Academia.eduAcademia.edu

Figure 6 – uploaded by EROL YILMAZ

See full PDFdownloadDownload figure
Fig. 4. The preparation process of tested CTB specimens. Then, the separated fibers, tailings and OPC 42.5R were poured into the cement mortar mixer named JJ-5 and mixed for at least 3 min, which was referenced Cao et al., [30]. Adding the pre-weighed dis- tilled water and stirring for 3 min with the JJ-5 mixer. Finally, pour the prepared CTB slurry into the cuboid mold. Xue et al., [37] has investigated the flexural strength of single fiber-reinforced CTB under a three-point bending test. The chosen width, height and length were 40 mm, 40 mm and 160 mm, respectively. In this study, the width, length and height of these molds were 40 mm, 160 mm and 40 mn, respectively. The CTB specimens were cured in a constant temperature (20 + 1°C) and humidity (90 + 5%) curing container named HSBY-4OB. The demolded time and whole curing

Figure 4 The preparation process of tested CTB specimens. Then, the separated fibers, tailings and OPC 42.5R were poured into the cement mortar mixer named JJ-5 and mixed for at least 3 min, which was referenced Cao et al., [30]. Adding the pre-weighed dis- tilled water and stirring for 3 min with the JJ-5 mixer. Finally, pour the prepared CTB slurry into the cuboid mold. Xue et al., [37] has investigated the flexural strength of single fiber-reinforced CTB under a three-point bending test. The chosen width, height and length were 40 mm, 40 mm and 160 mm, respectively. In this study, the width, length and height of these molds were 40 mm, 160 mm and 40 mn, respectively. The CTB specimens were cured in a constant temperature (20 + 1°C) and humidity (90 + 5%) curing container named HSBY-4OB. The demolded time and whole curing

Related Figures (19)

