Method for producing precast concrete members
By using a setting retarder to delay concrete hardening and washing away the delayed layer, the method addresses time constraints and ensures robust irregularities on precast concrete member joints, improving durability.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- ドーケン
- Filing Date
- 2024-11-06
- Publication Date
- 2026-05-19
AI Technical Summary
Existing methods for creating irregularities on the surface of precast concrete members to prevent slippage at construction joints are time-constrained and result in weak, easily damaged surfaces.
A method involving the use of a setting retarder to delay the hardening of concrete on the joint surface, followed by washing away the delayed concrete with a washing machine to create uneven surfaces.
This approach alleviates time constraints and ensures robust, uniform irregularities can be formed on the joint surfaces without manual damage, enhancing the strength and durability of precast concrete members.
Smart Images
Figure 2026082088000001_ABST
Abstract
Description
Technical Field
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[0001] The present invention relates to a member production method for producing precast concrete members.
Background Art
[0002] Concrete members include those cast in place and precast ones.
[0003] Cast-in-place concrete members are manufactured at the construction site by assembling a formwork at the construction site and placing concrete into the formwork. Since cast-in-place concrete members are worked at the construction site, a long period is required for the construction.
[0004] Precast concrete members are concrete members prefabricated in a factory or the like. Precast concrete members are manufactured in a factory or the like, transported from the factory to the construction site, and work such as installation is carried out. Therefore, the period required for the construction can be shortened.
[0005] In addition, generally, since precast concrete members are transported from a factory or the like to the construction site, a cleaning process such as water washing is performed (see Patent Document 1).
Prior Art Documents
Patent Documents
[0006]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0008] Figure 5 is a flowchart showing an example of a conventional method for producing precast concrete members. First, concrete is poured into the formwork (Step STB1). Next, the first curing period is allowed to pass (Step STB2), the surface of the joint is manually scratched (Step STB3), and the second curing period is allowed to pass (Step STB4). Between Steps STB2 and STB4, the precast concrete members are removed from the formwork. Then, the precast concrete members are washed with water using a washing machine (Step STB5), and the precast concrete members are produced (Step STB6).
[0009] However, the process of creating scratches on the concrete surface is subject to strict time constraints. Specifically, if the first curing period for Step STB2 is too short, the scratches on the surface will disappear, and the unevenness will vanish. Conversely, if the first curing period for Step STB2 is too long, it will not be possible to create scratches on the surface.
[0010] Furthermore, the scratches appeared as thin, raised lines, which meant that the required strength could not be maintained, and there was a problem where the material would crumble if struck with a hammer or similar object.
[0011] Therefore, the present invention aims to propose a method for producing precast concrete members that enables the formation of irregularities on the joint surface of precast concrete members without damaging them by hand. [Means for solving the problem]
[0012] A first aspect of the present invention is a method for producing precast concrete members, comprising: a pouring step of pouring concrete into a formwork and spraying a setting retarder on part or all of the surface of the joint surface; and a washing step of using a washing machine to wash away the concrete from the surface of the joint surface whose hardening has been delayed by the setting retarder, and washing the precast concrete member removed from the formwork.
[0013] A second aspect of the present invention is a method for producing the member of the first aspect, wherein the construction joint surface has a plurality of joint portions, and in the construction step, the setting retarder is scattered at least between the joint portions. [Effects of the Invention]
[0014] According to various aspects of the present invention, by spraying a setting retarder on the surface of the construction joint, the hardening of the concrete on the surface of the construction joint can be delayed, thereby creating an uneven surface. Since there is no need to manually scratch the surface, time constraints can be alleviated.
[0015] Furthermore, unlike the production of cast-in-place concrete members, precast concrete members are typically cleaned using a washing machine. Therefore, the washing machine used for cleaning precast concrete members can be used to wash away the surface layer of concrete at the joint surface, whose hardening has been delayed by the setting retarder. This effect is observed in precast concrete members but not in cast-in-place concrete members.
[0016] Furthermore, precast concrete members may have a plurality of joints on the joint surface in order to be joined to in-situ cast concrete members or other precast concrete members by a joint method. Here, the joint method is a method of joining by extending the joints in the material axis direction to increase the length of the members. The joints are provided protruding from the joint surface. Therefore, in manual work, it may be easy to damage the area far from the joints, but it may be difficult to damage the area near the joints. According to the second aspect of the present invention, by spraying a setting retarder between the joints, unevenness can be easily formed even near the joints.
Brief Description of Drawings
[0017] [Figure 1] It is a flowchart showing an example of a method for producing a precast concrete member according to an embodiment of the present invention. [Figure 2] It is FIG. 1 showing an experiment conducted by the inventors to confirm that unevenness can be formed on the surface of the joint surface by the operation of FIG. 1. [Figure 3] It is FIG. 2 showing an experiment conducted by the inventors to confirm that unevenness can be formed on the surface of the joint surface by the operation of FIG. 1. [Figure 4] It is FIG. 3 showing an experiment conducted by the inventors to confirm that unevenness can be formed on the surface of the joint surface by the operation of FIG. 1. [Figure 5] It is a flowchart showing an example of a method for producing a conventional precast concrete member.
