مصالح و سازه های بتنی

مصالح و سازه های بتنی

مطالعه آزمایشگاهی تاثیر میزان سنگدانه و الیاف برخصوصیات مکانیکی بتن‌ قلیافعال سرباره‌ای تک ‌جزئی

نوع مقاله : مقاله پژوهشی

نویسندگان
1 گروه سازه، دانشکده مهندسی عمران، دانشگاه صنعتی خواجه نصیرالدین طوسی، تهران، ایران
2 گروه سازه، دانشکده مهندسی عمران، دانشگاه صنعتی خواجه نصیرالدین طوسی، تهران، ایران.
چکیده
بیشتر شدن ترک‌های ناشی از انقباض، یکی از مشکلات بتن‌های قلیافعال سرباره‌ای نسبت به بتن سیمان پرتلندی می‌باشد که می‌تواند تأثیر مخربی بر خصوصیات مکانیکی و دوام بتن داشته باشد. با افزودن الیاف می‌توان میزان این ترک‌ها را کاهش داده و مانع از رشد آن‌ها شد. هدف از انجام این پژوهش بررسی اثر نسبت سنگدانه و الیاف بر خواص مکانیکی (مقاومت فشاری، مقاومت کششی دونیم شدگی و مقاومت خمشی) بتن قلیافعال سرباره‌ای تک جزئی می‌باشد. به منظور بررسی نسبت سنگدانه بهینه، سه طرح مخلوط با نسبت‌های 0/72، 0/75 و 0/78 ساخته و مورد بررسی قرار گرفت. در ادامه پژوهش به منظور بررسی اثر الیاف پلی‌پروپیلن (PP) و شیشه بر خواص مکانیکی بتن قلیافعال سرباره‌ای تک جزئی از الیاف پلی‌پروپیلن در سه درصد حجمی 0/15، 0/30 و 0/45 و الیاف شیشه مقاوم در محیط‌های قلیایی در دو درصد حجمی 0/15 و 0/30 استفاده شد. نتایج نشان می‌دهد که نسبت سنگدانه 0/75 بهترین عملکرد را در بین سایر نسبت‌ها داشته است. از این نسبت سنگدانه جهت ساخت نمونه‌های حاوی الیاف استفاده گردید. بررسی نتایج آزمایش‌های مذکور نشان ‌می‌دهد که بالا بودن مقدار pH در بتن قلیافعال سرباره‌ای می‌تواند کاهش مقاومت کششی الیاف شیشه را به دنبال داشته باشد. همچنین، با افزایش تخلخل بتن به دنبال افزودن الیاف شیشه، کاهش در مقادیر مقاومتی بتن قلیافعال سرباره‌ای مشاهده شده است. اثر پل زدن الیاف PP در بتن‌ سبب جلوگیری از توسعه و افزایش پهنای ترک شده که منجربه بهبود عملکرد بتن در مقاومت کششی و خمشی می شود. لازم به ذکر است که جهت بررسی برخی نتایج از نمونه‌های حاوی الیاف پلی‌پروپیلن تصاویر میکروسکوپ الکترونی روبشی (SEM) تهیه شد.
کلیدواژه‌ها

موضوعات


عنوان مقاله English

Experimental Study on the Effects of Aggregate Content and Fibers on Mechanical Properties of One-Part Alkali-Activated Slag Concrete

نویسندگان English

Keyhan Rahmani 1
Kourosh Nasrollahzadeh 2
Majid Rostami 2
1 Faculty of Civil Engineering, K. N. Toosi University of Technology, Tehran, Iran
2 Faculty of Civil Engineering, K. N. Toosi University of Technology, Tehran, Iran
چکیده English

Increased cracks caused by shrinkage are one of the problems associated with alkali-activated slag concrete as compared to ordinary Portland cement concrete, which can have destructive effects on the mechanical properties and durability of concrete. By adding fibers, the number of these cracks can be reduced, and their growth can be prevented. The purpose of this research is to investigate the effect of aggregate content and fibers on the mechanical properties (compressive strength, tensile strength, and flexural strength) of one-part alkali-activated slag concrete. To obtain the optimal aggregate ratio, three mixing designs with different aggregate ratios of 0.72, 0.75, and 0.78 were made and assessed. To investigate the effects of polypropylene (PP) and glass fibers on the mechanical properties of one-part alkali-activated slag concrete, PP fibers were used in three volume percentages of 0.15, 0.3, and 0.45 and glass fibers were used in two volume percentages of 0.15 and 0.30. The results showed that the aggregate ratio of 0.75 had the best performance among the other ratios. To make further samples containing fibers, the ratio of aggregate to the whole mixture was considered constant and equal to 0.75. Examining the results of the aforementioned tests showed that the high pH value in alkali-activated slag concrete can lead to a reduction in the tensile strength of glass fibers. Also, by increasing the concrete porosity due to the addition of glass fibers, the values ​​of compressive strength, tensile strength, and flexural strength decrease. The bridging effect of PP fibers in concrete prevents the development and increase of crack width, which leads to the improvement of concrete performance in tensile and flexural strength. It should be noted that scanning electron microscope (SEM) images were prepared from samples containing PP fibers in order to investigate some results.

کلیدواژه‌ها English

One-Part Alkali-Activated Slag Concrete
Polypropylene Fiber
Glass Fiber
Mechanical Properties
Flexural Strength
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  • تاریخ دریافت 12 آذر 1402
  • تاریخ بازنگری 06 بهمن 1402
  • تاریخ پذیرش 25 بهمن 1402