CN102944568A - Cement-based test piece in-situ loading instrument for industrial X-CT (X-ray computered tomography) and use method thereof - Google Patents

Abstract

The invention discloses a cement-based specimen in-situ loading instrument for industrial X-CT, which comprises an upper base plate, a lower base plate, an intermediate shaft, a fixed end and a displacement sensor, and the upper base plate and the lower base plate are respectively installed at both ends of the intermediate shaft , a test piece is arranged between the upper base plate and the lower base plate, the displacement sensor is inserted through the upper base plate and the lower base plate, and the upper base plate is provided with a fixed end capable of applying pressure to the test piece. The invention solves the problem of realizing 360° rotation without affecting the CT scanning effect and loading conditions, and can establish the relationship between deformation amount and crack initiation and expansion. The invention also discloses a method for using a cement-based specimen in-situ loading instrument for industrial X-CT.

Description

Cement-based specimen in-situ loading instrument for industrial X-CT and its application method

technical field

The invention belongs to the field of civil engineering material detection, and in particular relates to a cement-based test piece in-situ loading instrument for industrial X-CT and a use method thereof.

Background technique

In recent years, X-ray computerized tomography (X-CT) has been applied in the field of civil engineering materials. As an effective in-situ structure analysis method, X-CT will also play an important role in the quantitative analysis and in-situ observation of the microstructure evolution of cement-based composites.

For mature concrete, starting from the microstructure of the material, it is of great significance to track and observe the whole process of crack initiation and growth under loading conditions, and to study the quantitative relationship between the microstructure evolution and the macroscopic behavior in the process of material damage and degradation. No detailed reports have been seen yet. The few existing research results mainly use scanning electron microscopy and various fluorescence spectra to observe two-dimensional cross-sections, but the fact is that the extraction process of two-dimensional information has destroyed its authenticity. becomes impossible.

How to realize the 360° rotation under the loading condition of the sample, so as to be used with the X-CT stage, for the realization of in-situ observation, in-situ tracking of the initiation and propagation of cracks in cement paste, mortar and concrete specimens, to find Crack propagation pathways, exploring the mechanism of action of aggregates, pore structures, and impurities in concrete play a decisive role. At present, there is no mature plan for the in-situ loading device for cement-based specimens used in conjunction with industrial X-CT.

Contents of the invention

The purpose of the present invention is to overcome the defects of industrial X-CT scanning, provide a kind of in-situ loading instrument capable of observing the initiation and expansion of cracks in cement-based specimens in situ, and solve the problem of achieving 360° without affecting the CT scanning effect and loading conditions. Rotation, and the relationship between deformation and crack initiation and expansion can be established.

Another object of the present invention is to provide a method for using an in-situ loading instrument for cement-based specimens for industrial X-CT.

The technical scheme adopted in the present invention is: an in-situ loading instrument for cement-based specimens for industrial X-CT, including an upper base plate, a lower base plate, an intermediate shaft, a fixed end and a displacement sensor. A test piece is arranged between the base plate and the lower base plate, the upper base plate and the lower base plate, the displacement sensor is inserted through the upper base plate and the lower base plate, and the upper base plate is provided with a fixed end capable of applying pressure to the test piece.

A method for using the above-mentioned cement-based specimen in-situ loading instrument for industrial X-CT, comprising the following steps:

1) Test piece installation:

Pour the test piece according to the characteristics of the device, reserve a hole for the intermediate shaft in the center of the test piece, and reserve a hole for the displacement sensor. After curing the test piece for 28 days, place it between the upper and lower plates, insert the displacement sensor and the intermediate shaft, and fix it. ;

2) Specimen loading:

Keep the relative position of the test piece, the upper base plate, the lower base plate, and the displacement sensor unchanged, load the test piece by rotating the fixed end, observe the reading of the displacement sensor, and stop loading when the preset value is reached;

3) X-CT scan:

Place the specimen and the entire device at the center of the X-CT rotating table to ensure its stability; the displacement sensor attachment is placed outside the scanning field of view to prevent artifacts, adjust the parameters, and scan.

Preferably, the material of the upper base plate and the lower base plate is aluminum alloy, and the material of the intermediate shaft and the fixed end is glass fiber reinforced plastic. Steel, etc. have a strong ability to absorb X-rays, and using them as materials for loading instruments will seriously affect the final imaging effect of the test block. The X-ray absorption capacity of aluminum alloy and fiberglass fiber is basically equivalent to that of cement paste. In this plan, aluminum alloy and fiberglass fiber are used instead of steel to reduce the impact on the imaging effect of the test block under the premise of meeting the strength requirements.

