مطالعه پتانسیل واکنش‌زایی قلیایی سیلیسی سنگدانه‌های تعدادی از معادن شن و ماسه مورد استفاده در بتن در غرب ایران

نویسندگان

1 مرکز تحقیقات راه مسکن و شهرسازی

2 عضو هیئت علمی مرکز تحقیقات راه مسکن و شهرسازی

چکیده

سنگدانه‌ها به عنوان یکی از اجزاء اصلی بتن، تاثیر بسزایی بر مقاومت و دوام بتن خواهند داشت. یکی از مشکلات مهم سنگدانه‌های برخی نقاط کشور، احتمال واکنش‌زایی قلیایی سیلیسی بین سیلیس سنگدانه‌ها و قلیایی‌های موجود سیمان در آب حفره ای بتن در طول زمان است. به دلیل استفاده این سنگدانه‌ها در ساخت و سازهای مختلف به ویژه سازه‌های هیدرولیکی، ارزیابی دقیق این مصالح از نظر واکنش‌زایی با قلیایی‌های سیمان از اهمیت قابل توجهی برخوردار است.

در پژوهش حاضر ، به مطالعه و ارزیابی پتانسیل سنگدانه‌های تعدادی از معادن استان زنجان، کرمانشاه و کردستان پرداخته شده است. در این مطالعه جهت ارزیابی پتانسیل واکنش‌زایی مصالح از آزمون‌های پتروگرافی بر روی سنگدانه مطابق استاندارد ASTM C295، آزمون تسریع شده منشور ملات طبق استاندارد ASTM C1260 و آزمون تعیین تغییر طول منشور بتنی طبق استاندارد ASTM C1293 استفاده شد. بر اساس نتایج ، مشاهده گردید که پتانسیل واکنش‌زایی در برخی از معادن سطح هر سه استان‌ وجود دارد و می‌بایست جهت استفاده از این سنگدانه‌ها در سازه‌های بتنی در تماس با رطوبت از اقدامات پیشگیرانه همچون استفاده از سیمان‌های کم قلیا یا پوزولان با مقدار مشخص و بهینه استفاده نمود.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

A study of Alkali Silica Reactivity of Some of Aggregates Used in Concrete in the West of Iran

نویسندگان [English]

  • ali Dousti 1
  • Sohrab Veiseh 2
1 استادیار بخش مصالح
2 Faculty member of Road, Housing & Urban Development Research Center, Tehran, Iran
چکیده [English]

The aggregates as a prominent part of concrete mixture have significant impact on durability and strength of concrete. One of the most important problems attributed to some part of aggregates in Iran are reported to possibly deleterious alkali silica reaction between the hydroxyl ions (OH−) in the pore solution and reactive silica in the aggregate over the time. So, investigation of alkali-silica reaction potential for aggregate in this area is so invaluable because of high consumption of these suspicious materials in the construction of varied hydraulic structures.

In present study, alkali silica reactivity of aggregate in a number of mines in West of Iran including Zanjan, Kermanshah and Kordestan province has been investigated comprehensively. In this regard, in order to evaluate alkali silica reactivity of aggregates, petrography examination of aggregate according to ASTM C295, alkali silica reactivity mortar bar testing according to ASTM C1260 and determination of length change of concrete due to alkali silica reaction according to ASTM C1293 was used. Based on results obtained in present study, it was concluded that alkali silica reactivity was observed at a number of aggregates placed in every three studied province and in order to using of these aggregate at concrete structures exposed to water, preventive action including using low alkali cement or pozzolan could be useful.

کلیدواژه‌ها [English]

