Cementitious mortars containing pozzolana under elevated temperatures

Abstract

AbstractIn recent years, pozzolana are being increasingly used in different types of concretes and mortars. This investigation aims to evaluate the effect of replacing 7, 14, 21, and 28% cement (by weight) with silica fume (SF), granulated blast furnace slag (GBFS), zeolite, and fly ash (FA) under elevated temperatures. Forty mix designs were built with various water‐to‐cement ratios and plasticizers. Three hundred and six specimens were prepared, and the flexural, uniaxial compression and tensile tests were performed on specimens after exposure to elevated temperatures between 25°C and 900°C. The X‐ray diffraction (XRD) test was then performed on the two series of specimens. Accordingly, the results reveal that the average compressive strength of the control specimen and those containing SF, GBFS, Zeolite, and FA, respectively, is 23.17, 32.2, 34.87, 29.67, and 17.38 MPa. These values for the tensile and flexural strength tests are 0.77, 1.1, 1.02, 0.98, and 0.61 and 0.77, 1.23, 1.29, 0.93, and 0.87 MPa, respectively. Therefore, specimens containing zeolite and GBFS had better performance against heat. As per the increase in temperature, the size of the grains in the specimens containing the SF and GBFS in the XRD test shrunk less (about 6%) in contrast to those of the control specimen. The artificial neural networks (ANNs) were used to estimate the mechanical properties of the specimens at the age of 28 days.