JPS60264244A - Composite pile and manufacture thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composite pile formed integrally with a steel pipe and concrete, and to improvements in a method for manufacturing the same.

Generally, composite piles consisting of steel pipes and concrete centrifugally formed inside the steel pipes are manufactured by undergoing high-temperature, high-pressure curing using supersaturated steam at a pressure of 10 kg/r and a temperature of 180°C. It is known to apply a polyethylene coating layer to the outer surface of steel pipes to prevent the surface from rusting. In this case, if high-temperature and high-pressure curing is performed after providing a polyethylene coating layer, the heat resistance of polyethylene will change to a softening point of 95°.
C or higher, the melting point is 110°C, so when cured at high temperature and high pressure at a temperature of 180°C, an undesirable phenomenon occurs in which the coating layer flows and comes off.Therefore, attempts have been made to apply a polyethylene coating layer after curing at high temperature and high pressure. .

Conventionally, this type of composite pile has been developed, for example, in
As disclosed in Publication No. 012, after pouring concrete into a steel pipe, centrifugal molding is performed, and after curing at high temperature and high pressure as described above to form a steel pipe/concrete composite, the outer surface of the steel pipe is coated with polyethylene. Manufactured by applying layers. However, in such conventional technology, firstly, an expensive pressure vessel that can withstand the temperature and pressure is required to carry out high-temperature and high-pressure curing, and secondly, the work of coating (applying) a layer of polyethylene is troublesome. Therefore, there were drawbacks such as the product being expensive.

SUMMARY OF THE INVENTION An object of the present invention is to provide a composite pile and a method for manufacturing the same which eliminates the drawbacks of the prior art as described above.

In order to achieve this object, the present invention involves centrifugally forming high-strength expanded concrete inside a steel pipe that has been provided with a polyethylene coating layer in advance, and then curing this concrete with atmospheric pressure steam to form a composite pile. It is something.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, a steel pipe 2 having an anticorrosion coating layer 1 made of polyethylene on its outer peripheral surface is prepared. The steel pipe having this coating layer can be, for example, Nippon Steel's heavy corrosion-resistant steel pipe pile N5-PAC. The steel pipe with this coating layer is attached to the formwork 3 as shown in Figure 1.
The high-strength expansive concrete 4 is placed therein and centrifugally formed as usual (see Fig. 2). The formwork 3 has a normal shape consisting of an upper mold 3α and a lower mold 3b, each of which is approximately semicircular, but the inner diameter of the circular body when the upper mold and lower mold are combined is that of a steel pipe with a coating layer. 20 than the outer diameter of
It is set larger than 岨.

A plurality of band-shaped pads 5 are provided on the inner surfaces of the upper mold and the lower mold, which contact the outer surface of the steel pipe. In the embodiment shown, these bands are made of rubber. Preferably, these pads have a hardness of 60 to 70, a width of 50 to 150, and a plurality of grooves of 5 to 10 widths on the inner surface.

The steel pipe with the coating layer is firmly held in the formwork 3 by these pads, and the coating layer is not damaged. This pad may have a soft surface in contact with the steel pipe and a hard surface on the other surface.

Note that the formwork 3 is rotated in the usual manner.

High-strength expanded concrete 4 has a maximum temperature of 65 to 90 after demolding
C. atmospheric steam curing only is applied within about 24 hours after centrifugal molding. This concrete has a composition as shown in the following table so that it can develop a high strength of 800 to more than 800 by just this atmospheric pressure steam curing.

In addition, the cement in the above table has a content of at least 400 to 4 per 1 m3.
80 and f, and as a high-strength admixture, ``Suit Mix'' manufactured by Nippon Cement Co., Ltd., ``Σ1000j'' manufactured by Denki Kagaku Kogyo @), etc. can be used. According to the above formulation, the material can be so
It is possible to exhibit high strength as described above. Furthermore, which high-strength expansive concrete has a thickness of 50 to 150 mm. It is desirable that the ball be hit by Won.

According to the present invention, high-temperature and high-pressure curing is unnecessary, and therefore, an inexpensive composite pile can be obtained. In addition, since a steel pipe with a polyethylene coating layer provided in advance is used, there is no need to apply polyethylene after demolding or equipment for coating resin mortar as in the prior art shown in the above publication, making it extremely economical. There are real benefits.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a formwork showing a state in which the composite pile of the present invention is manufactured, and FIG. 2 is a sectional view of the composite pile of the present invention. ■... Polyethylene coating layer 2... Steel pipe 3... Formwork 4... High strength expanded concrete 5... Pad Patent applicant Asanopol Co., Ltd.

Claims (2)

[Claims] (1) Consists of a steel pipe with a polyethylene anti-corrosion coating layer on the outer circumferential surface and high-strength expanded concrete that is centrifugally formed on the inner surface of the steel pipe, and the high-strength expanded concrete is formed by centrifugally forming and then curing with atmospheric steam. Composite pile characterized by: (2) Prepare a steel pipe with a polyethylene anti-corrosion coating applied to the outer circumferential surface in advance, install the steel pipe in a formwork via a pad, centrifugally form high-strength concrete inside the steel pipe, and remove it. A method for manufacturing a composite pile, characterized by curing high-strength concrete in the form of hindlimbs with normal pressure steam.