JP2770741B2 - Manufacturing method of prestressed cement-based composite member - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a prestressed cement composite member by a post tension method formed by extrusion.

[0002]

2. Description of the Related Art In recent years, demand for precast members has been increasing in order to save labor in construction work. There is a great demand for high strength and light weight of the precast member, and introduction of prestress into the precast member can be considered as one method of achieving this. On the other hand, an extrusion method is known as a method for producing a precast member suitable for mass production in a factory and excellent in dimensional stability and formability. However, production of a precast / prestressed member by an extrusion molding method combining the two is not known.

The reason why a precast / prestressed member is not manufactured by the extrusion molding method is considered as follows.

(1) In the case of manufacturing by a pretensioning method, due to the structure of the extruder, it is difficult to insert the tendon into the cross section of the member while extruding the tendon while maintaining the tension applied to the tendon. Not possible, so virtually impossible.

[0005] (2) When manufacturing by the post-tension method, the following procedure can be considered. (A)
Extrusion molding is performed with a member section having a cavity penetrating in the extrusion direction. (B) After the hardening of the cement material, a tendon is inserted into the cavity. (C) The tension member is tensioned, and is fixed to the member by the fixing members at both ends to introduce tension to the member. (D) A grout material is injected into the cavity to integrate the tension member and the member.

[0006] In the production by the post-tension method, since the above-described multi-step process must be performed, the production cost is increased, and this cost increase cannot be completely amortized only by the effect of introducing the prestress.

Further, when producing a precast concrete by a normal formwork, a tension member coated with an uncured room-temperature curable resin whose time until the start of curing is adjusted to a long time is embedded in the concrete, There is known a method for producing a precast / prestressed concrete by hardening a tension member after hardening concrete, curing a room temperature-curable resin at room temperature, and fixing the tension member to concrete. In this method, the cold-setting resin must be kept in an uncured state until the concrete is sufficiently cured to a predetermined strength. Since the curing of the room-temperature-curable resin cannot be maintained in an uncured state when the heating and wet curing is performed in an attempt to promote the curing, the concrete curing and the curing of the room-temperature-curable resin are both performed at room temperature. It takes an extremely long time to manufacture a product on a monthly basis.

[0008]

According to the present invention, a tension member is inserted into the cross section of a member by extrusion molding, and a post-tensioning method is used to form a penetrating cavity and to fix a tension member end portion to a member by a fixing member. An object of the present invention is to eliminate the complicated work of fixing and injecting a grout material, to greatly reduce the manufacturing time as compared with the case of formwork, and to efficiently manufacture a precast / prestressed cement-based member.

[0009]

SUMMARY OF THE INVENTION According to the present invention, a cement-based material is extruded while inserting a linear material having a three-layer structure of a tendon, a sheath, and a thermosetting resin that fills a gap between the tendon and the sheath. A cement-based member cut to a predetermined length so as to be exposed from both ends is steam-cured or autoclave-cured (hereinafter collectively referred to as "cured") while the tension member is tensioned in a state where the thermosetting resin in the linear body is not cured. This is a method of manufacturing a prestressed cement composite member, which comprises curing a cement-based material and a thermosetting resin after heating and curing the thermosetting resin, and then releasing the tension of the tendon.

The gist of the present invention is that the process of heating and curing, which is considered to be almost indispensable for the production of a precast cement-based member by extrusion molding, is effectively used for the curing of a thermosetting resin. It promotes the hardening of thermosetting resins and the hardening of thermosetting resins to complete the fixation of the tendon material to the precast cement-based members in a short time. A cement-based member can be efficiently produced.

The tendon and sheath used in the present invention are not particularly different from those used for ordinary prestressed cement-based members. Examples of the tendon include a PC steel wire and high-strength fiber (such as carbon fiber and aramid fiber). And the like, which is obtained by hardening a twisted yarn with a thermosetting resin, and as a sheath, a steel pipe or a plastic pipe having an uneven surface is used.

As the thermosetting resin, a catalyst which exhibits a catalytic activity at a high temperature is added to an epoxy resin, a phenol resin, a furan resin, a urethane resin, a polyester resin, or the like.
At room temperature, the curing reaction hardly proceeds, but a resin adjusted so that the curing reaction easily proceeds when heated to about 60 ° C. or more is used. In addition, it is preferable to use a resin adjusted so that the curing is completed slightly after the curing of the cement-based material in the heating wet curing step.

Examples of the cement-based material used in the present invention include concrete and mortar. In particular, a material obtained by mixing a short-fiber reinforcing material into the cement-based material in advance is preferably used.