The invention pours the cement-based test piece into a test piece of a specific shape, places it between the upper and lower bottom plates, applies pressure to the test piece by rotating the fixed end, and uses a displacement sensor to record the displacement change between the upper and lower bottom plates. Place the whole device on the X-CT rotating table, adjust the parameters, and scan the initial specimen and the specimen after applying different pressures.

Beneficial effects of the present invention:

(1) A solution to achieve 360° rotation without affecting the CT scanning effect and loading conditions;

First of all, in order to avoid artifacts caused by parts of the device exceeding the scanning range of the specimen, the device uses a ring-shaped test block so that the bearing shaft passes through the center to avoid the above situation.

At the same time, aluminum alloy is selected as the upper and lower bottom plates, and fiberglass fiber is used as the intermediate shaft and fixed end. The X-ray absorption ability of aluminum alloy and fiberglass fiber is basically equal to that of cement paste, so it will not have a significant impact on the scanning effect of the specimen.

(2) The relationship between deformation and crack initiation and expansion can be established.

A displacement sensor is fixed at the upper base plate to record the displacement of the upper and lower base plates during the loading process, and correlate with the state of cracks generated inside the specimen under the displacement to establish a quantitative relationship.

Description of drawings

Fig. 1 is the structural representation of the in-situ loading instrument for cement-based specimens used in industrial X-CT of the present invention:

Fig. 2 is a schematic diagram of a test piece in the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figures 1 and 2: a cement-based specimen in-situ loading instrument for industrial X-CT, including an upper base plate 1, a lower base plate 2, an intermediate shaft 3, a fixed end 4 and a displacement sensor 5, the intermediate shaft 3 An upper base plate 1 and a lower base plate 2 are respectively installed at both ends, a test piece 6 is arranged between the upper base plate 1 and the lower base plate 2, the displacement sensor 5 is inserted through the upper base plate 1 and the lower base plate 2, and the upper base plate 1 is provided with There is a fixed end 4 which can apply pressure to the test piece 6 .

A method for using the above-mentioned cement-based specimen in-situ loading instrument for industrial X-CT, comprising the following steps:

1) Test piece installation:

Pour the test piece 6 according to the characteristics of the device, reserve a hole for the intermediate shaft 3 in the center of the test piece 6, and reserve a hole for the displacement sensor 5, put the test piece 6 between the upper base plate 1 and the lower base plate 2 after curing for 28 days, and insert the displacement sensor The sensor 5 and the intermediate shaft 3 are fixed;

2) Specimen loading:

Keep the relative positions of the test piece 6, the upper base plate 1, the lower base plate 2, and the displacement sensor 5 unchanged, load the test piece 6 by rotating the fixed end 4, observe the reading of the displacement sensor 5, and stop loading when the preset value is reached;

3) X-CT scan:

Place the test piece 6 and the whole device at the center of the X-CT rotating table to ensure its stability; the displacement sensor 5 accessory device is placed outside the scanning field of view to prevent artifacts, adjust the parameters, and scan.

The material of the upper bottom plate 1 and the lower bottom plate 2 is aluminum alloy, and the material of the intermediate shaft 3 and the fixed end 4 is glass fiber reinforced plastic.

It should be pointed out that those skilled in the art can make some improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention. All components that are not specified in this embodiment can be realized by existing technologies.

Claims (3)

1. an industrial X-CT is with cement based test specimen original position load apparatus, it is characterized in that: comprise upper plate, lower shoe, intermediate shaft, stiff end and displacement transducer, described intermediate shaft two ends are separately installed with upper plate and lower shoe, be provided with test specimen between upper plate and the lower shoe, described displacement transducer runs through and inserts upper plate and lower shoe, is provided with the stiff end that can exert pressure to test specimen on the described upper plate.

2. industrial X-CT according to claim 1 is characterized in that: described upper plate and lower shoe material employing aluminium alloy, described intermediate shaft and stiff end material employing reinforced plastic glass fibre with cement based test specimen original position load apparatus.

3. a claim 1 or 2 described industrial X-CT is characterized in that: may further comprise the steps with the using method of cement based test specimen original position load apparatus:

1) test specimen is installed:

Build test specimen according to device characteristic, reserve the intermediate shaft hole at the test specimen center, and reserved place displacement sensor hole, test piece maintenance after 28 days, is placed between upper plate and the lower shoe, insert displacement transducer, intermediate shaft, and fixing;

2) test specimen loads:

Keep the relative position of test specimen and upper plate, lower shoe, displacement transducer constant, by the rotation stiff end test specimen is loaded, observe the displacement transducer reading, stop when reaching preset value loading;

3) X-CT scanning:

Test specimen and whole device are placed X-CT universal stage center, guarantee its stability; The displacement transducer auxiliary equipment is placed in outside the scanning field of view, prevents pseudo-shadow; Adjust parameter, scan.

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