JP2000141328A - Form construction method for adhesion-requiring joint of precast concrete member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the uneven surface of the joint portion of a precast concrete member at low cost without exerting an adverse influence on its quality. SOLUTION: Under the state that a proofing sheet against the efflux of earth and sand 4, which is made of polyester spunbonded non-woven fabric or the like so as to be water permeable, is bonded onto the inner surface 11A of the edge face form 11 of a form 1 for forming a precast concrete beam 10 so as to cast a placing concrete 5 in the form 1 in order to solidify the concrete. Thus, a coarse aggregate 51 is exposed at the edge face 10A of the precast concrete beam 10 so as to make the face 10A uneven in order to improve an adhesion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a formwork method for a seam of a precast concrete member requiring adhesion for improving the adhesion between a precast concrete (Pca) member and a post-cast concrete. .

[0002]

2. Description of the Related Art For example, in order to ensure that the end face of a precast concrete beam can be sufficiently adhered to cast-in-place concrete to be subjected to post-processing, it is necessary to treat the end face with irregularities. For this reason, conventionally, the end of the precast concrete beam is hung by roughening, or a condensing retarder is applied to the end face frame to cast concrete, and high pressure water washing is performed on the end face of the completed member. Was uneven.

[0003]

However, the high pressure water washing treatment using a mechanical coarsening or a setting retarder with a manually-operated balance has a problem that labor and time are increased in cost. ing. In the case of the method using a setting retarder, there is another problem that the strength of the concrete at the end is adversely affected.

[0004] It is an object of the present invention to provide a formwork method for precast concrete member seams requiring adhesion, which can solve the above-mentioned problems in the prior art.

[0005]

A feature of the present invention to solve the above-mentioned problem is that a concrete is poured by bonding a water-permeable earth and sand outflow prevention sheet to an end joining portion of a formwork of a precast concrete member. In addition, the precast concrete member is provided with irregularities for improving the adhesive force at the end joint portion.

A sheet for preventing earth and sand from flowing out, such as a polyester spunbonded nonwoven fabric, attached to the inner end of a precast concrete member form has a water-permeable property, is flexible and easy to remove, and can be used to remove coarse aggregate. The projections and depressions can be easily formed by being exposed to the surface. As described above, the irregularities can be easily formed at the end joint portion of the precast concrete member simply by attaching the earth and sand outflow prevention sheet such as a polyester spunbonded nonwoven fabric to the end of the formwork. Cost reduction is possible compared to fishing. Further, as compared with the conventional method of forming irregularities using a setting retarder, there is obtained an advantage that it does not affect the concrete surface at the end and is preferable in quality control.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a process diagram for explaining an example of an embodiment in which unevenness for a seam is formed at an end of a precast concrete beam member according to the present invention.

In FIG. 1A, reference numeral 1 denotes a formwork provided for manufacturing a precast concrete beam, in which a main bar 2 and stirrups 3 are assembled in a required state. Are located. The inner surface 11A of the end form 11 of the precast concrete beam 10 in order to improve the adhesion of the precast concrete beam to the cast-in-place concrete at the spliced portion of the end surface of the precast concrete beam formed by pouring the cast concrete into the form 1. Further, a sediment outflow prevention sheet 4 made of a polyester spunbonded nonwoven fabric and having water permeability is adhered using an appropriate adhesive.

Next, as shown in FIG. 1 (B), the cast concrete 5 is poured into the form 1 and left to stand.
After 2 days, only the end face mold 11 is released.

FIG. 1C shows the end face form 1
The state of the end face of the precast concrete beam 10 formed in the formwork 1 when only 1 is removed from the mold is shown. As shown in FIG. 1 (C), the earth and sand outflow prevention sheet 4 has been pasted on the inner surface 11A of the end face mold 11, so that moisture is removed due to the water permeability of the earth and sand outflow prevention sheet 4, and the coarse aggregate 51 is removed. The exposed end face 10A of the precast concrete beam 10 is formed in an uneven state. For this reason, it becomes easy for the end face 10A to adhere to the post-cast concrete.

Therefore, labor and time can be remarkably reduced as compared with the conventional method in which the inner surface 11A of the end face frame 11 is mechanically peeled off manually or a setting retarder is applied to the frame. In addition, costs such as labor costs can be reduced. In addition, since no setting retarder is used, there is no effect on the concrete surface at the end, and the quality of concrete is not deteriorated.

In order to improve the removability, it is conceivable to use a combination of the earth and sand outflow prevention sheet 4 and a net.

[0014]

According to the present invention, as described above, a water-permeable earth and sand outflow prevention sheet such as a polyester spunbond nonwoven fabric which is rich in flexibility and easy to remove is attached to the inner end of the mold. As a result, unevenness can be easily formed at the end joint portion of the precast concrete member. As a result, cost reduction is possible as compared with the conventional roughening by manual power. Further, compared to the conventional method of forming unevenness using a setting retarder, a high quality product can be obtained because the concrete surface at the end is not affected.

[Brief description of the drawings]

FIG. 1 is a process diagram for explaining an example of an embodiment in which unevenness for a seam is formed at an end of a precast concrete beam member according to the present invention.

[Description of Signs] 1 Formwork 2 Main reinforcement 3 Stirrups 4 Sediment runoff prevention sheet 5 Casting concrete 10 Precast concrete beam 10A End face 11 End formwork 11A Inner surface 51 Coarse aggregate

Claims (1)

[Claims] The present invention relates to a precast concrete member, in which a permeation-preventing sheet is adhered to an end joining portion of a formwork, and concrete is poured into the precast concrete member. Forming method for precast concrete member joints requiring adhesion, characterized by having irregularities for the joints.