  • Concrete Durability
  • Aggregate
  • Concrete Structures
  • Hydraulic structure
  • Alkali silica reaction
Diamond S et al. On the physics and chemistry of alkali–silica reactions. In: Proc. 5th Conf. Alkali-Aggregate Reaction in Concrete 1981;S252/22:1–11.
[2]        Buck, A. D.  Houston, B. J. Pepper, L.  Effectiveness of mineral admixtures in preventing excessive expansion of concrete due to alkali-aggregate reaction, Journal of the American Concrete Institute, 1953, 30 (10); pp. 11-60.
[3]      Ramlochana, T. Thomasa, M.  Gruberb, K. A. The effect of metakaolin on alkali-silica reaction in concrete, Cement and Concrete Research, 2000, 30; pp. 339- 344.
[4]       Lindgård, J.   Andiç-Çakır. O,  Fernandes, I.  Rønning, T. F.  Thomas, M. D. A. Alkali–silica reactions (ASR): Literature review on parameters influencing laboratory performance testing, Cement and Concrete Research, 42 (2012) 223–243.
[5]        St John D.A., Poole A.B., I. Sims, Concrete Petrography—A Handbook of Investigative Techniques, Arnold, U.K, 1998, p. 474.
[6]       Dove, P.M. Rimstidt, J.D. Silica–water interactions, in: P.J. Heaney, C.T. Prewitt, G.V. Gibbs (Eds.), Silica: physical behaviour, geochemistry and materials applications Reviews in Mineralogy, Mineralogical Society of America, 1994, pp. 259–308.
[7]       RILEM TC 191-ARP: ‘Alkali-reactivity and prevention—assessment, specification and diagnosis of alkali-reactivity’, RILEM recommended test method AAR-1: detection of potential alkali-reactivity of aggregates—petrographic method, Mater. Struct. 36 (2003) 480–496.
[8]         Broekmans M.A.T.M., The alkali–silica reaction: mineralogical and geochemical aspects of some Dutch concretes and Norwegianmylonites, PhD. Thesis, in, University of Utrecht, 2002, pp. 144.
[9]      Böhm, M. Baetzner, S. The effect of the alkalinity of the pore solution on ASR, in: M.A.T.M. Broekmans, B.J. Wigum (Eds.), 13th International Conference on Alkali– Aggregate Reactions in Concrete, Trondheim, Norway, 2008, pp. 501–510.
[10]     Rivard, P. Bérubé, M.-A. Ollivier, J.-P. Ballivy, G. Alkali mass balance during the accelerated concrete prism test   for alkali–aggregate reactivity, Cem. Concr. Res. 33 (2003) 1147–1153.
[11]      Leemann, A. Lothenbach, B. The influence of potassium–sodium ratio in cement on concrete expansion due to alkali–aggregate reaction, Cem. Concr. Res. 38 (2008) 1162–1168.
[12]        Leemann, A. Lothenbach, B. The Na2O-equivalent of cement: a universal parameter to assess the potential alkali–aggregate reactivity of concrete? in: M.A.T.M. Broekmans, B.J.Wigum (Eds.), 13th International Conference on Alkali–Aggregate Reactions in Concrete, Trondheim, Norway, 2008, pp. 909–919.
[13]       Kollek, J.J. Varma, S.P.  Zaris, C. Measurement of OH− concentrations of pore fluids and expansion due to alkali–silica reaction in composite cement mortars, 8th International Congress on the Chemistry of Cement, Rio de Janeiro, 1986, pp. 183–189.
[14]        Thomas, M.D.A. Review of the effect of fly ash and slag on alkali–aggregate reaction in concrete, BRE Report, Building Research Establishment Report, BR 314, Construction Research Communications, UK, 1996, p. 117.
[15]         Kagimoto, H. Inoshita, I. Kawamura, M. Threshold OH− concentration in pore solution of mortar using alkali reactive aggregates, in: M. Tang, M. Deng (Eds.), 12th International Conference on Alkali–Aggregate Reaction in Concrete, Beijing, China, 2004, pp. 728–735.
[16]        Shehata, M.H. Thomas, M.D.A.  Alkali release characteristics of blended cements, Cem. Concr. Res. 36 (2006) 1166–1175.
[17]      Larive, C. Laplaud, A. Coussy, O. The role of water in alkali–silica reaction, in: M.-A. Bérubé, B. Fournier, B. Durand (Eds.), 11th International Conference on Alkali– Aggregate Reaction, Québec, Canada, 2000, pp. 61–69.
[18]      ASTM C295–12: "Practice for Petrographic Examination of Aggregates for Concrete", American Society for Testing and Materials.
[19]   ASTM C227: Test Method for Potential Alkali Reaction of Cement-Aggregate Combinations (Mortar-Bar Method), American Society for Testing and Materials
[20]     ASTM C 1260 Standard Test Method for Potential Alkali Reactivity of Aggregates (Mortar-Bar Method)
[21]      ASTM C1293-95: Test Method for Concrete Aggregates by Determination of Length Change of Concrete Due to Alkali-Silica Reaction, American Society for Testing and Materials
[22]     Thomas, M.D.A. Fournier, B. Folliard, K. Ideker, J. Shehata, M. Test methods for evaluating preventive measures for controlling expansion due to alkali-silica reaction in concrete, Cem. Concr. Res. 36 (10) (2006) 1842–1856.
[23]     Thomas M.D.A., The effect of supplementary cementing materials on alkali–silica reaction: a review, Cem. Concr. Res. 41 (2011) 1224–1231.
[24]        ASTM C702 – 87: "Practice for Reducing Field Samples of Aggregate to Testing Size", American Society for Testing and Materials.