Embodiments for Carrying Out the Invention
[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to these embodiments.
Examples
[0019] FIG. 1 is a flowchart showing an example of a method for producing a precast concrete member according to an embodiment of the present invention.
[0020] First, an operator places concrete into a formwork (step STA1). Subsequently, the operator sprays a setting retarder on part or all of the surface of the joint surface (step STA2). For example, the operation of step STA2 may be performed after about one hour has elapsed since the operation of step STA1.
[0021] In the flowchart showing the conventional operation in FIG. 5, it was necessary to elapse a long time for both the first curing period and the second curing period. Therefore, the timing of inflicting damage (step STB3) had severe time constraints. In contrast, for the timing of performing the operation of step STA2, it is not necessary to elapse a long time after performing the operation of step STA1. Therefore, the time constraints regarding the timing of spraying the setting retarder can be relaxed.
[0022] After the operation of step STA2, a curing period is elapsed (step STA3). Then, the operator washes away the concrete in the surface layer portion of the joint surface whose curing has been delayed by the setting retarder with a washer, and washes the precast concrete member taken out from the formwork (step STA4).
[0023] Between steps STA3 and STA4, the operator takes out the precast concrete member from the formwork.
[0024] In the flowchart showing the conventional process in Figure 5, unlike when manufacturing cast-in-place concrete members, when producing precast concrete members, the precast concrete members are usually cleaned using a washing machine (see step STB5). Therefore, in step STA4, the washing machine used to clean the precast concrete members can be used to wash away the surface concrete of the joint surface whose hardening has been delayed by the setting retarder. This effect is observed in precast concrete members but not in cast-in-place concrete members.
[0025] Then, precast concrete members are produced (Step STA5).
[0026] Precast concrete members may have multiple joints on the construction joint surface in order to join them with cast-in-place concrete members or other precast concrete members using a jointing method. Here, the jointing method is a technique that increases the length of the member by joining the joints in the axial direction of the member. The joints are provided protruding from the construction joint surface.
[0027] If scratches are made manually as in the conventional method (see step STB3 in Figure 5), it may be easy to make scratches in areas far from the joint, but it can be difficult to make scratches near the joint. For example, the joint may be curved near the surface of the joint, making it impossible to reach by hand. Therefore, it was difficult to make uniform scratches on the surface of the joint.
[0028] In step STA2 of Figure 1, by spraying a setting retarder on part or all of the surface of the joint, irregularities can be created even near the joint. For example, by spraying a setting retarder between the joints, irregularities can be easily formed even near the joint.
[0029] Figures 2 to 4 show experiments conducted by the inventors to confirm that irregularities can be formed on the surface of the joint by the procedure shown in Figure 1.
[0030] Figure 2 shows precast concrete members 15 and 17 produced by pouring concrete into formwork 11 and formwork 13, respectively.
[0031] When concrete was poured into formwork 11 and formwork 13, the undiluted and diluted solutions of the setting retarder were sprayed onto the surfaces of precast concrete members 15 and 17, respectively (see steps STA1 and STA2 in Figure 1). The setting retarder used here was Tupol T-21, a chemical admixture conforming to JIS A 6204, which allows for delaying the setting time of the concrete by adjusting the amount used. Figure 2 shows the state after a 3-day curing period (see step STA3 in Figure 1).
[0032] Figure 3 shows the process of removing precast concrete members 15 and 17 from formwork 11 and formwork 13 and cleaning them with a washing machine 19 (see step STA4 in Figure 1). Figure 3 confirms that the washing machine 19 used for cleaning precast concrete members can be used to wash away the surface concrete of the construction joint surface whose hardening has been delayed by the setting retarder.
[0033] Figure 4 shows the precast concrete members 15 and 17 after cleaning. It was confirmed that a uniform uneven surface can be formed on the surfaces of the precast concrete members 15 and 17 by using a setting retarder.
[0034] Furthermore, experiments conducted by the inventors confirmed that the distribution and depth of the surface irregularities can be altered by changing the concentration of the setting retarder or the curing period. [Explanation of Symbols]
[0035] 11 Formwork 13 Formwork 15 Precast concrete members 17 Precast concrete members 19 Washing machine
Claims
1. A method for producing precast concrete members, A concrete pouring step involves pouring concrete into the formwork and then spraying a setting retarder on part or all of the surface of the joint, A method for producing precast concrete members, comprising a washing step of using a washing machine to wash away the surface concrete of the joint surface whose hardening has been delayed by the setting retarder, and washing the precast concrete member removed from the formwork.
2. The aforementioned joint surface has multiple joint sections. A method for producing a precast concrete member according to claim 1, wherein in the pouring step, the setting retarder is sprayed at least between the joints.