KR101534839B1 - Three dimensional quantification of porous geopolymer using electron tomography - Google Patents

Abstract

The present invention relates to a method for three-dimensionally measuring a porous geopolymer using electron tomography, more specifically, a method for manufacturing a porous geopolymer by milling a geopolymer with an ion beam to produce a geopolymer having a plate- Continuously obliquely observing the prepared sheet-like geopolymer with a transmission electron microscope and photographing with a CCD camera (charge-coupled device camera); And reconstructing the photographed image in three dimensions using filtered back-projection. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional measurement method for a porous geopolymer using an electron tomography.

Description

TECHNICAL FIELD [0001] The present invention relates to a three-dimensional measurement method of porous geopolymers using electron tomography,

The present invention relates to a method for three-dimensionally measuring porous geopolymers using electron tomography.

The geopolymer is a kind of an alkali active binder prepared by chemical reaction of a silicate aluminum raw material with an alkali active solution at a low temperature. Pozzolans, including fly ash, meta kaolin, and natural pozzolans, are used as raw materials to produce geopolymers. Silicon and aluminum as raw materials are dissolved in an alkaline solution and the three-dimensional network structure is cured later, but the mechanism of the geopolymerization reaction has not yet been fully elucidated.

Geopolymers have advantages such as corrosion resistance, fire resistance, compressive and tensile strength, and fast strength strength compared to general Portland cement (OPC), and with these advantages they greatly reduce CO ₂ emissions , A geopolymer is one of the potential alternatives to OPC. However, long-term durability problems remain an obstacle to commercializing geopolymer cements for construction. In the case of OPC, much research has been done on the microstructure, pore structure and interface between aggregate and cement binder, and pore volume, pore size distribution, and pore connectivity have many properties of binder materials such as permeability, shrinkage, . Also, the long term durability is directly affected by the porosity of the geopolymer and OPC. The microstructure, including pore volume, porosity and pore distribution around the gel framework, determines the mechanical properties of the geopolymer. Penetration of chemicals such as chlorides into the pores of the geopolymer degrades the quality of the geopolymer concrete, so pore structure identification and quantification within the geopolymer is an important factor in understanding the impact on the durability of the geopolymer.

Gas adsorption and mercury intrusion (MIP) have been widely used to determine the bubble size distribution. However, in order to understand the data by the above method, it is necessary to assume that the pores are connected to each other with a regular structure in the material. The mercury intrusion method for cement and concrete has a problem that the pore size may be three times lower than the size obtained by the SEM image. In addition, some voids in the geopolymer appear to be not linked by gels in back-scattered electrons. X-ray micro-tomography is used to obtain information on the pore size distribution in Portland cement products, and is also used to evaluate the pore structure of geopolymers, but due to the limited resolution, information on the microporous structure of distinct three- There is a problem that can not be provided.

As a prior art related thereto, there is a carbon dioxide injection behavior evaluation method in porous sandstone in a stratum by electrical resistivity tomography survey disclosed in Korean Patent Registration No. 10-0964712 (published on Jun. 22, 2010).

Accordingly, it is an object of the present invention to provide a method for three-dimensionally measuring micropores contained in a porous geopolymer by using an electron tomography capable of accurately analyzing pore structure, pore distribution and size within the porous geopolymer.

The problems to be solved by the present invention are not limited to the above-mentioned problem (s), and another problem (s) not mentioned can be understood by those skilled in the art from the following description.

In order to solve the above-mentioned problems, the present invention provides a method for manufacturing a geomolecule comprising the steps of: milling a geopolymer with an ion beam to prepare a geopolymer having a plate-like structure; Continuously obliquely observing the prepared sheet-like geopolymer with a transmission electron microscope and photographing with a CCD camera (charge-coupled device camera); And reconstructing the photographed image three-dimensionally using filtered back-projection. The present invention also provides a three-dimensional measurement method of a porous geopolymer using electron tomography.

The geopolymer is produced by collecting coal ash from an embedding circuit, crushing and pulverizing the mixture and mixing with an activator.

The size of the pulverized and finely pulverized coal ash is 100-200 탆.

And wet milling using the rod mill after the crushing and pulverizing process.

Further, the method may further include removing unburnt carbon contained in the coal ash after the wet milling.

