JPH09195510A - Surfacing material for form - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease adhesion of concrete to forms. SOLUTION: In a slip-form method, a pair of forms 10 arranged oppositely are used. The forms 10 are supported with a yoke 12. The yoke 12 is supported with a lifting jack 18 attached to a rod 16 buried in a reinforced concrete building frame 14 to be built, and as the jack 18 is operated, the forms 10 are lifted together with the yoke 12. On constructing a towerlike structure, concrete is cast continuously into a paired forms 10 while the forms 10 are moved upward with the jack 18 operated. Surfacing material 20 is formed and fixed beforehand all over the inner surfaces of the forms 10 contacting with the cast concrete. The surfacing material 20 is composed of a powdery retarder and a binder that holds and fixes the retarder to the contacting surface contacting with concrete of the forms 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface material of a mold used for pouring concrete, and more particularly to a technique for improving the peelability between the mold and the concrete.

[0002]

2. Description of the Related Art In the case of constructing a concrete structure, usually, after reinforcing bars are assembled and the form frame is assembled so as to surround the outer periphery thereof, concrete is placed in the part separated by the form frame. After the cast concrete is hardened, it is constructed by removing the formwork. At this time,
In order to improve the peelability between the concrete and the form, an oily surface material such as grease is usually applied to the surface of the form that contacts the concrete.

However, such a conventional surface material for a mold has the technical problems described below.

[0004]

That is, in the conventional surface material for a mold as described above, the concrete and the mold are not in direct contact with each other to ensure peelability.
When it is used again, the oily surface material adheres to the concrete surface and its peeling function is almost lost. Therefore, it is necessary to apply the surface material each time the concrete is placed.

Further, for example, when a concrete structure is constructed by sliding a mold, the surface material is worn by the slide, the peeling property between the concrete and the mold is deteriorated, and the mold is forcibly removed. Then, there was also a problem that cracks or chipping would occur in the concrete surface layer. The present invention has been made in view of such conventional problems,
It is an object of the invention to provide a surface material for a mold which can solve the problems associated with the deterioration of peelability.

[0006]

In order to achieve the above object, the present invention provides a mold surface material formed on a concrete contact surface of a mold, wherein the surface material is a powdered set retarder. And a binder that holds the setting retarder and is fixed to the mold. According to this configuration,
When the setting retarder contained in the surface material comes into contact with the cast concrete, the hardening of the concrete is delayed, so that the adhesive force of the concrete decreases over a long period of time. As the binder and set retarder of the surfacing material wear away, new set retarder is exposed and if the surfacing remains on the form, it delays the setting of the concrete. The set retarder can be selected from inorganic powders such as zinc oxide and borax. Further, the binder can be selected from synthetic resins such as epoxy resin and urethane resin. The thickness of the surface material depends on the amount of the set retarder,
It is set appropriately in consideration of the number of times the formwork is diverted, for example,
It is set to about 1 to 2 mm.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG.
Shows an example of a surface material for a mold according to the present invention. The surface material shown in the figure is a case where the present invention is applied to a mold used in the slipform construction method, and in the slipform construction method, a pair of molds 10 arranged to face each other is used. The formwork 10 is arranged in a ring shape adjacent to each other in the circumferential direction. The formwork 10 is supported by a gate-shaped yoke 12.

The yoke 12 is supported by an ascending jack 18 attached to a rod 16 embedded in a reinforced concrete skeleton 14 to be constructed. Ascends with the yoke 12. When constructing the mounting structure, concrete is continuously placed between the pair of molds 10 while driving the jack 18 to move the molds 10 upward.

The basic construction of such a slip-form construction method is the same as the conventional construction method of this type,
The slip-form construction method of the present embodiment has remarkable features in the following points. That is, the surface material 2 is spread over the entire inner surface of the mold 10 that comes into contact with the cast concrete.
0 is fixedly formed in advance. The surface material 20 is composed of a setting retarder and a binder.

The set retarder is selected from inorganic powders such as zinc oxide and borax, and the binder is selected from synthetic resins such as epoxy resin and urethane resin and inorganic coatings such as water glass. The mixing ratio of the setting retarder and the binder is appropriately selected in consideration of the height of the column-shaped structure to be constructed, the rising speed of the mold 10, and the like,
For example, the setting retarder may be contained in the binder in a weight ratio of about 50 to 120%. In addition, the thickness of the surface material 20 is not particularly limited,
It is appropriately set in consideration of the height of the building structure to be constructed and the rising speed of the mold 10, and may be set to, for example, about 1 to 2 mm.

In the slip-form construction method carried out as described above, since the surface material 20 is fixedly formed on the inner surface of the mold 10 with which the cast concrete comes into contact, the concrete is placed between the molds 10. When cast, the set retarding material exposed on the outer surface of the surface material 20 comes into contact with the concrete. Therefore, the outer and inner surface portions of the concrete skeleton 14 to be formed cause a local setting delay and delay the hardening of the concrete in this portion.

