JP2000008545A - Cap for grout and grouting method using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an excess grout from being injected by sealing a sheath of prestressed concrete or an anchor at a fixed distance from the fixed section of a PC steel wire. SOLUTION: When a PC steel wire is inserted into a sheath 3 through the hole 11 of a grout cap 1 made of a soft synthetic resin plate, the grout cap 1 is closely stuck to the PC steel wire, the peripheral edge section of the grout cap 1 is closely stuck to the inner wall of the sheath 3 to seal it, and no grout is leaked out. The grout cap 1 is made of a layered product of the soft synthetic resin plate, the diameter of the center layered product is increased, and the grout cap 1 can be closely stuck to the inner wall of the sheath 3 more strongly. A rigid holding plate is provided on one or both faces of the grout cap 1, and the grout cap 1 is prevented from inclining or turning over at the peripheral edge.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grouting method for preventing corrosion of prestressed concrete tension steel and underground anchor steel, and a grout cap used therefor.

[0002]

2. Description of the Related Art In prestressed concrete and underground anchors, grout is filled in the space of a sheath in which a PC steel wire is disposed in order to prevent corrosion of the PC steel wire.
The filling tube is inserted into the sheath, the grout is pressed in while allowing the air in the grout to escape, and it is confirmed that the grout has been filled, thus completing the filling operation.

[0003]

However, the water which causes corrosion of the PC steel wire enters from the anchoring portion side of the PC steel wire, and it is almost conceivable that the moisture will enter from the middle portion of the sheath. And it is not necessary to fill the entire sheath with grout. However, there is no means for sealing the sheath in the middle, and the entire space in the sheath is filled with grout, so that unnecessary grout is consumed and the construction period is prolonged.

Therefore, an object of the present invention is to provide a grout injection method and a grout cap used for allowing the sheath to be sealed at a fixed distance from the fixing portion so that unnecessary grout is not injected.

[0005]

Means for Solving the Problems A grout cap having a hole in a soft synthetic resin plate is used, a tension steel material is inserted through the hole into a sheath, and the sheath is sealed with the grout cap. It is. The sheath was completely sealed by using a laminated soft synthetic resin plate as the grout cap. The diameter of the central portion of the laminated body of the soft synthetic resin plate was made larger than that of the other members so that the laminated body could easily adhere to the inner wall of the sheath.

[0006] A holding plate is provided on one side and / or both sides of a soft synthetic resin plate constituting a grouting cap, and when the grouting cap is inserted into a sheath or when a PC
The sealing was completed by making the steel wire tightly adhere to the inner wall surface of the sheath without inclining when the steel wire was tightened. The degree of adhesion to the inner wall surface of the sheath was increased by using a soft synthetic resin as a foam. Furthermore, by making the foam a continuous pore,
Air in the sheath was allowed to escape to the other through this hole during grouting.

[0007]

[Action] P is inserted into the hole of the grout cap of the soft synthetic resin plate.
Through the C steel wire, the inner surface of the hole is in close contact with the PC steel wire, the peripheral edge of the grout cap is in close contact with the inner wall of the sheath, and the sheath is sealed so that the press-fitted grout does not leak.

[0008] The grout cap is formed of a laminate of a soft synthetic resin plate, and the diameter of the laminate at the center is increased.
It can be more closely adhered to the inner wall of the sheath, and the sealing is strengthened. The grout cap set on the PC steel wire and installed in the sheath adheres tightly to the inner wall of the sheath. Since the material of the grout cap is a soft synthetic resin, it may be inclined with respect to the axis or the peripheral edge may be turned by friction with the inner wall, and it may not be possible to seal the sheath. Alternatively, rigid holding plates are provided on both sides to prevent the grout cap from inclining or turning around.

Further, when the soft synthetic resin is formed into a foam and is made into an open cell, the air in the sheath compressed by the grout injection can escape to the other through the open cells, so that the grout can be injected smoothly. At the same time, the grout is completely filled in the sheath space.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described by way of an example in which the present invention is applied to a box culvert made of precast concrete. As shown in FIG. 5, the box culvert 5 has a plurality of precast concrete boxes 51 connected to each other, and a connection portion is sealed with a sealing material. The PC steel wire 2 is passed through the sheath and fixed to the end 6 in a tensioned state. A helical bar 21 for reinforcement is provided near the anchoring portion 4 of the PC steel wire.

[0011] As shown in FIG.
A hole (sheath) 3 for installing the PC steel wire 2 is provided in the longitudinal direction, a fixing portion 4 is formed at the end 6, and a grout injection hole 61 and an exhaust hole 62 are provided at the end face side. is there.
The grout cap 1 is formed of a circular plate made of a soft synthetic resin as shown in FIGS. Holes 11 are formed according to the number of PC steel wires 2.
FIG. 4 shows three, six, and seven holes from above. The arrangement of the holes 11 is appropriately laid out. The illustrated one is arranged in a regular polygon.