The activator is characterized by comprising sodium silicate and sodium hydroxide.

And the continuous tilt is performed from -55 DEG to + 55 DEG at intervals of 1 DEG.

The three-dimensional measurement method of the porous geopolymer is characterized by analyzing nano-sized pores contained in the porous geopolymer.

The geopolymer is characterized in that the molar ratio of Si: Al is 1.5 - 2.8 and the molar ratio of Na: Al is 1.2 - 1.5.

The present invention also relates to a method for producing a geopolymer comprising the steps of: milling a geopolymer with an ion beam to prepare a geopolymer having a plate-like structure; Immersing the prepared flaky geopolymer in a gold colloid solution and then drying to apply gold particles; Continuously obliquely scanning the sheet-like geopolymer coated with the gold particles, observing the particles with a transmission electron microscope, and photographing the particles with a charge-coupled device camera; And reconstructing the photographed image three-dimensionally using filtered back-projection. The present invention also provides a three-dimensional measurement method of a porous geopolymer using electron tomography.

According to the present invention, it is possible to analyze the pore characteristics of a geopolymer by nondestructive analysis at the nanometer level, obtain an image by continuously tilting the geopolymer to an elevation angle, and then reconstruct the three- ), It is possible to accurately obtain the pore shape and the pore distribution information in the geopolymer that can not be obtained by X-ray tomography.

In addition, the durability of the geopolymer can be accurately predicted by quantitatively evaluating the pores of the nano-scale level present in the geopolymer.

FIG. 1 is a flowchart showing a three-dimensional measurement method of a porous geopolymer using an electron tomography according to the present invention.
2 is a photograph showing a buried structure and a bottom material, and is a backscattered electron image of iron oxide.
Fig. 3 shows the result of quantitative analysis of Rietveld of coal ash.
Figure 4 is a TEM bright field of a thin sheet geopolymer.
5 is a photograph showing two z-slice images at intervals of 10.7 nm.
6 is a graph showing the pore size distribution of each of the circles in the four z-slices.
FIG. 7 is a photograph of a three-dimensional rendering of a reconstructed tomographic photograph of a sheet-form geopolymer. FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving it will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings.

The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

The present invention relates to a method for producing a geopolymer comprising the steps of: milling a geopolymer with an ion beam to prepare a geopolymer having a plate-like structure;

Continuously obliquely observing the prepared sheet-like geopolymer with a transmission electron microscope and photographing with a CCD camera (charge-coupled device camera); And

And reconstructing the photographed image three-dimensionally using filtered back-projection. The present invention also provides a method for three-dimensionally measuring a porous geopolymer using electron tomography.

The three dimensional measurement method of the porous geopolymer using the electron tomography according to the present invention has an effect on the transmittance, shrinkage, elastic modulus and strength of the material, and the pore volume, pore size distribution and pore connectivity Can be accurately measured. In particular, the pore structure of the porous geopolymer can be accurately analyzed. In addition, it is possible to accurately analyze the pore structure of the geopolymer by recognizing the problem that a clear image can not be obtained due to the low resolution of the conventional X-ray tomography and reconstructing it in three dimensions by using electron tomography and back projection, Durability can be accurately predicted.

FIG. 1 is a flowchart showing a three-dimensional measurement method of a porous geopolymer using an electron tomography according to the present invention. Hereinafter, the present invention will be described in detail with reference to Fig.

The method for three-dimensionally measuring a porous geopolymer using electron tomography according to the present invention includes a step (SlOO) of producing a geopolymer having a plate-like structure by milling a geopolymer with an ion beam.

The geopolymer may be prepared by collecting coal ash from an embedding circuit, crushing it, and pulverizing it, mixing it with an activator, wet milling using the rod mill after the pulverization and pulverization, and after the wet milling, And removing the contained unburned carbon by float sorting.

The size of the pulverized and finely pulverized coal material is preferably 100 to 200 탆 passing through 65 mesh, and float sorting can be easily performed due to the size of the pulverized and pulverized coal material. When the size of the crushed and pulverized coal ash is less than 100 탆, it may be difficult to isolate individual particles by floating. When the particle size exceeds 200 탆, unburnt carbon and fly ash particles are not separated, .