“School of Civil and Resources Engineering, University of Science and Technology, Beijing 100083, China > State Key Laboratory of High-Efficient Mining and Safety of Metal Mines of Ministry of Education, University of Science and Technology Beijing, Beijing 100083, China “Department of Civil Engineering, Geotechnical Division, Recep Tayyip Erdogan University, Fener, Rize TR53100, Turkey The brittleness of the cemented tailings backfill (CTB) can easily cause collapse, which seriously threatens the safety of underground mining workers and equipment. Studies have shown that fibers can improve the ductility of the CTB. However, there are still few existing studies on the mechanical behavior of com- bined fibers. In this study, glass (G) fiber and polypropylene (PP) fiber were adopted to prepare fiber- reinforced CTB (FRCTB) specimens. The three-point bending and scanning electron microscopy (SEM) tests were adopted to investigate the mechanical properties of CTB and FRCTB. The main conclusions were shown that: the flexural strength (FS) values of FRCTB specimens first decreased and then increased with the glass fiber content decreased. However, the residual FS values of all FRCTB were larger than those none fiber-reinforced CTB. The average flexural modulus of all the FRCTB first decreased and then increased with the content of glass fiber decreased. The average toughness index (ATI) values of all FRCTB specimens were larger than those none fiber-reinforced CTB. Indicating that the addition of fibers can improve the bending performance of the CTB specimens. The failure patterns of the CTB were mainly the tensile failure along the loading direction. The main hydrate products were still AFt and C-S-H gels. The combined fibers had an impeding effect on crack propagation. The results of this study can provide references for elaboration combined fiber-reinforced mechanism of FRCTB and serve the industrial application. Zhiqiang Huang°, Shuai Cao*”*, Erol Yilmaz ‘°*
“School of Civil and Resources Engineering, University of Science and Technology, Beijing 100083, China > State Key Laboratory of High-Efficient Mining and Safety of Metal Mines of Ministry of Education, University of Science and Technology Beijing, Beijing 100083, China “Department of Civil Engineering, Geotechnical Division, Recep Tayyip Erdogan University, Fener, Rize TR53100, Turkey The brittleness of the cemented tailings backfill (CTB) can easily cause collapse, which seriously threatens the safety of underground mining workers and equipment. Studies have shown that fibers can improve the ductility of the CTB. However, there are still few existing studies on the mechanical behavior of com- bined fibers. In this study, glass (G) fiber and polypropylene (PP) fiber were adopted to prepare fiber- reinforced CTB (FRCTB) specimens. The three-point bending and scanning electron microscopy (SEM) tests were adopted to investigate the mechanical properties of CTB and FRCTB. The main conclusions were shown that: the flexural strength (FS) values of FRCTB specimens first decreased and then increased with the glass fiber content decreased. However, the residual FS values of all FRCTB were larger than those none fiber-reinforced CTB. The average flexural modulus of all the FRCTB first decreased and then increased with the content of glass fiber decreased. The average toughness index (ATI) values of all FRCTB specimens were larger than those none fiber-reinforced CTB. Indicating that the addition of fibers can improve the bending performance of the CTB specimens. The failure patterns of the CTB were mainly the tensile failure along the loading direction. The main hydrate products were still AFt and C-S-H gels. The combined fibers had an impeding effect on crack propagation. The results of this study can provide references for elaboration combined fiber-reinforced mechanism of FRCTB and serve the industrial application. Zhiqiang Huang°, Shuai Cao*”*, Erol Yilmaz ‘°*
Main characteristics of the PP fiber and Glass fiber. Table 1
Main characteristics of the PP fiber and Glass fiber. Table 1
Fig. 1. PP fiber and Glass fiber.
Fig. 1. PP fiber and Glass fiber.
The experimental component scheme of CTB specimens in this study. Table 2
The experimental component scheme of CTB specimens in this study. Table 2
Fig. 3. Chemical composition of the gold tailings and OPC 42.5R. Fig. 2. Particle size distributions of tested samples. (a) Gold tailings; (b) OPC 42.5R.
Fig. 3. Chemical composition of the gold tailings and OPC 42.5R. Fig. 2. Particle size distributions of tested samples. (a) Gold tailings; (b) OPC 42.5R.
Fig. 5. Three-point bending testing apparatus in this study.
Fig. 5. Three-point bending testing apparatus in this study.
Fig. 6. The Zeiss EVO18 SEM system.
Fig. 6. The Zeiss EVO18 SEM system.
Fig. 7. Bending performance parameters of the CTB specimens: (a) Flexural strength; (b) Average strength, residual strength, and strength degradation
Fig. 7. Bending performance parameters of the CTB specimens: (a) Flexural strength; (b) Average strength, residual strength, and strength degradation
Fig. 8. The average flexural modulus of tested CTB specimens.
Fig. 8. The average flexural modulus of tested CTB specimens.
Fig. 9. Schematic diagram of toughness evaluation method.
Fig. 9. Schematic diagram of toughness evaluation method.
Fig. 11. Deflection of CTB specimens. Fig. 10. Evaluation of post-peak toughness of CTB specimens.
Fig. 11. Deflection of CTB specimens. Fig. 10. Evaluation of post-peak toughness of CTB specimens.
Fig. 12. Failure modes of CTB specimens under Three-point bending test: (a) G-0.0-PP-0.0; (b) G-0.6-PP-0.0; (c) G-0.4-PP-0.2; (d) G-0.2-PP-0.4; (e) G-0.0-PP-0.6.
Fig. 12. Failure modes of CTB specimens under Three-point bending test: (a) G-0.0-PP-0.0; (b) G-0.6-PP-0.0; (c) G-0.4-PP-0.2; (d) G-0.2-PP-0.4; (e) G-0.0-PP-0.6.
the peak load, indicating that the addition of fibers can improve the bending performance of the CTB specimens. The average toughness index (ATI) values of all CTB specimens were calculated accordingly, which was shown in Fig. 10. It was found that the ATI of G-0.0-PP-0.0 was 0 after the peak load, which indicated that these CTB specimens collapsed instantaneously and were very brittle. However, the ATI values of G-0.6-PP-0.0 and G- 0.0-PP-0.6 specimens were 0.59 and 0.61, respectively. And the dif- ference was only 0.02. Besides, it was also found that both of the above specimens had good bending resistance. In addition, the flexural performance of the CTB specimens named G-0.4-PP-0.2 and G-0.2-PP-0.4 were the best, and the ATI values of the two groups were 0.68. This indicated that the combination of glass fiber and PP fiber was beneficial to the development of the post-peak toughness of CTB specimens.
the peak load, indicating that the addition of fibers can improve the bending performance of the CTB specimens. The average toughness index (ATI) values of all CTB specimens were calculated accordingly, which was shown in Fig. 10. It was found that the ATI of G-0.0-PP-0.0 was 0 after the peak load, which indicated that these CTB specimens collapsed instantaneously and were very brittle. However, the ATI values of G-0.6-PP-0.0 and G- 0.0-PP-0.6 specimens were 0.59 and 0.61, respectively. And the dif- ference was only 0.02. Besides, it was also found that both of the above specimens had good bending resistance. In addition, the flexural performance of the CTB specimens named G-0.4-PP-0.2 and G-0.2-PP-0.4 were the best, and the ATI values of the two groups were 0.68. This indicated that the combination of glass fiber and PP fiber was beneficial to the development of the post-peak toughness of CTB specimens.
Fig. 13. SEM micrographs of CTB samples: (a) and (b) G-0.6-PP-0.0; (c) and (d) G-0.4-PP-0.2; (e) and (f) G-0.2-PP-0.4; (g) and (h) G-0.0-PP-0.6.
Fig. 13. SEM micrographs of CTB samples: (a) and (b) G-0.6-PP-0.0; (c) and (d) G-0.4-PP-0.2; (e) and (f) G-0.2-PP-0.4; (g) and (h) G-0.0-PP-0.6.
Fig. 14. The main element mapping distributions of G-0.0-P-0.0 CTB samples.
Fig. 14. The main element mapping distributions of G-0.0-P-0.0 CTB samples.
Fig. 15. EDS values of G-0.0-P-0.0 CTB samples: (a) Aft area; (b) C-S-H gels area.
Fig. 15. EDS values of G-0.0-P-0.0 CTB samples: (a) Aft area; (b) C-S-H gels area.
580 California St., Suite 400
San Francisco, CA, 94104
© 2025 Academia. All rights reserved