تأثیر میدان مغناطیسی یکنواخت بر مقاومت پیوستگی میلگرد در بتن حاوی سنگدانه‌های کوارتز با بهره‌گیری از آزمایش Pullout

نوع مقاله : علمی - پژوهشی

نویسندگان

1 دانشجوی دکتری سازه، دانشکده مهندسی عمران، دانشگاه سمنان، سمنان، ایران

2 دانشیار، دانشکده مهندسی عمران، دانشگاه سمنان، سمنان، ایران

3 استاد، دانشکده مهندسی عمران، دانشگاه سمنان، سمنان، ایران

چکیده

هدف اصلی از انجام این تحقیق بررسی اثر اعمال مستقیم میدان مغناطیسی یکنواخت با چگالی شار 5/0 تسلا به نمونه‌های تازه و سخت‌شده بتن حاوی سنگدانه‌های کوارتز روی مقاومت پیوستگی بین بتن و میلگرد فولادی با بهره‌گیری از آزمایش بیرون‌کشیدگی میلگرد می‌باشد. همچنین به منظور بررسی اثر مقاومت فشاری بتن بر مقاومت پیوستگی، آزمایش مقاومت فشاری در سن 28 روز بر روی تمامی نمونه‌های مغناطیسی و غیرمغناطیسی انجام گردید. تصویربرداری میکروسکوپی الکترونی نیز به جهت بررسی ریزساختاری نمونه‌های بتن انجام شد. در این تحقیق از نمونه‌های استوانه‌ای بتن و میلگرد در دو قطر مختلف استفاده شد. سنگدانه های کوارتز در دو بیشینه اندازه مورد استفاده قرار گرفتند. نتایج آزمایشگاهی نشان دادند که گسیختگی همه نمونه‌ها از نوع لغزش در میلگرد بدون ترک های شکافت بود. همچنین اعمال میدان مغناطیسی به بتن موجب افزایش مقاومت پیوستگی تا حدود 55 و 73 درصد متناظر با میلگردهای مختلف گردید. از طرفی میدان مغناطیسی در افزایش مقاومت فشاری بتن نیز موثر است. بر این اساس مقاومت فشاری بتن تحت میدان مغناطیسی به بیش از 23 درصد افزایش یافت. نسبت تنش پیوستگی به مقاومت فشاری نمونه‌های بتن حاوی سنگدانه های کوارتز تحت تأثیر میدان مغناطیسی تا حدود 39 و 57 درصد افزایش یافت. تصویربرداری میکروسکوپی الکترونی مشخص کرد که اعمال میدان مغناطیسی به بتن تازه موجب تراکم بیشتر ساختار هیدراتاسیون سیمان می‌گردد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Investigation of the effect of uniform magnetic field on the bond strength of rebar in concrete containing quartz aggregates using pull-out test

نویسندگان [English]

  • Majid Taheri 1
  • Omid Rezayfar 2
  • Ali Kheyroddin 3
1 Ph.D. Student, Faculty of Civil Engineering, Semnan University, Semnan, Iran
2 Associate Proffessor, Faculty of Civil Engineering, Semnan University, Semnan, Iran
3 Professor, Faculty of Civil Engineering, Semnan University, Semnan, Iran
چکیده [English]

The present study was an attempt to investigate the effect of direct and uniform magnetic field on concrete-steel rebar bond strength in fresh and hardened concrete specimens containing quartz aggregates using pull-out test. Moreover, compressive strength test was performed on all magnetic and non-magnetic specimens at 28 days of concrete age in order to investigate the effect of compressive strength of concrete on bond strength. In the present study, a concrete mixture containing smart quartz aggregate was designed for a compressive strength of 30 MPa, . The water to cement ratio was selected to be 0.4 for concrete mixes. The method of fabrication and processing of samples was performed according to ASTM C192 . Accordingly, first one-third of the fine-grained and one-third of the mixing water were added to the mixer with one-third. The remaining cement and water were gradually added to the concrete mix. At the end, superplasticizer was gradually added to the concrete mix for 1 to 2 minutes and then the concrete mixing process was continued for 3 minutes. In order to prevent the magnetic field from being absorbed by the concrete mold, concrete samples were sampled in plastic molds. Concrete samples were covered with a wet sack at a temperature of 20–22 ° C for 24 hours and then removed from the formwork and stored under moist conditions until the experimental age. The device used in this study is able to convert electricity into a uniform magnetic field with an intensity of 0.5 Tesla. According to the results, the failures in all specimens are of slip type with no fissure cracks. The results also showed that applying a magnetic field to the concrete can lead to enhancement of bond strength by about 55% and 73%, in 14 and 20 mm rebar respectively.