Further, water can be added to the pulverized and finely pulverized coal materials to prepare a slurry, followed by wet milling using a rod mill, and since unburnt carbon contained in the coal material interferes with the geopolymerization reaction, can do. The float sorting may include a roughing step and a scavenging step.

After the fly ash separation, the coal ash is washed, dehydrated and dried in an oven to be used as a raw material for the production of a geopolymer. The activator may be added to the coal ash for the production of the geopolymer produced by the above method, mixed with the cement mixer, and cured to prepare the geopolymer.

Preferably, the activator comprises sodium silicate and sodium hydroxide, and the molar ratio of Si: Al and the molar ratio of Na: Al in the geopolymer are 1.5-2.8 and 1.2-1.5, respectively. (Poly (sialate siloxo)) can be prepared by setting the mole ratio of Si: Al to 1.5-2.8. The molar ratio of Na: Al is 1.2-1.5 because Na is volatile, (efflorescence) phenomenon can be prevented.

The prepared geopolymer is produced as a geopolymer having a plate-like structure by focused ion beam milling and can be milled after cutting with gallium ions to minimize milling defects.

The method for three-dimensionally measuring a porous geopolymer using the electron tomography according to the present invention comprises the steps of continuously obliquely observing the prepared sheet-like geopolymer with a transmission electron microscope, and then photographing with a CCD-camera (charge-coupled device camera) ).

The prepared sheet-like geopolymers can be continuously photographed at -55 ° to + 55 ° at intervals of 1 °, observed with a transmission electron microscope (TEM), and then photographed using a CCD camera. The transmission electron microscope can obtain a bright field image by observing the plate-shaped geopolymer with an energy of 120 keV, and photographs the obtained image with a CCD camera.

The method for three-dimensional measurement of porous geopolymers using electron tomography according to the present invention includes reconstructing the photographed photographs three-dimensionally using filtered back-projection (S120).

The photographed photographs are reconstructed in three dimensions using a filter back projection method. The reconstructed tomographic photographs can be analyzed using Chimera software v.16 and IMOD v.4.1.10.

The three dimensional measurement method of the porous geopolymer can analyze nano-sized pores contained in the porous geopolymer.

The present invention also relates to a method for producing a geopolymer comprising the steps of: milling a geopolymer with an ion beam to prepare a geopolymer having a plate-like structure;

Immersing the prepared flaky geopolymer in a gold colloid solution and then drying to apply gold particles;

Continuously observing the sheet-like geopolymer coated with the gold particles with a transmission electron microscope, and photographing the sheet with a charge-coupled device camera; And

And reconstructing the photographed image three-dimensionally using filtered back-projection. The present invention also provides a method for three-dimensionally measuring a porous geopolymer using electron tomography.

The size of the gold particles applied to the flaky geopolymer is preferably 10 nm and can be used as an index for precise alignment according to an angle change.

Example 1: Three-dimensional measurement of a porous geopolymer

1. Production of raw material of geopolymer from coal ash

The geopolymer samples were pond ash, a bottom ash mixed with a small amount of rejected fly ash from Samchunpo Thermal Power Plant. The flooring is coarse, porous coal particles, brownish gray. The remainder is a thick part of fly ash that is abandoned in landfills because of its high unburned carbon content and large particle size (> 45 μm). Ash (ash) was collected in a landfill and dried at room temperature for 3 days. Thereafter, the 65 mesh (212 탆) was pulverized and pulverized to have a powder throughput of 43%. 500 g of pulverized coal ash was slurried in 500 mL of water and wet milled to a size of less than 212 μm using a rod mill. The unburned carbon content was measured by proximate analysis and the unburned carbon was removed by froth flotation because it interfered with the geopolymerization reaction. About 60 g / t of kerosene and 20 g / t of fine oil were selectively absorbed on the surface of the particles, and the bonded carbon particles were frosted so as not to be lost. A dispersant (Na ₂ SiO ₃ ) of about 600 g / t was used to minimize heterogeneous aggregation and promote selectivity. Flotation screening consists of the first stage of roughing and the second stage of scavenging. Flocculant After washing, the washed coal ash was dehydrated and dried in an oven for one day to be used as a raw material for producing a geopolymer. The amount of carbon in the washed coal ash was measured by industrial analysis.

