بررسی آزمایشگاهی تاثیر دوده سیلیس، مواد هوازا و نسبت آب به مواد سیمانی بر ریز ساختار و دوام پوسته‌شدگی روسازی‌های بتنی

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشگاه صنعتی امیرکبیر

2 عضو هیئت علمی دانشکده عمران دانشگاه صنعتی امیرکبیر(پلی تکنیک تهران)

3 مرکز تحقیقات راه، مسکن و شهرسازی

4 مرکز تحقیقات راه مسکن و شهرسازی

10.22124/jcr.2021.19864.1502

چکیده

پوسته‌شدگی در مجاورت نمک‌های یخ‌زدا یکی از چالش‌های اساسی دوام در روسازی‌های بتنی در مناطق سردسیر شناخته می‌شود. در این تحقیق اثر دوده سیلیس و مواد هوازا در روسازی‌های بتنی با سه نسبت آب به سیمان 35/0، 4/0 و 45/0 بر مقاومت فشاری، مقاومت الکتریکی و دوام بتن در برابر پوسته‌شدگی در مجاورت نمک یخ زدا بررسی شده و ساختار میکروسکوپی با استفاده از روش تخلخل سنجی جیوه و تصاویر میکروسکوپ الکترونی مورد بررسی قرار گرفته است. نتایج حاکی از آن است که بهترین عملکرد در آزمایش پوسته شدگی متلعق به نمونه حاوی دوده سیلیس و مواد هوازا می باشد. نتایج تخلخل‌سنجی جیوه نشان داد که دوده سیلیس ضمن اصلاح ریزساختار باعث کاهش حجم حفرات کل و شعاع حفره بحرانی نسبت به طرح شاهد گردیده است و از سوی دیگر به علت فعالیت پوزولانی مناسب حجم حفرات کوچکتر از 10 نانو متر را افزایش داده است. تصاویر میکروسکوپ الکترونی طرح ها حاکی از آن است که دوده سیلیس به علت فعالیت پوزولانی موثر باعث متراکم تر شدن ژل گردید. تصاویر طرح های هوادار حاکی از تشکیل حباب های کروی ، پایدار و دارای توزیع یکنواخت می باشد که مشاهدات ریز ساختاری، یافته های ماکروسکوپی از جمله دوام پوسته شدگی، مقاومت فشاری و مقاومت الکتریکی را تایید می‌نماید.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Experimental study of the effects of water-binder ratio, silica fume and air-entrainment on the microstructure and salt scaling resistance of concrete pavements

نویسندگان [English]

  • Mojtaba Nili 1
  • Ali Akbar Ramezanianpour 2
  • Jafar Sobahni 3
  • A. M. Raeiss ghasemi 4
1 Amirkabir University of Technology
2 Amirkabir University of Technology
3 Departement of concrete Technology, Road, Housing and Urban Development Research Center
4 Road, Housing and Urban Development Research Center
چکیده [English]

Salt scaling of concrete pavements is known as a serious problem in cold regions. In the present study the effect of water-binder (W/B) ratio, silica fume and air entraining on the salt scaling resistance, compressive strength and electrical resistance were investigated. Microstructure of the concretes was assessed by mercury intrusion porosimetry and scanning electron microscope. Water-binder ratios were 0.35, 0.40 and 0.45. Silica fume was used, by 8% weight of cement, in the predetermined mixtures. The results showed that the best salt scaling resistance was correspondent to the air entrained silica fume specimens. By reducing the water-binder ratio, the amount of surface scaling was decreased. The MIP results declared that silica fume refined the microstructure and also decreased the total porosity and critical pore radius compared with those for the reference specimens. Furthermore, the MIP results of the silica fume specimens declared that the pores smaller than 10 nano were increased, due to the effective pozzolanic reaction. The scanning electron microscope images showed that the concrete containing silica fume had a denser gel compared with those for the reference ones. Introducing silica fume into the specimens had remarkable effect on the later age electrical resistance of the concrete. It was concluded that the highest electrical resistance belonged to the durable specimens. The results of the present study clarify how the micro structure may influence the salt scaling resistance of concrete pavement, this achievement will surely reduce the cost of rehabilitation of concrete pavements in the cold regions.

کلیدواژه‌ها [English]

  • Salt scaling: Microstructure
  • : Silica fume
  • : air-entrainment
  • : Concrete pavement

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