The extrusion of the present invention can be carried out as usual by a conventional extruder, and the linear body is inserted into a predetermined position in the flow of the cement-based material immediately before the die.

[0015] The extruded member is cut to a predetermined length so that the tendons are slightly exposed at both ends. Tension is given by gripping the exposed portion of the tendon.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view of a precast member obtained by extruding a cement material while inserting a linear body.
(A) is a beam member, and (b) is a floor or outer wall member. FIG. 2 (a) is a cross-sectional view showing a method of introducing tension into the floor or outer wall member of FIG. 1 (b), and FIG. 2 (b) is a cross-sectional view of an example of a linear body used in the present invention. FIG. 2 (c) is a plan view.
Is a partially cutaway side view of the linear body.

As the cement material, ordinary concrete was used. When the concrete 1 is extruded, the linear body 2 is linearly inserted into the concrete 1 and both ends thereof are slightly exposed. As shown in FIGS. 2 (b) and 2 (c), the linear body 2 is composed of three layers: a tendon 6, a thermosetting resin 7, and a sheath 8. In this state, the tension member 6 is not tensioned, and the thermosetting resin 7 is not cured. The extruded and cut floor member is placed on a pallet (not shown) and left in the frame 3. The ends of the tendon members 6 exposed from both ends of the floor member are connected to the PC steel bar 5 by the fixing jig 4, and the PC steel bar 5 is jacked (not shown).
The PC steel bar 5 is fixed to the frame 3 in a state where the tension member 6 is tensioned.

The floor member is heated and cured while being fixed to the frame 3. (60-80 in steam for steam curing)
° C, about 2 hours to 6 hours; in autoclave curing, about 140 to 200 ° C in saturated steam, about 5 hours to 15 hours) During the heating and wet curing, both the concrete 1 and the thermosetting resin 7 are cured, 6 is fixed to the concrete 1 via the thermosetting resin 7 and the sheath 8. After the completion of the heat and wet curing, the floor member is removed from the frame 3 to complete the precast / prestressed floor member. Of course, the frame 3, the fixing jig 4, and the PC steel bar 5 are used repeatedly.

The time required from completion of extrusion molding to completion of a precast / prestressed member is 10 hours to 2 hours in a normal operation.
0 hours, and 12 hours including the time required for extrusion.
A precast / prestressed member is manufactured in about 24 hours to about 24 hours, and the manufacturing time is significantly shortened as compared with the case where the manufacturing time by room temperature curing is a monthly unit.

[0021]

As described above, the drawbacks of the extrusion post-tension method are as follows: (1) a through hole must be formed; (2) a fixing body is required; and (3) grout material is injected. Is eliminated, the manufacturing process is simplified, and the manufacturing cost is greatly reduced.

Further, the production time is remarkably reduced as compared with the mold forming method and the room temperature curing method, and the production efficiency is remarkably increased.

[Brief description of the drawings]

FIG. 1 is a perspective view of a precast member obtained by extruding a cement-based material while inserting a linear body, where (a) is a beam member and (b) is a floor or outer wall member.

2 (a) is a cross-sectional view showing a method for introducing tension to the floor or outer wall member of FIG. 1 (b), and FIG. 2 (b) is a cross-sectional view of an example of a linear body used in the present invention. FIG.
Is a partially cutaway side view of the linear body.

[Explanation of symbols]

1 ・ ・ Concrete 、 2 ・ ・ Linear body 、 3 ・ ・ Frame 、
4 ··· Fixing jig, 5 ·· PC steel rod, 6 ·· Tensioning material, 7
.. Thermosetting resin, 8. Sheath.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroaki Nakagawa 2-191, Tobita-Shi, Chofu-shi, Tokyo Kashima Construction Co., Ltd. (72) Mimeo Kobayashi 2--19, Tobita-Shi, Chofu-shi, Tokyo No. 1 Kashima Construction Co., Ltd. Technical Research Institute (56) References JP-A-63-167836 (JP, A) JP-A-63-147047 (JP, A) JP-A-60-70255 (JP, A) JP 52-82921 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) E04C 5/00-5/20 B28B 23/00-23/04 E04G 21/12

Claims (1)

(57) [Claims] 1. A cement-based material is extruded while inserting a linear material having a three-layer structure of a tendon, a sheath, and a thermosetting resin filling a gap between the tendon, a sheath, and a predetermined material so that the tendon is exposed from both ends. The cement-based member cut to length was steam-cured or autoclaved in a state in which the thermosetting resin in the linear body was not cured and the tendon was tensioned to cure the cement-based material and the thermosetting resin. A method for producing a prestressed cement-based composite member, characterized by subsequently releasing the tension of the tension member.