2. Geopolymer production

And Al ratio of 2.0 Na:: sodium silicate solution _{(SiO 2 36.50%, 18.00%} Na 2 O, Kanto Chemical Co., INC) and sodium hydroxide (Wako Pure Chemical Industries, Ltd) a Si to Al ratio of activator 1.2. ≪ / RTI > The mixture of coal ash and activator was mixed in a cement mixer for 15 minutes, poured into a 5 cm cube mold, sealed, cured at 70 ° C for 24 hours and then separated from the mold. After one day curing, the compressive strength of coal ash and activator mixture paste was 49.8 MPa and the standard deviation was 4.7 MPa.

3. TEM data acquisition and 3D reconstruction method

Platelet-shaped geopolymers were prepared from focused ion beam milling (Quanta 3D FEG, FEI) from the areas identified as geopolymer gels and not reacting with the coal precursor. Cutting with gallium ions at 30 keV and 15 nA, then polishing at 5 keV and 48 pA minimized milling defects. The gold colloid solution was diluted 10 times with distilled water and 10 ㎚ gold particles were applied to the upper and lower surfaces of the sample and used as indexes for precise alignment of angle changes. To place the gold particles on the specimen, the platelet-shaped geopolymer was immersed in a diluted gold colloid solution for 1 minute and then dried to place the gold particles on both surfaces of the specimen. TEM images were obtained using FEI TECNAI G ² Spirit equipped with a large inclination holder and a 2048 × 2048 pixel CCD camera. The bright field image (acceleration of 120 keV) along the angle of the plate geometry was obtained from -55 ° to + 55 ° at an angle of 1 ° inclination. Accurate alignment with angle changes is an essential step in the electronic tomography and Diez et al. Filter back-projection, which is used for three-dimensional reconstruction of the TEM image, was used. Each image size reduced the image size in half by an average pixel of 1024 pixels by 1024 pixels to minimize computer computation time. Reconstructed tomographic images were analyzed using Chimera software v.16 and IMOD v.4.1.10.

Experimental Example 1: Chemical composition and phase analysis of coal ash

The chemical composition and phase of the carbonaceous material were analyzed in the three dimensional measurement method of the porous geopolymer using the electron tomography according to the present invention.

As shown in Fig. 2, the collected buried sludge showed various sizes and shapes (see Fig. 2 (a)). The bottom material was porous with a large particle size, sandy and grayish gray (see Fig. 2 (b)). Most of the coal particles were on aluminum silicate with small amounts of iron, calcium, potassium, magnesium and sodium (cf. Fig. 2). Table 1 below shows the results of XRF analysis of the chemical composition of the landfill with unburned carbon removed.

Furtherance SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ CaO MgO K ₂ O Na ₂ O TiO ₂ MnO P ₂ O ₅ Weight loss content 57.7 22.6 9.70 4.13 1.48 1.47 0.68 1.12 0.13 0.32 0.39

Referring to Table 1, the landfill was composed mainly of 57.7% of SiO ₂ , 22.6% of Al ₂ O ₃ and 9.70% of Fe ₂ O ₃ , and contained only 4.13% of CaO. The residual carbon content was 4.69%. No carbon was found in the coal ash after removal of unburned carbon.

Fig. 3 shows the result of quantitative analysis of Rietveld of coal ash. The main crystal phase of coal ash was quartz (16.1 wt%), mullite (15.5 wt%), albite (7.4 wt%) and hematite , 1.5 wt%), the amorphous portion was 59.5 wt%, and the composition of the amorphous portion was calculated as the difference between the bulk chemical composition and the crystalline constituent as the oxide. .

Furtherance SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ CaO MgO K ₂ O TiO ₂ MnO P ₂ O ₅ content 25.9 17.1 8.3 4.2 1.5 1.5 1.1 0.1 0.3

The Si: Al ratio of coal ash removed unburned carbon was determined to be 1.30. Silicon and sodium were added to the coal ash so that the molar ratio of Si / Al was 2.0 and the molar ratio of Na / Al was 1.2. The mixing ratio of the geopolymer gel was 61.5 wt% of coal ash, 24.3 wt% of silicate solution, 4.2 wt% of NaOH and 10 wt% of distilled water.

Experimental Example 2: Analysis of nanoscale pore structure in a geopolymer

The porosity of the geopolymer prepared by the three-dimensional measurement method of the porous geopolymer using the electron tomography according to the present invention was analyzed.