The diameter of the grout cap 1 is slightly larger than the diameter of the sheath in order to make it close to the inner wall of the sheath, and it is convenient to prepare a cap of about 95 mm to 105 mm. The diameter of the hole 11 through which the PC steel wire 2 passes is such that the PC steel wire fits tightly and the grout does not leak. On one or both sides of the grout cap 1, a holding plate 12 of a thickness of about 5 mm, such as hard plastic or steel plate, having a diameter smaller than that of the soft synthetic resin plate is bonded and fixed. The holding plate 12 has a hole through which the PC steel wire 2 passes as in the case of the soft synthetic resin plate.

At the time of construction, the PC steel wire 2 is inserted into the sheath 3 of the box culvert 5 and set, and the grout cap 1 is passed through the PC steel wire 2 with a bar provided with a scale so that the pushed distance can be recognized. Push it deeper than a predetermined position. The elongation of the PC steel wire is calculated in advance from the tension to be introduced, and it is confirmed by calculation how far the grout cap should be pushed in according to the elongation. Then, when the tension hydraulic jack is set and the PC steel wire 2 is tensioned, the grout cap 1 moves toward the fixing portion as the PC steel wire 2 is tensioned, and moves to a predetermined position.

When the tension of the PC steel wire 2 is completed, the PC
A steel wire is fixed to the anchor plate 24, grout is injected into the sheath 3 from the grout injection hole 61, and the inside of the sheath is filled with grout. Since the sheath 3 is sealed by the grout cap 1, the injected grout cannot go further. Further, the grout does not leak since the grout cap 1 is in close contact with the inner wall surface of the sheath. If the soft synthetic resin is made of open-cell foam, the air inside the sheath that has no escape due to the injected grout can be released to the other through the open cells, so that the grout can be completely filled into the sheath. it can. As described above, the grout can be completely filled with the grout only at locations necessary for the corrosion prevention of the PC steel wire.

A head cap 22 is put on the fixing portion, and a space for the fixing portion is filled with a rust preventive agent 23. As another example of the grout cap, FIG. 3 (2) shows a laminate of soft synthetic resin plates, and FIG. 3 (3) shows that the diameter of the central member is larger and smaller than that of the other members. And the adhesion to the inner wall of the sheath is improved.

[0016]

As described above, the grout cap made of a soft synthetic resin can seal the sheath at an arbitrary position, thereby saving grout for filling, and completely grouting the portion necessary for preventing corrosion of the PC steel wire. Can be filled. By making the material of the grout cap a soft synthetic resin laminate and increasing the diameter of the central laminate, it is possible to make the grout cap more closely adhere to the inner wall of the sheath. Since a rigid holding plate is provided on one or both sides of the grout cap, the grout cap is prevented from being inclined or the peripheral edge is turned up, and the sheath can be completely sealed.

Further, when the soft synthetic resin is made of an open-cell foam, the air in the sheath compressed by grout injection can escape through the open cells.
The grout can be smoothly injected, and the grout is completely filled in the sheath space.

[Brief description of the drawings]

FIG. 1 is a sectional view of a grout injection part.

FIG. 2 is an end view of a box culvert.

FIG. 3 is a side sectional view of a grouting cap.

FIG. 4 is an arrangement diagram of holes in a grout cap.

FIG. 5 is a side view of a box culvert.

[Explanation of symbols]

 1: Grout cap 2: PC steel wire 12: Holding plate 3: Sheath 61: Injection hole 62: Exhaust hole

Claims (8)

[Claims] 1. A grout cap in which a soft synthetic resin plate is provided with a hole for inserting a tension steel material. 2. The grout cap according to claim 1, wherein a soft synthetic resin plate is laminated. 3. The grout cap according to claim 2, wherein the diameter of the soft synthetic resin plate located at the center of the laminate is larger than the other ones. 4. A grout cap according to claim 1, wherein a holding plate is provided on one or both sides of the soft synthetic resin plate. 5. The grout cap according to claim 1, wherein the soft synthetic resin is a foam. 6. The grout cap according to claim 5, wherein the foam has open cells. 7. A grouting method for a PC tensioned steel material, wherein the grout cap according to claim 1 is passed through a tensioned steel material and grout is injected. 8. The grouting method according to claim 7, wherein the grout cap is inserted to a position deeper than a predetermined position, and the tension steel is tensioned to move the grout cap to the predetermined position.