JPS61275647A - Seal structure for concrete test body heated to high temperature - Google Patents

Abstract

PURPOSE:To measure the percentage of water content of concrete with high reliability by putting a concrete test body in which a sensor is embedded in a sealed container and charging a packing which does not absorb water and has high heat resistance in a space in the container. CONSTITUTION:A couple of restraint frames 8 is clamped by machine screws 9 to hold the test body 2, a temperature sensor 10 and an electrode 11 for resistance value measurement are embedded, and leads 12 and 13 penetrate the boss 14 of an end plate 4 and are sealed with a screw lid 16 by fitting a 'Teflon(R)' ring 15. The packing 17 of Si resin is packed between the space surrounded with a cylinder 3, the end plate and the test body 2 and a rod 18 is run through it in the middle of curing, and the end plate 4 is mounted. When this container 1 is heated to about 200 deg.C, the leak of water in the container 1 and the leak of water in the test body itself are eliminated through the sealing operation of the packing 17 with high heat resistance, a measurement is taken without causing variation in water containing state before and after heating, and no cracking in the test body 2 is caused by the frames 8.

Description

Detailed Description of the Invention (Industrial Application Field) This invention provides a method for measuring concrete specimens used when creating a calibration curve when measuring the moisture content in concrete used for nuclear structures etc. by an electrode method. , relates to a structure that maintains a preset hydrated state and completely seals the specimen when heated at high temperatures without damaging the specimen.

(Prior art and its problems) The moisture content measurement method using the electrode method uses a thermocouple in advance.

A small specimen with embedded sensors such as electrodes and artificially changed moisture content is placed in a sealed container, heated inside the container without changing the moisture content, and the concrete temperature, moisture content, and electrodes are measured. A calibration curve is created by determining the relationship between the inter-electrode resistance value, and then the inter-electrode resistance value of the electrodes embedded in the concrete of the actual part is measured, and the results are compared with the calibration curve to determine the moisture content of the actual part. It is a method of reading.

In this measurement method, when a small concrete specimen is heated to a high temperature of, for example, 200°C, the vapor pressure of the water in the concrete increases to nearly 10 atm due to heating, but at the end of the lead wire from the sealed container, Since the seal conventionally uses an O-ring, the sealing performance in this area tends to deteriorate.

In addition, since there is a gap between the seal container and the specimen, the seal may be incomplete, such as dehydration from the specimen or cracks in the concrete due to differences in thermal deformation between the electrode embedded in the concrete and the concrete. It had become a thing.

(Objective of the invention) This invention provides a method for heating specimens at high temperatures without damaging them.
It is also intended to completely seal the externally drawn end of the lead wire.

(Means for Achieving the Object) In order to achieve the above object, the present invention stores a concrete specimen in which sensors such as thermocouples and electrodes are embedded in advance in a sealed container, and connects the lead wires of the sensors to the sealed container. In the measurement sample drawn from the concrete specimen, a space between the concrete specimen and the closed container contains a non-water-absorbing material,
It is characterized by being filled with a highly heat-resistant packing agent.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a plan view of a measurement sample to which the present invention is applied, and FIG. 2 is a sectional view thereof.

In the figure, the sample is a concrete specimen 2 sealed in a sealed container gs1 in an airtight state.

The sealed container 1 includes a cylindrical tube portion 3 with a vertical opening and a tube portion 3.
upper and lower end plates 4 attached via O-rings 5 to the upper and lower surfaces of the
It consists of a Stibbolt 6 which is attached to the outer periphery of the cylindrical part 3 and penetrates between each end plate 4, and a nut 7 screwed into the Stibbolt 6. When the nut 7 is tightened, the inside of the cylindrical part 3 is tightened. It is hermetically sealed.

The specimen has a rectangular shape, and a pair of restraint frames 8 are disposed facing each other on both sides thereof, and both breast bundle frames 8
is tightened with a plurality of screws 9 to hold the specimen 2 under pressure.

Inside the specimen 2, a temperature sensor 10 such as a thermocouple and a pair of electrodes 11 for measuring resistance value are embedded in a state in which they face each other. being pulled outside. At the lead wire drawing end of each end plate 4, there is a boss portion 14 for inserting the lead wire.
is provided protrudingly, and by inserting each lead wire 12, 13 into the outer periphery and fitting a Teflon ring 15 into the outer periphery, and further covering the open end with a screw cap 16, the lead-out end is airtightly sealed by the Teflon ring 15. has been done.

In addition, by coating the outer periphery of each lead wire 12.13 with Teflon, the lead wire 12.1 can be coated with Teflon during high temperature heating.
It is possible to prevent the sealing performance of No. 3 from deteriorating.

A space surrounded by the cylindrical portion 3 and the upper and lower end plates 4 and the specimen 2 is filled with packing 17 that has no water absorption and is resistant to high temperatures. A large number of rods 18 such as reinforcing bars are inserted vertically.

The packing 17 is made of silicone resin, for example, and the specimen 2 is attached to the cylindrical part 3 with the lower end plate 4 attached.
It is an elastic body obtained by attaching it to the inside of the body, then injecting silicone resin and curing it. Then, each rod 18 is inserted during the curing, and then the upper end plate 4 is attached to complete the measurement sample.

In the above configuration, when the sealed container 1 is heated to a high temperature of approximately 200°C, due to the sealing action of the packing 17, there is no dehydration to the outside of the sealed container 1 or dehydration of the specimen itself, and the heating Measurements can be performed without changing the water content of the specimen before and after.

Further, the restraint frame 8 prevents cracks from occurring in the specimen 2.

For measurement, loosen the nut, remove the end plate 4, and pull out the rod 18 from inside the packing 17. Since the packing 17 is originally an elastic body, it easily shrinks in the radial direction in which the iron 18 is removed. , packing 1 from cylinder part 3
7 can be easily pulled out together with the specimen 2. Furthermore, separation of the specimen 2 and the packing 17 becomes easy.

(Effects of the Invention) As described above in detail in the examples, the seal structure according to the present invention does not change the moisture content of the specimen itself before and after heating the specimen, and Sealing performance will also be improved.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a measurement sample according to the present invention, and FIG. 2 is a cross-sectional view of the same measurement sample.

Claims (3)

[Claims] (1) In a measurement sample in which a concrete specimen in which sensors such as thermocouples and electrodes are embedded in advance is housed in a sealed container, and a lead wire of the sensor is pulled out from the sealed container, the concrete specimen and the sealed container are In the space with
A sealing structure for a concrete specimen heated to a high temperature, characterized by being filled with a non-water-absorbing and highly heat-resistant packing agent. (2) A sealing structure for a concrete specimen to be heated to a high temperature as set forth in claim 1, wherein the outer circumferential surface of the concrete is held under clamping pressure by a restraining frame. (3) A concrete specimen to be heated at a high temperature according to claim 1 or 2, wherein a large number of gap adjustment rods are removably inserted into the space filled with the packing agent. Seal structure.