Figure 4 is a TEM light field of a sheet-form geopolymer. As shown in FIG. 4, the pore structure of the flaky geopolymer was apparent due to the high contrast difference between the paste and the pores. Due to bragg scattering contrast at successive angular changes, dark spherical gold particles and numerous small crystals Were identified. The crystalline phase was present in the geopolymer even though the gel phase was amorphous. The crystal phase was generally larger, darker, and asymmetric than gold particles. The diffuse diffraction ring generated from the gold particles was found in the electron diffraction analysis and no diffraction spot or ring appeared on the crystal. The distinctive shape or ring in the diffraction pattern reflects the degree of long-range regularity. On the other hand, unaligned nanoparticles did not provide an identifiable diffraction pattern or ring because of their extremely small size. For this reason, the crystalline phase is judged to be a low-order zeolite based on energy scattering X-ray spectroscopic data. It is judged that zeolite is formed to some extent in the zeolite reaction.

Figure 5 is a photograph showing two z-slice images spaced apart by about 10.7 nm. The outer diameters of some pores are shown in Figs. 4 (a) and 4 (b). Most of the pores were almost circular or elliptical, but some were somewhat amorphous in shape.

6 is a graph showing the pore size distribution of each of the circles in the four z-slices. As shown in Fig. 6, the diameters of the outer diameters of 145 pores in the four z-slices ranged from 13.5 to 147 nm. The number of pores was about 20 to 60 nm, the number of pores out of the range was 8, and the pores having long and narrow pores (the part circled in FIG. 4 (b)) were 80 nm or more. Multiple pores are present in two or more slices with a slice spacing of 10.7 nm. Thus, this size range does not represent 145 pore diameters, but provides an approximation of the size of the pores.

Experimental Example 3: Analysis of Geopolymer Pore at Nano Size

In order to express the porosity in the geopolymer as a quantitative value, it was segmented and reconstructed into three dimensions as shown in Fig. The segmentation is a process of grouping pixels based on different contrast values to distinguish between different images. For example, pores are distinguished by large contrast differences from the gel in the geopolymer. However, manual sorting, which manually distinguishes between contrasts without using an automated program, can be time-consuming and subjective. Quantification based on classification by thresholding can quickly distinguish images from other images. Thus, the present invention quantifies pores by manual sorting because the binarization may not be able to completely separate pores and gels in z-slices. The process of immersing the sheet-like geopolymer in a diluted gold colloid solution and then drying will cause the sheet-form geopolymer to bend slowly and reduce the volume of interest for quantifying the porosity. The width, length, and thickness of the sheet-form geopolymers selected for sorting were 482 nm, 482 nm, and 32.2 nm, respectively, and the volume was 0.00748 mu m, which is a value of 19.3 It is a value corresponding to%. The porosity in this region was 7.15%. This value is much lower than the 30.5% and 23 ~ 28% measured by the conventional method. These differences may be different depending on the different chemical composition, formulation, curing conditions of the raw material, and the year of manufacture of the sample, but above all are related to the resolution and volume difference in the porosimetry device. Electron tomography analyzes pore structures for very small volumes at the nanometer level at higher resolutions than mercury porosimetry (MIP), metal infiltration and X-ray tomography methods used in large objects of tens of millimeters or more. can do. Large pores of several hundred nanometers or more coexist with sizes ranging from microns to less than 5 nm, and pore sizes range from 100 nm to 10 nm. As shown in FIG. 6, the presence of micropores can be observed directly by visual observation. The artifacts in the reconstructed image have a wormhole structure much smaller than the pores and arise from the scattering noise of the zeolite crystals present in the plate geometry polymer. Typical algorithms for reconstruction in bright field electron tomography are filtered back projection (FBP) and simultaneous iterative reconstruction technique (SIRT). These algorithms are based on three-dimensional Performing reconfiguration always causes defects. The spatial distribution of the dark portions in the crystal can be offset by the reconstruction of the entire sequential angle change. Therefore, it is considered that the wormhole structure is formed due to the effect of lightness error caused by bragg scattering and the uneven chemical composition in the solid phase region. However, since such defects do not seriously distort the visual details such as the shape or size of the pores within the z-slice image or the reconstructed three-dimensional image, the pore size data is reliable.