کلیدواژه‌ها [English]

  • Uniform magnetic field
  • Alternating current
  • Bond strength
  • Quartz sandstone coarse aggregate
  • Pull-out test
[1] American Concrete Institute, ACI 408. Bond and Development of Straight Reinforcing Bars in Tension. (ACI 408R-03) Farmington Hills, MI, USA, (2003).
[2] Arezoumandi, M., Steele, A.R., Volz, J.S. “Evaluation of the bond strengths between concrete and reinforcement as a function of recycled concrete aggregate replacement level,” Structures (2018); 16: 73-81.
[3] Alhawat, M., Ashour, A. “Bond strength between corroded steel reinforcement and recycled aggregate concrete,” Structures (2019); 19: 369-385.
[4] Saleh, N., Ashour, A., Sheehan, T. “Bond between glass fibre reinforced polymer bars and high-strength concrete,” Structures (2019); 22: 139-153.
[5] ACI (American Concrete Institute), Building code requirements for structural concrete and commentary. ACI 318-14, Farmington Hills, MI, USA, (2014).
[6] Gholhaki, M., Kheyroddin, A., Hajforoush, M., Kazemi, M. “An investigation on the fresh and hardened properties of self-compacting concrete incorporating magnetic water with various pozzolanic materials,” Constr. Build. Mater. (2018); 158: 173-180.
[7] Ghorbani, S., Sharifi, S., Rokhsarpour, H., Shoja, S., Gholizadeh, M., Rahmatabad, M. A. D., & de Brito, J. “Effect of magnetized mixing water on the fresh and hardened state properties of steel fibre reinforced self-compacting concrete,” Constr. Build. Mater. (2020); 248: 118660.
[8] Hajforoush, M., Madandoust, R., Kazemi, M. “Effects of simultaneous utilization of natural zeolite and magnetic water on engineering properties of self-compacting concrete,” Asian J. Civ. Eng. (2019); 20: 289–300.
[9] Kciuk, M., Turczyn, R., Properties and application of magneto rheological fluids, J. Achiev. Mater. Manuf. Eng. (2006); 18 (1–2): 127–130.
[10] Hajforoush, M., Kheyroddin, A., Rezaifar, O. “Investigation of engineering properties of steel fiber reinforced concrete exposed to homogeneous magnetic field,” Constr. Build. Mater. (2020); 252: 119064.
[11] Ferrández, D., Saiz, P., Morón, C., Dorado, M.G., Morón, A. “Inductive method for the orientation of steel fibers in recycled mortars,” Constr. Build. Mater. (2019); 222: 243-253.
[12] Abavisani, I., Rezaifar, O., Kheyroddin, A. “Alternating magnetic field effect on fine aggregate steel chip-reinforced concrete properties,” J. Mater. Civ. Eng. (2018); 30: 04018087.
[13] Abavisani, I., Rezaifar, O., Kheyroddin, A. “Alternating magnetic field effect on fine aggregate concrete compressive strength,” Constr. Build. Mater. (2017); 134: 83-90.
[14] Soto Bernal, J.J., Gonzalez Mota, R., Rosales Candelas, I., Ortiz Lozano, J.A. “Effects of static magnetic fields on the physical, mechanical, and microstructural properties of cement pastes,” Adv. Mater. Sci. Eng. (2015); 1-9.
[15] Abavisani, I., Rezaifar, O., Kheyroddin, A. “Magneto-electric control of scaled-down reinforced concrete beams,” ACI Struct. J. (2017); 114: 233-244.
[16] Rezaifar, O., Abavisiani, I., Kheyroddin, A. “Magneto-electric active control of scaled down reinforced concrete columns,” ACI Struct. J. (2017); 114: 1351-1362.
