بررسی اثر شرایط محیطی مختلف بر زمان تعادل آب انداختگی و تبخیر در جمع شدگی خمیری روسازی‌های بتنی

نوع مقاله : مقاله پژوهشی

نویسندگان

1 راه و ترابری دانشکده مهندسی عمران دانشگاه علم و صنعت ایران

2 گروه راه و ترابری، دانشکده مهندسی عمران، دانشگاه علم و صنعت ایران، تهران، ایران

3 دانشکده مهندسی عمران،دانشگاه آزاد اسلامی، واحد تهران، شمال، تهران، ایران

چکیده

یکی از عوامل ایجاد ترک‌های زود هنگام در روسازی‌های بتنی، جمع شدگی خمیری می‌باشد. این جمع شدگی پس از تعادل نرخ آب انداختگی و تبخیر و تشکیل فشارهای مویینگی منفی در سطح روسازی اتفاق می‌افتد. شرایط محیطی مختلف باعث تغییر در نرخ تبخیر شده و در نتیجه زمان تعادل و به دنبال آن شدت ترک خوردگی را نیز دست خوش تغییر می‌کند. در این تحقیق، با استفاده از روش استاندارد ASTM C 1579، به بررسی ارتباط بین زمان تعادل آب انداختگی و تبخیر و مساحت ترک خوردگی در بتن در 27 شرایط محیطی مختلف، شامل ترکیبی از سه دمای محیط، سه سرعت جریان باد و سه رطوبت نسبی هوا، با استفاده از سیستم تصویربرداری پیوسته و تحلیل تصاویر دیجیتال پرداخته می‌شود. نتایج تحلیل آماری داده‌ها نشان داد که بین زمان تعادل و مساحت خوردگی، ارتباط معناداری وجود دارد. با کاهش زمان تعادل به مقدار 69 دقیقه، مساحت ترک خوردگی به بیش از 4 برابر افزایش یافت. دیده شده که ترکیب هر سه عامل محیطی تاثیر بیشتری نسبت به بحرانی بودن تنها یک عامل، بر شدت ترک خوردگی دارد. همچنین رطوبت نسبی هوا بیشترین اثر را بر زمان تعادل و  شدت ترک خوردگی داشته، و اثر دمای محیطی و سرعت جریان باد نزدیک به هم می‌باشد. با توجه به نتایج، بیان شد که زمان تعادل می‌تواند به عنوان معیاری مناسب جهت بررسی اثر شرایط محیطی مختلف بر شدت ترک خوردگی خمیری در روسازی‌های بتنی، مورد استفاده قرار گیرد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Investigation of Effects of Different Environmental Conditions on Balance Time of Bleeding and Evaporation in Plastic Shrinkage of Concrete Pavements

نویسندگان [English]

  • hassan ziari 1
  • Seyed Javad Vaziri Kang Oleyaei 2
  • Hassan Fazaeli 3
1 school of civil engineering.IUST
2 Transportation, school of civil engineering, Iran University Of science and Technology, Tehran,Iran
3 School of civil engineering, Islamic Azad University,Tehran North Branch, Tehran, Iran
چکیده [English]

One of the causes of early-age cracking in concrete pavements is plastic shrinkage. This shrinkage occurs after the balance of bleeding and evaporation and the formation of negative capillary pressures at the pavement surface. Different environmental conditions cause the rate of evaporation to change, resulting in a change in time of balance and subsequent cracking. This study, using the standard ASTM C 1579 method, examined the relationship between time of balance of bleeding and evaporation and cracking area in concrete in 27 different environmental conditions, including a combination of three ambient temperatures, three wind speeds, and three relative humidities with using a continuous video recording system and digital image analysis. The results showed that there is a significant relationship between time of balance and cracking area. By reducing the time of balance to 69 minutes, the cracking area increased more than four times. It has been shown that the combination of all three environmental factors has a more significant effect on the severity of cracking than the criticality of only one factor. Relative humidity also has the most excellent effect on the time of balance and cracking area, and the effect of ambient temperature and wind speed is close to each other. According to the results, it was stated that the time of balance might be used as a good factor to investigate the effect of different environmental conditions on the severity of plastic shrinkage cracking in concrete pavements.

کلیدواژه‌ها [English]

  • Plastic shrinkage
  • concrete pavement
  • Time of balance
  • Severity of cracking
  • Different environmental conditions
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