The mold 10 is moved up by the jack 18 as the concrete is continuously cast, and the binder of the surface material 20 is scraped away by friction due to this movement. Since the setting retarder contained is newly exposed, the hardening retarding effect of the concrete is maintained thereafter, so that the adhesive force of the concrete decreases over a long period of time.

Therefore, as in the conventional construction method of this kind, the cement particles in the cast concrete gradually adhere to the surface of the mold 10 and grow in a lump form, thereby forming the surface of the structure. There is no problem that a concave streak is generated in the mold, and even if the rising of the mold 10 is stopped for a long time, the mold 10 can be easily raised after that. We have
In order to confirm the action and effect of the surface material 20 described above, a shear adhesion test of concrete was performed under the conditions described below. FIG. 2 is an explanatory diagram of the sample used in the shear adhesion test at this time. The sample was prepared by preparing an iron plate A used as a material for the mold 10 and directly adhering mortar B on the polished iron plate A, and by applying an epoxy-based paint on the surface of the iron plate A and curing it. Three types were prepared: one with mortar B adhered on the surface that was later polished, and one with mortar B adhered on the surface on which a surface material consisting of a setting retarder and a binder was fixedly formed on the surface of iron plate A. .

Zinc chloride powder is used as the setting retarder of the surface material, and a two-component mixed epoxy resin having a ratio of the main agent to the curing material of 2: 1 is used as the binder. , 80% by weight to the epoxy resin was added and mixed. This mixture was applied to the surface of the iron plate A at room temperature to cure it, and the surface was polished. The thickness of the formed surface material was about 2 mm.

As the mortar B, ordinary Portland cement and river sand having a size of 5 mm or less were used. These were kneaded by a small mixer for about 1 minute and 30 seconds, and after kneading, they were kneaded for 2 minutes. The water cement ratio at this time was set to 50%. Mortar B prepared in this way has a cross-sectional area of 5 x 5c.
It was filled in a frame C installed on the iron plate A so as to have a rectangular shape of m, and the shear adhesive force was measured every 4 hours immediately after the placing.

The mortar B was cured by applying a film on the upper surface of the frame C so that the mortar B was cured in an airtight manner. The shear adhesive force was measured by fixing the mortar B, pulling the iron plate A in the horizontal direction, measuring the tensile force when the mortar B was detached from the iron plate A, and obtaining the adhesive force per unit area from the measured value. . FIG. 3 shows the test results of the shear adhesion test at this time. As is clear from the figure, both the time when the mortar B was directly adhered to the iron plate A and the case where the surface of the iron plate A was coated with an epoxy resin and the mortar B was adhered to this coated surface, the passage of time While the shear adhesive strength is greatly increased, when a surface material made of zinc chloride powder and epoxy resin is formed on the surface of the iron plate A,
It was confirmed that even after the mortar B was cured for 24 hours, the shear adhesive force of the mortar B was almost zero.

In the above test, the adhesion of a surface material made of a combination of zinc powder and an epoxy resin was measured, but it was confirmed that the same effect could be obtained by a combination of borax and an epoxy resin. doing. Also,
In the above embodiment, the case where the surface material 20 according to the present invention is fixed to the inner surface of the slip-form mold 10 has been exemplified, but the practice of the present invention is not limited to this construction method, and a mold is used. When forming a concrete structure by applying the method, it can be applied not only when it is moved but also when it is allowed to stand.

[0018]

As described above in detail in the embodiments,
According to the mold surface material of the present invention, the following effects can be obtained. Since the concrete is prevented from adhering to the surface of the form, cracks and chipping due to the adhering do not occur. Since the peeling function of the surface material is maintained for a long period of time, the coating work is greatly reduced. Since the settling delayed concrete is only a local part of the surface, it does not affect the concrete strength of the structure.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an implementation state when a mold using a surface material according to the present invention is adopted in a slipform method.

FIG. 2 is an explanatory diagram of a measurement state when the shear adhesive force of the surface material used in the present invention is measured.

FIG. 3 is a graph showing test results of the shear adhesion test shown in FIG.

[Explanation of symbols]

 10 Formwork 12 Yoke 14 Concrete Body 16 Rod 18 Lifting Jack 20 Surface Material

Claims (3)

[Claims] 1. A surface material for a mold formed on a concrete contact surface of the mold, wherein the surface material is a powdery set retarder and holds the set retarder and is fixed to the form. A surface material for a formwork, which is composed of a binder. 2. The surface material for a mold according to claim 1, wherein the setting retarder is selected from inorganic powders such as zinc oxide and borax. 3. The surface material for a mold according to claim 1, wherein the binder is selected from synthetic resins such as epoxy resin and urethane resin.