual usage form was demonstrated, the case where it manufactures with the precast concrete pillar lying down as shown in FIG. Also, the present invention can be applied.
[0045]
Also in this case, the outer periphery of the horizontally assembled mold 31 is covered with the heat insulating material 32, and the top end portion 33a of the concrete 33 placed in the mold 31 is covered with the heat insulating material 34, so that the precast can be performed in a short time. Can produce concrete pillars. In FIG. 11, reference numeral 35 denotes a reinforcing bar, 36 denotes a pressing plate, 37 denotes a reinforcing-restraining template, and 38 denotes a base.
[0046]
In the above-described embodiment, the case where the present invention is applied to a precast concrete column has been described. However, the present invention is not limited to this and can be applied to various precast concrete members.
[0047]
【The invention's effect】
As described above, according to the present invention, the heat of hydration generated when the cement component in the concrete reacts with water is accumulated in the concrete by the heat insulating material, and the concrete is forced by the heat of hydration. Since it is dried, the precast concrete member can be manufactured in a short period of time.
[0048]
In addition, by covering the top end portion of the concrete with a heat insulating material, the top end portion and the inside are dried at a substantially uniform speed, so that it is possible to prevent surface cracks due to initial hardening from occurring at the top end portion.
[0049]
Further, when the heat insulating material is a foam material, it is easy to handle because it is lightweight and has high rigidity, and the thickness can be reduced because the heat insulating effect is high.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view for explaining a method for producing a precast concrete member of the present invention.
FIG. 2 is a cross-sectional view taken along the line AA of FIG.
3 is a cross-sectional view taken along the line BB in FIG.
FIG. 4 is a plan view showing a rebar constraining template according to the present invention.
FIG. 5 is a diagram showing a construction procedure of the present invention.
FIG. 6 is a diagram showing a construction procedure of the present invention.
FIG. 7 is a diagram showing a construction procedure of the present invention.
FIG. 8 is a plan view showing surface cracks occurring at the top edge of concrete.
9 is a view taken in the direction of arrow C in FIG.
FIG. 10 is a cross-sectional view showing another embodiment of the present invention.
FIG. 11 is a cross-sectional view showing another embodiment of the present invention.
[Explanation of symbols]
11, 31 Formwork 12, 33 Concrete 12a, 33a Top end parts 13, 17, 32, 34 Heat insulating material 26 Cover member

Claims (3)

After forming the formwork of the precast concrete member whose outer periphery is covered with a heat insulating material, concrete is placed in the formwork and foamed on the top edge of the concrete placed in the formwork It is a method for producing a precast concrete member that is covered with a heat insulating material made of a material, and that cures the concrete in a state where the outer periphery of the formwork and the top end portion are covered with the heat insulating material,
A method for producing a precast concrete member, characterized in that when the water on the top end is exhausted, the top end is covered with the heat insulating material. The method for producing a precast concrete member according to claim 1 , wherein a cover member is disposed on the top end portion, and the heat insulating material is disposed on the cover member. The said precast concrete member is a precast concrete pillar, The manufacturing method of the precast concrete member of Claim 1 or 2 characterized by the above-mentioned.

Images