Investigation and extraction of compressive strengths of concrete containing zeolite and bentonite, according to the dimensions and type of samples (cubic and cylindrical) at different temperatures

Cement production is one of the major pollution contributors owing to its large rates of energy consumption and gas emission. Moreover, high temperatures could detrimentally impact the concrete infrastructure and thus, it would be essential to study performance of such structures under exposure to the elevated temperatures. In this paper, post-heat performance of the concrete whose cement has been replaced by zeolite and bentonite at ratios of 6 and 10% (by cement weight) under exposure to temperatures of 28, 150, 300 and 700°C, was studied. For this purpose, cubic specimens with sizes of 100×100×100, 150×150×150 and 200×200×200mm and cylindrical specimens with sizes of 200×100 and 300×150mm, were produced. Based on the results, replacing cement by zeolite and bentonite at the age of 90 days under ambient temperature, increases the compressive strength compared to the control specimen. Moreover, it was observed that heating the cubic and cylindrical specimens containing 10% bentonite at 150°C, increase the compressive strength by 40%.Conversely, the results indicate that when exposed to temperatures of 300 and 700°C, a decreasing trend is seen in the tensile strength of both cubic and cylindrical specimens containing the pozzolans. Besides, to study micro-structure of the specimens, the X-ray diffraction tests were carried out on the specimens at the age of 28 days. The difference between conversion ratio of the cubic and cylindrical specimens in this study, to the values provided by the codes, is less than 10%.