FIG. 7 is a photograph of a three-dimensional rendering of a reconstructed tomographic photograph of a sheet-form geopolymer. FIG. As shown in FIG. 7, most of the pores are not connected, and some large pores appear to be formed by a combination of a plurality of adjacent small pores. The irregular structure of the pores in a 3-D tomographic image appears to be consistent with that observed in the z-slice image. As described above, the electron tomography of the dark night scanning transmission electron microscope (ADF-STEM) is considered to be more appropriate for studying the geopolymer, but has a disadvantage in that it has a low resolution of less than 1/5 of the bright field mode. Pores smaller than those identified in the present invention can be identified by high magnification electron tomography. On the other hand, the missing wedge effect is caused by the inclination angle limit up to + 70 °, and defects occur due to the reduction in projection in three-dimensional reconstruction. The porosity changes when the sample to be measured is tilted to more than ± 90 °, and the sewing wedge effect can be completely eliminated. However, the porosity obtained in the present invention is a three-dimensional quantitative evaluation of micropores in a geopolymer gel, and provides a method for more specifically understanding the pore structure of a geopolymer at a spatial resolution on the order of nanometers. One way is not to completely characterize the pore size range in the sample, but the method of the present invention is based on the use of TEM and filter corrected back-projection electron tomography in which nanopores at nanometer resolution Dimensional pore network and pore connectivity.

It should be understood that the present invention is not limited to the three-dimensional measurement method of the porous geopolymer using the electron tomography according to the present invention, but various modifications may be made without departing from the scope of the present invention.

Therefore, the scope of the present invention should not be limited to the above-described embodiments, but should be determined by the scope of the appended claims and equivalents thereof.

It is to be understood that the foregoing embodiments are illustrative and not restrictive in all respects and that the scope of the present invention is indicated by the appended claims rather than the foregoing description, It is intended that all changes and modifications derived from the equivalent concept be included within the scope of the present invention.

Claims (12)

Milling a geopolymer with an ion beam to produce a geopolymer having a plate-like structure;
Observing the prepared flaky geopolymer with a transmission electron microscope while continuously tilting to obtain a bright field image and photographing the obtained bright field image with a CCD camera (charge-coupled device camera); And
And reconstructing the photographed image three-dimensionally using filtered back-projection to analyze the pore structure in the geopolymer. The three-dimensional measurement of the porous geopolymer using electron tomography Way.
The method according to claim 1,
Wherein the geopolymer is prepared by collecting coal ash from the buried circuit, and then crushing and pulverizing the mixture and mixing with an activating agent.
3. The method of claim 2,
Wherein the size of the crushed and pulverized coal ash is 100-200 탆.
3. The method of claim 2,
Further comprising wet milling using the rod mill after the crushing and milling process. ≪ Desc / Clms Page number 13 >
5. The method of claim 4,
Further comprising the step of removing the unburnt carbon contained in the coal ash after the wet milling by floating.
3. The method of claim 2,
Wherein the activator comprises sodium silicate and sodium hydroxide. ≪ RTI ID = 0.0 > 11. < / RTI >
The method according to claim 1,
Wherein the continuous tilt is performed from -55 DEG to + 55 DEG at intervals of 1 DEG.
delete The method according to claim 1,
Wherein the geopolymer has a molar ratio of Si: Al of 1.5-2.8 and a molar ratio of Na: Al of 1.2-1.5.
Milling a geopolymer with an ion beam to produce a geopolymer having a plate-like structure;
Immersing the prepared flaky geopolymer in a gold colloid solution and then drying to apply gold particles;
Observing the plate-like geopolymer coated with the gold particles with a transmission electron microscope while continuously tilting to obtain a bright field image, and photographing the obtained bright field image with a CCD camera (charge-coupled device camera); And
And reconstructing the photographed image three-dimensionally using filtered back-projection to analyze the pore structure in the geopolymer. The three-dimensional measurement of the porous geopolymer using electron tomography Way.
11. The method of claim 10,
Wherein the geopolymer is prepared by collecting coal ash from the buried circuit, and then crushing and pulverizing the mixture and mixing with an activating agent.
11. The method of claim 10,
Wherein the continuous tilt is performed from -55 DEG to + 55 DEG at intervals of 1 DEG.

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