[17] Ballato, A. “ Piezoelectricity: History and New Thrusts,” IEEE Ultrasonics Symposium, (1996); 575-583.
[18] Bishop, J. R.,  “Piezoelectric Effects in Quartz-Rich Rocks,” Tectonophysics, (1981); 77: 297-321.
[19] Ikeda, T.,  “Fundamentals of Piezoelectricity,” Oxford University Press., (1996).
[20] Kumar, S., Gupta, R. C., & Shrivastava, S. Strength, abrasion and permeability studies on cement concrete containing quartz sandstone coarse aggregates. Construction and Building Materials, (2016);125: 884-891.
[21] Kumar, S., Gupta, R. C., & Shrivastava, S. Effective utilisation of quartz sandstone mining wastes: A technical note on its thermal resistance. Journal of cleaner production, (2017); 140: 1129-1135.
[22] Kumar, S., Sharma, A. K., Sherawat, D., Dutt, M., & Gupta, R. C. Technical note on sorption and permeability of concrete containing rubber and quartz sandstone aggregates. Construction and Building Materials, (2017); 145: 311-317.
[23] Kumar, S., Gupta, R. C., Shrivastava, S., Csetenyi, L., & Thomas, B. S. Preliminary study on the use of quartz sandstone as a partial replacement of coarse aggregate in concrete based on clay content, morphology and compressive strength of combined gradation. Construction and Building Materials, (2016); 107: 103-108.
[24] Kumar, S., Thomas, B. S., Gupta, V., Basu, P., & Shrivastava, S. Sandstone wastes as aggregate and its usefulness in cement concrete–A comprehensive review. Renewable and Sustainable Energy Reviews, (2018); 81: 1147-1153.
[25] Aufort, J., Aktas, O., Carpenter, M. A., & Salje, E. K. Effect of pores and grain size on the elastic and piezoelectric properties of quartz-based materials. American Mineralogist, (2015); 100(5-6): 1165-1171.
[26] Pachideh, Gh., Gholhaki, M., Moshtagh, A. On the post-heat performance of cement mortar containing silica fume or Granulated Blast-Furnace Slag, Journal of Building Engineering 24, 100757.
[27] Pachideh, Gh., Gholhaki, M. an experimental study on the effects of adding steel and polypropylene fibers to concrete on its resistance after different temperatures, Journal of Testing and Evaluation 47 (2), 1606-1620
[28] ASTM C33 / C33M-18, Standard Specification for Concrete Aggregates, ASTM International, West Conshohocken, PA, (2018).
[29] ASTM C494, Standard Specification for Chemical Admixtures for Concrete, Annual Book of ASTM Standards, American Society for Testing and Materials, West Conshohocken, PA, USA, (2004).
[30] ASTM A615. Standard  Specification  for  Deformed  and  Plain  Carbon-Steel  Bars  for  Concrete Reinforcement. (ASTM A615/615M-16), ASTM International, West Conshohocken PA. (2016).
[31] ASTM C192, Standard Practice for Making and Curing Concrete Test Specimens in the Laboratory, ASTM International, West Conshohocken. PA, USA, (2018).
[32] Grant, I.S., Phillips, W.R. Electromagnetism. John Wiley & Sons, (2013).
[33] RILEM 7-II-128. RC6: Bond Test for Reinforcing Steel. 1. Pull-Out Test. RILEM technical recommendations for the testing and use of construction materials, E & FN Spon, U.K., (1994); 102-105.
[34] Garcia Taengua, E., Martí Vargas, J.R., Serna, P. “Bond of reinforcing bars to steel fiber reinforced concrete,” Constr. Build. Mater. 2016; 105: 275-8