مقایسه اثر پودرسنگ و افزودنی اصلاح‌کننده لزجت در رئولوژی بتن خودتراکم تحت شرایط محیطی مختلف

نوع مقاله : یادداشت پژوهشی

نویسندگان

1 مهندسی نگهداری و تعمیرات، دانشکده علوم و مهندسی دفاعی، دانشگاه امام حسین(ع)، تهران، ایران.

2 دانشجوی دکتری مهندسی و مدیریت ساخت دانشگاه آزاد اسلامی واحد تهران‌جنوب، تهران، ایران.

چکیده

تأثیر آب‌وهوای گرم در عملکرد بتن تازه خودتراکم سبب بروز مشکلاتی مثل پائین آمدن کارایی می‌شود این موضوع به علت ترکیبی از نیازهای متنوع بتن تازه خودتراکم، طرح مخلوط فوق‌العاده پیچیده‌تر و تنش جاری کم آن هست. بنابراین برای طراحی بتن خودتراکم علاوه بر اجزای تشکیل‌دهنده، شرایط محیطی نیز در نظرگرفته می‌شود. در این تحقیق، بتن‌های خودتراکم با مقادیر متفاوت پودرسنگ و افزودنی اصلاح‌کننده لزجت ساخته شده است و همچنین دمای مخلوط‌های بتن با توجه به شرایط محیطی فصل‌های مختلف انتخاب شده است. پس از رساندن دمای بتن به دمای محیط، خواص رئولوژی بتن تازه خودتراکم حاوی اثر پودرسنگ یا افزودنی اصلاح‌کننده لزجت به‌عنوان یک تابع از زمان اختلاط، دما با نسبت آب به سیمان 42/0، مورد بررسی قرار گرفته است. بر اساس نتایج به‌دست‌آمده، افزودنی اصلاح‌کننده لزجت نسبت به پودرسنگ، اثر بهتری در لزجت پلاستیک دارند و سبب کاهش 50 درصد افت اسلامپ می‌شوند بنابراین برای شرایط آب‌وهوای گرم، که هدفمان حفظ کارایی هست بتن‌های نوع اصلاح‌کننده لزجت می‌تواند بهترین انتخاب باشد.

کلیدواژه‌ها

عنوان مقاله [English]

Comparing Between the Effects of Limestone and Viscosity-Modifying Admixture on the Rheology of Self-Compacting Concrete Under Different Ambient Conditions

نویسندگان [English]

  • Farshid Farokhizadeh 1
  • ali Zal Nezhad 2
1 Maintenance Engineering, Faculty of Defense Sciences and Engineering, Imam Hossein University, Tehran, Iran.
2 PhD student in Construction and Management Engineering, Islamic Azad University, South Tehran Branch, Tehran, Iran.
چکیده [English]

The effect of hot climate on the performance of fresh self-compacting concrete causes a number of problems including the reduced workability. This issue is due to the various demands of the fresh self-compacting concrete, much more complicated mix design and low yield stress of this type of concrete. Therefore, in design of the self-compacting concrete, in addition to the constituent elements the ambient conditions also are taken into consideration. In this research, the self-compacting concrete specimens with different amounts of limestone and viscosity-modifying admixture were made. Also the temperature of the concrete mixtures was selected with respect to the ambient conditions of different seasons. After the concrete specimen temperature reached the ambient temperature, the rheological properties of the fresh self-compacting concrete specimens containing limestone or viscosity-modifying admixture being a function of mixing time, and temperature with water to cement ratio of 0.42 were investigated. According to the obtained results the viscosity-modifying admixture has a better effect on the plastic viscosity with respect to limestone and reduces the slump loss by 50%. Thus in the hot climate where our goal is to maintain workability, the concretes with viscosity-modifying agents are the best options.

کلیدواژه‌ها [English]

  • Self-Consolidating Concrete
  • Limestone
  • Viscosity-Modifying Admixture
  • Rheology
  • Temperature

مراجع

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تحقیقات بتن
دوره 14، شماره 1 - شماره پیاپی 33
فروردین 1400
صفحه 157-149

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