Contribution of refractory brick aggregates to improving the behavior of concrete subjected to high temperature

Mohammed, KHATTAB (2022) Contribution of refractory brick aggregates to improving the behavior of concrete subjected to high temperature. Doctoral thesis, Faculté des Sciences et de la technologie.

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Abstract

Today, the use of recycled aggregates as a substitute for natural aggregates in concrete production is an important process for sustainable concrete. Moreover, one of the most important processes of physical deterioration in the concrete structures is the exposure to high temperatures that influences their durability and stability during service life. This study aims, firstly, to investigate the possibility of using recycled refractory bricks (RBA) as coarse aggregate for concrete, and secondly, to find the ideal replacement percentage of coarse Natural Aggregate (NA) by RBA. Two types of RBA from two different sources were used, RBA-1 was obtained from the grinding of new refractory bricks and RBA-2 was obtained from refractory bricks used in the furnace recovered from the cement plant. When the optimum replacement percentage of coarse NA by RBA was finding, three types of concrete formulations were prepared: concrete made with 20% of coarse RBA-1, concrete made with 20% of coarse RBA-2 and concrete made with 20% of coarse and fine RBA-2. For each of the mentioned concrete families, three water/cement ratios (w/c = 0.59, 0.47 and 0.38) were used. All studied concretes were subjected to heating-cooling cycles of 150°C, 250°C, 400°C, 600°C and 800°C. After cooling down to ambient temperature, the following properties were evaluated and compared with conventional concretes made with 100% of coarse and fine NA: density, porosity, mass loss, change of volume, ultrasonic pulse velocity, damage degree, compressive strength and dynamic elastic modulus. Based on the experimental results obtained, it can be concluded that RBA is a potential alternative for natural aggregates in concrete manufacturing. Furthermore, concretes made with RBA show the best performance when subjected to high temperatures.

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